Currently available agricultural residues could provide up to 1.6 billion litres (423 million gallons US) of ethanol for transportation fuel or 6.9 terrawatt hours of electricity in Ontario, according to a recent study examining the near-term potential of cellulosic biomass in the Canadian province.
Researchers at the University of Toronto used life cycle analyses to determine that co-firing available residues (an estimated 2.3 to 4.2 million tonnes annually) in existing coal-fired power plants could reduce greenhouse gas emissions in the province by 2.3 million tonnes. Alternatively, using the residues to produce ethanol/gasoline blends for transportation would reduce emissions by up to 2.5 million tonnes.
Using other sources of biomass, such as dedicated bioenergy crops, could provide additional emissions reductions; however, the near-term supply of such crops is uncertain and thus was not considered in the study.
At current oil prices, the most cost-effective option for reducing greenhouse gases is co-firing the residues, in large part because it would benefit from existing capital; in contrast, producing cellulosic ethanol would require a standalone facility.
Despite the difference in cost-effectiveness, the researchers say that producing ethanol is still an attractive end-use for the biomass for several reasons, including the need to meet the province’s 5% renewable fuel standard, the potential for improvements in cellulosic ethanol technology and economics, and the lack of other alternatives for reducing greenhouse gas emissions from transportation.
(A hat-tip to Bob!)
Y. Zhang, S. Habibi and H.L. MacLean. 2007. “Environmental and economic evaluation of bioenergy in Ontario, Canada.&rduqo; Journal of the Air & Waste Management Association, 57:919–933.