Zhang Yimin, Habibi Shiva, MacLean Heather L
Department of Civil Engineering, University of Toronto, Toronto, Ontario, Canada.
J Air Waste Manag Assoc. 2007 Aug;57(8):919-33. doi: 10.3155/1047-3289.57.8.919.
We examined life cycle environmental and economic implications of two near-term scenarios for converting cellulosic biomass to energy, generating electricity from cofiring biomass in existing coal power plants, and producing ethanol from biomass in stand-alone facilities in Ontario, Canada. The study inventories near-term biomass supply in the province, quantifies environmental metrics associated with the use of agricultural residues for producing electricity and ethanol, determines the incremental costs of switching from fossil fuels to biomass, and compares the cost-effectiveness of greenhouse gas (GHG) and air pollutant emissions abatement achieved through the use of the bioenergy. Implementing a biomass cofiring rate of 10% in existing coal-fired power plants would reduce annual GHG emissions by 2.3 million metric tons (t) of CO2 equivalent (7% of the province's coal power plant emissions). The substitution of gasoline with ethanol/gasoline blends would reduce annual provincial lightduty vehicle fleet emissions between 1.3 and 2.5 million t of CO2 equivalent (3.5-7% of fleet emissions). If biomass sources other than agricultural residues were used, additional emissions reductions could be realized. At current crude oil prices ($70/barrel) and levels of technology development of the bioenergy alternatives, the biomass electricity cofiring scenario analyzed is more cost-effective for mitigating GHG emissions ($22/t of CO2 equivalent for a 10% cofiring rate) than the stand-alone ethanol production scenario ($92/t of CO2 equivalent). The economics of biomass cofiring benefits from existing capital, whereas the cellulosic ethanol scenario does not. Notwithstanding this result, there are several factors that increase the attractiveness of ethanol. These include uncertainty in crude oil prices, potential for marked improvements in cellulosic ethanol technology and economics, the province's commitment to 5% ethanol content in gasoline, the possibility of ethanol production benefiting from existing capital, and there being few alternatives for moderate-to-large-scale GHG emissions reductions in the transportation sector.
我们研究了两种近期将纤维素生物质转化为能源、在现有燃煤电厂中与煤共燃生物质发电以及在加拿大安大略省的独立设施中利用生物质生产乙醇的情景对生命周期环境和经济的影响。该研究盘点了该省近期的生物质供应情况，量化了与利用农业残余物发电和生产乙醇相关的环境指标，确定了从化石燃料转向生物质的增量成本，并比较了通过使用生物能源实现的温室气体（GHG）减排和空气污染物减排的成本效益。在现有燃煤电厂中实施10%的生物质共燃率，每年将减少230万公吨二氧化碳当量的温室气体排放（占该省燃煤电厂排放量的7%）。用乙醇/汽油混合燃料替代汽油，每年将减少该省轻型车辆车队130万至250万公吨二氧化碳当量的排放（占车队排放量的3.5% - 7%）。如果使用农业残余物以外的生物质来源，还可实现额外的减排。在当前原油价格（70美元/桶）和生物能源替代技术的发展水平下，所分析的生物质与煤共燃发电情景在减轻温室气体排放方面比独立乙醇生产情景更具成本效益（10%共燃率时为22美元/公吨二氧化碳当量）（独立乙醇生产情景为92美元/公吨二氧化碳当量）。生物质与煤共燃的经济性得益于现有的资本，而纤维素乙醇情景则不然。尽管有此结果，但仍有几个因素增加了乙醇的吸引力。这些因素包括原油价格的不确定性、纤维素乙醇技术和经济性显著改善的潜力、该省对汽油中乙醇含量达到5%的承诺、乙醇生产可能从现有资本中受益，以及在交通运输部门中大规模温室气体减排几乎没有其他替代方案。
