As an intern at COSMOS Online:
While biofuels have significant environmental advantages over petroleum, they cannot be expected to solve the world's energy problems any time soon. A recent analysis of the costs and benefits of biodiesel and corn ethanol has revealed that while biodiesel is more than 3.5 times as efficient a fuel as ethanol, neither can be produced in sufficient quantities to replace much petroleum without affecting food supplies.
A viable fuel alternative, according to David Tilman of the University of Minnesota, U.S. who led the study, must satisfy a number of conditions: it should have environmental benefits over fossil fuels; provide a sufficient energy gain; be economically competitive; and be producible in quantities large enough to make a meaningful impact on energy demands.
Here's where both biodiesel, made from soybean, and ethanol, made from corn grain, fail. The study found that only 11 per cent of gasoline demand and 8.7 per cent of diesel demand would be satisfied, even after dedicating all U.S. corn and soybean production to biofuels.
"Current food-based biofuels can only supply about two per cent to five per cent of our transportation energy needs without significantly impacting food prices," Tillman said.
"Because global demand for both food and energy are likely to more than double in the coming 50 years, food-based biofuels are not a good long-term solution to our energy needs. It would be unwise, and expensive, to have food and energy crops compete for the world's limited supply of fertile soils."
The researchers suggest mixtures of native plant species as alternatives to food-based biofuels. Native plants may be grown on otherwise barren land and periodically harvested for conversion into energy fuels.
"Our results show that biofuels can be greatly improved by using biomass grown with low inputs of energy and agrichemicals," Tilman said. "Reducing energy use in conversion of biomass into biofuels is also of great importance. These results can help guide us to the next generation of biofuels."
Tilman mentioned two methods by which the biomass of plants can be converted into fuel. In the first method, plant cellulose is digested into sugars, which are then fermented to form alcohol. Alternatively, the plants are heated in a process called gasification to produce synthetic fuels such as gasoline and diesel.
Of the 14 billion litres of diesel consumed in Australia every year, perhaps 15 to 20 million litres of that is biodiesel, according to Brian Stewart, Corporate Affairs Manager of the Australian Biodiesel Group (ABG). ABG's biodiesel is produced from used cooking oil, tallow (animal fat) and vegetable oils such as those derived from canola.
"In Australia," Stewart said, "the view with any alternative fuel sector is that a mix of fuels will be part of the solution going forward as oil declines.
"I don't think anybody would ever say that biofuels will entirely replace fuels derived from oil at the present time, but they do certainly support a significant percentage."
But Tilman says his research serves as a warning against overly optimistic forecasts for biofuels.
"Current short-term expectations for biofuels are much too high," Tilman explained, anticipating "a bubble of over-investment" into current technologies.
"Its a major new industry – we should expect some serious bumps along the road. In the long-term, I believe that biofuels have great potential to give us both energy and environmental wins.
"In combination with various strategies for aggressive energy conservation, it is plausible that biofuels, once fully developed, could help allow the world's greenhouse gas emissions to hold steady, and not to double as has been projected. This would be a major step toward controlling global climate change."
