European Bio-Energy Projects

BIO-HPR
Objectives
Decentralised conversion of biomass and
wastes requires cheap and efficient
conversion systems with a power range
below 1 MW thermal input. Common
concepts with integrated gasification of
biomass and internal combustion engines
are still not commercially available due to
the so-called tar problem.
The “Biomass Heatpipe Reformer” concept
comprises a quite simple solution for this
problem: Hot gas cleaning avoids
condensation of tars and allows the use of
these tars in micro turbines and in high
temperature fuel cells. However suitable
small-scale engines like gas turbines and
fuel cells require hydrogen rich fuel gases
with comparably high heating values. The
conversion of solid biomass and organic
wastes in decentralised plants especially
demands a small-scale gasification system
which is able to produce high calorific
product gases with a simple,
easy-to-handle gasification set-up
and thus so-called allothermal or
indirect gasification.
Indirect gasification solves
tar problem
Challenges
The Biomass Heatpipe Reformer design focuses
on small-scale combined heat and power systems
(CHP-systems) with hot gas cleaning and micro
turbines. Hydrocarbons and tars condense at
temperatures below 200 – 250°C forming tar
layers in the piping or in the engine. Conventional
internal combustion engines require fuel gas
inlet temperatures below 100°C, whereby the
condensation of tars cannot be avoided.
Appropriate gas cleaning technologies are too
expensive for small-scale systems and cause
additional environmental problems. Possible
solutions are systems with hot gas cleaning
and micro turbines. Hot gas cleaning avoids
quenching of the product gas, associated
efficiency losses and the condensation of tars.
However micro turbines require heating values
above 10000 kJ/kg. The required heating values
are only achievable by means of allothermal
gasification in fluidized bed gasifiers. A new
concept – indirectly heating of a gasifier by
means of high temperature heat pipes –
promises to improve the performance of indirect
heated gasifiers significantly.
The expected heating value of the product gas
allows its combustion in standardized micro
turbines without significant modification of the
combustion chamber.
The hot gas cleaning will not only avoid the
condensation of tars it will also allow the reduction
of the gasifier dimensions. The tar content
depends not only on the reaction conditions like
excess steam ratio, temperature and pressure it
depends also on the retention time of the product
gas in the reactor. Accepting higher tar
concentrations will therefore allow the reduction
of the height of the reactor and will reduce the
necessity for costly catalysts.
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Project structure
The project is aimed at the development and
demonstration of two prototypes for a smallscale
allothermal gasifier. The first prototype
will test the main components of the gasifier
separately. The second prototype comprises an
integrated design, which meets the requirements
of a commercial application.
The consortium consists of six partners from
Germany, Austria and Greece. The RTD partners
are the Technische Universität München
(Coordination), University of Stuttgart and
National University of Athens. Industrial partners
are the companies DMT, Germany (engineering)
Luft- und Feuerungstechnik (former Polytechnik,
manufacturer), Austria and Saarenergie, Germany
(end user). An NAS extension of the project
includes three additional partners from Hungary
(University of Budapest), Romania (ICCPTE) and
Cyprus (Hyperion). The project extension will
focus on the gas cleaning and micro turbine
subsystems in order to demonstrate the whole
system.
Expected impact
Due to political boundary conditions there is
actually a large demand for biomass conversion
systems especially in Central Europe and
Scandinavian countries. Within a few years more
than one thousand heating plants with a power
range between 100 kW and a few MW thermal
input will be established in Bavaria and Austria
alone. The German market for heating plants with
wood chips amounts actually to approximately
50-60 M€ per year. The investment costs for the
Biomass Heatpipe Reformer will not considerably
exceed the costs for heating plants. Heating grid,
housing and the ancillaries like fuel feeding
system, control system, boiler and flue gas