possible integration of biogas+bioethanol processing - bioenergybaltic

Integration of biogas and bioethanol process 

Piotr Oleskowicz-Popiel 

PhD student 

Biosystems Department 

Risø DTU – National Laboratory for Sustainable Energy 

Technical University of Denmark 

Email: piotr.o.popiel@risoe.dk 

Co-authors 

Erik Steen Jensen 

Mette Hedegaard Thomsen 

Henrik Haugaard-Nielsen

Bioresources for bioenergy purposes 

Piotr Oleskowicz-Popiel 

2000 – 2003: bachelor at Poznan University of Technology, 

Department of Chemical Technology, PL 

2003 – 2005: MSc in Eng in Industrial Biotechnology, 

Aalborg University Esbjerg, DK 

2005 – 2007: research assistant, Department of Bioenergy 

Aalborg University Esbjerg/University of Southern Denmark 

2007 – present: PhD student, Biosystems Department, 

National Laboratory for Sustainable Energy 

and Technical University of Denmark (Risø DTU)


1. Sustainable production of biofules: biogas and bioethanol 

2. Second generation biofuels: IBUS concept 

3. BioConcens Project 

4. Bioprocess modelling (with SuperPro Designer®) 

What is sustainability? 

What are the advantages from 

the co-production of biofuels? 

First or second generation biofules?

Solar CO 2 H 2 O 

energy N,P,K, 

Sustainability assessment 

Biorefinery 

Products 

Industrial chemicals 

Biofuels 

Electricity 

Heat 

Polymers 

Materials 

Fertilizers 

Food ingredients 

Feed 

Bioresources 

Biochemical 

Thermochemical 

Extraction 

Sustainability assessment 

4

Multifunctional land use 

Land use 

Goods 

Food 

Fibers 

Fuels 

Chemicals/materials 

Water protection 

Soil fertility 

Biodiversity 

Recreation 

Bioremediation 

5

Biomass-to-biofuel pathways 

Biomass 

Lignocellulosic 

biomass 

Thermoche 

mical/gasification 

Pretreament and 

enz.hydrolysis 

Syngas 

2G technology 

Catalysed 

synthesis 

BTL 

F-T diesel 

DME 

Methanol 

Sugar 

Fermentation 

og destillation 

Ethanol 

Sugar- and 

starch crops 

Oil plants and animal 

fat 

Milling and 

enz. hydrolysis 

Extraction 

1G technology 

Transesterification 

Biodiesel 

Residues and 

organic waste 

Fermentation 

and cleaning 

Biogas 

and H 2 

Adapted from: Erik Steen Jensen: Lignocellulose-based biofuel production –bioresources, technologies and sustainability 

6

Biomass-to-biofuel pathways 

Biofuels in the EU. A vision for 2030 and beyond. Final draft report of the Biofuels Research Advisory Council 

7

Crops for 1G biofuel 

8

1G biofuels (ethanol and biodiesel) and associated crops 

• The use of known 1G crops and cultivations methods is not likely 

to influence positively the environment – but will increase the 

competition for land with other uses (feed and food) 

• The protein fraction of the biomass can be used for feed (DDGS 

and rapeseed cake) 

• Crop residues from food and feed crops can be used for 2G 

biofuels to some extent 

• Cultivation of marginal soils (including set-aside) with annual crops 

increases the risk for loss of nutrients and transport of pesticides to the 

aquatic environment. 

• Some annual crops are problematic from an environmental point 

of view – e.g. maize and oilseed cultivation are associated with large 

leaching losses (table) 


9

Perennial crops for 2G bioethanol and BTL 

10

Lignocellulose - residues and waste 

11

Anaerobic Digestion (AD) 

Suspended organic matter 

Hydrolysis 

Proteins Carbohydrates Lipids 

Polypeptides 

Peptides Mono and disaccharides Volatile acids and glycerine 

AD is commonly used for the treatment 

of animal manure, organic waste from 

agriculture and urban areas and food 

industry. 

Acidogenesis 

Acetogenesis 

Organic compounds: volatile 

fatty acids, alcohols, lactic acid 

Mineral compounds: CO 2 

, 

H 2 

, NH 4+ 

/NH 3 

, H 2 

S 

Acetic acid CO 2 

, H 2 

Microbiological conversion of organic 

matter to methane in the absence of 

oxygen. The process is also known as 

the biogas process and has been 

widely utilized in wastewater treatment 

plants. 

Methanogenesis 

Methane production: 

CH 3 

COOH => CH 4 

+ CO 2 

(Acetotrophic methanogenesis) 

CO 2 

+ H 2 

=> CH 4 

+ H 2 

O (Hydrotrophic methanogenesis) 

adapted from: Benabdallah El-Hadj T. (2006) ISBN: 84-690-2982-7 

12

Sustainable cycle of Anaerobic Digestion 

Anaerobic digestion is a natural 

process during which bacteria 

break down the carbon in 

organic material 

The biogas plant has 

three main products: 

-biogas (source of energy) 

-liquid fertilizer 

-fiber for compost 

Al Seadi T.: Good practice in Quality Management of AD Residues; Task 24 – Energy from Biological Conversion of 

Organic Waste; Department of Bioenergy; University of Southern Denmark. 

13

Utilisation of digestate 

• To be recycled as fertilizer, digestate must 

have a defined content of macronutrients. 

Average samples of digestate must also 

be analyzed for heavy metals and 

persistent organic contaminants, making 

sure that these are not exceeding the 

detection limits permitted by law. 

• The application of digestate must be done 

on the basis of a fertiliser plan, elaborated 

for each agricultural field. The experience 

shows that an environmental and 

economic suitable application of digestate 

fulfils the phosphorus requirements of the 

crops and completes the nitrogen 

requirements from mineral fertiliser. 

Al Seadi T. ed.: Biogas from AD, Bioexell training manual; Department of Bioenergy; University of Southern Denmark. 

14

Digestate as a fertilizer 

Highly efficient fertiliser can be achieved 

from co-digestion of cow manure (high in 

potassium), pig manure (high in 

phosphorous), and suitable agricultural 

wastes and by-products. Due to the fact 

that the digestate is nutritionally defined, it 

can be used very efficiently. Application of 

digestate as bio-fertiliser decreases 

nutrients loss as well as pollution of water 

from nutrients. Additionally, it results in 

saving energy consumption for production 

of chemical fertiliser. To obtain all these 

benefits though it is necessary to apply 

what is called a “good agricultural practice” 

Nordberg A., Edstrom M.: Waste management in 

northern Europe: experiences from the Linkoeping 

biogas plant. European workshop: Impact of Waste 

Management Legislation on Biogas Technology, 

Tulln, Austria, September 12-14, 2002. 

Parameter 

Total solids [%] 4.5 

Volatile solids [%TS] 75 

pH 8.1 

Total-N [kg/m 3 ] 7.2 

Ammonia-N [kg/m 3 ] 4.9 

P [kg/m 3 ] 0.7 

K [kg/m 3 ] 1.0 

Digestate 

Linkoeping 

Pb [mg/kgTS]

Digestate as a fertilizer 

Average concentrations of nitrogen, ammonia, and phosphorous in digestate from Danish 

centralised co-digestion plants 

http://www.mst.dk/default.asp?Sub=http://www. 

mst.dk/udgiv/publikationer/2004/87-7614-282- 

5/html/kap04.htm - Danish Environmental 

Protection Agency, Danish Ministry of the 

Environment 

Biogas plant 

Total N 

[kg/ton] 

NH 4 

-N/NH 3 

[kg/ton] 

P 

[kg/ton] 

Blaabjerg 4,75 3,25 1,1 

Blåhøj 5,30 3,8 0,84 

Fangel 5,83 4,38 0,92 

Filskov 4,90 3,7 0,94 

Hashøj 5,05 3,9 0,78 

Lemvig 4,28 3,02 1,2 

Lintrup 5,00 3,26 1,3 

Nysted 4,84 3,79 0,90 

Ribe 4,6 3,2 0,9 

Sinding-Ørre 2,6 2,2 1,2 

Snertinge 4,3 3,0 1,3 

Studsgård 3,86 2,79 0,86 

Thorsø 4,80 3,6 0,96 

16

Safe recycling of digestate 

Good agricultural practice - experience from Denmark 

• Source sorting and separate collection of digestible wastes, preferably in 

biodegradable recipients. 

• Selection / excluding from AD of the unsuitable waste types / loads, based 

on the complete declaration of each load: origin, content of heavy metals 

and persistent organic compounds, pathogen contamination, other potential 

hazards etc. 

• Periodical sampling and analysing of the biomass feedstock. 

• Extensive pre-treatment/on site separation (especially for unsorted waste). 

• Process control (temperature, retention time etc.) to obtain a stabilised end 

product. 

• Pasteurization / controlled sanitation for effective pathogen reduction. 

• Periodical sampling, analysing and declaration of digestate. 

• Including digestate in the fertiliser plan of the farm and using a “good 

agricultural practice” for application of digestate on farmland. 

Al Seadi T. ed.: Biogas from AD, Bioexell training manual; Department of Bioenergy; University of Southern Denmark. 

17

Ethanol fermentation 

IBUS 

http://www.nasa.gov 

H(C 6 H 10 O 5 ) n OH enzymes n C 6 H 12 O 6 

162 kg 180 kg 

n C 6 H 12 O 6 yeast 2n C 2 H 5 OH + 2n CO 2 

180 kg 92kg 88kg 

From the chemist/engineer point of view 

Jacqus K. et al.: The Alcohol Textbook. 3rd edition, Nothingam 

University Press, 1999. 

From the microbiologist point of view 

18

Biomass to bioethanol 

Mandil C. eds.: Biofules for transport. An international perspective. IEA, 2004. 

19

Lignocellulose degradation 

Lignocellulose 

pre-treatment 

cellulose* 

carboxylic acids + CO 2 + H 2 O 

+ lignin degradation products 

hemicellulose* 

*source: Bjerre A.B., Skammelsen 

Schmidt A.: Development of Chemical 

and Biological Processes for Production 

of Bioethanol: Optymalization of the Wet 

Oxidation Process and Characterization 

of Products, Risø National Laboratory, 

1997, Roskilde, Denmark [Riose-R- 

967(EN)] 

20

Bioethanol and Biogas potential 

Petersson et al.: Potential bioethanol and biogas production using lignocellulosic biomass from winter rye, oilseed rape and 

faba bean. Biomass and Bioenergy 31 82007) 812-819. 

21

Biogas and Bioethanol potential 

Petersson et al.: Potential bioethanol and biogas production using lignocellulosic biomass from winter rye, oilseed rape and 

faba bean. Biomass and Bioenergy 31 82007) 812-819. 

22

Real life example 

The principles: 

-About one-third of the corn—the starch—is converted 

into ethanol, and another one-third into thin stillage, 

which is used in the anaerobic digesters for heat and 

biogas. The other one-third, a combination of protein, 

oils, and fibers called distiller's grain, is usually sold as 

feed for cattle. However, this grain is wet when it exits 

the ethanol plant, and traditionally equipment costing 

several million dollars must be used to dry it before 

transport in order to prevent spoilage 

-Corn byproducts, including cellulose from the corn 

stalks, also go into the biogas brew. 

- the water pollution problems are solved by removing 

manure from feedlots 

How can we improve the system? 

How can we increase sustainability of the process? 

http://www.e3biofuels.com 

23





4. Bioprocess modelling (with SuperPro Designer®) 

First or second generation biofules? 

Based on: Mette Hedegaard Thomsen 

Biomass & Bioenergy Conference, 27th-29th of February 2008, Tallinn, Estonia

1. generation 2. generation 

The use of known 1G crops and 

cultivations methods is not likely to 

influence positively the environment – but 

will increase the competition for land with 

other uses (feed and food) 

Crop residues from food and 

feed crops can be used for 2G 

biofuels to some extent 


25

Lignocellulose degradation 

Lignocellulose 

pre-treatment 

cellulose* 

carboxylic acids + CO 2 + H 2 O 

+ lignin degradation products 

hemicellulose* 

*source: Bjerre A.B., Skammelsen 

Schmidt A.: Development of Chemical 

and Biological Processes for Production 

of Bioethanol: Optymalization of the Wet 

Oxidation Process and Characterization 

of Products, Risø National Laboratory, 

1997, Roskilde, Denmark [Riose-R- 

967(EN)] 

26

2. generation Bioethanol production 

Enzymes 

Microorganism 

C5 

Pretreatment 

Hemicellulose 

Hydrolysis 

Enzymes 

Fermentation 

Yeast 

Cellulose 

C6 

Bio-Ethanol 

Lignin 

Hydrolysis 

Fermentation 

Distillation 

27

Co-production Biofuels (EU-project: 2003-2006, Danish project: 2006-2009) 

Objective: Co-production of electricity and bioethanol 

Goal: Construction and testing of a pilot scale pretreatment reactor system 

with a planned capacity of 1000 kg of biomass per hour. 

Integrated Biomass Utilisation System (IBUS) 

1.step: Pilot scale reactor with a capacity of 100 kg/h 

Partners: 

Elsam A/S (DONG Energy) 

Risø National Laboratory - DTU 

The Royal Veterinary and 

Agricultural University 

TMO Biotech (EU-project) 

BioCentrum - DTU (Danish 

project)

IBUS 1000 kg/h plant 

195-200ºC 

90-100% cellulose 

convertibility 

50% hemicellulose 

recovery 

180ºC + 195ºC 

90-100% cellulose 

convertibility 

83% hemicellulose 

recovery

Advantages of the IBUS process 

• Simple and fast process 

• Enzymes and hot water 

• Process time < 100 h 

• Can be upscaled 

• Energy efficient 

• No milling 

• High dry matter (40%) 

• Power plant integration 

• Flexible biorefinery 

• The lignin fraction contains sufficient energy to 

run the process!

Cut wheat straw 

Heat pretreated wheat straw 

31

High dry matter liquefaction of fibre fraction 

Larsen et al, 2006 

32

GHG balance for IBUS 

Grain 

Straw 

van Maarschalkerweerd, Risø (2006) 

33

How far are we? - Feasibility study 

Production cost for straw-based ethanol 

Ethanol prod. costs [$/gal] 

8 

7 

6 

5 

4 

3 

2 

1 

0 

20% 30% 40% 50% 60% 70% 80% 90% 100% 

Case 1 

Case 2 

Case 3 

Case 1 = C6, stand alone 

Case 2 = C6, integrated (with power plant) 

Case 3 = C6+C5, integrated 

Cellulose conversion ratio [%] 

Ref. Jan Larsen, Dong Energy, 28th Symposium on Biotechnology for Fuels and Chemicals, May 2006, Nashville. 

Latest feasibility study based on 1000 ton pr day IBUS ethanol plant located in the US (cost and 

income), corn stover 40 EUR/t DM and enzyme cost 0.14 EUR/liter ethanol. 

Raw production cost: 0.43 EUR/liter ethanol (2.40 US$/gal) 

World market price 0.35 EUR/liter, EU-market price 0.55 EUR/liter [Morgan Stanley Equity Research, oct. 2007]

AD manure as water and nutrient source 

Pre-treatment (Wet-Oxidation) 

Straw, Water or AD Manure 

SSF: Enzymes, Yeast 

Product: Ethanol 

Xylose Fermentation 

Product: Ethanol 

Source: Thomsen A.B., Medina C., Ahrling B.K.: Risø Energy Report 

2. Biotechnology in ethanol production. Risø National Laboratory, 

Denmark, November 2003. 

Anaerobic Digestion 

Product: Biogas 

Oleskowicz-Popiel P. et al.: Ethanol production from maize silage as lignocellulosic biomass in anaerobically 

digested and wet-oxidized manure. Bioresource Technology. in press 

35

AD manure as water and nutrient source 

fermentation of IBUS straw in pre-treated AD manure and water 

ethanol [g/100g] 

1,8 

1,6 

1,4 

1,2 

1 

0,8 

0,6 

0,4 

0,2 

0 

0 20 40 60 80 100 120 140 160 

time [h] 

Straw+121.0 

Straw+121.12 

Straw+Water 

manure 121.12 

Successful ethanol 

fermentation in AD manure as a 

water and nutrient source 

3400 

3200 

ammonia [mg/L] 

3000 

2800 

2600 

2400 

2200 

2000 

0 20 40 60 80 100 120 140 160 

time [h] 

Straw 1 Straw 2 Maize 1 Maize 2 

Nitrogen uptake during ethanol 

fermentation. 

AD manure can be recirculated 

several times as a N-source 

36





4. Bioprocess modelling (with SuperPro Designer) 

Is there a future for organic farming?

BioConcens 

• Biomass and Bioenergy Production in Organic Farming – 

Consequences for Soil Fertility, Environment, Spread of Animals 

Parasites and Socio-Economy. 

• The production of biofules in organic agriculture can reduce its 

dependency of fossil fuels and decrease GHG emission 

• It might increase sustainability of organic farming 

organic 

farming 

Main stream agriculture 

38

• DARCOF – The Danish Research Centre for Organic Farming: 

”The remit of DARCOF is to coordinate research for organic farming, 

with a view to achieving optimum benefit from the allocated 

resources. Its aim is to elucidate the ideas and problems faced in 

organic farming through the promotion of high quality research of 

international standard.” 

http://www.darcof.dk 

• DARCOF III – research programme “International research 

cooperation and organic integrity”: 

BioConcens http://www.bioconcens.elr.dk/uk/ 

39

• BioConcens – Biomass and bioenergy production in organic 

agriculture – consequence for soil fertility, environment, spread of 

animal parasites and socio-economy 

• work package 1: Co-production of biogas, bioethanol and animal 

feed from organic raw materials: 

1. biogas potentials of raw materials 

2. co-production of biogas and fodder protein 

3. co-production of biogas and bioethanol 

40

BioConcens 

41

BioConcens – co-production of biogas and bioethanol 

• Bioethanol from starch can be substitute for diesel or gasoline. The 

method for bioethanol production from rye grain by utilizing the 

inherent amylase activity of the seed is going to be developed (to 

avoid GMO based enzymes) 

• Usage of natural enzymes and whey permeate as nutrients and 

process water in bioethanol fermentation will decrease production 

cost and increase sustainability of the process. Application of the 

effluent into the biogas process will be the additional advantage. 

42

BioConcens – co-production of biogas, bioethanol and fodder 

• The goal is to develop farm-scale, low energy demanding and “easy to 

handle” technology for production of bioethanol from rye grain. To keep the 

frame of organic farming natural enzymes will be applied (commercial 

enzymes will be used only for reference experiments). The remaining 

compounds will be recycled into biogas process. 

• Co-fermentation of clover grass (commonly grown in OA) with animal manure 

• Co-fermentation of clover grass with whey (co-production of energy and animal 

feed) 

43

BioConcens 

• From the energy balance point of 

view, the most relevant utilization of 

feedstocks and co-products will be 

modelled in SuperPro Designer 

(Intelligen, INC) 

• Bioenergy from organic sources 

should not negatively influence the 

carbon and nutrients cycle – the 

intelligent management of organic 

residues and crop rotation is 

necessary 

• Design and evaluate a combined 

concept for biomass and bioenergy 

production in OA (considering the 

soil fertility) 

44

Initial results – the idea does really work 

Ethanol concentration (g/L) 

50 

40 

30 

20 

10 

0 

Malted rye, 13% dw 

Malted rye, 13% dw 

Comm. enz., 13% dw 

Comm. enz., 13% dw 

0 10 20 30 40 

Time (h) 

400 

300 

[mL CH4 / gVS] 

200 

100 

0 

0 5 10 15 20 25 30 35 40 

time [day] 

dry grass (low conc.) 

dry clover grass (low conc.) 

clover grass silage (low conc.) 

dry grass (high conc.) 

dry clover grass (high conc.) 

clover grass silage (high conc.) 

45





4. Bioprocess modelling (with SuperPro Designer ® ) 

How to design 

an environmentally friendly process?

Modeling of a bioprocess 

Process concept 

Process design and 

development 

Modeling and 

simulation 

Literature 

Patents 

Expert 

knowledge 

Improvements 

needed 

Sustainability 

assessment 

Not 

eco-efficient 

Stop 

Eco-efficient 

Industrial application 

adapted from: 

Heinzle E., et al., (2006)Development of 

Sustainable Bioprocesses – Modelling and 

Assessment. John Wiley & Sons Ltd. 

47


• in process development we should try 

understand of the actual production process 

as early and as detailed as possible 

• the modeling of the process under 

development and a through assessment 

helps to improve this knowledge 

• the assessment should include economic 

and environmental evaluation 

• the simulation results are used to evaluate 

the process and to guide the R&D effort to 

the most promising directions and the most 

urgent problems 

• it is important to look at the whole process 

and not only to optimize single parts 

• the created models and the assessment 

based on these models include a certain 

inherent uncertainty; this uncertainty has to 

be considered and quantified 

48


• besides the economic structure of a process, environmental and 

social aspects should be considered 

• process modeling and simulation enhances our insight and 

understanding of a process and helps to identify potential 

improvements as well as possible difficulties 

• in process development, simulation can supplement experiments 

49


Define goal & process boundaries 

Collect data (internal and external) 

Define bioreactions 

Identify process flow diagram (unit operations and streams) 

Define unit operation models 

Perform simulations 

Make inventory analysis and assessment 

adapted from: 

50 

Heinzle E., et al., (2006)Development of Sustainable Bioprocesses – Modelling and Assessment. John Wiley & Sons Ltd.


• What are required amounts of raw materials and utilities? 

• What is the required size of process equipment and supporting utilities? 

• Can the product be produced in an existing facility or a new plant is required? 

• What is the total capital investments? 

• What is the manufacturing cost? 

• What is the optimum batch size? 

• How long does the single batch take? 

• How much product can be generated per year? 

• What is the demand for raw materials, labor, utilities, etc.? 

• Which process step can be a bottleneck? 

• What changes can increase throughout? 

• What is the environmental impact of the process? 

• Which design is the best among several possible alternatives? 

adapted from: 

Petrides D., Bioprocess Design and 

Economics. Oxford University Press, 2003. 

51


• After a model for the entire process is developed on the computer, 

tools like SuperPro Designer ® can be used to ask and readily answer 

”what if” questions and carry out sensitivity analysis with respect to 

key design variables. 

• SuperPro Designer ® - simulation program that is able to estimate 

both process and economic parameters. 

52


• Computer simulations provide the ability to estimate the effect of 

increasing costs of raw materials or utilities, variations in material 

compositions, and the incorporation of new technologies 

• Beginning with a base-case scenario and designing the model to 

simulate those conditions effectively allows the user to estimate 

results of alternative processes with confidence. 

photo: www.siteselection.com 

Kwiatkowski J.R. et al: Modeling the process and costs of fuel ethanol production by the corn dry-grind process. 

Industrial Crops and Products 23 (2006) 288-296 

53

Modeling the process - simplified flow diagram 

150 million l/year plant 



54


• Grain receiving 

• Liquefaction, saccharification, and fermentation – all the reaction, 

volumes, residence times, agitation/pumping power required, and 

other operating parameters may be adjusted to imitate an existing 

fermenter or make use of experimental data. The model will scale 

the unit to accommodate any change in raw material plant 

throughput 

• distillation and ethanol recovery 

• stillage processing – 

• final products – fuel ethanol (with app. 5% denaturant – gaoline), 

DDGS (an animal feed rich in protein – 27.8%) 



55


• The actual process contains more than 100 pieces of equipment and unit 

operations 

• The process simulator quantifies the processing characteristic, energy 

requirements, and equipment parameters of each major piece of equipment 

for the specified operating scenario. 

• Volumes, composition, and other physical characteristic of input and output 

streams for each equipment item are identified. This information becomes 

the basis of utility consumptions and purchased equipment costs for each 

equipment item. 

• Composition of a raw agricultural feedstock varies by year and location, this 

can be easy adjusted 

• Different raw materials can be input in the model. although, maybe some 

extra unit operation need to be given 



56

Cost model description 

• Equipment costs 

• Feedstock costs 

• Product values 

• Utility costs 

• Capital costs 

• Annual production and unit costs 

• Sensitivities 



57

Lysine flow sheet 

The lactic acid fermentation of brown juice in the green crop drying plant as it 

was simulated in SuperPro Designer 

Thomsen MH: Complex media from processing of agricultural crops for microbial fermentation. 

Mini-Review, Appl. Microbiol. Biotechnol (2005) 68: 598-606 

58

Priority of sustainable land and bioresource use 

Erik Steen Jensen 

59

possible integration of biogas+bioethanol processing - bioenergybaltic

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