November 25, 2020

5.5.3 Anaerobic Digestion

Anaerobic digestion is a proven technology that extracts energy in the form of biogas from organic waste. The process provides several environmental benefits. Digestion of agricultural slurries yields a substance that has lower pollution potential and is more suitable than raw slurries for plant uptake. Global warming dividends arise because electricity generated from biogas displaces fossil fuel generated electricity and thus reduces carbon dioxide emissions to the environment.

Environmental Benefits of Anaerobic Digestion:

  • Anaerobic digestion has the potential to deliver multiple environmental benefits, including reduced water pollution potential, lower greenhouse gas emissions, and reduced odours from agricultural slurries. In places that have high concentrations of animal waste threatening water quality centralised anaerobic digestion can play a significant role in managing the problem.
  • It affords greater water quality benefits than standard slurry storage because Anaerobic digestion digestates has lower pollution potential, and its nutrients are more amenable to plant uptake and thus avoid leaching into the soil.
  • Anaerobic digestion also provides additional benefits in terms of meeting our targets under the Kyoto Protocol and EU Directive 2001/77/EC on electricity from renewable energy sources.
  • EU funded research concluded that the external cost, in terms of global warming, public health, occupation health, and material damage related to coal sourced electricity production is €0.06-0.08/kWh.46 In the case of the 500 tonne/day AD plant external costs averted would amount to some €600,000 per annum.

The major stumbling block for Anaerobic digestion is that its financial return is insufficient to repay the significant  investment outlay.  More information on