中国林木生物质能源替代煤炭的减排效益评估

Quantifying the mitigating effects and benefits from substituting wood biomass for coal in energy production in China

应对全球气候变化的能源转型方案中,生物质能源替代化石燃料是重要的选项,中国资源丰富的林木生物质在替代化石燃料的能源转型中具有重要价值。本文以木质颗粒燃料及传统的化石燃料(煤炭)为研究对象,基于生命周期思想梳理不同能源系统的温室效应排放指标与经济评价指标边界,从传统的生命周期分析与经济指标分析两方面,探讨中国木质颗粒燃料替代煤炭的减排效益和经济效益。结果表明:①木质颗粒燃料替代煤炭供热或供电时,单位能量的供应能耗降低0.01~0.176 MJ,在碳中性假设下,木质颗粒燃料具有显著的碳减排效益;②平均市场价格下,木质颗粒的单位热能成本高于煤炭,即用木质颗粒燃料替代煤炭供能时,单位热能或电能的使用需要付出较高的燃料成本,约为16.06~34.16元;③敏感性分析表明,能量转换率、燃料热值和燃料的价格对替代效益的影响最为显著,提高能源使用效率、降低燃料价格等措施可以大幅度降低燃料替代使用成本,实现环境与经济双赢。生物质能源的开发及利用在未来中国能源结构转型中具有重要地位,本文从碳中性下的净减排、生物质原料问题、提高减排效率和财政补贴等方面提出了针对性建议。

Substituting fossil fuels with bioenergy is one of the most promising options for energy transition in China, and abundant forest biomass plays an important role in this process. In this study, the mitigation effects and economic benefits from substituting wood pellets for coal in heat and power generation in China were investigated, based on a life-cycle assessment and economic contribution analysis using the system boundaries defined for the two energy systems in terms of greenhouse gas emissions and economic cost. The results suggest that:(1) When wood-based pellet replaces coal in heat and power generation, the life cycle energy consumption per unit of energy produced decreases(0.01-0.176 MJ), and the greenhouse gas emissions are significantly reduced if wood pellets are assumed to be carbon neutral;(2) Based on the average market prices of wood pellets and coal, the cost per unit heat or electricity generation by burning wood pellets is higher than that of coal(16.06-34.16 Yuan), because the energy used in wood pellets production is more costly;(3) The sensitivity analysis suggests that energy conversion efficiency, fuel energy content,and fuel price are the most important factors that affect the effectiveness of energy substitution;and reducing energy consumption and the overall cost for producing wood pellets is most effective for reducing the substitution cost and creating a win-win situation for both climate mitigation and economic development. The development and utilization of forest biomass play an important role in China’s energy structure transformation. This study can inform policy development from the aspects of emission reduction under carbon neutrality assumption, source of biomass, emission reduction efficiency, and financial subsidies.