Comparison of life cycle assessment of large-scale biogas projects with different raw materials in China

The anaerobic digestion (AD) disposal of stover and cattle manure is of great significance to the development of low-carbon economy and green energy in China, but it will also have an impact on the environment, and the degree of influence is different for various raw materials. In this study, life cycle assessment (LCA) methods were applied to analyze and compare the impact of corn stovers biogas projects (CSBP) and dairy manure biogas projects (DMBP) on the environment during the whole operation stage. The results of inventory analysis were evaluated by ReCiPe2016 Hierarchy(H) mid-point (problem-oriented) and end-point (destruction-oriented) method, respectively. The results showed that the net energy efficiency of CSBP was higher (763.903 kW·h/FU) and the greenhouse gas (GHG) emission reduction of DMBP was more (5541.418 kg CO₂-eq/FU). The anaerobic digestion (AD) units have the greatest environmental impacts, and human carcinogenic toxicity is the largest environmental impact category (1.16-1.43 PE). The key to reducing environmental impact is reducing the input of chemical substances and the waste of electric energy. Both CSBP and DMBP have a favorable impact on ecosystem quality and resources, and CSBP is more beneficial to the environment (–10.297 Pt). Co-digestion is an important measure to reduce the environmental damage from biogas projects. These research results provide theoretical support for the selection of raw materials for large-scale biogas projects in China, provide technical basis for reducing the impact of actual operation on the environment, and promote the resource utilization of agricultural waste and carbon dioxide emission reduction and sequestration.