Give your car a drink, save the planet, and end dependence on foreign oil. That's more or less the plan George W. Bush unveiled during his State of the Union message earlier this week, in which he also declared his intention to "fund additional research in cutting-edge methods of producing ethanol, not just from corn, but from wood chips and stalks, or switch grass." By throwing tax dollars at research on how to turn vegetation into alcohol to burn in our cars and trucks, Bush hopes to move the country "beyond a petroleum-based economy, and make our dependence on Middle Eastern oil a thing of the past."
Currently, about 3.4 billion gallons of ethanol for fuel is produced from fermenting sugars and starches derived from corn. This ethanol is blended into gasoline in the United States and is equal to about 2 percent of all gasoline sold by volume and 1.3 percent of its energy content. The federal Energy Policy Act of 2005 requires that 7.5 billion gallons of renewable fuels be blended into gasoline by 2012 and the government offers a $0.51 per gallon of ethanol tax credit. A federal government study in 2005 envisioned biofuels replacing 30 percent of petroleum consumption by 2030.
The motivations behind the push for ethanol vary. For farmers and farm state politicians it's another agriculture subsidy. For foreign policy hawks, it's a way to free our country from dangerous dependence on unstable and hostile regimes. It's also an answer to peak oilers who claim that the world is about to run out of fossil fuels. Environmentalists see ethanol as fuel that does not add more man-made heat-trapping gases to the atmosphere and thus helps curb global warming. But will producing alcohol to burn in internal combustion engines really save the planet and cut dependence on foreign oil? Maybe.
For years, scientists have been fighting over whether making ethanol from crops uses more energy than it produces. On negative side stand Cornell University ecologist David Pimentel and University of California-Berkeley environmental engineer Tad Patzek. They published a study last July that found that producing ethanol using crops used 29 to 57 percent more fossil fuel energy than it saved.
Last week, the Energy and Resources Group at UC-Berkeley headed by Alex Farrell published an analysis in Science of six energy balance studies on producing ethanol, including the Pimentel and Patzek study, and came to the opposite conclusion. The Berkeley team found that current methods of producing ethanol from crops, chiefly corn, generate about 20 percent more energy than they use. Farrell argues that the Pimentel and Patzek study included out-of-date information and did not count the co-products such as animal feed that result from ethanol production. Stay tuned—this spat among ecologists and environmental engineers is far from over.
In any case, most researchers agree that turning what is essentially food into fuel is not a good strategy in the long term. As President Bush mentioned, they envision a future of biorefineries churning out ethanol from non-food biomass including wood chips, corn stalks, willow trees, and switch grass. The idea is that the tough cellulose and lignin that hold plant cells together can somehow be broken down into simpler sugars and starches that can be fermented into ethanol. One problem—producing ethanol in this manner costs way too much now.
However, in Science last week, another team of researchers outlined a path toward a future fueled by billions of gallons of cellulosic ethanol. Their vision of the biofueled future involves a great deal of genetic engineering that is guaranteed to give unending nightmares to the anti-biotechnology wing of the environmentalist movement.
For example, the researchers foresee plant scientists engineering "energy crops" to at least double the biomass produced per acre. They note that plants typically capture less than 2 percent of the light that falls on them for use in photosynthesis. They suggest boosting plant photosynthesis by installing more efficient genes from bacteria. They point to research in which genes dealing with nitrogen metabolism taken from a species of pine tree and inserted into poplars increased the poplars' height by 41 percent and stem diameter by 36 percent over three years.
Other research aims to make the biomass produced by energy crops easier and cheaper to break down into sugars and starches that can be fermented into ethanol. For example, some forestry geneticists already use bioengineering to insert a molecular switch that reduces the amount of tough lignin a tree produces while increasing the amount of cellulose. Another idea for softening up cellulose is to install a gene for the enzyme cellulase in energy crops, a gene which will later be activated to break down cellulose by spraying the crops with a trigger compound just before harvest. On the plus side for leery anti-biotech types, energy crops could be engineered so that they did not produce seeds or flowers—which, incidentally, would encourage them to stop wasting resources on reproduction and just make more biomass.
The pathway to a partially biofueled future may actually work technically and may produce more energy than it uses. One can even imagine that biofuels could become cheaper than fossil fuels. If that's the case, the industry will not need any federal subsidies to take off. And there is great side benefit for culture war spectators: They can pull up a ringside seat and watch as the global warming faction of the environmentalist movement thrashes the anti-biotechnology wing.