Biogas Journal Spring 2025

German Biogas Association | ZKZ 50073 | www.biogas.org
ENGLISH ISSUE | SPRING_2025
The trade magazine
Including reports from
Portugal
Belgium
Uganda
Ghana
Cambodia
Working Safely
in Shafts 12
New Bacterial
Order Discovered 24
Ghana: Biogas Sector
is Slowly Growing 52

2 BIOGAS Journal Spring_2025
BIOGAS TO BIOMETHANE!
YOUR STEP TOWARDS THE FUTURE.
BIOMETHANE – THE ALL-ROUNDER
Upgrading biogas to biomethane opens up new and economically
attractive marketing opportunities for both new and existing
biogas plants by transforming sustainably produced energy into
a valuable, green fuel. With our standardized agriPure ® system,
we offer a comprehensive turnkey solution – from biogas upgrading
and compression to BioCNG, through to the refinement into
BioLNG and the liquefaction of the separated CO 2
stream.
Our two modular upgrading systems – agriPure ® Cube and
agriPure ® Smart – provide tailored plant concepts for every
requirement, covering raw biogas capacities from 130 m³/h to
2,000 m³/h. Whether you’re planning a new facility or upgrading
an existing one, agriKomp is your reliable partner for innovative
technologies in biogas and biomethane, delivering efficient,
future-proof energy solutions.
Proven components and a high level of standardization ensure reliable
operation and high availability
Fully automated system with integrated gas analysis
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Clever plant design: synergies are utilised through intelligent linking of
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Redesigned modular structure for easy extension of the system
BIOGAS PLANTS & COMPONENTS. efficient. flexible. sovereign.
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EDITORIAL
3
Biogas: Valuable
Reserve Energy
Dear Readers,
A new federal government has been in
office in Germany since early May. The
CDU/CSU and SPD parties have formed
the governing coalition. Their coalition
agreement includes a clear commitment
to bioenergy, specifically the production
of biogas. This marks a positive shift, as
some elements of the previous “traffic
light” coalition were less supportive of
biogas.
Support from the new federal government
is especially important now, as the
so-called “biomass package”, which was
adopted late in the previous legislative
period by the CDU/CSU, SPD, and Greens,
clearly needs to be revised. While it does
finally set higher auction volumes for
2025 and 2026, the legislation has not
yet been approved by the EU, leaving
us in a state of limbo. This means that,
for the first auction round for bioenergy
plants on 1 April this year, the provisions
of the biomass package – including the
increased auction volumes – had not
come into effect yet.
Background: Biogas plants, whose initial
20-year EEG support period is ending,
have to compete in a tendering process
for continued financial support. The
results of the spring auction were not
available by the editorial deadline, so
that it is not clear how much interest
there was in the auction or how many
operators are waiting for the more
favourable conditions of the biomass
package.
On the other hand, the industry needs a
strong political commitment to biogas
in order to be able to play a role in the
power plant strategy. With the phaseout
of nuclear and coal power and
increasing electricity demand driven
by greater electrification, Germany will
run into a power shortfall from 2030
onwards, which is likely to be around
30 gigawatts. This requires so-called
reserve power plants, particularly due to
the expansion of fluctuating renewable
energies such as wind and solar. A
strategic plan for the future power
system is therefore essential.
The new Federal Minister for Economic
Affairs, Katherina Reiche, plans to
bridge the electricity gap with new gasfired
power stations, with an installed
capacity of around 20 gigawatts
(GW). They will likely be combined
with CO₂ capture in the future, as the
coalition agreement aims to advance
CCS technology. However, this path is
misguided from an energy, climate and
economic perspective.
Gas-fired power stations are
significantly more expensive than the
decentralised expansion of biogas
plants, as they generally do not utilise
waste heat externally, and as a result,
they do not contribute to the essential
heat transition. Decentralised biogas
plants, on the other hand, operating
as highly flexible combined heat and
power (CHP) units – capable of building
up to ten times their installed electrical
capacity, equipped with large gas and
heat storage facilities, and enabling local
municipal heat transitions – represent
the solution of the future.
Biogas plants can provide the required
residual load at half the cost of gas power
stations and can be scaled up much more
quickly to meet the demand by 2030.
In contrast, gas-fired power stations
require lengthy approval processes,
construction, and commissioning. Even
now, it is clear that the 20 GW capacity
projected from these plants will not be
fully operational by 2030.
The article on page 6 of this BIOGAS
Journal provides an example of how
a biogas plant site can be developed
into a so-called regenerative storage
power plant as a highly flexible CHP
site. Germany’s current fleet of biogas
plants has an installed capacity of
approximately 6 GW. This could easily be
doubled by 2030. With some effort and
supportive legal framework, this could
increase to 20 GW by 2035.
In future, biogas plants in Germany will
primarily operate during the colder
months of the year. From spring to
autumn, electricity from solar energy will
be so cheap on the market that it will no
longer be economical for biogas plants
to generate electricity during this period.
Around-the-clock operation will become
a thing of the past. Plant operators need
to prepare for a maximum of 2,500 full
load hours per year or less.
Biogas plants stand for ensuring supply
reliability, strengthening domestic
value creation, and independence from
energy imports. The latter is especially
important in geopolitically challenging
times. Bioenergy is the energy of peace.
Sincerely yours,
Martin Bensmann
Editor BIOGAS Journal

4
ENGLISH ISSUE
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BIOGAS Journal Spring_2025 5
EDITORIAL
3 Biogas: Valuable Reserve Energy
By Dipl.-Ing. agr. (FH) Martin Bensmann
GERMANY
6 Flexible Biomethane CHP Peak Load
Power Plant Helps Organic Food Grow
By Dipl.-Ing. agr. (FH) Martin Bensmann
18
12 Working Safely in Shafts
By Thomas Gaul
Hydrogen Field Test in Hohenwart
18 Future Gas Grid or Pilot Project for
a Premium Product?
By Christian Dany
Micro4Biogas
24 New Bacterial Order Discovered
By Dipl.-Ing. Pascal Otto and Prof.
Christian Abendroth
40
60
Photos: Jörg Böthling (Cover), Christian Dany, Martin Egbert (Uganda + Cambodia)
COUNTRY REPORTS
Portugal
28 Portugal’s First Biomethane Village
By Dipl.-Pol. Oliver Ristau
Belgium
34 Too Many Cooks, Not Enough Biogas
By Dipl.-Pol. Oliver Ristau
Uganda
40 When Will Biogas go Mainstream?
By Klaus Sieg
Ghana
52 Biogas Sector is Growing, but Slowly
By Dierk Jensen
Cambodia
60 Many Small Plants, Not Many Large Plants
By Klaus Sieg

6
ENGLISH ISSUE
Biogas Storage Power Plant
Flexible Biomethane CHP
Peak Load Power Plant
Helps Organic Food Grow
It is not only biogas plants themselves that are capable of generating electricity
and heat on demand. Combined Heat and Power (CHP) plants, which operate using
biomethane from the natural gas grid, are also highly suited to this task. A flagship
project is drawing attention by demonstrating that energy production and food
cultivation need not be in conflict with one another.
Author: Dipl.-Ing. agr.(Graduate Engineer in Agricultural Sciences) (FH) Martin Bensmann
Photos: Martin Egbert

BIOGAS Journal Spring_2025 7
Rainwater storage tanks and water pumps
inside one of the greenhouses.
Fitters installing catalyst blocks on the CHP unit.
The Querdel family runs a special farm in Sassenberg-
Füchtorf in the district of Warendorf in northern North
Rhine-Westphalia. The farm is run according to the ecological
standards of two associations – Bioland and Naturland – and
features an organic biogas plant, greenhouses, and, as the
latest addition, a biomethane-fuelled peak load CHP plant.
Over the past 20 years, the organic farm has undergone
continuous development. “In December 2005, my brother Bernd
and I commissioned the biogas plant with an installed electrical
output of 250 kilowatts (kW). At the time, we used most of
the generated heat to warm the turkey sheds, particularly for
rearing day-old chicks,” explains Andreas Querdel.
Today, the farm operates a MAN combined heat and power
(CHP) unit with an electrical output of 210 kW, alongside
two Schnell gas-powered CHP units, each rated at 250 kW –
providing a total installed electrical capacity of 710 kW. The
farm has been operating organically since 2005, initially in
accordance with EU regulations. Since 2016, it has been a
member of the Bioland farming association and is now also
certified by Naturland.
have a heat requirement of 25 gigawatt hours [=25 million
kilowatt hours (kWh)]. The biogas plant is fed with around
40 per cent manure from cattle and pig farms in the region.
Up to 20 per cent of the input material can come from
conventional farms.
In addition, silage maize, clover grass, vetch-rye mix and cup
plant are fermented. According to Querdel, the manure is
shredded prior to fermentation with a biomass shredder. The
horizontal digester, with a fermentation volume of 700 cubic
metres (m³), is equipped with a gas-tight dome holding
Greenhouses Increase Heat Utilisation
Animal husbandry was discontinued in 2013. One turkey
barn was converted into a machinery hall, another into staff
accommodation, and the third is now used for sorting and
packing vegetables. “Since 2015, we have been utilising 100 per
cent of the waste heat from the CHP units, particularly due to
the construction of greenhouses. We built the first glasshouse
covering 2.5 hectares in 2015. A year later, the greenhouse was
extended by a further 2.5 hectares, and in 2022, we added
another 4 hectares of greenhouse area,” Querdel reports.
In the greenhouses, he grows tomatoes, cucumbers and
peppers. Outdoors, he produces asparagus, strawberries and
sweet potatoes – all organically grown. The greenhouses
Andreas Querdel next to one of three new INNIO Jenbacher CHP units,
operated as highly flexible peak-load power plants.

8
ENGLISH ISSUE
The woodchip heating system with two boilers made by Kohlbach
has a thermal output of 4 megawatts.
Flue gas condensation and exhaust heat recovery at the
woodchip heating system.
530 m³ of gas and a horizontally mounted paddle agitator
running the full length of the tank.
The secondary digester has a fermentation volume of 1,300
m³. The old digestate storage facility holds 2,000 m³, while
the new one has a capacity of 4,000 m³. Two submersible
motor agitators mix the substrate in the secondary digester.
Three agitators are installed in the digestate storage tank. The
biogas plant operates as a dry fermentation system without
the addition of farm fertiliser.
The dry matter content in the digester is 14 to 15 per cent,
in the secondary digester 12.5 per cent, and in the digestate
storage 11 per cent. When the substrate leaves the digester
and enters the secondary digester, it is further disintegrated
using a Rotacut by Vogelsang to improve the decomposition of
organic matter and the viscosity of the digestate. A progressive
Wangen cavity pump is used to transfer the digestate. The
fermentation temperature is 40 degrees Celsius. The digestate
remains in the gas-tight system for 200 days.
Separated Solids Provide Nutrients for the Greenhouses
Part of the digestate that leaves the secondary digester for
the digestate storage passes through a FAN screw press
separator. This separates a significant proportion of the nondegraded
solids, which have a dry matter content of 25 per
cent. Among other uses, the solids are used to fertilise the soil
in the greenhouses. Fertilisation is based on the results and
requirements determined by soil analysis. Between 40 and
50 tonnes of solid material are applied in the greenhouses
every year.
However, the biogas plant does not cover the heat requirement
in the greenhouses alone. A woodchip heating system with two
boilers provides additional heat. Together, they have a thermal
output of four megawatts. Of this, one megawatt of thermal
output is generated solely through flue gas condensation.
In the course of planning the expansion of the greenhouse area,
the Querdel brothers began to consider additional heat sources.
In June 2021, they brought in energethik Ingenieurgesellschaft
mbH from Osnabrück for the planning process. This led to the
development of the idea to build a biomethane storage power
plant. At the end of 2021, the Querdel brothers participated in
the first EEG auction for highly flexible biomethane plants held
by the Federal Network Agency and were awarded a contract.

BIOGAS Journal Spring_2025 9
9 hectares under glass – tomato plants being tied
in one of the greenhouses.
A fitter carrying out installation work on the new
biomethane storage tank.
Highly Flexible Biomethane Peak-Load CHP Units
Supply Heat to the Greenhouses
The biomethane peak-load power plant consists of three
CHP units, each with an electrical output of 3,352 kilowatts.
They are permitted to operate at full load for 2,000 quarterhours
per year. The heat is stored in a new buffer tank with a
capacity of 4,000 cubic metres. Each CHP unit is housed in its
own separate, concrete building.
The new buffer storage is a steel tank that was welded together
on site from individual segments. It is insulated on the outside
with a 30-centimetre-thick layer of mineral wool and clad with
trapezoidal sheet metal to protect it from weather effects. The
roof is made of steel sheeting and is also insulated. Inside, a
nitrogen bladder seals the roof. “We filled the buffer storage
with rainwater from our retention basin. It previously passed
through a final mineralisation unit,” explains Andreas Querdel.
The heat from the woodchip boilers and the biogas plant is
fed into an existing buffer tank with a capacity of 1,500 cubic
metres. The demand for woodchips is expected to be reduced
by 40 per cent in the future. “For 2024, we procured 19 gigawatt
hours of biomethane as a base quantity. The biomethane is
supplied virtually by two plants – one located in northern,
and the other in southern Germany. The gas suppliers

10
ENGLISH ISSUE
The Querdel farm with the biogas plant, the boiler house with the woodchip heating
system, the former turkey barns, the greenhouses, and the new biomethane peak-load
power plant in the background.
Woodchips being pushed into the feed
hopper of the boiler house using a
telescopic loader.
must meet the legally prescribed sustainability criteria. The
electricity from the highly flexible biomethane storage power
plant is marketed by the company Trianel on our behalf. The
electricity from the biogas plant is marketed by EWE,” Andreas
Querdel reveals.
Marketing Electricity on the Intraday Market
“The storage power plant is operated when the exchange
electricity price on the so-called intraday market is at its
highest. Electricity is marketed via our virtual power plant in
Aachen. In addition to the price of electricity, it is important
for us to know how full the gas storage is and how much heat
is available in the buffer tank. There are defined thresholds
for the buffer tank’s minimum fill level. We operate the plant
in close coordination with the Querdel brothers,” explains
Wolfgang Buchwitz, Senior Sales Manager at Trianel GmbH.
Trianel receives information, for example, on whether the
heat storage units are empty and what the current heat
demand is. Operating parameters are defined and taken into
account in the virtual power plant in Aachen. “If the storage
units are empty, a minimum electricity price is set at which
the CHP units are to be operated. We will at least comply with
the 2,000 quarter hours (=500 hours per year) required by
the EEG surcharge. The storage power plant may produce
electricity for up to 1,300 hours annually,” Buchwitz continues.
It is crucial that sufficient biomethane is available.
Revenues are shared between Trianel and Querdel according
to a fixed ratio. When the CHP units are in standby mode,
they must be able to feed in the first electricity within 60
seconds of being called up. Full-load electricity production
must be achieved within 5 minutes. According to Buchwitz,
the engines are kept warm at all times for this purpose. The
intake air is also preheated.
To ensure that the three peak-load CHP units always have
sufficient biomethane available, an external, hemispherical
gas storage tank was constructed on a concrete slab. The gas
storage has a capacity of 10,000 cubic metres. It is connected
via a 1,700-metre pipeline to a natural gas line from which the
biomethane is withdrawn virtually.
This example clearly demonstrates that large gas-fired power
plants, which may eventually become hydrogen-ready, are
not necessarily required. Agricultural entrepreneurship proves
that even organic farming can significantly contribute to the
energy transition.
Author
Dipl.-Ing. agr. (Graduate Engineer
in Agricultural Sciences) (FH)
Martin Bensmann
Editor Biogas Journal
German Biogas Association
00 49 54 09 90 69 426
martin.bensmann@biogas.org
www.biogas.org

BIOGAS Journal Spring_2025 11
Biomethane peak-load power plant consisting of three combined heat and
power units with a total output of 10,056 kWel, a hemispherical biomethane
storage tank, and a hot water buffer tank.
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12
ENGLISH ISSUE
WHICH WORK SPACES ARE CONSIDERED
“CONFINED SPACES“?
Confined spaces refer to any type of containers, silos, tanks,
or shafts that are surrounded by solid walls and typically
have limited air exchange. Due to the restricted airflow,
these spaces often experience oxygen shortages. Work in
these spaces can also pose risks from mixtures, gases, or
pollutants that accumulate in the confined space, whether
through deposits, chemical processes, or other dangerous
substances reacting with one another. Overall, these spaces
are characterised by inadequate ventilation.
Working Safely
in Shafts
Most biogas plants have valves and pipes in shafts. If work needs
to be carried out on them, special safety rules must be observed.
Serious accidents have occurred here in the past.
Author: Thomas Gaul
Working in confined spaces like shafts, silos, or tanks is one
of the most hazardous tasks on biogas plants, exposing
workers to a wide range of risks. Consequently, plant
operators are required to conduct a risk assessment to
determine whether alternative work methods are possible
– for instance, whether maintenance could be carried out
externally instead.
However, on many plants, this is not easily feasible, as the
technology was installed during construction. Nevertheless,
entering a shaft should never be a leap into the unknown.
This is because a hazardous atmosphere in shafts can lead
to explosions, poisoning or asphyxiation. Yet, when pipelines
become blocked or shut-off valves require maintenance,
working in confined spaces is often unavoidable.
Photos: Josef Ziegler

BIOGAS Journal Spring_2025 13
Pipelines often lead
into confined shafts.
Gas Accumulates at the Lowest Point
Work carried out in confined spaces is subject to strict safety
regulations and requires carefully planned protective measures.
Workers operating in such environments face unique conditions
and hazards that make tasks more challenging and significantly
increase the risk of injury due to the unfavourable atmosphere.
These difficult conditions arise partly from the restricted
space, which limits movement at the worksite. In addition, the
availability of oxygen and the lack of natural light are critical
factors that must be carefully considered. Furthermore,
hazardous substances can accumulate in confined spaces,
worsening working conditions and creating a constant risk of
exposure to a contaminated atmosphere.
Experience has shown that serious accidents frequently
occur in shafts, pits, and tunnels because the hazardous
atmosphere is not detected and the danger is
underestimated. Accident investigations reveal that, in most
cases, the underlying cause is the presence of a dangerous
atmosphere. The density of biogas can vary depending
on its composition, humidity, and temperature, further
complicating the risks involved.
Biogas: Sometimes Lighter, Sometimes Heavier Than Air
Biogas can be either lighter or heavier than air, a factor that
must be considered carefully when implementing safety
measures, such as installing fixed gas detection systems.
Unlike most other occupational hazards, the danger is not
confined to a specific, localised area, but rather, the entire
space within shafts, pits, and tunnels can pose a risk. As a
result, not only are accident victims in danger, but rescuers are
equally at risk. A defining characteristic of accidents involving
entry into and work within shafts, pits, and tunnels is their
severe consequences, which often result in fatalities.
The provisions of the German Regularity TRGS 529 are clear:
condensate separators must be designed for easy and safe
inspection and maintenance without requiring entry into
shafts or pits. Both construction and maintenance must ensure
that gas leakage is prevented under all operating conditions.
Operational and maintenance access points, as well as control
elements for valves, agitators, pumps, and flushing systems,
must generally be located above ground. If this is not possible,
sufficient technical ventilation with at least fivefold air
exchange must be provided. The German DGUV Rule 113-004,
“Working in Containers, Silos, and Confined Spaces”, requires
that anyone assigned to gas monitoring in confined spaces—
such as silos, tanks, shafts, and pits—must be properly trained
and certified.
How can accidents in confined spaces and tanks be prevented?
The better the preparation for confined space entry, the lower
the risk. Before allowing a person to enter a confined space,
operators should carefully consider the following key questions:
Are qualified personnel and appropriate
equipment available?
Do all the involved parties understand
their responsibilities?
Are the necessary operating instructions in place?
Have employees been properly trained for their
specific tasks?
Are they familiar with the use of personal
protective equipment (PPE)?
Is there an alarm and rescue plan specifically for this task?
Have the recommended safety measures been
thoroughly assessed?
Some operators are not even aware that their facilities have
confined or enclosed spaces. A result of this lack of awareness
is that a risk assessment is not conducted, as the hazard is not
recognised in the first place. Information and consultation are
the first step. This should be followed by training for working
in confined spaces (CSE training).
Proper training is essential in order to prevent accidents
and ensure worker safety. Such training includes realistic
work simulations inside tanks and confined spaces. For
example, it begins with a demonstration of correct clearance
measurement and the use of personal protective equipment,
followed by entry and exit exercises.

14
ENGLISH ISSUE
A particular hazard in many
facilities is that shafts are not
immediately identifiable as such.
Clearance Measurement Is Essential
Clearance measurement in confined spaces is a job for
experts. Before entering such potentially hazardous work
environments, standard safety measures for confined spaces—
such as atmospheric testing—must be carried out. The air
quality must be assessed using special gas detectors, with
continuous monitoring for hazardous substances. Ensuring
worker safety requires both extensive knowledge and handson
expertise.
Clearance measuring must be conducted immediately before
entry—delays can be dangerous. If workers take a break after
the initial test and later enter the space without retesting, they
may face unexpected hazards. Environmental factors such as
temperature and ventilation can alter the atmosphere within
a short period.
For instance, if methane detection is required inside a tank
and the sample is taken only from the bottom, a serious
miscalculation could occur. Methane is a light gas that readily
mixes with the surrounding air and tends to rise. Measuring
gas concentration at the bottom of a shaft or pit provides little
indication of the actual explosion risk within the space.
COMMON CAUSES OF ACCIDENTS IN
CONFINED SPACES AND CONTAINERS
●
●
●
●
●
●
Failure to adequately identify and analyse risks.
Lack of awareness of hazards.
Inadequate or inappropriate selection
of gas detection devices.
Use of unsuitable protective equipment.
Insufficient training of personnel responsible for
entry into confined spaces.
Vehicle traffic.
Left: Ladders leading down must be securely fastened.
Right: Leaks in pipes can also occur due to different materials.
Measuring in the Wrong Place Can Be Fatal
If hydrogen sulphide (H₂S) is suspected in a tank, taking
a sample from the upper part of the container will be
ineffective. With a molar mass of 34 g/mol, considerably
heavier than air (29 g/mol), H₂S will sink to the bottom.
These examples highlight a critical safety risk: measuring at
the wrong location can have fatal consequences. Hydrogen
sulphide is an extremely toxic gas that can cause sudden
unconsciousness and respiratory paralysis, leading to death if
inhaled in high concentrations.
Lower concentrations can damage the respiratory system,
cardiovascular system, digestive tract, and central nervous
system. Although H₂S has a distinctive rotten egg smell, one’s
olfactory senses quickly become desensitised to it, making it
an unreliable warning signal.
As a general rule, light gases mix quickly with air, the
gas volume increases rapidly, and the light gas ascend.
Measurements in open air should therefore be taken close
to the leak. In containers, concentrations of light gas

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16
ENGLISH ISSUE
Shafts at new plants
have more space.
tend to increase at higher points. Heavy gases flow along the
ground like a liquid, stream around obstacles or cling to them,
have limited mixing with the surrounding air, and a long range.
Measurement is best carried out at ground level within the
flow area. However, the molar mass and physical properties
of the expected hazardous substances are only two aspects
that play a role in defining suitable measurement points. The
type and shape of the confined space must also be taken into
account: heavy gases accumulate where the floor is lower,
light gases in the highest area. Bulges, installations, etc., must
also be considered.
Ventilation is another key factor, as air currents can shift
gas clouds, altering their concentration and positioning. It
is also important to assess whether the work area can be
fully isolated from connected pipelines. If not, the risk of gas
inflow must be carefully evaluated.
Hazards Inside the Manhole
Ex-Ox-Tox—this is a summary of the three potential hazards
lurking in the space in the manhole. When working in shafts,
confined spaces, or tanks, a clearance measurement must
be conducted before entry to ensure that there is sufficient
oxygen and that the air is free from toxic or explosive
concentrations of hazardous substances.
From personal workplace monitoring to leak detection and
clearance measurements, portable gas detectors can be used
for a wide range of measurement tasks. When purchasing
such a device, the key question is which type best meets the
specific requirements.
Personal protection devices are typically small, compact,
and designed to be worn directly on clothing. They generally
operate in passive diffusion mode, allowing gases from the
surrounding air to pass through membranes to the sensors of
the gas detection device. Using an external pump in this case
would not be practical, as it would provide little additional
airflow to the sensors. The flow rates of available pumps are
too low to significantly expand the measurement range.
ADDITIONAL HAZARDS
Shafts, pits, and channels, as well as their surrounding areas,
pose further risks, such as:
●
●
●
●
●
●
●
●
Structural defects (missing, incorrectly installed,
corroded, or improperly secured entry points).
Failure or misuse of lifting equipment.
Unsecured shaft openings.
Falling objects.
Slippery standing surfaces.
Strong currents, especially when water levels rise quickly
during heavy rain.
Electric shocks.
Vehicle traffic.
Clearance Measurement of Shafts: Sampling
Usually with a Pump
On the other hand, clearance measurements before work in
tanks and confined spaces often require testing an atmosphere
that is difficult to access—such as at the bottom of a tank,
inside a container, or deep inside a shaft. For this clearance
measurement, a sample is taken and air from the space to be
tested is directed to the sensor in the gas detection device via
a probe and hose. Probes and pumps are also frequently used
when searching for leaks.
Author
Thomas Gau
Freelance Journalist
0049 1 72 512 71 71
gaul-gehrden@t-online.de

BIOGAS Journal Spring_2025 17
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18
ENGLISH ISSUE
Hydrogen
condensing boiler in
one of Hohenwart’s
boiler rooms.
Hydrogen Field Test in Hohenwart
Future Gas Grid or Pilot Project
for a Premium Product?
Few research projects are attracting as much attention as H2Direkt, the hydrogen network
initiative in Hohenwart, Bavaria. The key objective is to determine whether converting the gas
grid to hydrogen can be achieved without further ado. However, opinions remain divided on
whether hydrogen should be used for heating.
Author: Christian Dany
Just about every second home in
Germany is heated with natural gas. In 13
federal states, it remains the most widely
used heating fuel. However, the German
government’s climate policies and
efforts to reduce dependence on Russian
energy are now insisting that natural gas
should be replaced as much as possible
– posing significant challenges for the
entire gas infrastructure.
Under these circumstances, a field test
is currently underway in Hohenwart,
located between Munich and Ingolstadt,
to test the gas grid of the future. A
section of the gas distribution grid was
disconnected here and connected to a
specially built hydrogen feed-in plant.
Since October 2023, ten households
and a joinery have been supplied with
hydrogen - not with a gas mixture, but
with 100 percent hydrogen. This is the
first time in Germany that household
customers have been supplied with
pure hydrogen.
In the H2Direkt research project, Thüga
AG, the energy supplier Energie Südbayern
and its subsidiary Energienetze Bayern
want to show that the existing gas
infrastructure can continue being used
with pure hydrogen – and with minimal
conversion effort. However, the project
partners’ initial optimism was mixed
with great concern when, in March, the
Federal Ministry for Economic Affairs
and Climate Action published its “Green
Paper on the Transformation of Gas and
Hydrogen Distribution Networks”.
Federal Ministry of Economics in
Favour of Heat Pumps and District
Heating
The discussion paper contains terms
such as “decommissioning of gas
distribution networks” and “dismantling
obligation”, which are abhorrent to
the gas industry. The Federal Ministry
of Economics makes no secret of its
preference for heat pumps and district
heating to achieve its goals, while
expressing scepticism about hydrogen
as a heating solution.
Photo: Vaillant

BIOGAS Journal Spring_2025 19
the classic for the discontinuous
analysis of CH 4
, H 2
S, CO 2
, H 2
and O 2
with and without gas
preparation
However, Manuel Gaßner, Head of
Network Technology at Energienetze
Bayern, argues, “We have approximately
530,000 kilometres of gas distribution
grid in Germany, and local authorities
and energy suppliers have invested
heavily in this over many years.
According to studies by the German
Technical and Scientific Association for
Gas and Water (DVGW), nearly 96 per
cent of the gas network is hydrogencompatible.
Continuing to utilise this
infrastructure is not only sustainable, it is
also economically viable and practically
feasible.” The exact figure of 95.9 percent
hydrogen-compatible gas networks was
determined as part of the H2vorOrt
project, in which the DVGW collaborates
with gas industry companies to advance
hydrogen transformation plans.
Lars Klinkmüller, owner of the
CarboCycle engineering consultancy
in Berlin, spokesperson for the Gas
Feed-In Working Group at the German
Biogas Association, and a member
of various DVGW working groups, has
warned against overestimating such
percentages. He has emphasised the
need for case-by-case assessments,
as the locations of the remaining 4
per cent of non-compatible pipelines
remain unknown.
“In the case of a hydrogen feed-in
request, a comprehensive examination
of the gas infrastructure affected by
hydrogen must always be carried out
first, which also determines the material
used in the pipes,” Klinkmüller explains.
“To facilitate this, the DVGW is currently
developing a database encompassing
all elements of the gas infrastructure,
including pipelines, fittings, measurement
technology, gas appliances, and
underground gas storage. This database
will provide insights into the suitability
of hydrogen. The network operators
also maintain ‘Gas Atlases’ that typically
allow them to identify materials, which
can then be cross-referenced with the
database,” he adds.
The H2Direkt project is now planning
to develop a guideline and thus a
kind of blueprint for the conversion of
distribution grids throughout Germany.
Together with Tanja Erb, Head of
Municipal Management and Corporate
Communications at Energie Südbayern,
Gaßner came to the Hohenwarter
hydrogen feed-in plant not far from
the striking Klosterberg.
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Photos: Jost Listemann for Zukunft Gas, Christian Dany (small image)
Top: Am Kerschberg development
area in Hohenwart: The hydrogen
customers in the H2Direkt
project are mainly located on
St.-Georg-Straße, vertically in the
center of the picture.
Left: Entrance to the Am
Kerschberg construction area,
where the ten household
customers are supplied with
hydrogen. The joinery, which is
also supplied, is located on the
other side of the road.
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www.pronova.de

20
ENGLISH ISSUE
Young Local Network is Suitable
for Hydrogen
Pointing to a forest edge nearby, Gaßner
explains: “The connecting pipeline from
the feed-in plant to the rededicated gas
grid was laid under the dirt track that
runs along here. This local network is
relatively new, equipped with modern
components, and was well suited
for separation into an independent
hydrogen supply system. And above
all, the local community was open to
our initiative. Through this isolated
network, which has a total pipeline
length of approximately 1.2 kilometres,
eleven customers are now supplied with
hydrogen (H2),” he says.
“The pipes, made of high-density
polyethylene (HDPE), have a nominal
diameter of 160 millimetres (mm) for
the main line and between 32 and 63
mm for household connections. These
are suitable for hydrogen,” Gaßner adds.
A study by the Association for Plastic
Piping Systems (Kunststoffrohrverband)
has also confirmed the general suitability
of HDPE pipes for hydrogen transport
under the typical gas pressures found in
distribution networks.
Gaßner refers to the scientific support
provided by the Engler-Bunte Institute,
a research facility affiliated with the
German Association for Gas and Water
(DVGW). “Every component in contact
with hydrogen – such as gas flow
monitors and household inlets – has
been thoroughly tested. In the end, all the
elements received the green light,” he
states. The only necessary modification
was the installation of larger gas meters
in homes to accommodate hydrogen’s
higher volumetric flow rate.
Significant Difference in
Heating Value
One cubic metre of hydrogen has a lower
heating value of just 3 kilowatt-hours
(kWh), whereas natural gas has around 10
kWh. As a result, customers’ gas boilers
had to be replaced with condensing
boilers designed specifically for 100%
hydrogen operation, manufactured by
Vaillant.
“Hydrogen and natural gas have different
properties – for example, hydrogen
has a higher combustion speed and
temperature compared to natural gas,”
Gaßner explains. “The control system
that regulates combustion in a boiler
must therefore be specifically developed
and calibrated for these conditions.”
Vaillant is actively working on H2
compatibility and recently announced
that there will be conversion kits for
new H2-ready gas boilers from 2026,
consisting of gas-flow components and
control elements.
The conversion can be carried out
quickly and easily with the time required
for normal maintenance of less than
an hour. Vaillant has therefore issued
a manufacturer’s declaration for its
new gas condensing boilers in the
10 to 30 kilowatt output range that
they can be converted to 100 percent
hydrogen in accordance with section
71k of the German Building Energy Act
(Gebäudeenergiegesetz).
Gas Cylinder Bundles on
Lorry Trailers
As Tanja Erb emphasises, Hohenwart’s
customers are supplied with certified
“green hydrogen”, which is provided by
the gas provider Westfalen AG using
articulated lorries. Each trailer carries
a massive bundle of ten gas cylinders,
securely strapped in place. “To ensure
a fully reliable heat supply, everything
in the hydrogen supply system is
designed with redundancy,” Gaßner says,
explaining the trailer solution.
A second, fully loaded trailer is always
on standby, ready to be connected in
case of emergency. Each trailer has a
storage capacity of 300 kilograms of
hydrogen at a filling pressure of 200
bar. “In severe frost, one full load lasts
about a week, while in milder transition
periods, it can last up to a month,” says
the industrial engineer. At the lorry
docking station, the gas pressure is
initially reduced to 16 bar.
As soon as the pipes turn yellow, the
gas pressure regulation and measuring
system begins. “Here, the gas pressure
is adjusted to 250 millibar (mbar) for
the distribution grid,” Gaßner explains
while describing the ‘inner workings’ of
the GDRM (Gas Pressure Regulation and
Metering) unit housed within a steel
Photo: Ilona Stelzl for Energie Südbayern
Hydrogen feed-in system
– here with only one
trailer. However, up to three
trailers can be connected.

BIOGAS Journal Spring_2025 21
Disconnection point from the existing
natural gas grid of the network converted
to hydrogen.
Control board at the lorry docking station.
Manuel Gaßner from Energienetze Bayern
explains the GDRM system. The picture on the
left shows a safety shut-off valve upstream of
the gas pressure regulation.
Photos: Vaillant (left), Christian Dany
enclosure. The lower section contains the
operating rail, while the upper reserve rail
ensures redundancy. A key component is
the green GDR device, which regulates
the pressure according consumption
requirements from the grid.
250 mbar Gas Pressure in the
Distribution Grid
A gas leak sensor is installed on
the ceiling, and to the far left is the
odourisation unit. Sulphurous THT
(tetrahydrothiophene) is injected here
to be able to smell escaping gas. “This
is all standard gas technology,” says the
gas network technician. “The setup and
equipment are the same as for natural
gas.” The gas pressure of 250 millibar
(mbar) in the distribution grid is further
reduced to 23 mbar in the homes of
connected customers.
“So far, we’ve had no losses along the
pipeline,” Gaßner insists. “The claim that
hydrogen diffuses through pipe walls is
a myth,” Erb adds. According to Gaßner,
operations have been running smoothly,
with only a few power outages in the
area. “If that happens, a solenoid valve
closes, and the system registers a fault.
You just have to acknowledge the error,
and it starts working again.” The most
important aspect, Gaßner stresses, is that
“consumers do not notice any difference
compared to a natural gas supply.”
Christoph Schartel, one of the eleven
hydrogen customers, later confirms that
his heating system has been working
perfectly so far. Hydrogen also does
not require any changes in heating
behaviour. However, he notes that
two other participants had to replace
components in their gas boilers at the
start of the project.
Burner Replacements Due
to Odorant Additive
“Two burner units had to be replaced
because a high concentration of the
sulphur-containing odorant led to
contamination. Excessive sulphur levels
can alter the flame pattern,”
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22
ENGLISH ISSUE
“Insides” of the gas pressure regulation and measuring system with the operating rail at the
bottom and the practically identical reserve rail at the top.
“Key components” – inside the green gas
pressure regulation devices, a valve responds
to network demand and adjusts the pressure
accordingly to 250 mbar.
Odourising system housed within the steel
enclosure of the gas pressure regulation and
metering station. On the left, the container
with THT (tetrahydrothiophene); it remains
to be determined whether the sulphur in THT
can be tolerated or if sulphur-free odorants
are recommended.
explains Alexander Schuh from Vaillant,
who has been involved with H2Direkt
from the outset. The fact that only two
boilers were affected may be due to their
location within the gas grid.
Gaßner explains that when
commissioning a gas grid like the one in
Hohenwart, the initial dose of odorant is
deliberately higher to ensure thorough
saturation of the gas infrastructure. This
dosage is then gradually reduced. Since
this adjustment, normal operations in
Hohenwart have been running smoothly.
Low-sulphur and sulphur-free odorants
have generally been an issue in the natural
gas industry for years and could become
even more important for hydrogen
networks. “Because hydrogen-rich gases
have a lower volumetric heating value,
odorant consumption increases for the
same energy flow,” states a report from
the DVGW’s H2-OdoSen project.
“For this reason, sulphur-free or at
least sulphur-reduced odorants should
be used to minimise sulphur dioxide
emissions in burner exhaust gases and
reduce the strain on desulphurisation
filters in fuel cell applications.” In as
early as 2021, the HYPOS project “H2-
Netz” at the Bitterfeld-Wolfen chemical
park suggested developing a dedicated
odorant for hydrogen networks – one
that would also be optimally suited for
fuel cell applications.
Plan to Produce Hydrogen Locally
The H2Direkt project is set to run
until the end of March 2025. However,
Gaßner and the project partners hope to
continue it indefinitely. In the long term,
the aim is to produce hydrogen on-site
using an electrolyser, reducing the need
for trailer deliveries, which would then
serve only as a backup. Wind turbines
have long been a topic of discussion in
Hohenwart, and the use of solar power
for electrolysis is also a viable option.
Hohenwart’s mayor, Jürgen Haindl, is
determined to drive the energy transition
forward at a local level. The municipality
recently established a public utility
company that focuses on energy projects
and approved the construction of a large
solar farm. Haindl’s core belief is clear:
“Germany has no oil or gas, but we have
wind and solar.” His vision is to generate
and utilise energy within the region itself.
However, he acknowledges that longterm
storage requires molecules. “If we
can manage storage using hydrogen, we
can make a small region independent of
energy,” he explains.
Tanja Erb highlights that for H2Direkt,
costs are not the primary concern –
the focus is on proving the technical
feasibility of using the existing gas
network for hydrogen. Despite repeated
inquiries, no concrete figures on the
overall cost of the project have been
disclosed. This is partly because there
is currently no established market price
for green hydrogen.
Westfalen AG has only confirmed
that the project is primarily supplied
from sources in southern Germany.
The project sponsor Jülich, which
administers funding on behalf of
the Federal Ministry of Research,
announced that H2Direkt is part of the
TransHyDE hydrogen flagship project
and was receiving approximately €2.5
million in funding.
Project Participants Pay Nothing
for the Hydrogen
However, H2Direkt is really cheap
for participating gas customers: As
Christoph Schartel explains, the eleven
participants receive the hydrogen they
need free of charge for 18 months. “That
was a major incentive to join the project.
However, it also serves as compensation
for the increased risk. If the project
continues, I would be willing to bear
some additional costs, but only to a very
limited extent,” he says.
If the project is to result in regular
energy supply, costs will inevitably play
Photos: Christian Dany

BIOGAS Journal Spring_2025 23
a decisive role. This inevitably leads to
the question of whether hydrogen is
actually the right energy source for
heating normal residential buildings?
Here, too, the aforementioned paper
from the Federal Ministry of Economics
puts a bitter damper on things:
“A decentralised hydrogen supply,
particularly for heating customers or
individual households, currently seems
unlikely due to the high cost of hydrogen
in the heating sector and, above all, the
expected limited availability.”
Many energy experts see the use of
hydrogen in the future playing a key
role in sectors that are particularly
difficult to decarbonise, such as the
chemical industry – especially fertiliser
production – the steel sector, and heavy
goods transport. Given the likely ongoing
scarcity of supply, high demand could
make green hydrogen a highly soughtafter
and therefore expensive commodity.
Economist Claudia Kemfert has been
particularly sceptical about hydrogen,
frequently describing it as the
“champagne of the energy transition.”
According to Handelsblatt, projected
prices for green hydrogen from
2030 range between €5 and €8 per
kilogram. This translates to an average
cost of 13 to 20 cents per kilowatthour
(kWhHs), reinforcing concerns
about its affordability as a mainstream
heating solution.
Dr. Jan Rosenow, a German energy
and environmental expert from the
“Heating a house
with green hydrogen
requires around
five times more
wind or solar power
than heating the
same house with an
efficient heat pump”
Dr. Jan Rosenow
University of Oxford, outlines the
inefficiency of heating with hydrogen:
“Heating a house with green hydrogen
requires around five times more wind or
solar power than heating the same house
with an efficient heat pump,” he writes in
Focus. Applied to Germany as a whole,
this means that replacing heating oil and
gas for space heating and hot water with
green hydrogen would require more than
three times the total electricity generated
from renewable sources in 2023.
However, there are also strong
advocates for hydrogen. One prominent
figure here is Bavaria’s Minister of
Economic Affairs Hubert Aiwanger, who
also wants hydrogen for the heating
transition, likes to cite Hohenwart as a
role model and criticises the “ideological
predetermination of the heat pump by
the federal government”. “It would be a
real shame not to use the underground
infrastructure with thousands of
kilometers of pipelines, this valuable,
buried treasure. And for consumers,
switching to a different gas is by no
means as expensive as converting to
pellets or a heat pump. In residential
areas where oil has been the primary
heating source, other energy solutions
certainly have their justification. But
where a well-established gas network
already exists, we should make use of it,”
Tanya Erb says.
These are certainly valid arguments.
However, even hydrogen supporters
often drive the debate based on vested
interests, frequently overlooking
alternative and compromise solutions.
A more balanced approach could involve
limiting hydrogen blending to 20 percent,
which would allow the existing gas
infrastructure to be used with minimal
modifications. In addition, incorporating
biomethane, gas heat pumps, and both
biological and catalytic methanation
of hydrogen could drastically reduce
natural gas consumption, allowing
methane to remain the predominant
gas in the grid.
Author
Thomas Gau
Freelance Journalist
0049 1 72 512 71 71
gaul-gehrden@t-online.de
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24
ENGLISH ISSUE
Micro4Biogas
New Bacterial Order Discovered
Scientists from the European research project Micro4Biogas have discovered and classified
a new taxonomic order of bacteria that are specialized in the decomposition of organic
material and could be the key to optimized biogas production. The order, which they call
Darwinibacteriales, is one of the most common bacterial orders in biogas plants but has
not been scientifically classified so far.
Authors: Dipl.-Ing. Pascal Otto and Prof. Christian Abendroth
As part of the EU research project
“Micro4Biogas” 15 partners from 6
countries are working over a period
of four years to research natural and
synthetic microorganisms to improve
biogas production. The 15 partners
include five academic institutions,
nine European companies, and the
local government of the Spanish
town of Aras de los Olmos. Aras de
los Olmos is working on achieving an
independent energy supply, aiming for
sector coupling with hydropower, solar
energy, wind power and biogas. The
plan is to incorporate the findings from
Micro4Biogas into this initiative.
The general goals of the project include
increasing the efficiency and robustness
of biogas plants through improved
microbiomes. The project includes
several sub-projects that address
research, industry, and educational
training. Initial project results are
presented as examples in this article.
Further information is available on the
project website (https://micro4biogas.
eu/). Current topics related to the
microbiome of biogas plants, as well as
a general technical overview, have been
provided in a roadmap in the form of a
free e-book. A draft of the roadmap is
available on the project website.
The Microbial Biogas Landscape
One of the central themes of the
Micro4Biogas project is the study of
microorganisms with potential relevance
for optimising biogas plants (see Figure
1). To achieve this goal, a wide range of
different biogas systems were specifically
sampled and analysed based on DNA. A
very diverse spectrum of reactors was
selected for the investigation in order to
cover a variety of reactor systems.
The systems differed, for example, in
terms of plant size, operating conditions,
and feedstock composition. The
sampled systems included stirred tank
reactors, plug-flow reactors, two-stage
Figure 1: The central guiding principle of the Micro4Biogas project: the search for
high-performance organisms that are crucial to improve biogas plants
Search for Essential Microorganisms for Biogas Production
Anaerobic Digestion
Sampling at Biogas Plants

BIOGAS Journal Spring_2025 25
Figure 2: A DIY reactor for research and teaching: Design and use were published
within the project framework under scientific standards
The reactor consists of (1) fermentation
chamber, (2) filtration system, (3) Biogas
storage system, (4) flame testing system,
(a) outlet valve, (b) T-connector, (c) closure
clamp for sampling (Vogel et al., 2023).
reactors, UASB reactors, and several
unique reactor configurations. Sampling
took place between August 2021 and
December 2021.
A total of 80 different biogas samples
were collected in Germany, the
Netherlands, and one in Austria. These 80
samples contained 61 different microbial
strains with over 1,800 subspecies. On
average, the biogas plants in this study
were dominated by 53.5% Bacillota,
followed by 10.0% Bacteroidota and
10.1% Euryarchaeota (methanogens).
To better understand the functions
of the individual strains in the biogas
plants, they were examined at the genus
level. This study is one of the most
extensive taxonomic comparison studies
for biogas plants. The draft of the article
is available on the bioRxiv server under
the title “Multivariate comparison of
taxonomic, chemical, and technical data
from 80 full-scale anaerobic digesterrelated
systems” (Otto et al., 2023).
The work has helped to further specify
representatives of the core microbiome.
Particularly the organisms MBA03,
Proteiniphilum, a member of the
family Dethiobacteraceae, the genus
Caldicoprobacter, and the methanogen
Methanosarcina show high relative
frequency across a variety of plants.
The study also provides a detailed
description of other relevant groups and
their correlation, based on multivariate
analysis, taking into account technical
and chemical process parameters.
Darwinibacteriales
Two main tasks can be identified
in terms of the functions of the
discovered core microbiome. On
one hand, microorganisms from the
genera MBA03 and Dethiobacter
demonstrate syntrophic conversion
of acetic acid, thereby contributing to
hydrogenotrophic methanogenesis.
On the other hand, the genera MBA03,
Proteiniphilum, and Caldicoprobacter
exhibit hydrolytic activities.
In detail, this means that MBA03 can
degrade complex carbohydrates such
as xylan, cellulose, and lignocellulose.
Proteiniphilum can degrade both
peptides and complex carbohydrates,
and Caldicoprobacter is credited with
the ability to hydrolyse lipids, peptides,
and carbohydrates. It is worth pointing
out that MBA03 is the only strain that
can perform both main functions in
anaerobic digestion, exhibiting both
hydrolytic activities and syntrophic
conversion of acetic acid.
Due to its potential key role in the system,
this strain is the focus of our research.
Over the course of the project, the strain
was thoroughly analysed and classified
as a new order, Darwinibacteriales.
Results have been published as a preprint
on bioRxiv under the title of “Unveiling
the ecology, taxonomy and metabolic
capabilities of MBA03, a potential key
player in anaerobic digestion” (Puchol-
Royo et al., 2023).
In addition to the classification of microorganisms,
the isolation and cultivation
of individual strains plays an important
role. This way enables potentially
high-performance microorganisms to
be used. To date, over 100 different species
have been isolated as part of the
project, and their effects on the biogas
process are currently being studied at
the laboratory scale.
Biogas for Education and Training
The University of Valencia and the
company Darwin Bioprospecting
Excellence have developed a DIY reactor
that could, in the future, be constructed
and operated by students themselves.
The reactor essentially consists of a
reaction chamber, a filter, a gas storage
unit, a flame test, as well as valve and
connection components. The reactor is
schematically illustrated in Figure 2 and
has already been published in the journal
Fermentation (Vogel et al., 2023).
The biogas process is essentially very
complex in terms of technical equipment
and microbiology. In research and
industrial pilot laboratories, the process
is carried out using various reactor
concepts. In the article published by
Vogel et al., the authors present a very
simple do-it-yourself biogas reactor,
which they have designed, operated, and
characterised.
They have proposed this technology
as a cost-effective alternative

26
ENGLISH ISSUE
Figure 3: Diagram of the modified process in which the digestate from a digester
is reactivated with oxygen in an additional stage
In the demonstration plant, air oxygen was used instead of pure oxygen for simplification. The sludge is then thickened, and the activated
digestate is returned to the digester. As a result, the biogas yield in the demonstration plant was increased by up to 55 per cent, while the
amount of digestate requiring disposal was reduced by 25 per cent (Otto et al., 2023).
to biogas reactors in both academic
and private laboratories. Furthermore, it
serves as an effective tool for spreading
knowledge about the potential of biogas
as a key technology for the development
of a global bioeconomy.
Air for the Optimisation of
Biogas Processes
The following presents another article
that deals with a demonstration plant
already in operation at a municipal
wastewater treatment facility. It
particularly focuses on the collaboration
with the company Pro-Entec East
GmbH. This partnership was initiated
through an M4B lecture at the 16th
Rostock Bioenergy Forum. An article
titled “Microscopic Heroes of the
Biogas Industry” was published in the
conference transcript and presented
at the conference (Abendroth et al.,
2022). The published article examines
a process that the company has already
demonstrated as a patented procedure
in a 1,500-cubic-metre digestion tower.
This process involves an intermediate
stage featuring aerobic sludge
reactivation. The treatment increased
biogas yield by up to 55 per cent while
simultaneously reducing digestate
volume by 25 per cent and significantly
lowering residual nitrogen levels.
The company was keen to deepen
its understanding of the microbial
processes involved in the patented
procedure, which led to collaboration
with partners from Micro4Biogas.
Using 16S rRNA gene amplicon highthroughput
sequencing, the reactivated
digestate exhibited a lower number of
methane-producing archaea. However,
this did not result in any losses in
methane formation. Several ammoniumoxidising
bacteria were identified,
including multiple genera from the
Chitinophagaceae family (18.8 per
cent) and a small amount of the genus
Candidatus Nitrosoglobus (<0.3 per cent).
Of particular interest was the frequent
occurrence of Chitinophagaceae, as
this family has hardly been described
in other denitrification processes until
now. As a result, the process led to
an unusual microbiome. In summary,
the described method represents an
economically viable approach to further
reducing nitrogen from already digested
sludge, lowering residual loads, and
simultaneously achieving higher biogas
yields. In addition, potential pathogens
are minimised. The collaboration with
Pro-Entec East GmbH has also been
published and can be found in the journal
Fermentation (Otto et al., 2023b).
Authors
Dipl.-Ing. Pascal Otto 1
Prof. Christian Abendroth 2
1
Technische Universität Dresden
2
Brandenburgische Technische Universität
Cottbus-Senftenberg

BIOGAS Journal Spring_2025 27
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LUBRICANTS
made in Germany
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28
ENGLISH ISSUE
Construction work
is underway for the
supply of biomethane
in Cachao.
Manuel Coreia displays
the connection box
for biomethane.
It is waiting to be
connected to the
biomethane network.
Portugal’s First
Biomethane Village
So far, biogas has been a rarity in Portugal, found almost exclusively at landfill sites and
wastewater treatment plants. However, this is set to change. In mid-January 2024, the
government unveiled a Biomethane Action Plan aimed at tapping into the country’s potential.
The goal: to replace nearly 20 per cent of natural gas imports by 2040.
Author: Dipl.-Pol. Oliver Ristau
Photos: Oliver Ristau

BIOGAS Journal Spring_2025 29
Cachao-Vilaeste is
the first community
in Portugal to receive
biomethane.
A blanket of fog rests over the Douro River and its tributaries in
northern Portugal. It casts a milky light over the valleys – and
also over the villages. One such village is Cachão, located in
the district of Bragança, around 12 kilometres from the town
of Mirandela, consisting mainly of a main road with a few side
streets, a modest cafeteria serving lunch, and an industrial area
that has clearly seen better days. Many of the former factory
buildings are in a state of decay, and the advertising has peeled
off from what was once a restaurant. Below, the dark waters of
the Tua River, which gives its name to the nearby natural park,
meander through the landscape.
At first glance, there is little to suggest that this sleepy
village is home to an innovative energy project. But the few
inhabitants who are out and about on the streets know all
about it. “Biomethane? Yes, that’s in the new neighbourhood,”
says a woman strolling through the industrial area. “Just head
up the hill,” she says.
The neighbourhood is called Vila Nordeste and winds its way
up a hill. It consists mainly of narrow single-family homes with
small verandas. A man playing with the dogs outside his house
can give more details on where the construction work is taking
place. He also mentions that the workers are taking a break –
after all, it’s lunchtime, and everyone’s at the restaurant.
Actually, both the excavator and the delivery van are standing
idle on the street he mentioned. The excavator has dug a
trench at the edge of the pavement – one and a half meters
deep and barely a meter wide. A rolled-up hose lies ready to
bring biomethane to the houses in the future.
Biomethane for the Kitchen
Like Manuel Coreia, who lives one street up the hill and is
waiting for it. In his late sixties, he came back to his home
village two years ago. He spent more than 30 years in Germany,
in Münster and Pinneberg. Now, he explains, he is growing
olives. “I have 4,000 trees,” he says proudly. A local cooperative
processes the harvest into olive oil.
The sprightly retiree points to the connection box in front
of his house. The new supply pipe is still sealed for now. He
estimates that his property will be connected to the local
distribution grid later this year. In other streets, biomethane
is already flowing into the homes. The plan is to supply the
entire neighbourhood with renewable gas. “For the kitchens,”
as Coreia puts it. So far, he and his wife have been cooking
with natural gas and electricity.
Portugal’s First Community with Its
Own Biomethane Grid
With roughly 500 residents, Cachão is a unique project. For the
first time, a community in Portugal is being equipped with its
own dedicated biomethane grid. The system is set to supply
not only 80 households but also businesses, namely those still
operating within the industrial estate. Even the local football
club may receive a connection.
Manuel Coreia is about to take out the rubbish and says
goodbye. With that, the circle is complete. His waste – along
with that of tens of thousands of other residents in the region
– will continue to secure the community’s biomethane supply
in the future. The source of the biogas is the Urjais landfill site,
located less than two kilometres away as the crow flies.
Landfill Supplies the Gas
A narrow country road winds its way uphill, passing a few
villages. Olive trees line the route on both sides, occasionally
interrupted by a cork oak stretching its sturdy branches into
the sky. The view extends across a mountainous landscape
with meadows reaching to the horizon. The fog is still in the
valley. There is no sign of the district’s central landfill – until
the road dips back down into the mist and the smell becomes
obvious. Soon, garbage trucks appear, and with them, the
operations yard of the waste management company Resíduos
do Nordeste.
A little further there is a Dourogas-branded filling station,
flanked by a large photovoltaic field. It supplies fuel (compressed
natural gas = CNG) for gas-powered vehicles. The biomethane
processing plant is clearly visible in large lettering. It stands
behind a heavy metal fence. According to a Resíduos

30
ENGLISH ISSUE
Portugal produces a large proportion of its biogas with sewage gas. This photo
shows the Frielas plant, which also processes the biogas into biomethane.
do Nordeste employee who monitors the facility, it has been
in operation since 2022. Since then, the landfill gas has been
purified of all components except methane and fed into the
grid. From here, it also flows to Cachão.
However, the owner, Dourogas, has declined to provide further
or technical details. Repeated requests from Biogas Journal for
a dialogue went unanswered. What is clear is that the company,
based in Vila Real in northern Portugal, operates a network of
natural gas filling stations across the country and entered the
biomethane business three years ago.
Biogas at Filling Stations
The fuel sold at most stations is typically fossil-based CNG.
However, biogas also plays a role at some Dourogas filling
stations. One example is Carregado, an industrial town not
far from Lisbon. There are also mobile biogas containers from
Gecrio, a company that equips CNG and LNG filling stations.
According to the company, these contain bottled biogas,
which is upgraded to biomethane on site and blended with the
remaining methane. Judging by the external condition of the
containers, however, biogas does not appear to play a major
role at that particular station.
Back to Urjais to the landfill site, which processes its landfill
gas into biomethane. Resíduos do Nordeste has been
producing biogas there since 2011, making it more than ten
years of operation. A 716-kilowatt gas engine is in place to
convert the gas mixture into electricity and heat. Until now,
the company has fed the electricity into the regional grid
– enough to supply 1,500 households, as stated in a press
release at the time.
Portugal’s Feed-in Tariff
In the mid-2000s, Portugal introduced a kind of feed-in tariff
for biogas – applicable to all plants that could not make use
of the electricity and heat they generated. This incentive was
utilised almost exclusively by waste management companies,
such as Resíduos do Nordeste, and wastewater treatment
facilities. According to the relevant 2007 regulation, the
average tariff for electricity generated from landfill gas ranged
from €102 to €104 per megawatt hour (MWh). Other types of
biogas were entitled to €115 to €117 per MWh. An additional
environmental coefficient was also applied. The regulation
specified a duration of 15 years.
That grant has now expired. Companies must either sell the
electricity on the market or find alternative solutions. In the
case of the Urjais landfill, the new option for the organic fraction
of the waste is biomethane. Besides Urjais, there is at least one
other biomethane plant in operation in Portugal that feeds gas
into the grid. It is located at the Frielas wastewater treatment
plant, less than half an hour’s drive from Lisbon Airport.
Wastewater specialist Águas de Tejo Atlântico has been
producing biogas there from sludge for many years. In mid-
2021, the facility was converted to biomethane production,
again in partnership with Dourogas. The technology was
supplied by Portuguese company Sysadvance. According to a
press release, Dourogas also plans to produce hydrogen and
e-fuels at the site in the medium term.
At the official inauguration of the Urjais project in summer 2022,
Portugal’s environment minister, Duarte Cordeiro, travelled all the
way from Lisbon and was full of praise. It was, he said, “a signal
to the entire country” to collect more bioresources and convert
Photo top left: Aguas Tejo Atlantico

BIOGAS Journal Spring_2025 31
One of the first biomethane projects for feeding into the
grid is located at the Urjais landfill site.
There are mobile biogas containers at this filling station. The bottled gas
can be processed into biomethane on site and added to the other CNG.
them to biogas and eventually biomethane. This, he noted,
would enable Portugal to reduce future imports of natural gas.
In mid-January 2024, Lisbon clarified how this vision will take
shape. The National Laboratory for Energy and Geology (LNEG)
presented a draft action plan for biomethane, outlining how
biomethane could play a significant role in Portugal’s gas
supply from 2024 to 2040. Consultations on the plan were
scheduled to conclude in early February 2024.
Biomethane to Reduce Natural Gas Imports
The plan specifically identifies the potential to reduce the
demand for fossil natural gas by 9.1 per cent by 2030 and by
18.6 per cent by 2040 through the use of biomethane upgraded
from biogas. At present, Portugal imports all of its gas from
abroad. Due to its reliance on pipeline supply via Spain, the
country has been using liquefied natural gas (LNG) for many
years. LNG arrives at the Atlantic port of Sines from Nigeria,
for example, which provides an important part of the demand.
According to the EU, Portugal imports a total of around 5.5
billion cubic metres of natural gas annually.
However, for biomethane to eventually take over, Portugal must
first develop its biogas sector. According to the action plan,
the country produced just 87 million cubic meters of biogas
in 2023. This corresponds to less than two percent of natural
gas imports. Portugal currently has an estimated 70 plants.
The action plan is aware of the dilemma, noting that there is
not yet a national industry. At the same time, it stresses that
biomethane is essential for Portugal to decarbonise the gas
demand of its industry, transport sector, and energy supply.
The plan sets out two phases: The market must be built up
over the next two years until 2026. In the subsequent phase,
up to 2040, it must be scaled up and professionalised.
Twenty measures have been proposed to ensure sustainable
production and distribution. The initial focus is on upgrading
existing biogas capacity. This primarily concerns facilities such
as those in Urjais and Frielas.
As things stand, the majority of biogas still comes from
municipal solid waste (resíduos sólidos urbanos – RSU) and
sludge. The potential for waste in particular could be further
increased through more consistent separation and collection.
The potential at wastewater treatment plants, on the other
hand, is largely exhausted. At the same time, new plants are to
be added at both existing and new sites.
Portugal wants to use biomethane to reduce imports of natural gas,
which is handled via the port of Sines (pictured).

32
ENGLISH ISSUE
Portugal is a major wine
producer. In the future, the
residues are to be used for
biogas production.
Biomethane (in the
background in the fog)
and photovoltaics at
the Urjais landfill site.
The local football club
could also become a
biomethane customer.

BIOGAS Journal Spring_2025 33
Livestock Sector to Invest in Biogas Plants
In addition, the plan lists three further sectors expected to
produce biogas and upgrade it to biomethane in the future.
The most significant one is the livestock sector. To date,
facilities for processing slurry, manure and other residual
materials are virtually non-existent. However, by 2030,
this sector could supply one third of the projected biogas/
biomethane output. The action plan forecasts a contribution
of around one terawatt hour (TWh) of biomethane per year
from Portuguese livestock farming.
By comparison, municipal solid waste could increase
production by a further 0.36 TWh, while sludge could add
just 0.05 TWh. The next-largest sector, which also remains
underdeveloped, is general agriculture. Crops such as barley,
maize, sunflower stalks and straw could be used for anaerobic
digestion. Their potential contribution to biomethane
production is 0.56 TWh.
The agri-food industry could also contribute 0.07 TWh. This
refers to large food processing operations such as those
producing wine, olive oil, and fruit juice. Suitable feedstocks
include grape and olive pomace, wash water from oil presses,
and fruit pulp.
Synthetic Biomethane
The LNEG also accounts for smaller contributions from the
gasification of forestry residues (0.01 TWh) and synthetic
biomethane. The latter is a product derived from the
CO2 separated from biogas and externally sourced green
hydrogen, with a potential output of 0.29 TWh. Altogether,
the institute has calculated a total of 2.7 TWh per year by
2030. This corresponds to 9 per cent of Portugal’s projected
gas demand.
In the next stage, the production of biomethane from biogenic
CO2 is expected to become the dominant factor by 2040.
According to the scientists, this process could provide a total
of 2 TWh in synthetic biomethane. The gasification of forestry
residues could contribute an additional 0.5 TWh. Overall, the
institute calculates a biomethane production volume of 5.57
TWh, meeting the 18.6 per cent share of national gas demand.
In addition to the targets, the plan outlines a series of “actions”
to ensure Portugal’s success on this path. They include the
development of more biomethane communities like Cachao,
where part of the gas can be consumed locally at the point of
production. The plan also emphasises the need to strengthen
the existing gas grid infrastructure and coordinate it with the
anticipated demand for green hydrogen.
A central element is ensuring economic viability. The
action plan states that financial support is essential to
enable companies to make the necessary investments. This
applies to both capital expenditure (Capex) and operational
expenditure (Opex). The LNEG cites contracts for difference
as one example. The first tenders could be launched with
the adoption of the action plan in 2024. At the end of 2023,
the European Commission approved €140 million in state
aid under the REPowerEU programme. Lisbon intends to use
these funds for biomethane and hydrogen auctions. One
circulated idea: Portugal’s gas company Galp could purchase
the offered volumes and feed them into the gas grid.
Allianz Acquires Gas Distribution Network
A key role in this process is played by the gas distribution
network operator, formerly Galp Gás Natural Distribuição. A few
years ago, Galp sold the infrastructure to financial investors,
who then rebranded the company as Floene. The largest
shareholder is the Munich-based Allianz insurance company
holding 75 per cent. The remaining 25 per cent is held by the
Japanese company Marubeni.
In an interview with Portuguese media, Floene CEO Gabriel Sousa
explained in 2023 that biomethane could be available much
faster than green hydrogen. The approximately 70 biogas plants
should all invest in biomethane upgrading. The company has
already received several dozen applications to feed biomethane
and green hydrogen into the distribution network. Floene itself
plans to produce solar hydrogen in a demonstration project in
Seixal, near Lisbon, and feed it into its grid.
The example of the US drinks and snack giant Pepsi shows how
attractive biomethane already appears to be for the Portuguese
industry. The company operates a factory in Carregado, near
Lisbon, which produces, among other products, potato crisps.
As the first corporate example in Southern Europe, Pepsi
announced the construction of a biogas plant at the Portuguese
site, which will ferment wastewater from production as well as
potato peels and other waste into biogas.
The project was launched in 2023. Pepsi also plans to upgrade
the biogas into biomethane, thus reducing its natural gas
consumption. The CO2 emissions at the site are expected to
decrease by 30 per cent. Given the positive impact on climate
protection, the €7.5 million investment seems a modest sum,
especially since the beverage giant can also use the CO2 from
biogas upgrading as a basis for the carbonation of its products.
Beverage and snack company Pepsi produces biomethane for its own
supply at its Portuguese site in Carregado. The captured CO2 could be
used for carbon dioxide.
Author
Dipl.-Pol. Oliver Ristau
Editorial Department and Communication
00 49 40 38 61 58 22
ristau@publiconsult.de
www.oliver-ristau.de

34
ENGLISH ISSUE
Belgium
Too Many Cooks,
Not Enough
Biogas
Brussels
Photos: Oliver Ristau
Regional bioenergy: This biogas plant supplies the Van der Valk Hotel in Arlon, Belgium.
Belgium has the potential to double its production of biogas and biomethane over
the coming years. However, complex regulations and the political stalemate between
Flanders and Wallonia are holding things back. Yet exemplary projects demonstrate
what a self-sufficient future powered by Belgian bioenergy could look like.
Author: Dipl.-Pol. Oliver Ristau

BIOGAS Journal Spring_2025 35
Expansion into a Surfer’s Paradise: The hotel is planning a new building
featuring an artificial wave for surfing, powered by electricity from biogas.
Up until now, Belgium has not made a name for itself as a
surfing spot. Conditions along the Belgian North Sea coast
are simply not suitable for the sport. However, that may soon
change, though the surfboards won’t be hitting the beach, but
rather the water in a swimming pool in Arlon.
The Dutch Van der Valk group is planning to install an artificial
surf wave as part of a new spa and fitness area at its hotel in
the capital of the Belgian province of Luxembourg. The wave,
which can reach heights of up to 1.5 metres, is designed to be
suitable for training Olympic-level athletes. The project is part
of an expansion of the design hotel.
The hotel’s energy centre can easily be seen from the upper
floors of the architecturally striking complex. The domed roofs
of the biogas plant’s fermenters are visible beyond a busy dual
carriageway. Designed by the German company Ökobit, hotel
operator Steven Zeeuw van der Laan plans to use the biogasgenerated
electricity and green heat not only to power the
entire hotel, but also the artificial surf wave facility.
A 500-kilowatt (kW) combined heat and power (CHP) unit
from Münsterland-based manufacturer 2G is available for this
purpose. It continuously generates electricity and heat, which
are delivered to the hotel via two underground cables. The
entire system is designed to make the hotel and its guests
fully energy self-sufficient. Three gas boilers are available as
a backup for peak times and maintenance. “We also have the
option to draw electricity from the grid if needed,” a hotel
spokesperson explained when asked.
The Dutch Van der Valk Group intends to power its hotel in Arlon,
Belgium, autonomously with biogas.
The combined heat and power (CHP) unit from 2G is intended to
provide the hotel with an independent supply of electricity and heat
from locally sourced biogas.
Farm Fertiliser for the Perfect Wave
This setup is unique (not only) in Belgium. Van der Valk’s aim is to
close material cycles and reduce greenhouse gas emissions. In this
context, the toucan figure adorning the hotel’s façade and which
symbolises sustainability, is more than just a marketing tool.
This aligns well with the use of locally sourced materials. “We
work with a total of 30 suppliers,” says the spokesperson.
The supplier is the Pastoret family from nearby Sterpenich. In
addition to supplying organic waste, they also provide beef for
the hotel restaurant. The biogas facility plans to process the
following feedstocks: 10,300 tonnes of slurry, 6,000 tonnes
of manure, 1,500 tonnes of maize silage and 1,500 tonnes of
agricultural residues, meaning that only around 15 per cent is
non-agricultural waste.
This is because in the future, biogas plant operators could lose
their entitlement to subsidies if they exceed this limit. At Van
der Valk, this primarily affects eligibility for green certificates.
For now, the origin of the biogas is not a deciding factor. But
market participants expect this to change.
In Belgium, a wide range of actors are involved in biogas
production. Not many other EU countries have such a
heterogeneous and complex regulatory landscape to promote
biogas and biomethane. This is largely due to Belgium’s federal
structure, with two powerful regions – Flanders and Wallonia.
Both have an influence on national politics via the national
elections - often leading to political deadlock.

36
ENGLISH ISSUE
Sigrid Farvaque is a manager at Bioelectric. The company, based near Antwerp, manufactures container-based biogas plants.
Over 400 Days to Form a Government
After the 2019 federal elections for the Belgian Chamber
of Representatives, it took more than 400 days to form a
government due to the strong gains made by the regional
parties. Whether the results of the most recent parliamentary
elections, held concurrently with the European elections in
early June 2024, will make it easier to form a new government
remains to be seen.
Against this backdrop, it is easier to understand why, after
lengthy negotiations, Belgium did not submit its National
Energy and Climate Plan (NECP) until the end of 2023. This
plan sets out the country’s climate targets for 2030 and largely
consists of the individual regional strategies. Alongside Flanders
and Wallonia, the third region, Brussels, is also pursuing its own
path. As noted in the foreword of the 750-page document
by Belgium’s four federal entities – the Belgian federal state,
Brussels, Flanders, and Wallonia – these regional plans are not
coordinated with one another.
The Belgian regions hold primary responsibility for the
promotion of renewable energy. While biogas hardly plays a role
in Brussels, Flanders and Wallonia have each created a complex
set of instruments for this purpose. In both regions, the focus is
on issuing green certificates.
Support Through Green Certificates
To understand how the system works, Biogas Journal consulted
Valbiom, the Walloon bioenergy organisation. According to
Valbiom, Wallonia issues green certificates to all renewable
energy producers, based on specific conditions. Each certificate
has a value of 6.5 cents. Producers of biogas-generated electricity
can receive up to 2.5 certificates per kilowatt-hour (kWh) of
electricity if they meet certain requirements. The allocation is
based on a detailed return-on-investment calculation.
“One prerequisite is the use of waste heat,” explains Sigrid
Farvacque from the Belgian biogas provider Bioelectric. Currently,
there is no mandatory minimum quota for heat utilisation, but
a requirement could be introduced soon, similar to existing
regulations for manure. The subsidy applies regardless of
whether operators consume the electricity themselves or feed
it into the grid. Operators can either trade the certificates or sell
them to a regional authority. If the electricity is fed into the grid,
it is sold at the market price through traders – currently around
11 cents per kWh. “In Wallonia, biogas plants can also benefit
from investment subsidies,” adds Sigrid Farvacque.
Flanders has been allocating green certificates for electricity
generated by biogas plants since 2013. It also offers a form of
heat bonus for combined heat and power (CHP) operations.
These certificates represent one megawatt-hour (MWh)
of electricity, multiplied by a banding factor that accounts
for capacity, costs, and feedstock used. Operators can sell
certificates to the grid operator for a minimum of €93 or directly
to an electricity trader. The subsidy lasts for 17 years, but the
maximum amount of electricity eligible for support is limited
to what the plant would produce under full load over 15 years.
The heat bonus is calculated based on the amount of primary
energy saved per MWh, also multiplied by the banding factor.
Operators receive at least €31 per heat certificate. However,
according to the Flemish Biogas Association Biogas-E, the
Flemish government has announced plans to phase out the
system by 2025. Furthermore, in its National Energy and
Climate Plan (NECP), it has outlined plans to introduce tenders
for green heat in the future.

BIOGAS Journal Spring_2025 37
François Corbiau is the
project manager for
biomethane production
at Cinergie, near Namur.
In future, Cinergie will supply a new
residential area in Fleurus, Belgium,
with heat generated from biogas.
Basins and dredgers: Cinergie
produces its biogas from a range
of feedstocks.

38
ENGLISH ISSUE
100 Percent Manure
The Belgian regions aim to unlock the potential of agricultural
waste with their subsidy schemes. According to an industry study
by Guidehouse, this could double Belgium’s biogas production to
600 million cubic metres by 2030. Bioelectric, a company that
specialises in micro-scale plants with electrical outputs between
11 and 74 kW, is targeting this market. Based near Antwerp, the
company has installed around 100 such units in Belgium, primarily
on dairy farms with 60 to 300 cows. These installations account
for roughly half of all biogas plants in the country.
“The principle is that farmers can use 100 per cent slurry and
manure in our plants,” explains Sigrid Farvacque. The primary
goal is to cover their own energy needs. The rest is fed into the
grid and compensated by grid operators. For a typical farm with
120 cows and a 22-kW system, the self-consumption rate is
around 45 per cent. Each tonne of agricultural waste produces
approximately 33 cubic metres of biogas. Depending on the
plant size, the payback period ranges from three to seven years.
Bioelectric supplies the units in standard shipping containers,
which it initially purchased empty from the port of Antwerp. The
company, part of the investment firm Ackermans & van Haaren,
then customises each container with the necessary equipment for
individual customers. The energy centre includes petrol engines
from a Japanese manufacturer, which Bioelectric converts to
run on gas. The reason for this modification? “The gas engines
available on the market just aren’t good enough,” says Farvacque.
Converting Chicken Manure to Biomethane
While Bioelectric’s customers are primarily interested in
electricity and heat for their own use, Belgium has around
200 biogas plants, including a handful of larger ones that
produce biomethane. In Wallonia, three of these feed into the
distribution grid operated by Ores. One of them is located in the
agricultural town of Fleurus, near the Walloon capital, Namur. On
the outskirts of fields, the company Cinergie produces around
600 cubic metres of biomethane per hour, headed by project
manager François Corbiau.
Cinergie is majority-owned by the local Pierart poultry farming
family. However, a school in Fleurus is also one of its shareholders.
“We supply 3,500 pupils with our heat,” says Corbiau. The idea
behind the project is to make use of the poultry farm’s residual
materials. “Up to 15 per cent of the input materials consist of
chicken manure,” explains the engineer Corbiau. A further 15 per
cent is maize silage, while the remainder consists of plant-based
waste from the food industry, which does not require hygienisation.
Each year, the plant processes 120,000 tonnes of material.
Part of the biogas is converted into electricity and heat by a
2.2-megawatt combined heat and power (CHP) unit. Half of
the electricity (10,000 MWh annually) is fed into the grid in
exchange for certificate payments, while the other half is used
on-site. The heat is supplied to the school and a new housing
development, both located 4 kilometres away.
Using membrane technology, the company processes the
remaining biogas into 5 million cubic metres of biomethane
annually and feeds it into the grid. For this, it receives €100 per
MWh, generating an annual revenue of approximately €5.5 million.
The subsidy scheme works in such a way that the government in
Namur provides a premium, the amount of which depends on the
market price. In total, this always amounts to €100 per MWh.
Wallonia Sees Great Potential
The Walloon government sees great potential for biomethane
in the French-speaking region, estimating that up to 8
terawatt-hours (TWh) could be produced. That equals 20 per
cent of the region’s gas demand. To achieve a 10 per cent
share of biomethane (4 TWh) by 2030, gas grid operator Ores
Namur, located on the River Meuse, is the
capital of Wallonia. The region sees great
potential in biomethane.

BIOGAS Journal Spring_2025 39
anticipates an investment of up to €250 million. Although
Cinergie also plans to increase its gas production, Corbiau
notes that the current price of €100 per MWh is too low to
encourage new investments in biomethane processing.
Jerome Breton shares this view. He is the managing director
of Bois d’Arnelle, the second of three biomethane plants in
Wallonia. Located just a few kilometres from the Cinergie
project in Les Bons Villiers, his facility began producing
biomethane from agricultural waste and feeding it into
the Ores grid in 2020. Today, however, he sounds almost
resigned: “The biomethane market in Belgium is highly
complex, with intricate legal and political frameworks and
very little regulatory flexibility. This makes the development
of biomethane projects almost impossible.”
Guarantees of Origin in Flanders
Things aren’t exactly running quickly and simply in Flanders
either. The promotion of biomethane there works via
guarantees of origin. Gas grid operator Fluxys offers these
documents for feed-in and pays €20 per MWh for the green
property. However, the certificates do not entitle the holder
to participate in EU emissions trading. Instead, households,
businesses and organisations in Flanders can purchase them
as a voluntary commitment to climate action. In addition, the
regional government provides an investment cost subsidy, the
amount of which depends on various parameters.
Meanwhile, the grid operator Fluxys is considering entering
the biomethane sector itself. “We are currently examining the
construction of a biomethane plant in the port of Zeebrugge,”
a spokesperson stated in response to an inquiry. So far, the
Brussels-based company has been offering importers the
option of landing bio-LNG at the port and distributing it via
the necessary infrastructure.
Whether biomethane gains momentum in Belgium will likely
depend on the outcome of the elections in early June. “It will
take several months for a government to be formed and to set its
priorities and objectives, particularly regarding biomethane,” says
producer Jerome Breton. “After that, it will be up to all involved
parties to establish a regulatory framework that is favourable to
biomethane so that new projects can be developed.” He fears
that this issue will hardly become clearer before 2025 or 2026.
AUTHOR
Dipl.-Pol. Oliver Ristau
Freelance journalist
00 49 40 38 61 58 22
ristau@publiconsult.de
www.oliver-ristau.de
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40
ENGLISH ISSUE
A metropolis built on hills, a view of Uganda’s capital, Kampala.

ENGLISH ISSUE
41
Uganda
When Will
Biogas go
Mainstream?
Kampala
Uganda has great potential for biogas, yet the technology is still not
widely adopted in the country. What there is, however, is partly promising.
Author: Klaus Sieg
Potholes and dusty roads on which honking trucks, cars and
countless motorcycle cabs jostle for every inch of space.
Along the roadside, small traders sell SIM cards, tissues, or
banana chips. The industrial area of Bugoloobi, in Uganda’s
capital Kampala, lives up to all the clichés of an African
metropolis. And yet, is this really where the most modern
and one of the largest wastewater treatment plants in East
Africa is located?
“We treat 45,000 cubic metres of wastewater every day,” says
James Miiro Maiteki, spreading his arms in cheerful welcome.
But what excites the engineer and director of the Bugoloobi
Wastewater Treatment Plant even more is the state-of-theart
biogas plant attached to it. After solids are removed,
the wastewater enters two light blue digesters, each with a
capacity of 3,800 cubic metres, where it stays for 21 days.
CHPs by MTU
The biogas obtained in this way supplies a burner for process
heat. And it drives two combined heat and power units (CHP)
with 315 kilowatts (kW) of electrical power, which also generate
heat. “This covers a third of our energy demand, saving us
10,000 dollars per month.” The goal, once the plant is fully
optimised, is to produce 80 per cent of the facility’s electricity
and heat requirements in-house. No wonder that Maiteki is in
good spirits. He pushes open the door to the generator hall.
“These are our two Rolls Royces,” he says with a laugh, pointing
to the CHPs from MTU, the power systems brand of the British
luxury car manufacturer. Both units gleam under the neon
lights. The concrete floor is also bright and clean. The control
panels, the man-high switch cabinets, and the monitors in the
control room all look almost unused.
Wastewater Treatment Plant Funded by KfW
The treatment plant was commissioned at the end of 2023.
Only a few weeks ago, James Miiro Maiteki and his team took it
over from the main contractor, OTV, a subsidiary of the French
company Veolia. The nameplates on the boilers, pumps, tanks,
cooling systems and other technical components read like a
who’s who of European manufacturers, including Siemens,
Weishaupt and De Dietrich.
Photos: Martin Egbert
The digester tanks of the biogas plant at the Bugoloobi sewage
treatment plant shine in bright blue.
Everything is still gleaming and sparkling in the generator hall of the
Bugoloobi wastewater treatment plant.

42
ENGLISH ISSUE
Village scene
beneath the fig tree:
Uganda’s agriculture
is predominantly
small-scale.
The €53 million project was financed by the German
development bank KfW and the African Development Bank. It
is intended to serve as a model for similar projects in Uganda
and other African countries. “In the past, we didn’t make use
of wastewater as a resource. Now, not only are we saving
costs, but we’re also reducing our methane emissions,” Maiteki
explains. “In addition, we sell the residual material as fertilizer
– 21 cubic metres a day go to timber plantations and nurseries.”
Kampala: 15% of Households Connected to the Sewer System
But how likely is it that this type of wastewater utilisation will
become widespread? Currently, only 15 per cent of households
in Uganda’s capital are connected to the sewer system. The
aim is to increase this figure to 30 percent by 2030, among
other things by making it mandatory for new buildings to be
connected to the sewer system. However, most households
still rely on septic tanks, which are often only emptied by
lorries at long intervals. “As a substrate, this wastewater is
then no longer particularly rich,” says Maiteki. In some of the
poorer districts of Kampala, there are not even septic tanks.
Uganda’s potential for biogas is considerable. In Kampala alone,
7.62 million cubic metres (m³) of wastewater are generated
each year. In addition, 2,800 tonnes of solid municipal waste
are produced daily – around two-thirds of which is organic.
Situated on Lake Victoria, the country is agriculturally
oriented, with fertile soils and widespread livestock farming.
In its National Biogas Strategy Plan 2023–2033, the Ministry of
Energy and Mineral Development estimates the annual volume
of dung and manure at approximately 18.5 million tonnes. In
theory, this could generate 1,900,236 m³ of biogas. However,
farming in Uganda is largely small-scale. For a farmer with only
one or two cows, a biogas plant is not economically viable.
Tea, coffee, and sugar, on the other hand, are produced and partly
processed in larger volumes. Yet fewer than half of agro-processing
industries comply with the discharge standards set by the National
Environmental Management Authority. This could be improved by
utilising biogas. So far, however, there are only five industrial biogas
plants in the country – four of them in the sugar industry.

BIOGAS Journal Spring_2025 43
09 – 11 December 2025
Nuremberg, Germany
James Miiro Maiteki, Engineer and
Director of the Bugoloobi wastewater
treatment plant.
Sugar Producer with Biogas Plant
“Biogas is an important part of our environmental
and sustainability strategy,” says Timothy Muwonge,
Sustainability Manager at the Sugar Corporation of Uganda
Limited (SCoU), part of the Mehta Group. Founded in Uganda
in 1900 by the Indian immigrant Nanji Kalidas Mehta, the
group now employs 15,000 people worldwide. The sugar
refinery in Lugazi alone has a workforce of 7,000.
The large site on the outskirts of the small town includes sports
fields, kindergartens, schools, green spaces, and housing for
part of the staff. In front of the office building, a puja ceremony
is taking place for a new car. There are flower garlands on the
bonnet, and the scent of incense drifts through the air. Timothy
Muwonge invites us on a tour. The company cultivates 12,000
hectares of sugar cane around the extensive site.
“We produce 100,000 tonnes of sugar annually, making us
the third-largest producer in Uganda,” Muwonge explains.
A significant share is exported to neighbouring African
countries. The bagasse produced during sugar
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44
ENGLISH ISSUE
processing is burned in an on-site power plant to generate
electricity for the company’s own use, as well as for feeding
into the national grid. Private power producers have been
permitted to supply electricity in Uganda since 2007.
Sugar, Industrial Alcohol, Biogas
In addition to sugar, the group has also been producing industrial
alcohol from the by-product molasses since 2014. This process
generates nearly 300 cubic metres of distillery wastewater
per day. It contains high levels of both organic and inorganic
substances, including nutrients such as nitrogen, phosphorus,
and potassium. However, the discharge of untreated distillery
effluent poses a threat to the environment and groundwater
and is now prohibited in Uganda.
“We recover energy from the distillery effluent in our biogas
plant,” says Timothy Muwonge. Behind him, the 70-degreehot
effluent cools, steaming, in two lagoons before being
pumped into an 11,000 cubic metre digester. This produces
20,000 cubic metres of biogas within 24 hours, which is
then combusted in a burner to generate process heat. The
agitators, digester, gas holder and other equipment are
supplied by Indian manufacturers.
“With the biogas, we meet the entire heat demand of the
distillery,” Muwonge continues. Above all, however, the
residues from the distillery wastewater can be used as
fertiliser after treatment in the biogas plant. On a large area
at the edge of the site, the residues are mixed with filter cake
from the sugar production and composted. A compost turner
moves through long rows of dark compost. “This helps us
control the temperature in the compost,” explains agricultural
engineer Daniel Ebong.
Digested Manure Regenerates Depleted Soils
“Our organic fertiliser is sufficient for 25 to 40 per cent of
the cultivation area, and it’s ideal for regenerating depleted
soils,” explains Ebong. He points to the vast, hilly landscape
filled with sugarcane at various stages of growth. The refinery
operates around the clock, processing between three and
four thousand tonnes of sugarcane per day.
Fertiliser production is also a key focus of the African
Biodigester Component (ABC) programme, which runs until
2026, alongside the objective of promoting clean cooking
solutions. Besides Uganda, ABC is being implemented in
Mali, Niger, Burkina Faso and Kenya. The programme in
Timothy Muwonge,
Sustainability Manager at the
Sugar Corporation of Uganda
Limited (SCoU).
The Sugar Corporation of Uganda Limited (SCoU)
needs sugarcane 24/7. Most of the company’s crop
is grown on 12,000 hectares of its own land.

BIOGAS Journal Spring_2025 45
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Distillery wastewater from industrial alcohol production steams in two lagoons
before being pumped into the 11,000-cubic-metre digester.
So far, kitchen waste from the Uganda Christian
University (UCU) is only used in a pilot plant but
would be an available daily substrate.
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Agricultural engineer Daniel Ebong is
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produced by the biogas plant.
awi2go.de/en/

46
ENGLISH ISSUE
Sistema biogas plant at the Jesus on the Rocks farm. The fertiliser ensures soil fertility despite the rocky terrain.
Uganda is led by the Dutch development organisation SNV,
with the involvement of GIZ. Its goal is “to facilitate access
for 8,000 households to their own biogas plants”. While the
wording may sound a little bureaucratic, the intent is clear:
to avoid repeating the mistakes of previous domestic biogas
programmes. In other words, nothing is being given away for
free – at least not to the users of domestic biogas systems.
Donated Domestic Plants Not Running Smoothly
“Users often don’t take proper care of plants they received
for free,” says project manager Esther Nyanzi. According to
the Ministry of Energy and Mineral Development, there are
10,000 domestic biogas plants in Uganda, as well as 56
in schools and other institutions. However, many of these
donated plants are non-operational. They are either not
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BIOGAS Journal Spring_2025 47
Can the SNV product manager Esther
Nyanzi avoid the mistakes made by
previous biogas programmes?
used correctly, not maintained, or poorly constructed. Others
lack spare parts or the required volume of substrate, because
livestock has been sold or lost.
“We want to build a sustainable and economically viable
biogas sector,” Nyanzi explains. Hence the focus on the
production, application and marketing of organic fertilisers,
for which market and quality standards are currently being
developed in cooperation with the Ministry of Agriculture.
“Demand for organic fertiliser is very high.” The programme
is designed to support biogas companies directly, enabling
them to expand capacity and train staff. Subsidies are paid out
in stages, but only after companies can demonstrate proper
installation, appropriate plant sizing, and regular operation and
maintenance over defined intervals. This is documented and
audited by KPMG. The companies themselves decide whether
to sell the plants in instalments or offer credit.
At present, eleven companies are registered with the programme.
Initially, there were nearly twice as many, but not all were able to
meet the strict criteria over time. “The number is slowly rising
again,” says Nyanzi. This also explains why, of the 8,000 plants
planned by 2026, only 674 have been installed so far. Widespread
adoption looks different. But Esther Nyanzi points out the
concept of a free market and long-term sustainability.
When Vincent Lwanyaga has an issue with his biogas system, he
simply dials the number etched into the lid of the inlet. “So far,
we’ve only had to call once, when the gas valve needed replacing,”
says the 63-year-old. He has been operating the 12-cubic-metre
fixed-dome plant on his farm in Mpigi District, east of Kampala
near Lake Victoria, for the past three years. He grows beans,
maize, bananas and papayas on about four hectares.
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48
ENGLISH ISSUE
“I wanted the biogas plant
for the fertiliser, my wife
wanted it for cooking”
Vincent Lwanyaga
Vincent Lwanyaga and
his wife fill cow dung
into the digester of their
fixed-dome biogas plant.

BIOGAS Journal Spring_2025 49
“Just look at these beans – only two months since planting
and already this tall. That’s thanks to the fertiliser from my
biogas plant,” Vincent Lwanyaga says proudly. With his thin
but sinewy arm tucked into a tattered blue work shirt, the
farmer points to dense rows of man-sized bean plants. “I
wanted the biogas system for the fertiliser; my wife wanted it
for cooking,” he adds with a cheeky grin.
Now, they can save twice as much: around €500 per year on
fertiliser and approximately €200 on cooking fuel. With the
extra money, Vincent has leased additional land. To avoid
having to buy any more fertiliser, he wants to buy an additional
cow and switch to indoor husbandry, as well as pave the floor
of the pigsty so that he can also use the manure from his six
pigs in the facility. The biogas plant has clearly set a number
of things in motion.
Richard Mogisha has made it his mission to communicate
this. He runs his Jesus on the Rocks farm south of the
capital, Kampala, along the road to Entebbe Airport. “The
ground here really is very rocky,” he stresses. The 47-yearold
greets visitors with an elbow bump, his hands are far too
muddy for a handshake. “Despite the rocky soil, everything
thrives here, thanks to the fertiliser from the biogas plant,”
he reports confidently.
The wastewater from the treatment tanks at Uganda Christian
University (UCU) is also being tested in the biogas plant.
Demonstration Farm Illustrates Closed-Loop Systems
His demonstration farm is not much larger than a football
field, but it offers great diversity. Tomatoes, mangoes, cabbage,
amaranth and much more thrive on terraced plots. Here, he
holds seminars on organic farming for aspiring farmers or city
dwellers seeking to create self-sufficient gardens. School groups
also frequently visit. The topic of biogas is always part of the
programme. He demonstrates it using a 12-cubic-metre Sistema
biogas plant. He has even managed to convince his neighbour.
So far, Richard Mogisha has supplied him with Napier grass for
his cattle in exchange for manure for his biogas plant. Now, the
neighbour plans to buy his own biogas plant, and Richard
Richard Mogisha in the demonstration garden of the
Jesus on the Rocks-Farm.
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50
ENGLISH ISSUE
Mogisha wants to purchase a cow. “That’s how we do things
here,” he says with a laugh as they part ways. Cattle manure
plays a central role in most domestic biogas plants. However,
this often becomes a problem. During the dry season, cattle are
driven to graze in search of sufficient food. No one follows them
to collect the manure. Some animals die or are sold off.
University Lecturer Researches Biogas Fridge
Miria Frances Agunyo is therefore exploring alternative solutions.
As an engineer and lecturer at the private Uganda Christian
University (UCU), she conducts research and teaches the
application of biogas technology. In the laboratories at the edge of
the university campus, surrounded by expansive, lush green lawns,
she is working with other scientists to develop a biogas-powered
fridge and transport containers made from fibreglass mats.
Above all, she is experimenting with substrates. “Alternatives
are especially important for biogas plants at institutions
like schools or prisons, which often have food waste from
their kitchens as well as large amounts of black water
from toilets,” says Agunyo. She studied for 6.5 years at the
Europa University Flensburg. She is researching alternative
substrates at UCU in collaboration with the environmental
education centre Artefact in Glücksburg.
In a 12-cubic-metre experimental reactor, she tests various
mixtures. The best methane yield so far came from a mixture
of 70 per cent manure and 30 per cent food waste. “We want to
reduce the proportion of manure and instead use more kitchen
waste and faecal matter,” explains the enthusiastic volleyball
player. If she is successful, this could be a crucial step towards
expanding the use of biogas in Uganda.
Increasing deforestation
– the growing population
and the settlement
of many refugees from
the war-torn Sudan and
South Sudan threaten
nature and resources.
AUTHOR
Klaus Sieg
Freelance Journalist
00 49 1 71 6 39 42 62
klaus@siegtext.de
www.siegtext.de

BIOGAS Journal Spring_2025 51
Zentralgerührte
Hochfermenter.
Edelstahlbehälter von
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Produktionsabfällen.
Biogas plays an
important role in the
Science Lab at the
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Tel. +49 4443 9666 - 0
www.stallkamp.de

52
ENGLISH ISSUE
Ghana
Biogas Sector is Growing,
but Slowly
Although there are still only a small number of biogas plants
in the West African country, industry insiders anticipate
an imminent breakthrough for digestion technologies.
However, significant changes are needed in the feed-in
tariffs for electricity generated from biogas in order to
establish sustainable business models. Moreover, biogas
production will only be able to realise its full potential in
Ghana when circular economy structures are firmly in place.
Ghana
Author: Dierk Jensen
Gyankobaa near Kumasi: A combined biogas and composting plant is located there, financed as a pilot project by the German Federal Ministry of
Education and Research.
There is a pungent smell. A tank lorry, fully loaded with
pasteurised faecal matter, pulls up. The cargo is pumped into a
pit. At the same time, workers shovel fine grain residues from
a local mill, along with various waste products from a nearby
dairy belonging to Fan Milk Ghana, a subsidiary of the global
food corporation Danone.
The agitator vigorously mixes the porridge-like biomass until
it finally enters the underground digester. The (mesophilic)
digestion process takes place at a temperature of 38 degrees
Celsius, with a retention time of around 45 days. This ensures
that pathogenic germs are largely eliminated during digestion.
Behind the digester and its supporting roof, in a corner of the
extensive premises of the Safisana company in Ashaiman, east
of the capital Accra, there are two gas engines in a container,
each with a capacity of 100 kilowatts.
The units were supplied by the Dutch company Sandfirden
Technics B.V. from Den Oever on the IJsselmeer. The electricity
generated from the biogas is fed directly into the Ghanaian
power grid just beyond the site’s perimeter fence, where a few
pigs are grazing, at an absurdly low tariff. But more on that later.
Photos: Jörg Böthling

BIOGAS Journal Spring_2025 53
First Composting Plant set up in 2017
Safisana currently has 40 employees, all of whom wear masks
as they work. The combined biogas and composting plant was
set up in 2017 and is one of the first of its kind in Ghana, a West
African country where not more than two-thirds of the waste,
an estimated 3,500 tonnes daily, is collected at all.
The organic fraction is remarkably high at around 60%,
according to Ghanaian experts. Wastewater treatment is even
more inadequate. According to Safisana Ghana’s managing
director, Elikplim Asilevi, a mere 20% of Accra’s wastewater
is collected. The rest flows through open surface channels
directly into rivers and ultimately into the Atlantic.
A disaster, for both the environment and the people. At
temperatures of 30 degrees Celsius and above, the open
sewers are an extremely dangerous medium for a number of
pathogens. In fact, it is an ideal breeding ground for malaria
mosquitoes. Even cholera is a real issue in Ghana’s major cities.
Many people die due to a lack of sanitary facilities.
The company aims to expand this model to other African
countries, including Uganda, Côte d’Ivoire, Kenya, and Rwanda.
Currently, around 11,000 tonnes of faecal matter and 3,000
tonnes of vegetable waste, which is collected from major
markets across Greater Accra, are processed at Safisana’s site
in Ashaiman. Additional organic waste streams, such as grain
residues and by-products from juice, dairy, tomato, and cocoa
processing, are also utilised. Given the fact that Ghana is the
world’s second-largest cocoa producer after neighbouring Côte
d’Ivoire, cocoa waste plays a significant role in the process.
In 2023 alone, the organic waste collected by Safisana
generated 685 megawatt-hours of electricity. Compost
production has also been impressive: approximately 864
tonnes, certified by the state-run Plant Protection and
Regulatory Services Directorate (PPRSD) under Ghana’s
Ministry of Agriculture. The compost is primarily purchased
by small-scale farmers in Greater Accra, as well as plantation
owners cultivating oil palms, bananas, and cocoa.
Small lorries deliver the organic waste fractions, collected from
wholesale markets, to the biogas plant.
A Safisana Ghana employee transports grain residues into the pre-pit of
the biogas plant.
Human faeces are a key component digested at the Safisana facility.
Well mixed, the substrate enters the digester.
Safisana Purifies Wastewater
Easing, or even better changing, these precarious conditions
was the main motivation for the Dutch founders of Safisana
Holding, headquartered in Weesp, near Amsterdam. They started
by collecting faecal waste from more than 20,000 private and
public toilets across Ghana. Their primary goal is to improve
sanitation in the district and protect the health of its residents.
Safisana combines this core mission with the circular economy
principles: the collected waste undergoes an upcycling
process that generates both green gas and valuable compost.
Teaching Farmers About Composting
Since composting has little agrarian tradition in Ghana, and
many farmers have not given much thought to the purpose
and benefits of compost products, Safisana is demonstrating
the excellent results that can be achieved in gardens and fields
through compost application, using its own greenhouse and
open beds. “We invest a great deal of time and effort in raising
awareness about compost. And we’ve been successful, as the
farmers’ attitude towards compost is changing, and they are
increasingly recognising its advantages,” says Elikplim Asilevi.

54
ENGLISH ISSUE
Demonstration: Safisana maintains greenhouses and open beds to
convince future customers of the positive effects of using compost.
Safisana’s laboratory is well-equipped.
Interest in organic fertiliser is also growing, Asilevi adds,
because since the start of the Russia-Ukraine war, there have
been significant disruptions in the West African fertiliser
market. Over the past two years, severe shortages have led
to massive price increases. To put things into perspective:
in 2023, the total amount of compost produced in Ghana
was approximately 18,000 tonnes, generated by just twelve
composting companies. There is no doubt that Ghana’s young
composting industry still has considerable room for growth.
Meanwhile, Safisana employees turn their compost heaps
outdoors numerous times. As is the case everywhere in the world,
the compost contains a significant amount of foreign materials,
which, by the end of the 90-day composting process – during
which a temperature of at least 60 degrees Celsius is maintained
for at least a week – must be meticulously sieved out.
The finished compost, with a dry matter content of about 80 to
90 per cent, is packed into 30-kilogram sacks. At the start of 2024,
the price per sack was €4. While this may seem relatively high,
compost producers in the east of Accra generate no more than
€120,000 per year. Given the substantial effort involved, this is a
modest income that falls far short of covering operational costs.
Only 2 Euro Cents for Biogas Electricity
Especially since the production of biogas currently generates
very little income due to the outrageously low feed-in tariff,
which is less than 2 euro cents per kilowatt-hour. Why is that?
“Because of the ignorance of energy policy. The energy sector
in Ghana is not liberalised. Large-scale hydropower accounts
for 30 per cent of electricity supply,” explains Elikplim Asilevi,
“while the remaining renewable energies – wind, solar, and
biogas – make up only 3 per cent. That is remarkably low.” That
obviously annoys him.
In view of these energy policy structures, the idea that Ghana
could be a potential producer of hydrogen for export to
Germany seems puzzling to any critical observer. “And yet, the
potential for biogas alone in this country is enormous,” Asilevi
emphasises, “not least because international food corporations
are putting pressure on their subsidiaries, as they want – or
rather, need – to produce in a more climate-neutral way in the
future. The use of biogas could be a key lever in achieving that.”
For Safisana, this could also present a new opportunity to escape
the ‘electricity trap’. The organisation is considering whether the
biogas that is produced could be compressed and transported
via tanker lorries to industrial plants, where it could be used as
needed for electricity, heating, cooling, or pressure applications.
Hope in Carbon Credit Trade
But that is still just a dream for the future. The biogas currently
produced at the facility continues to be converted into
electricity and fed into the national grid at unfavourable tariff
rates. In the face of this unsatisfactory situation, Safisana is
hoping to generate new revenue through the international
carbon credit trade. For this purpose, the organisation has
engaged KliK, a private Swiss body dedicated to climate
protection and CO2 compensation.

BIOGAS Journal Spring_2025 55
Experiments with wood
gasification were conducted at
KITA some time ago.
The Institute for Tropical
Agriculture (KITA) offers biogas
seminars for interested farmers.
KliK operates within the framework of Switzerland’s CO2 Act
and is intended to serve the public interest. It was established
twelve years ago by the Swiss Petroleum Association (now
Avenergy Suisse) to help fuel importers comply with their legal
obligations. Today, its role is to offset a portion of greenhouse
gas emissions from the Swiss transport sector by financing,
supporting, planning, and implementing climate protection
projects both at home and abroad.
Since 2022, KliK has also been authorised to operate under
Article 6.2 of the Paris Climate Agreement in countries that
have signed a bilateral climate accord with Switzerland,
Ghana being one of them. It is therefore quite possible
that KliK will soon begin purchasing emissions reduction
certificates, representing the tonnes of CO2 saved by
Safisana’s operations.
However, this is not a reality yet, and so Ghana’s composting
pioneers will need considerable entrepreneurial resilience
to continue their plans of building additional composting
facilities across different regions of the country. There is
some progress: Safisana has already put another composting
plant into operation in Kumasi. It does help that the current
Ghanaian government at least supports local composting
efforts, partly because, given the country’s strained public
finances, subsidising imported chemical fertilisers makes
far less long-term sense than promoting the use of locally
produced organic alternatives.
Top: Ghana is the world’s number 2 cocoa grower – the waste that has
often gone unused in production has huge biogas potential.
Bottom: The situation is similar with the waste from palm oil production.
Biogas Research Facility Fully Funded by Germany
But back to biogas. Since April 2022, a hybrid “waste-toenergy”
facility has been in operation near Kumasi, Ghana’s
second-largest city and the home region of former UN
Secretary-General Kofi Annan. This demonstration plant,
inaugurated by Ghanaian President Akufo-Addo, has

56
ENGLISH ISSUE
High-quality
compost: Collecting
waste, generating
energy, and closing
cycles – this is the
principle at the pilot
plant in Gyankobaa.
Top: The Chinese CHP unit remains idle as the
grid connection is still pending.
Bottom: Delivered waste contains far more
than just organic material!
The laboratory facilities in Gyankobaa
are state-of-the-art and offer excellent
research opportunities for graduates
and doctoral students.

BIOGAS Journal Spring_2025 57
been entirely funded by Germany’s Federal Ministry of
Education and Research (BMBF) and primarily acts as a centre
for research and training.
Our taxi driver, Frederick Monsah, who takes us in his electric
car, a model made by the Chinese manufacturer Dongfeng,
on the 250-kilometre journey from Accra to the “University
of Rostock Road” the street leading directly to the entrance
gate of the new biogas plant, is overjoyed when he spots the
electric charging station on the premises.
“This is fantastic! I never expected this,” Frederick exclaims
with delight as he drives his Dongfeng straight to the charging
station. “I wish we had one of these along the main road
between Kumasi and Accra.” Wishful thinking, perhaps. The
electricity that Frederick spontaneously charges his vehicle
with is ordinarily reserved for the facility’s own operational
car and comes from a stationary photovoltaic system installed
on the roofs of the plant’s buildings, with a total capacity of
200 kilowatt-peak. A 100-kilowatt-hour lithium-ion battery
serves as a backup storage unit in case the sun is not shining.
Chinese CHP Unit Causing Problems
In theory, the biogas combined heat and power (CHP) unit
could also be used to generate electricity on demand. It
seems like a smart idea, yet the 100-kilowatt engine from
the Chinese manufacturer Jingcheng remains strangely idle.
“There are issues,” says employee Isaac Mensah as he wards
off critical inquiries while hoping for better days ahead.
To put it briefly, there is simply no grid connection yet – despite
the fact that the Ghanaian government firmly committed to
it during the planning phase. However, the connection is still
nowhere in sight. Meanwhile, several components intended
for the construction of a planned hydrogen production and
methanation unit remain untouched. They are lying around,
unpacked, behind the 1,100-cubic-metre high digester and
the inactive CHP unit, waiting for progress to be made.
External BioCNG Production
Despite the many unresolved issues at the biogas plant, the
digestion process is in place and biogas is being produced. It
is mostly still flared off, while a smaller portion is compressed
to 60 bar, transported off-site, and processed into compressed
natural gas (CNG) at another location. Meanwhile, the
16-member team of employees is busy processing incoming
waste and sorting it as efficiently as possible. Around 50 tonnes
of waste from within a 35-kilometre radius are delivered daily.
However, this is not predominantly organic material, but rather
mixed waste from any conceivable source, with the organic
content averaging only about 20 per cent, says Isaac Mensah.
The largest, painstakingly sorted out fraction is plastic, which
is compacted into large bales and sent to a cement factory
in the region for use as fuel. In addition to organic waste, 15
tonnes of pig and cattle manure are delivered every week,
mixed together, and fed into the digester.
“Not everything is running smoothly yet,” admits Professor
Satyanarayana Narra from the Chair of Waste and Resource
Management at the University of Rostock. Narra, who helped
design the facility on behalf of the BMBF together with his
colleagues, had to make significant compromises in choosing
the location, plant technology, and other specifications in order
to carry out this pioneering project.
Despite the challenges, Narra strongly emphasises the
significance of the biogas plant in Gyankobaa, even though
the site poses logistical and infrastructural difficulties. “This
demonstration facility and its integrated laboratory are not
about commercial viability, but primarily about creating an
important learning environment for the entire spectrum of
biogas, bioenergy, and waste management,” he explains.
“Thanks to this facility, we have already completed two PhD
dissertations and are currently supervising another ten doctoral
candidates and 17 Masters students,” Says Narra, pointing out
the role of the plant in building biogas expertise in Ghana.
Gas Storage
Concrete Protection
Emission Protection
Substrate Storage

58
ENGLISH ISSUE
The wastewater problem: A large part of the capital, Accra, is not
connected to a sewage system.
Agricultural Sector: 3 Billion m³ of Methane Could Be Tapped
And experts are truly needed to be able to exploit the
great potential that exists in Ghana, in addition to waste
management alone, through the numerous residues from
intensive and diverse tropical agriculture. Dr. Narra estimates
that the agricultural sector alone could potentially yield around
3 billion cubic metres of methane.
In order to actually implement this, however, we also need an
energy policy that articulates a greater commitment to energy
from biogas in general and electricity from biogas in particular
in order to achieve higher feed-in tariffs in the long term. If
this does not happen, then Ghanaian biogas production will
inevitably be concentrated as a stand-alone solution for food
processing industries, such as a brewery in Kumasi and a fruit
processing company in Adaiso.
Meanwhile, electricity in the national grid remains largely “grey,”
despite the contribution of large-scale hydropower, with two
major plants – including one at the legendary Akosombo Dam –
accounting for about a third of the country’s power generation.
The remainder is still heavily dominated by fossil fuels. So, there
is still much work to be done in Ghana’s energy sector.
AUTHOR
Dierk Jensen
Freelance Journalist
00 49 1 72 4 53 45 47
dierk. jensen@gmx.de
www.dierkjensen.de
A dire situation: Some coastal areas are practically sinking under piles
of waste, suffocating from pollution – a real disaster.
View of the Akosombo Dam on the Volta River, which was built in the
1960s following Ghana’s independence. The associated hydroelectric
power plant has a capacity of over 900 megawatts.
Satyanarayana Narra is a
professor of waste and material
flow management at the
University of Rostock and advises
the biogas plant in Gyankobaa.
Dr. Noah Owusu-Takyi from
the Institute for Tropical
Agriculture (KITA) will focus on
expanding biogas use in rural
areas in the future.

BIOGAS Journal Spring_2025 59
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60
ENGLISH ISSUE
Cambodia
Small rice fields and small farms:
Domestic biogas plants suit
Cambodia’s rural structure.
Cambodia
Many Small Plants,
Not Many Large Plants
Not only small farms use biogas in Cambodia, but also the growing
food industry. However, a lack of know-how and technical resources
limit the possibilities in the Southeast Asian country.
Author: Klaus Sieg
Bun Heang and Bun Houn are obviously in a good mood. The
sisters are sitting on the wooden steps of Houn’s house in
the Cambodian province of Seam Reap and beaming with
excitement. Their expressions darken for just a few seconds
when they scold Houn’s grandson, who is once again pulling the
cat’s tail and chasing one of the many ducks that is honking and
fleeing across the yard. After all, the animals are meant to fatten
up so they can fetch a good price at the market.
The reason for the sisters’ excellent mood is there in the shade
of some banana trees, a barrel made of green plastic with a
filler neck, gas pipe and overflow. Houn’s husband is just tipping
in a bucket of cow dung mixed with water, the legacy of the two
zebu cattle that are dozing in the heat in the house stable.
Firewood is no Longer Needed
“That’s all we need to prepare the three daily meals with biogas,”
says Bun Heang, pointing to the gas stove in front of the large
farmhouse made of dark tropical wood. “It saves time and
protects our health; we no longer have to search for firewood,
and we don’t have to stir the rice in the smoke.” This is why not
only the two sisters Heang and Houn each bought their own
plant, but also the third sister in the group, who is currently
selling spices from her garden at the market. Three sisters. Three
small farms. Three biogas plants. Three times good mood.
Siem Reap Province in northern Cambodia is mainly known for
its impressive Angkor Wat temple complex. The jungle-covered
temples from the heyday of the Khmer Empire have greatly
Photos: Martin Egbert

ENGLISH ISSUE
61
A mini biogas plant made by the Australian provider ATEC.
Two of the three happy sisters: Hean and Bun Houn.
Bun Houn’s husband feeding cow dung into the digester.
contributed to the development of tourism in the country.
However, the majority of people here still rely on agriculture for
their livelihood. This is evidenced by an endless patchwork of
small rice fields in various stages of ripening, glowing in a whole
range of fresh green hues.
In contrast, the harvested fields are a dusty yellow-grey, dotted
with upright bundles of rice straw. Bony zebu cattle are driven
over the remaining stubble to graze. Many farmers grow rice for
their own consumption. They usually earn money from fruits and
vegetables, which thrive in their gardens thanks to the tropical
climate and good irrigation, as well as from small-scale livestock
farming. This is how the three sisters manage things as well.
“Since we’ve been fertilising our gardens with the residuals from
the biogas plant, everything grows even better,” says Bun Heang.
Mini Biogas Plants from Australia
The plant from the Australian provider ATEC has a capacity of
just 1.4 cubic metres, enough to process the dung from two to
three cows or five to six pigs. The plastic tanks, with their two
chambers and nozzles, are made by a Cambodian manufacturer.
The cookers are imported from China. “The capacity of the
plant is suited to the average size of most farms in Cambodia,”
explains Nikolai Schwarz, Head of Global Operations at ATEC.
The German national has lived in Cambodia for 11 years and has
worked for ATEC for three years.
He welcomes the author of this text and the accompanying
photographer at the company’s offices in a former textile
factory, which the startup rents in Phnom Penh. With its
galleries, co-working spaces, kindergartens, cafés, unisex
toilets, and yoga studios, The Phnom Penh Factory could easily
be located in Berlin. Visitors can cycle around the extensive
grounds on free yellow bikes. “With this location, we attract the
kind of employees we need, competing with other companies
for talent,” explains Nikolai Schwarz.
Behind him sit young people in front of laptops wearing
headsets, making calls. ATEC’s business focuses on clean
cooking. The team of 15 sells energy-efficient induction cooktops
in Cambodia. A further branch, with more staff, operates in the
much larger market in Bangladesh.
So far, ATEC has sold 2,500 biogas plants and cookers in
Cambodia. The team uses methods that might seem unusual
for this customer base. “Most of our business comes through
social media and phone calls; we don’t send representatives out
into the countryside.” Most customers, or their working children,
are introduced to ATEC’s biogas plants through Facebook ads.
Through online surveys, the team filters out those who are
genuinely interested in a biogas plant. Only then does a sales
conversation take place over the phone.
Instalment Payments Finance Upfront Costs
A biogas plant – including piping, stove, and installation – costs
around 800 US dollars. This is equivalent to four times the
monthly minimum wage, or approximately twice the average
monthly household income in Cambodia. Most customers
pay for the plant in monthly instalments of around 30 dollars.
Around 10 percent of customers fall behind on payments, but
the majority eventually meet their obligations. Only a small
proportion default entirely.

62
ENGLISH ISSUE
CAMBODIA – A BRIEF OVERVIEW
During the Vietnam War, parts of Cambodia were heavily
bombed by the United States. After the war, a quarter of
the population fell victim to the brutal regime of the Khmer
Rouge. The country’s educated elite was almost entirely
wiped out, and much of the infrastructure was destroyed.
Although the Khmer Rouge were largely overthrown by
the Vietnamese occupation in 1979, it was not until 1993,
following a prolonged civil war, that the first free elections
were held. The last remaining Khmer Rouge fighters only just
surrendered in early 1999. For 38 years, Cambodia was ruled
by autocrat Hun Sen, who handed over power to his son in
the summer of 2023.
The farm kitchen of Yourn Samnang is intended to run
entirely on biogas.
Initially, the startup had installed a box with the biogas plant that
could block the plant if installments failed to materialize. The
company now relies on intensive support, both on the phone
and through visits by the technical team. This hands-on support
strategy benefits the customers as well – as seen in the case
of fruit farmer Yourn Samnang, who grows durian and cashews.
With his forty hectares of land, the former restaurant owner
is one of the larger farmers in the region. A new pickup truck
is parked outside his farmhouse. Phone numbers of delivery
drivers, friends and customers are scribbled in marker on the
roughly plastered wall of the open kitchen. A business card
from ATEC hangs nearby – Yourn Samnang had called them.
His biogas plant was not producing enough gas. Komsan Neo
arrived with a colleague to assess the situation. Did the farm
workers add too little cow dung? Was the substrate mixture
off? Or could there be a fault in the pipeline?
Komsan Neo shuts off the gas line at the digester. If residuals are
pushed out of the system over the next few days, it is okay. The
issue probably lies with the pipeline. If not, the problem is in the
digester. “I’ll call you soon – we’ll find a solution,” he says taking his
leave, folding his hands respectfully in farewell. “If he’s not satisfied,
word will spread quickly in rural areas – that’s something we can’t
afford,” the agricultural economist explained on the drive back.
Komsan Neo and Nikolai
Schwarz from ATEC.
ATEC staff: The company focuses primarily on social media
for sales outreach.

BIOGAS Journal Spring_2025 63
The Director of Biogas Technology & Information Center (BTIC) at the
Royal University of Agriculture in Phnom Penh.
Core research focuses on testing various substrates.
National Biogas Programme Has Set Up
28,000 Domestic Plants
Biogas plants are not a sure-fire success. Service and support
are essential. With the National Biogas Programme, the
Ministry of Agriculture, Forestry and Fisheries has installed
around 28,000 domestic plants in Cambodia, supported by
the Dutch development organization SNV, GIZ and the German
energy company Polarstern, among others.
However, there is no guarantee that these plants function
properly or are used consistently. Farmers require technical
know-how. Some lack sufficient feedstock throughout the
year, for example, because they have sold their livestock. It is
also important that the size of the plant is appropriate. The
majority of the plants installed through the programme are
masonry-built, underground units, available in sizes of 4, 6,
and 8 cubic metres. These so-called fixed dome digesters
are not always gas-tight. Inspection and maintenance are
difficult. The plants cannot be easily opened or cleaned. The
programme has only recently begun to offer smaller plastic
units, which are mostly installed above ground.
Tra Hean has also had to overcome challenges. He is responsible
for the generators of the lagoon biogas plant on one of the farms
of M’s Pig ACMC, one of the country’s largest pig producers.
Cambodia’s national food industry is only just beginning to
develop. Many food products are imported from Vietnam or
China. With several farms and its own feed production, M’s Pig
ACMC has grown significantly since it was founded in 2008.
Gas Quality Poses Challenges for CHP Units
One of the farms is located along the motorway between
Phnom Penh and Sihanoukville. 45,000 Animals are kept
in long rows of large barns. At the edge of this “pig city”
there is an open hall, resembling a second-hand market for
generators. The noise is deafening, though it comes from
only one machine. Over the past ten years, various models
from international manufacturers have been used here for
electricity generation. Many did not last. It was only two
years ago, with support from the United Nations Industrial
Development Organization (UNIDO) and others, that an
improved gas cleaning system could be installed to treat the
biogas. The two current generators, each with an installed
capacity of 550 kilowatts (kW), now operate reliably in
alternating shifts. “With 212,000 kilowatt-hours (kWh), we are
getting closer to our target of 250,000 kWh per month,” says
Tra Hean. This is paying off for the pig farmers. In Cambodia,
one kilowatt-hour of electricity costs 0.15 US dollars.
The institute houses the only
methane analysis device in
the country.
Equipment for domestic
biogas systems is also tested
at the institute.
Each semester, up to 15 students are trained in the fundamentals of
biogas technology.

64
ENGLISH ISSUE
Fully filled lagoons on one of the farms operated by M’s Pig.
Electricity for lighting and ventilation represents the highest
cost on the farm – even more than feed. “At this point,
we’re covering half of our electricity needs with the biogas
generators,” Tra Hean states with satisfaction. Besides cost
savings, environmental concerns were a major factor in the
management’s decision to cover the slurry lagoons and make
use of the biogas. As a result, less climate-damaging methane
is being released into the atmosphere, odour nuisance has been
reduced, and groundwater pollution mitigated. Tra Hean points
to two lagoons beside the generator hall, covered with grey
plastic sheeting. “During the rainy season, it’s cooler and the
methane yield drops. We then tighten the ropes stretched over
the covers to protect them against the wind.”
Left: Tra Hean has overcome several challenges.
Right: His colleague is now also well-versed in generator operations.
Top: Feed silos at M’s Pig, one of Cambodia’s largest pig producers.
Butom: Generator hall at M’s Pig: Due to poor biogas quality,
several engines have already failed.

BIOGAS Journal Spring_2025 65
Left: The fruit grower Yourn Samnang paid for his biogas plant in cash.
Right: Chiv Reaksmey, Managing Director at Kirirom Food Production.
In addition to the two covered lagoons, there are three more
which are still open. They will also be covered in the future to
capture more methane for electricity generation. Light blue
pipelines are already in place. However, due to currently low
meat prices, this investment has been postponed.
Many Pig Farms Flare Off Biogas
There is biogas potential in Cambodia, and it is currently
growing. There are now around twenty large pig farms in the
country. While they do collect slurry in lagoons, the methane is
mostly flared off without being used. Kirirom Food Production
in Kampong Speu Province, however, is making use of its
potential. The vast pine forests of the Kirirom Mountains, just
two hours by car from the capital city, are more reminiscent of
Mediterranean landscapes than of Southeast Asia. The national
park that has the same name was Cambodia’s first.
Top: Biogas burner for process heat at
Kirirom Food Production.
Bottom: In the factory canteen, biogas is
used to cook for 200 hungry staff.
Quality control – the dried mangoes are mainly
exported to Europe and the USA.

66
ENGLISH ISSUE
Kirirom Food Production is located in the middle of vast
mango plantations. The company cultivates 120,000 trees on
600 hectares – a substantial operation. During the harvest
season, up to one thousand workers pick and process 100
tonnes of mangoes per day into dried fruit, primarily for
export to Europe, Japan, China and the United States. Less
than 10 percent is sold on the local market. Cambodians tend
to prefer unripe, sour mangoes, which they enjoy with salt
and chillies as a snack with a drink.
“We are one of the largest processors in Cambodia,” says Chiv
Reaksmey. In the conference room, the Deputy Managing Director
offers us dried mangoes. The scent and flavour are outstanding.
Achieving this delicious final product requires large volumes of
water and heat – for peeling, blanching and drying the fruit. What
remains are the stones and peels, which are shredded and dried
into animal feed, as well as significant quantities of wastewater.
Mango Farm Utilises Biogas Plant
Unlike its competitors, Kirirom Food Production does not
discharge its wastewater into the river without being treated.
“We have invested 300,000 dollars in wastewater treatment
and an additional 50,000 dollars in biogas technology,”
explains Chiv Reaksmey during the tour. At Kirirom Food
Production, the biogas is also collected under tarpaulins
stretched over lagoons. When full, they resemble the humps
of whales. During peak season, when all three lagoons are
well filled, the company produces up to 20,000 cubic metres
of biogas per month.
The process is optimised by recirculating material from the
lagoons back into the settling tank. “This allows us to work
with a consistently controlled substrate,” says Chiv Reaksmey.
However, since the methane content rarely exceeds 50
percent, the gas is not suitable for use in generators for
electricity production. Instead, it is used in a large burner to
generate process heat. Prior to commissioning the biogas
plant, the factory burned 34 cubic metres of wood from old
mango and cashew trees each day. One cubic metre of this
wood costs 18 dollars. “Thanks to the biogas, we have been
able to cut wood consumption by half.”
In the factory canteen kitchen, biogas has even replaced wood
completely. “Have a look,” calls the cook, pointing to the high
ceiling, blackened with soot. “This is how smoky it used to
be.” She then turns back to her oversized woks, in which leeks,
garlic and onions are sizzling. Large bowls contain tamarind
seeds, water spinach and other vegetables. On a wooden
block, a colleague is chopping chickens with a cleaver.
Rice fields at lake Tonle Sap, which swells to four times its size during the rainy season.

BIOGAS Journal Spring_2025 67
The two women don’t have much time for a chat. In an hour,
around 200 hungry staff members will take their seats at the
long tables in the canteen. Kiriom Food Production produces
all the ingredients for their meals on a small company-owned
farm, which lies at the end of a row of six ponds. Treated
wastewater from the settling tanks and lagoons flows into
the ponds. Propellers churn oxygen into the water. In the last
two ponds, water striders, fish and frogs bear witness to the
good water quality.
Surrounded by mango plantations: Kirirom Food Production.
Treated Wastewater Allows the Cultivation of
Fruit and Vegetables
“During the dry season, we use it to irrigate the fruit and
vegetables on our small farm, where we also successfully apply
fertiliser derived from the residual materials of the biogas plant,”
explains Chiv Reaksmey. The good, healthy food, fair wages for
workers, high environmental standards and sustainable energy
production benefit Kirirom Food Production for its marketing on
the export markets of Europe, Japan and the USA. In addition to
wastewater use, the management also considered using mango
peels as substrate. However, this is not feasible in a lagoonbased
system, as the solids are difficult to remove. All the other
technical solutions have so far been ruled out as too costly.
A visit to the Biogas Technology & Information Center (BTIC),
established in 2016 at the Royal University of Agriculture in
Phnom Penh, further illustrates the limitations in Cambodia,
despite its dynamic economic growth, which has experienced
setbacks since the COVID-19 pandemic. Alongside research into
various substrates and other projects, 15 female students are
trained at the BTIC each semester.
The BTIC is home to the only biogas analysis device in the
entire country. All the major biogas projects in Cambodia have
collaborated with the BTIC. The centre also worked on developing
a locally produced, low-cost biogas filter. However, this work
could not be completed due to the expiry of research funding.
The limited resources in the country do little to dampen the
spirits of the two sisters in Siem Reap. Their biogas plants
operate reliably, above all thanks to regular feeding with the
right mixture of dung and water. After finishing their work in the
garden, they will sit down in the evening at their gas stoves and
begin preparing dinner. Even the wild grandson settles down and
climbs onto Bun Houn’s lap. And the ducks can finally rest.
Treatment of process water at Kirirom Food Production.
Lake Tonle Sap is one of the world’s largest and most fish-rich lakes.
AUTHOR
Klaus Sieg
Freelance Journalist
00 49 1 71 6 39 42 62
klaus@siegtext.de
www.siegtext.de
Wastewater treatment facility at Kirirom Food Production.