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!)

Resources

• 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.