Sustainable evaluation and optimization strategies for black tea production: insights from emergy analysis

The extensive scale of tea production has resulted in a substantial demand for inputs such as fertilizers and pesticides in tea gardens, contributing to increased greenhouse gas emissions and environmental challenges. Therefore, it is critical to assess the environmental impacts of the tea industry quantitatively to improve the sustainability of tea production. Based on preliminary data and materials, exergy analysis and life cycle impact assessment theory were employed in our work to comprehensively evaluate the sustainability of Chinese black tea production system through the planting, processing, and packing stages. The results indicate that the planting stage dominates emergy inflows, accounting for 67% of the total emergy. The dominant emergy contributor in the planting stage is fertilizer (1.53×1020 sej/year). Electricity and labor (un-renewable) are the primary emergy inputs in the processing stage, contributing 2.53×1019 sej/year and 3.44×1019 sej/year, respectively. Moreover, the contribution of packaging materials (aluminum, 3.92×1019 sej/year) to the system’s emergy is highlighted, signaling their substantial influence. This study recognizes key factors which affect the sustainability of the black tea production system, providing a scientific basis and actionable strategies for the sustainable development of China’s black tea production system.