Anaerobic fermentation of agricultural wastes such as crop residues and animal manure, producing biogas, is an example of an advanced biofuel that can contribute to the EU target of a minimum 10% of transport fuels from renewable sources in 2020. A recently published f3 report presents a spatially explicit approach for estimating the availability of agricultural wastes across the EU, also including an analysis of how key economic and technical constraints such as minimum viable plant size, maximum collection distances for substrates, and substrate composition affects the total potential for biogas production.
In the study, researchers Rasmus Einarsson, Martin Persson, Christel Cederberg and Göran Berndes from Chalmers University of Technology, Mikael Lantz, Lund University (LTH) and Johan Torén, SP Technical Research Institute of Sweden, found that three quarters of the manure and a fifth of the crop residues may be technically and economically exploitable for biogas production, yielding a total biogas potential from agricultural wastes of almost 700 PJ (HHV) per year in the EU (28 countries).
They also found that constraints regarding, e.g., maximum DM content, minimum C:N ratio, and minimum production scale all play a large role in determining the biogas potential from crop residues and manure. However, these limitations can be tackled either by loosening the constraints on the substrate supply (e.g. using dry digestion technology, or small-scale biogas plants) or by changing the substrate supply itself (adding energy crops or other suitable co-substrates to improve the chemical composition and support a larger production scale).