Life cycle environmental impacts of electricity from biogas produced by anaerobic digestion

Lead University: The University of Manchester

Professor Adisa Azapagic, Dr Allesandra Fusi

Collaboration:Università degli Studi di Milano

Associate Professor Marco Fiala, Dr Jacopo Bacenetti

Summary

The need to mitigate climate change and improve security of energy supply is driving a growing interest in renewable energy sources, with many world regions and countries setting ambitious targets. For example, the EU directive on the promotion of the use of energy from renewable sources sets the target of achieving a 20% share of energy from renewable resources by 2020, including biogas produced by anaerobic digestion of agricultural feedstocks. The aim of this study was to evaluate life cycle environmental impacts associated with the generation of electricity from biogas produced by the anaerobic digestion of agricultural products and waste. Five real plants were considered, using maize silage, slurry, and tomato waste as feedstocks and cogenerating electricity and heat (the latter is not utilised).

Highlights

  • The biogas from animal slurry is the best option for most impacts.
  • Electricity from biogas is environmentally more sustainable than grid electricity for most impacts.
  • If climate change is the priority, electricity from other renewables is a better option than from biogas.
  • Subsidies for heat utilisation would improve significantly the environmental sustainability of biogas electricity.
  • Open digestate storage should be banned and spreading on land should be minimised.

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