Economic optimization of a bioenergy-based hybrid renewable energy system under carbon policies—from the life-cycle perspective

Rural areas are rich in renewable energy sources, such as wind, solar, and biomass. Bioenergy is a “zero-carbon energy”; therefore, bioenergy-based hybrid renewable energy systems (HRESs) are expected to be an important path for rural energy transformation. However, economic conditions make it difficult to mobilize investors in rural areas. Based on carbon emissions measured via life cycle assessment, an economic optimization mechanism was developed for HRESs under three carbon policies. The impacts of these three policies, carbon tax, carbon cap-and-trade, and carbon offset, on the economic and emission reduction benefits of HRESs were explored. The results showed that the introduction of biomass intermediate pyrolysis poly-generation could significantly reduce HRES emissions. Particularly, “carbon fixation” in biochar accounts for >60% of negative carbon emissions. By participating in the carbon mechanism, the economic benefits of the HRES in this study increased by $6776 compared with that of the integrated energy system in the urban area. This would effectively improve the dynamism of bioenergy-based HRESs. Considering the demands of different stages, the carbon policy implementation path “carbon offset – carbon cap-and-trade – carbon tax – carbon cap-and-trade” for HRESs was proposed. Based on a sensitivity analysis, the reference point of government carbon pricing can be obtained. The optimization mechanism may provide a reference for policymakers and investors, as well as help form a replicable and scalable HRES model in rural areas in the future.