How sustainable is biogas?

This study, carried out for the Dutch Ministry of Infrastructure and Environment, explores the sustainability of domestically produced biogas using different types of biomass for use varying applications. To this end an LCA of each individual supply chain was performed, using the methodology prescribed by the National Waste Management Plan (LAP), with consideration given to global warming, acidification, eutrophication, summer smog, land use, toxicity and costs (euro per tonne CO2 reduction).
Biogas from manure, green manure crops and waste streams like domestic green waste and verge cuttings score high to very high on sustainability aspects. Biogas from feedstocks that can also be used as fodder score moderately well (fodder maize) to low (beet pulp). This is because global warming impact assessment includes the emissions associated with the crops replacing beet pulp, such as soya and wheat, which means biogas from beet pulp has around 1.5 times higher emissions than fossil gas.
In terms of reducing global warming, the greatest gains derive from use of biogas in a gas engine producing both heat and power (cogeneration). Use as ‘green gas’ in households or transport, as bio-LNG, and direct use in boilers lead to around 25% less cuts in greenhouse gas emissions.

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