EU research project increases biogas yield by up to 40%, improves utilisation efficiency

Energy experts participating in a European Union research project called EU-AGROBIOGAS, recently held a meeting at the invitation of the Leibniz Institute for Agrarian Technology Potsdam Bornim (ATB), in order to discuss results from their research. The project, funded under the 6th Framework Program, and involving universities from seven EU member states, runs from 2007 until 2009. First results and the consensus amongst the participants indicated large-scale biogas production and utilization can be improved substantially.

The EU project's main goal is aimed at increasing the efficiency of all stages of producing and using biogas made in medium to large facilities. The use of biomass for the production of renewable methane is climate friendly and already relatively efficient. Feedstocks used range from manure to organic waste and dedicated energy crops.

By anaerobically fermenting the biomass, a gas mixture consisting of around 50 to 70 percent methane and carbon dioxide is obtained. The EU-AGROBIOGAS aims to increase these yields and tilt the fraction further in favor of methane. This methane fraction can be burned in cogeneration plants and thus delivers renewable heat and electricity. However, most biogas facilities do not optimally use the heat, so here too improvements can be made. Finally, biomass supply chains and preprocessing steps are currently rather inefficient.

Given these inefficiencies, the unanimous opinion of the scientists from seven countries, who met at the Seddiner lake near Potsdam, was that the project can contribute to improving the overal lifecycle efficiency of biogas production substantially. Ten key areas for intervention and research were put on the agenda:

1. To optimise the planning and operating process of agricultural biogas plants based on the European online substrate atlas-database and standardised methane energy valuation model with the aim to reduce investment costs (including quality control)
2. To optimise the biogas production through a demonstration of an innovative feeding technology to bring in the substrate or mixtures into the agricultural biogas plant
3. To monitor, identify and benchmark the main influence factors during the technological process in agricultural biogas plants based on already available data and newly monitored medium and large agricultural biogas plants (16 biogas plant operators have already agreed to co-operate)
4. To test, implement and demonstrate a newly developed monitoring, management and early-warning system for agricultural biogas plants and new and innovative technological solutions under full-scale operating conditions in agricultural biogas plants
5. To improve the degree of efficiency in the fermenter of about 35%
6. To increase the biogas yield of about 40%
7. To optimise and guarantee quality and safety of digested material
8. To improve, optimise and demonstrate several selected conversion technologies which will lead to an improvement of the degree of efficiency (CHP, heat utilisation)
9. To reduce the investment and operational costs of medium and large agricultural biogas plants of about 20 to 30%
10. To disseminate and present the demonstration projects to planners, investors and farmers as potential users and to provide inputs for the future development of energy policy and legislation

Results
Matthias Ploechl of the ATB said the potential for efficiency increases in farm based biogas operations is "almost inexhaustible". Presenting results of a first trial aimed at rationalising the utilization of cogenerated heat - a fairly simple intervention - showed the room for improvement: by coupling the process to dry biomass feedstock to the utilization of heat from the CHP plant and to waste heat recycling, the overall efficiency of heat utilization was improved by 80 percent, and the energy yield in the fermenter increased by more than 40 percent as a result of improved preprocessing of the feedstock.

Another set of results showed that a new technique to manipulate the behavior of methanogenic microorganisms used in the reactor can double biogas output. By introducing magnetic particles in the fermenter, the bacteria spontaneously flocculate around the particles and are thus far more easy to recycle; the new technique allows more continuous biogas production and keeps using the same bacteria at the height of their productive capacity and concentration:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: biogas :: biomethane :: cogeneration :: efficiency :: biotechnology :: EU ::

In current practise large amounts of active bacteria are washed away in batch systems, and new communities have to be build from scratch with each new batch. Low concentrations take a long time to grow into productive communities. By preventing this expensive work and by reusing bacteria at the point when they have become most active, overall biogas yields and the productivity of the system can be improved dramatically.

The magnetic particles in the biogas substrate attract the bacteria, which can then be recycled simply by applying a permanent magnet. Low doses of commerical materials like ferrite do the trick (0.1 gram per gram of dry matter substrate). A variant can be found in using magnetic particles contained in brown coal fly ash. Biogas yield increases of 200% have been achieved with the technique.

EU-AGRO-BIOGAS runs from January 2007 to December 2009 under the EU's 6th Framework Program. Agricultural and environmental research institutes and universities from Germany, Austria, Denmark, Great Britain, Italy, the Czech Republic and Poland are involved. The co-ordination is taken care off by the Universität für Bodenkultur Wien (University of Soil Sciences, Vienna).

The Leibniz-Institut für Agrartechnik Potsdam-Bornim e.V. (ATB) ranks among the most prominent agro-technical research organisations in Europe. Its research into the utilisation of biomass resources - not only for the generation of CO2-neutral energy but also for the production of bio-products - includes economic and ecological evaluations. The ATB takes an integrated approach to studying biomass utilisation and value creation chains - from the raw material to the product and/or from the field to the tank.

References:
Informationsdienst Wissenschaft: 30 Prozent mehr Biogas aus bestehenden Anlagen - February 11, 2008.

ATB: Mehr Leistung im Kessel - neues Verfahren macht die Biogaserzeugung effizienter [*.pdf].

EU-AGRO-BIOGAS project page.