By Laura Palombi
In my first review, I focused on how the oils sands industry is one reason why Canada is not on track to meet its Kyoto emissions reduction targets. Despite this setback, Canada is working to expand its biofuel industry and has set targets of 5% renewable content for gasoline by 2010 and 2% renewable content for diesel and home heating oil by 2012. In this review, I will explore how wood biomass and warm-season prairie grasses could contribute to meeting these targets and the implications for land use demands and large-scale commercial production.
In 2007, gross sales of gasoline in Canada were 40.9 billion liters and gross sales of diesel were 17.2 billion liters (1). Accounting for increased demands for fuel, Canada’s Prime Minister Stephen Harper estimates that approximately 3 billion liters/year will be required — a 750% increase in production, given that only 400 million liters were produced in 2006 (2). New, efficient feedstocks must come on line in order to meet demand without jeopardizing the food supply or creating a net CO2 e input to the atmosphere over the lifecycle of the feedstock production.
Although the biofuels industry started with an emphasis on corn ethanol production, it soon became clear that reductions in CO2 emissions could not be realized by using corn as a feedstock. For example, US Department of Energy Studies indicated that corn ethanol produces 79% of the CO2 emissions of gasoline (3). In a 5% gasoline blend, as Canada is targeting, emissions would only be reduced by about 1%. 2006 data shows that only 53% of agricultural land was used for crops (4), leaving approximately 64 million hectares of land available for agricultural production of feedstocks. Although one crop may be more efficient than another at reducing emissions compared to using unblended fuel, the diversity of habitat conditions and soil types throughout Canada requires a portfolio of products that are adapted to various local growing conditions. The actual number of tones of CO2 e offset by meeting the renewable content goals will depend on the process of growing, harvesting, processing and replanting of the feedstock crop or forest land.
A promising second-generation feedstock crop is one of several varieties of warm season (C4) prairie grasses. Using native prairie grass species, such as switchgrass, for cellulosic ethanol production has several advantages. First, it is inexpensive to grow since it is perennial, it thrives on marginal land and the variety of species makes it possible to choose a mix that is adapted to local soil and climate conditions. Yield estimates are about 10 t/ha in southern Canadian grasslands. About 2.5 kg of switchgrass are required to produce 1 liter of ethanol (5). Therefore, about 7.5 million ha of cropland (24% of 2006 unplanted agricultural land) could produce enough switchgrass/ethanol to meet Canada’s targets. In the US, production of 10.6 billion liters of ethanol required 3.3 million ha of crop land in 2004 (6), or about 25% more than what would be required to produce the same volume of ethanol from switchgrass.
Unfortunately, the major disadvantage for prairie grass at this point in time is the lack of technology to efficiently convert the biomass to ethanol. In fact, the conversion process is even less efficient than for corn, resulting in 50% more energy required to produce a liter of ethanol than the energy yield of the ethanol compared to 29% for corn (7). This hurdle must be overcome before policy encourages agricultural production of prairie grass species for ethanol production. In the mean time, the dry biomass does have a significant advantage if used as fuel substitute for natural gas, coal or oil. 1 GigaJoule of energy from production of switchgrass produces 1.9 kg of CO2 emissions, compared to 13.8 kg for natural gas, 22.3 kg for petroleum, 24.7 kg for coal and 30.0 kg for oil sands (8). This provides a good incentive for developing switchgrass production and conducting further studies about the potential to store carbon in soils by establishing prairie biomass crops.
Cellulosic ethanol production from wood waste biomass also has potential. Canada’s forest lands cover approximately 402.1 million hectares and produced a harvest volume of 188.2 million m3 in 2006. Less than 1% of forest land is harvested each year, so an estimate of harvest volume per hectare can be estimated as 46.8 m3/ha. Using a conversion factor of 0.361 (9) to calculate the oven-dry weight, this is equivalent to 16.89 ODt/ha. 1 ODt produces 350 liters of ethanol. Therefore, 507,485 ha of forest land would be required to produce 3 billion liters/year of ethanol from wood biomass. This is about 0.12% of Canada’s total forest land or 13% of harvested area each year. This assumes that 100% of the above-ground biomass is used for ethanol production. An alternative calculation is to use an estimate from the Canadian Center for Policy Alternatives which measured post-logging biomass waste in British Columbia at 4.5%. If this proportion is extrapolated across the Canada’s total harvest, the post-logging waste accounts for 0.76 ODt/ha; enough to produce 8731 liters of ethanol per year.
Since removing waste biomass from harvest areas and transporting it long distances to processing facilities drastically reduces the energy efficiency and carbon benefits of using wood biofuel, and the potential for ethanol production volume is low, it makes more sense to establish aforestation projects specifically for wood biomass for ethanol production near a processing facility. A case study by the Canadian Forest Service estimates that a new facility capable of producing 122 million liters of ethanol per year would require up to 960 oven-dry tones of wood biomass per day (10). Over a 12-year harvest rotation, this would require 4,161,000 ha of land for the aforestation project, or about 13% of the unplanted agricultural land in 2006 converted to forest crops. As is the case with switchgrass, the energy required to produce ethanol from wood biomass is more than the energy yield by 57% in this case (11).
The technological “silver bullet” to bring these promising sources of ethanol to market is yet to be found. Interestingly, some of the same investors in the oil sands projects are also investing in finding the breakthrough. For example, the Iogen Corporation, in which Royal Dutch Shell has a 50% equity stake, has a demonstration wheat straw cellulosic ethanol plant in Ottawa. ExxonMobile notes in their energy outlook report that they expect to see an impressive growth rate of 9% in wind, solar, and biofuels combined, which will account for 2% of global energy demand by 2030. However, after hearing a recent presentation at the University of Michigan by an ExxonMobile strategic planner, it was clear that they are not as involved in pursuing the technology necessary for advancing these fuels as Shell or BP. Federal dollars are also available to farmers wishing to pursue new market opportunities in the agricultural bioproducts sector. When the renewable fuels standard was introduced, Agriculture Minister Chuck Strahl also announced US $300 million for 2 programs, the Agricultural Bioproducts Innovation Program and the Capital Formation Assistance Program for Renewable Fuels Production. Still, investment in biofuels is dwarfed by the US $85 billion in international investments in oil sand production(12).
If the cost and technology barriers can be overcome, Canada’s goals will easily be accomplished and will lead to better renewable energy options. The Canadian government should continue to work on encouraging international investment and providing financial incentives for biofuels research and development in order to make these investment options more attractive on all scales. The growing body of knowledge about land use consequences of biofuel crop production will aid Canada in making policy decisions and offering incentives that reflect the best practices for producing biofuel crops with minimal negative impacts on soil carbon and maximum benefit for offsetting fossil fuel use.
1. Government of Canada. Sales of fuel used for road motor vehicles, by province and territory. http://www40.statcan.gc.ca/l01/cst01/trade37a-eng.htm (Accessed April 9. 2009).
2. Government of Canada. “Government’s new biofuels plan a double win: Good for the environment and farmers.” Press Release. 5 July 2007. http://www.pm.gc.ca/eng/media.asp?category=1&id=1731 (Accessed April 9, 2009).
3. Samson, Roger A. and Omielan, Joseph A. Switchgrass: a potential biomass energy crop for ethanol production. Proceedings of the Thirteenth North American Prairie Conference: Spirit of the Land, Our Prairie Legacy. Wicket, Robert et al eds. 1992.
4. Government of Canada. Total farm area, land tenure and land in crops by province (Census of Agriculture, 1986-2006).
5. Pimentel, David and Patzek, Tad W. Ethanol Production Using Corn, Switchgrass, and Wood;
Biodiesel Production Using Soybean and Sunflower. Natural Resources Research. Vol 14:1, March 2005.
8. Samson, Roger A. and Omielan, Joseph A. Switchgrass: a potential biomass energy crop for ethanol production. Proceedings of the Thirteenth North American Prairie Conference: Spirit of the Land, Our Prairie Legacy. Wicket, Robert et al eds. 1992.
9. Graham, Peter J. Potential for climate change mitigation through afforestation: an economic analysis of fossil fuel substitution and carbon sequestration benefits. Agroforestry Systems 59: 85-95. 2003.
11. Pimentel, David and Patzek, Tad W. Ethanol Production Using Corn, Switchgrass, and Wood;
Biodiesel Production Using Soybean and Sunflower. Natural Resources Research. Vol 14:1, March 2005.
12. Krauss, Clifford (2006). “Oil sands shift economic power in Canada.” International Herald Tribune. March 28, 2006. http://www.iht.com/articles/2006/03/27/business/alberta.php (accessed March 2, 2009).