Multi-dimensional performance evaluation of straw heat utilization scenarios based on transportation and boiler type

Biomass energy utilization is one of the effective technological ways to achieve the goal of carbon neutrality. Different scenarios for heat utilization of straw in China, namely straw pellet fuel boiler for heating, straw gasifier for cogeneration and straw direct combustion boilers for cogeneration (circulating fluidized bed, water-cooled vibrating grate and combined grate) and were evaluated and compared by energy flow analysis (EFA), life cycle assessment (LCA) and life cycle costing (LCC) methods. The system boundary includes two stages: (Ⅰ) straw collection, processing and transportation; (Ⅱ) straw energy conversion. EFA results show that the heat utilization efficiency of corn straw direct combustion cogeneration scenarios is 35.50 %–39.81 %, which is higher than the 30.13 % of the gasification cogeneration scenarios. LCA results show that the straw direct combustion cogeneration scenarios is more environmentally friendly, in which the combined grate exhibits the lowest environmental impact with an ECER value of −2.8 × 10−9. LCC results show that the combined grate scenario has the lowest economic cost of −165.05 RMB, but the payback time as 16 years. The straw heating scenario has the highest economic cost of −66.89 RMB, but it only takes 7 years to break even. Overall, combined grate cogeneration is more environmentally friendly, but less economically sustainable. Transportation accounts for 2.3 %–3.8 % of the environmental impact throughout the entire lifecycle and increases with factory scale.