This May, a comprehensive test on the use of biochar for the fermentation of maize silage will be started in a biogas plant with a rated output of 2.4 MW(el) in Nordrhein-Westfalen (Germany).
An increase in biogas production of more than 5% can be achieved by adding biochar to the fermentation substrate. This has been proven at a previous field test conducted at three biogas plants (each with 0.5 MW nominal capacity) in Mecklenburg-Vorpommern (Germany).
In the applied test currently being carried out, 13.5 tonnes of biochar are deployed in the biogas plant of a regional utility over a period of 3 months. Approx. 40 t of CO2 will be long term sequestered in the soil (since the biogas digestate mixed with biochar is used for soil amelioration) and thus removed from the atmosphere as a direct result of the trial.
By using biochar in biogas plants, the use of fermentation substrate can be reduced and the flowability of the fermentation substrate can be increased. Besides that, the fermentation residues are upgraded to a higher-quality fermentation fertilizer, since biochar has a high water storage capacity and helps to minimize nitrogen losses from the fermentation substrate.