Estimating the EU biogas potential from manure and crop residues — A spatial analysis
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. Producing biogas from residues has received increasing attention following the debate on the impact conventional biofuel production has on food prices, poverty and land-use change. The EU, as well as major producers of biogas such as Germany and Italy, are currently revising their policy framework to incentivize the sourcing of biogas substrates from waste streams.
Given these developments it is important to improve our understanding of how large the potential is for producing biogas and biomethane from agricultural wastes in the EU, how that potential is distributed across member states, and what the main limitations to this potential are. Previous studies on the potential for producing biogas from agricultural wastes in the EU, however, have either been local cases studies that account for a host of detailed economic and technical constraints, an approach that is almost impossible to scale up to the EU level, or top-down assessments of gross substrate potentials that do not account for any of the technical and economic limitations specific to biogas production.
In this report we present a spatially explicit approach for estimating the availability of agricultural wastes - crop residues and animal manure - across the EU, which also allows for 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.
Our main results from this analysis can be summarized as follows:
* Total annually available biogas substrates from agricultural wastes in the EU28 amounts to roughly 80 million tonnes of crop residues (dry matter) and 110 million tonnes (dry matter) of animal manure.
* In our base case scenario, three quarters of the manure and a fifth of the crop residues are technically and economically exploitable for biogas production, yielding a total biogas potential from agricultural wastes of almost 700 PJ (HHV) per year.
* Animal production and arable farming are spatially highly segregated in some parts of the EU28. This leads to some areas having considerable surpluses of either dry, carbon-rich crop residues or nitrogen-rich manures which cannot be fully utilized due to technical constraints on dry matter content and carbon-to-nitrogen ratios. There are, however, potential ways to relax these constraints, for example using dry fermentation technology or adding wet, carbon-rich co-substrates, such as energy crops.
* If we assume a larger minimum viable biogas plant size of 8 MW, typical if the biogas is to be upgraded to vehicle fuel quality, the potential decreases by about a quarter. However, the base case potential can still be reached or even surpassed under this constraint if one allows for a somewhat increased collection radius for substrates or if the constraint on maximum dry matter content is relaxed.