Evaluating production and utilisation pathways of a coupled Anaerobic Digestion (AD) and Gasification/Pyrolysis system using Life Cycle Analysis (LCA).

Life Cycle Analysis modelling has been applied to an operational Anaerobic Digestion (AD) plant, (utilising Cattle Slurry/Grass Silage), currently producing biogas for electricity and heat production, with digestate going to land-spreading. The aim of the research was to evaluate the environmental costs and benefits of coupling the existing plant with Gasification or Pyrolysis systems for the utilisation of digestate from the plant, producing either predominantly Syngas (Gasification) or Oils/Tars (Pyrolysis). Utilisation pathways evaluated as part of the research include the following: Gasification: Syngas to Methanation to Synthetic Natural Gas (SNG); and Pyrolysis: Syngas and bio-oil to dual-fuel electricity production. While the focus of the evaluation will be the potential GHG-eq emissions reductions achievable from the different processing and utilisation pathways, the full range of impact areas are included in the analysis. The analysis will include reflection on the challenges of applying LCA to complex biorefinery/bioenergy systems to inform future methodological developments and guidance.