Emergy analysis of a biogas-linked agricultural system in rural China – A case study in Gongcheng Yao Autonomous County

• Emergy is used to assess the sustainability of a biogas-linked agricultural system.
• An emergy-based CO2 emission indicator is proposed.
• The biogas-linked agricultural system has a favorable carbon mitigation potential.

Efforts have been made to establish a biogas-linked agricultural production mode to alleviate poverty and pressure on the environment in rural China. In this paper, we evaluate the performance of biogas engineering using emergy analysis in the context of a compound agricultural system. A set of emergy indices are incorporated in the analysis to describe the transformation of energy and materials in the system. We also performed a case study in Gongcheng Yao Autonomous County, China. The carbon mitigation performance, environmental and economic trade-offs, and sustainability level of the system encompassing biogas engineering, crop production and livestock subsystems was investigated in detail. The results showed that the biogas-linked agricultural production mode characterized by further metabolism within the system made a favorable contribution to carbon mitigation and material recycling, although its conversion efficiency was low. Finally, suggestions regarding local agricultural sustainability are provided to shed light on the policies of biogas promotion in rural China.