Exploring Farm Anaerobic Digester Economic Viability in a Time of Policy Change in the UK

The combination of a post-Brexit agricultural policy, the Global Methane Pledge announced during last United Nations Climate Change Conference in Glasgow (COP26), and urgency meeting climate goals means UK has unique opportunity to create an exemplar through recognition benefits small-scale farm anaerobic digesters that valorise on-site wastes for renewable electricity heat, cushioning agri-businesses against energy perturbations. To explore economic viability farm-based biogas production, combinations support levels, prices, capital cost, internal rate return (IRR), digestate value were analysed, employing 550-cow dairy with access other wastes. A 145 kWe system utilising 100% CHP (grid value: £0.1361 per kWh) 70% heat (heating oil £0.055 could achieve IRR above 15.5% median tariff £0.1104 kWh at from £0.0309 £0.0873 thermal. Under subsidy-free regime, same 10% prices range £0.149 £0.261 kWh. High fertiliser increase value, further improving viability. With late-2021 high technology approaches viability, but uptake is unlikely unless wider environmental societal on-farm systems can be explicitly valued.