1. New biogas concepts for increasing the overall economy of biogas production
Hinrich Uellendahl
Section for Sustainable Biotechnology
A.C. Meyers Vænge 15, 2450 Copenhagen ph

2. Biogas research Denmark @ Aalborg University Copenhagen (AAU Cph)
From March 1, 2019:
Biogas research group
Hochschule Flensburg
University of Applied Sciences
Hochschule Flensburg, Germany
Section for Sustainable Biotechnology
Department of Chemistry and Bioscience
Aalborg University Copenhagen (AAU)
Hinrich Uellendahl
Biogas Research on:
Process optimization by
Reactor design & configuration
Process control
Biomass pretreatment
Biogas as part of biorefinery

3. 27 Centralized biogas plants
Biogas research with respect to full-scale operation
27 Centralized biogas plants
Capacity:
20 – 600 kton/year
Full-scale biogas plants in Denmark
WWTP
Industry
Waste disposal
Centralized plant
Farm-scale plant
Production
(TJ/year)
(MW)
0.7 – – 12.7
Under construction
New plant

4. Full-scale biogas plants in Denmark - Recent trends:
LARGE SCALE Capacity ≥ 500 kton/year
Combined with biogas upgrading for use in natural gas grid or as transportation fuel
Biogas plants as nutrient banks
Biogas to counteract fluctuating renewable electricity production - Power-to-gas technologies - Flexible biogas production
Maabjerg Biogas (2012)

5. Full-scale biogas plants in Denmark - Challenges:
CHP
plant +
BioGAS
Manure as main feedstock
Additional organic waste with high biogas yields is limited
Increasing shares of solid (lignocellulosic) biomass - straw, deep litter, grass, biowaste etc.
Digestate as valuable fertilizer product
Biogas upgrading has significant costs
Adaptation to flexible biogas production
Biogas
Upgrading
≥ 75% Manure
≤ 25% Organic waste,
Solid biomass
Natural Gas Grid
Digestate
Fertilizer N,P,K

6. Full-scale biogas plants in Denmark - Challenges:
Manure as main feedstock - High water content,
Additional organic waste with recalcitrant fibers high biogas yields is limited
Increasing shares of solid - Treatment for enhanced (lignocellulosic) biomass hydrolysis necessary - straw, deep litter, grass, biowaste etc.
Digestate as valuable fertilizer - Separation and distribution product of nutrient fractions
Biogas upgrading has significant costs - New upgrading technologies
Adaptation to flexible biogas production - Process control

7. Biogas potential of solid waste biomass
Biogas plant
Clover grass
Sugar beets
Majs/corn
Sugar beet tops
OFMSW
Aquatic biomass
Garden waste
Road-side biomass
Non-cultivated fields
Nature areas
Catch crops
Straw
Ind. Organic waste
50% Manure
Organic fraction of municipal solid waste
Agricultural
residues

8. Improving the biogas plant economy
Increasing biogas yields of manure - Solid-liquid separation to and nutrient management lower transportation costs
Increasing biogas yields of - Improved process, new lignocellulosic biomass process concepts, integration of pretreatment
Biogas as part of a biorefinery - Extraction of high-value biomass fractions before biogas production

9. New concepts to increase the biogas yield per ton of biomass supplied
Solid-liquid separation at farm – only manure fibers to biogas plant
Manure
Biogas plant
BioGAS
Manure fibers
Mixing tank
6-8%TS
15-30%TS

10. New concepts to increase the biogas yield per ton of biomass supplied
Increasing the biogas yield of manure fibers
Manure
Biogas plant
BioGAS
Manure fibers
Mixing tank
Enhancing hydrolysis by
Increasing HRT (DK: d, DE: 100 d), several reactors in series
Increasing the temperature (from 37°C to 52°C)
Pretreatment of lignocellulosic biomass

11. New concepts to increase the biogas yield per ton of biomass supplied
Pretreatment methods for lignocellulosic biomass
Physical/mechanical
Thermal
Chemical
Biological
Grinding, milling, maceration, ultrasound etc.
Steam explosion, Wet oxidation @ ºC, +/- O2
Addition of acid, base etc.
Fungi, hydrolytic bacteria and their enzymes

12. Change in biogas potential
New concepts to increase the biogas yield per ton of biomass supplied
Effect of pretreatment dependent on content of lignocellulosic biomass
Increase of biogas yield by mechanical maceration of manure
Change in biogas potential
after maceration (%)
Biogas potential of influent (L-CH4/kg-VS)

13. New concepts to increase the biogas yield per ton of biomass supplied
Effect of pretreatment dependent on content of lignocellulosic biomass
Increase of biogas yield by pretreatment in combination with TS increase

14. Digested fiber fraction Pretreated digested fibers
New concepts to increase the biogas yield per ton of biomass supplied
Pretreatment of the digested fiber fraction
Separation
Digested fiber fraction
Liquid
fertilizer
Pretreatment
Pretreated digested fibers
Manure
Biogas plant
BioGAS
Manure fibers
Mixing tank 51 m3
/tonfeed 35 43
+ Pretreatment
+ Recirculation

15. Biomass Biogas as part of a biorefinery Biogas
Organofinery project: Biorefinery for organic protein feed, fertilizer & energy
Mechanical
Fractionation
Green Juice
Organically grown
Biomass
Brown Juice
Protein
precipitation
Press cake
Biogas
Protein concentrate
Biogas
plant
Organic
Fertilizer
Organic Feed

16. Biogas as energy storage buffer
Energy storage of fluctuating excess electricity
Power-to-gas
Using H2 to convert CO2 into CH4 or other products
Flexible electricity production from biogas

17. Biogas as energy storage buffer
XEL2Gas project: Acetic acid as a storage molecule for excess electricity
Combination of H2 utilization and biogas upgrading

18. Main conclusions for improved biogas concepts
Increasing yield per m3: Combination with solid-liquid separation
Reactor design and configuration: Process parameters (OLR, HRT, temperature) dependent on biomass characteristics and if biogas yield or productivity should be increased
Pretreatment: specifically on recalcitrant fraction, combination with solid-liquid separation, pretreatment of digested manure fibers
Higher valorization/New biomass options for integration with other biorefinery processes
Utilization of excess electricity combined with biogas upgrading
Flexible biogas production vs. larger gas storage capacity

19. New biogas concepts for increasing the overall economy of biogas production
Vielen Dank für Ihre Aufmerksamkeit! Tak for opmærksomheden! Thank you for your attention!
Hinrich Uellendahl