WASHINGTON—The government may be saying full steam ahead on biofuels, but some scholars say the merits of alternative fuels still are debatable.
“Why is it that we think that bioenergy has the potential to save greenhouse gas emissions?” asked Timothy Searchinger, a Princeton University lecturer and research scholar at the Princeton Environmental Initiative.
In part, because biofuels don’t stay in the atmosphere as long as petroleum and other traditional fuels, responded Bruce E. Dale, professor of chemical engineering and material science at Michigan State University, who faced off against Searchinger at the World Congress on Industrial Biotechnology and Bioprocessing last week.
The event, which brought together business leaders, investors and policy makers in biofuels, biobased products, and renewable chemicals, culminated in the debate between the two scholars that focused on biofuels and their impact on greenhouse gas emissions.
When bioenergy is burned, Searchinger pointed out, what’s produced is carbon dioxide. And, bioenergy generates more CO2 per unit of energy than fossil fuels because there’s more carbon per unit of energy in biomaterial than in fossil fuels. Simply put, bioenergy itself does not reduce the emissions from combustion.
But, the government doesn’t seem to agree.
Earlier this year the Environmental Protection Agency finalized revisions to the National Renewable Fuel Standard program that increased the volume of renewable fuel required to be blended into transportation fuel from about 13 billion gallons now to 36 billion gallons by 2022. The increased use of renewable fuels to meet the 36 billion gallon mandate is estimated to displace approximately 13.6 billion gallons of petroleum-based gasoline and diesel, reported the agency, and prompt a decrease in gas prices by 2.4 cents per gallon.
The agency also predicts that these measures will reduce greenhouse gas emissions by 138 million metric tons by that same year; the equivalent of taking about 27 million vehicles off the road.
The key issue ought to be replacing petroleum, Dale said.
Searchinger “leaves something very important out of this discussion,” Dale said. “Unless you think that we are going to stop using petroleum fuels, then the comparison he’s made here is a false one.”
According to Dale, biological carbon in the atmosphere will be recycled through plants, while carbon taken from below ground and burned as fuel will stick around in the atmosphere for a long time.
He suggests that while biofuels still emit carbon, they are a better option than fossil fuels because they can be recycled.
But Searchinger said the atmosphere doesn’t care where its carbon comes from. There is little benefit from burning one source of carbon dioxide instead of another, he said. Rather, there has to be plant growth to offset what is being burned, and burning biofuels doesn’t increase plant growth any more than burning fossil fuels does.
“Ultimately you have to have additional plant growth or you have to take biomass that would otherwise go back into the atmosphere if you want to have a greenhouse gas reduction,” he said.
He uses the example of crop residue—things like corn cobs, husks and stalks—as biomass that would go back into the atmosphere as carbon dioxide even if the corn is used to make an alternative fuel—ethanol.
The use of such biomasses for fuel may increasingly become a reality as a proposal by the U.S. Department of Agriculture would provide financing to increase the conversion of biomass to bioenergy.
Under the Biomass Crop Assistance Program , which started in June 2009, producers can obtain funds from the Department of Agriculture to match the costs of collecting and transporting eligible materials to biomass conversion plants. The production of new biomass crops was not included.
In February, a new rule was proposed to expand the funding to all parts of biomass farming. The USDA is reviewing thousands of comments submitted on this proposal and is expected to draft a final rule to be published this fall.