By David Suzuki with Faisal Moola

Not long ago, the question at the pump was always, "regular or unleaded?" Today, leaded gasoline isn't even an option in most developed countries. And with the need to drastically reduce our consumption of fossil fuels, the question of the future just might be "switchgrass or algae?"

Of course, I'm being somewhat facetious. In their raw form you couldn't run your car on either. However both organisms have the potential to be made into biofuels such as ethanol or biodiesel. And that, if done in a careful and sustainable way, could greatly reduce the greenhouse gas emissions that cause global warming.

However, in spite of some of the hoopla about biofuels, there are still many obstacles to overcome. Yes, you can already get ethanol mixed with your gasoline or biodiesel mixed with your regular diesel in many North American cities. In fact, in countries like Brazil, gasoline is always blended with at least 20 per cent ethanol and you can easily get 100 per cent ethanol for your car. So far, so good. But these biofuels have problems too.

As I discussed in a column last fall, a widespread adoption of biofuels, such as biodiesel and ethanol could cause serious damage to the environment and provide few benefits if the crop used to make the fuel isn't chosen carefully. Corn, for example, is the largest source of ethanol in the United States, but it is a poor choice for fuel because if you do a life-cycle analysis (looking at all the energy needed to make the stuff), the energy obtained from corn-based ethanol is only marginally better or worse than the energy you get out of it. Plus, corn is heavily reliant on fertilizers and pesticides.

Thankfully, there are plenty of other options. Canola does better in a lifecycle analysis, for example, and sugar cane — which is where Brazil gets its ethanol from — better still. However, sugar cane requires a hot climate and there are concerns that displacing Brazilian subsistence farmers to grow sugar cane will push them into slashing and burning the rainforest for cropland. So all biofuels still have an environmental, economic or social cost. If these fuels are to be sustainable, such costs need to be minimized.

One promising biofuel that scores well in preliminary studies is cellulosic ethanol made from switchgrass. According to results of a recent study published in the prestigious journal Proceedings of the National Academy of Sciences, switchgrass grown and managed for biofuel can produce 500 per cent more renewable energy than the energy it needs to be grown and processed.

For the study, researchers conducted field trials (the first for switchgrass) over five years on 10 farms in the Midwestern United States. Looking at all the production and management information from each farm, they were able to estimate greenhouse gas emissions and net energy inputs to outputs. After a life-cycle analysis, the results were very positive: greenhouse gas emissions from switchgrass-derived cellulosic ethanol on the farms were 94 per cent lower than if the energy had come from gasoline.

Another benefit of switchgrass, and part of the reason for its success in the trials, is that it is a native prairie grass that grows on agriculturally marginal land. This means that fewer chemical inputs are required to maintain the crop and makes it less likely that growing large crops of switchgrass would take away land that would otherwise be used for food production.

Biofuels have the potential to help reduce pollution and global warming emissions, as well as the regional conflicts caused by our dependence on fossil fuels. But choosing the right fuel crop for the right geographic area is critical, as is making sure that all social and environmental factors are considered. If we can overcome those hurdles, you can look for more biofuels made from waste wood, used vegetable oil, and yes, even algae, at our pumps in the future.

February 8, 2008