National-level evaluation of the economic and environmental advantages of retrofitted biomass-coal co-firing power plants

Biomass–coal co-firing is an effective strategy to mitigate greenhouse gas emissions from coal-fired power plants, yet its economic benefits remain insufficiently assessed. This study develops a national-level economic benefit evaluation model integrated with a computable general equilibrium (CGE) framework to assess both economic and environmental outcomes of biomass–coal co-firing retrofits. The model examines the effects of technological options, co-firing ratios, fuel prices, biomass subsidies, and their interactions. Results indicate that upgrading existing equipment offers greater profitability than adopting biomass torrefaction. Higher co-firing ratios, lower coal and biomass prices, and increased subsidies significantly enhance economic performance, with the co-firing ratio exerting the strongest influence. Coal price changes also have a greater impact than biomass price variations. Under optimal conditions—10% subsidy increase, 15% coal price reduction, 70% co-firing ratio, and equipment upgrade—the unit economic benefit reaches £0.287/kWh, yielding total benefits of £1675.3 million. Conversely, under adverse conditions—5% subsidy cut, 15% coal price rise, 30% co-firing ratio, and torrefied biomass—the benefit drops to £0.135/kWh, or £718.9 million in total. These findings provide practical insights for policymakers in optimizing co-firing strategies under diverse economic and environmental conditions.