Anaerobic digestion produces biogas from wet organic waste such as leaves, roadside and natural grass, straw and organic waste. Wageningen Food & Biobased Research explores new possibilities for biorefinery concepts based on anaerobic fermentation.
During the process of anaerobic fermentation, microorganisms break down biomass in an oxygen-free environment. Fermentation takes place in four steps: Hydrolysis, fermentation (acidogenesis), acetogenesis and methanogenesis. The last step leads to the production of biogas and digestate (a wet residue).
Positive business case for fermentation
Anaerobic digestion from waste usually achieves a low level of biogas production. There are high costs associated with the disposal of the digestate, and efficient application of biogas may be cumbersome at the (remote) locations where it is produced (usually farms). This is part of the reason why it is difficult to make a positive business case for the production of biogas. Applying different pretreatment techniques allows us to increase and accelerate the production of biogas. This improves yields and reduces the capital cost of the fermenting plant. The cost of the disposal of digestate can be reduced by removing nitrogen and phosphate from the digestate using separation techniques. The resulting substances can then be sold as fertiliser or processed into animal feed.
Markets for biogas
Biogas is currently mostly burned in combined heat and power plants (CHP) on farms. Such plants often struggle to find a useful application for the produced heat. Wageningen Food & Biobased Research is investigating opportunities to refine biogas for different markets: Car and truck fuel, CO2 for greenhouses and heat for companies. We are also researching possibilities to produce nitrogen and phosphate fertilizers from digestate (manure refining).