The CO2 cutting cost of biogas from humanure and livestock manure

The European Union is accelerating its rollout of sustainable energy production and promotion of a circular economy. Electricity from biogas has synergy with energy-policy and rural-development goals yet its economic value is often convoluted. This study assessed the economic potential of biogas electricity using a representative rural case and quantified the cost and level of state support required for viability. The cost of CO2-equivalent emission reductions was determined using the recast Renewable Energy Directive (RED II). The results showed that a feed-in tariff of 0.33 sic kWh(-1) for green electricity was required for economic feasibility. This yielded a CO2 cutting cost of 251 sic t(-1). The methane energy potential was 78 467 kWh a(-1) from 31 498 kg (dry mass) of substrates, 80% livestock manure and humanure and 20% plant-based. Circular use of the digestate from anaerobic digestion, enabled a nitrogen recovery potential of 1 575 kg a(-1). The conclusions reached are that the economic value of the avoided emissions, through the RED II framework, is significant but it does not substantially improve the cost-effectiveness of biogas as an emission-mitigation technology. For biogas plant capacities less than 500 kW, current EU feed-in tariffs do not support economic viability.