The study is described as the most detailed examination to date of the energy costs associated with production of biofuels such as biodiesel, which is basically a non-toxic, animal or plant oil-based fuel that can be burned in any standard, unmodified diesel engine in pure form (B100) or in a blend with petroleum diesel.

The controversial study, which could have an impact on both soybean and corn producers, concludes that soybean biodiesel nets 93 percent more energy than what's required to produce it, while corn-based ethanol nets just 23 percent more energy, CanWest News reports.

However, the authors point out that regardless of net benefits, neither soybeans nor corn should be the foundation of an alternative fuel industry because neither can replace much petroleum without impacting food supplies. While global demand for food is expected to double within 50 years, the demand for fuel will double in 32 years at current consumption rates.

"Turning a food crop into energy when we actually need food, when the demand for food is going up around the world, is just not a very wise policy," co-author David Tilman told CanWest.

Still, the report challenges earlier studies that argue there is a net energy loss in the production of ethanol from corn once the cost of farm equipment, environmental impacts and distillation are factored in.

Last year, Dr. David Pimentel, professor of ecology and agriculture at Cornell University said, "the environmental benefits of mandating the use of biodiesel are overstated." His study found that biodiesel production using soybean required 27 percent more fossil energy than the biodiesel fuel produced and that biodiesel production using sunflower required 118 percent more fossil energy than the biodiesel fuel produced.

"These [ethanol and biodiesel] strategies are not sustainable," Pimentel wrote in his report, which was later trumpeted by opponents of mandatory biodiesel legislation like the Ontario Trucking Association.

The National Biodiesel Board, along with other government and academic officials, were quick to blast the study because it didn't stand up to "other more thoroughly conducted, peer-reviewed studies that show biodiesel actually yields more than three times the amount of energy it takes to produce."

While University of Minnesota's Dr. Tilman for the most part concurs, he holds out hope that more cost-effective methods of producing biofuels could be developed -- such making it from grass or wood fiber.

Biofuel, specifically ethanol, is growing in popularity in the U.S. at a much faster pace than in Canada, due in part to economic subsidies for American corn farmers.

Ontario in fact is one of the largest producers of soybean in North America, but it's a commodity whose price can swing wildly depending on the success of the soybean crop.

The State of Minnesota was one of the first states in the U.S. to mandate a B5 biodiesel blend for trucks filling up in that jurisdiction.

-- with files from CanWest News