Emergy-based Cost-benefit Analysis for Urban Biogas Project

Urban biogas project is important to satisfy the growing energy demands and improve the energy mix. Since the economic profits and environment impacts are essential factors for feasibility of construction and utilization of urban biogas projects, it is crucial to assess their economic and ecological performances. This paper modified the traditional cost-benefit analysis based on emergy accounting. Supporting environment which was neglected by conventional cost-benefit analysis was incorporated into the accounting boundary from emergy perspective. Moreover, the costs and benefits were calculated with emergy metric to quantify both economic and environmental contributions. The results showed that the payback period was 4.26 years due to the potential environment investments. The modified accounting framework through combining emergy theory with conventional cost-benefit analysis may unveil the real cost and benefit of urban biogas project via an energy numeraire.