Two-stage pressurized anaerobic digestion - An invention to foster biogas injection into a natural gas grid
- Publication Type
- Contribution to conference
- Authors
- Wonneberger, A.-M.; Graf, F.; Lemmer, A.; Reimert, R.
- Year of publication
- 2011
- Published in
- International Gas Research Conference Proceedings
- Band/Volume
- 2/
- ISBN / ISSN / eISSN
- 978-162276385-6
- Page (from - to)
- 903-915
- Conference name
- International Gas Union Research Conference 2011 (IGRC 2011)
- Conference location
- Seoul; South Korea
- Conference date
- 19 October 2011 through 21 October 2011
The DVGW Research Station at the Engler-Bunte-lnstitute of the Karlsruhe Institute of Technology, Germany (DVGW-EBI, KIT) and the State Institute of Agricultural Engineering and Bioenergy at the University of Hohenheim, Germany (LAB) are developing a two-stage pressurized anaerobic digestion process for biogas production. This development aims for facilitating a subsequent injection of produced biogas into a natural gas grid by adjusting already the anaerobic digestion process for the gas grid injection. In two-stage pressurized anaerobic digestion the two main decomposition steps hydrolysis/acidogenesis and acetogenesis/methanogenesis are spatially separated. Further, the methanogenesis reactor is operated under elevated pressure whereby a biogas at injection pressure (> 5 bar) is produced. Additionally, at elevated pressure the fermentation liquid has a (chemical) scrubbing effect on the produced gas resulting in higher methane content. Experimental investigation of the process has started at the LAB. A model based upon material balances, solubilities and liquid phase reactions was set up to quantify the effect of pressurized anaerobic digestion on gas composition. First results of the simulation predict that the methane content of the biogas can exceed 80 % while being supplied at pressures above 5 bars. The additional expenses due to the higher complexity of the process compared to conventional biogas production and upgrading could be balanced by savings in process energy and additional gains by electricity from the hydrolysis gas.