Searchinger: Biofuel trend poses unforeseen hazards

In a 2008 paper in the journal Science, Searchinger said that cutting down forests to clear more land for growing biofuel crops could double greenhouse gas emissions over the next 30 years.

Biofuels are derived from relatively recently dead biological material, whereas fossil fuels — such as coal, oil and natural gas — are derived from biological material that has decayed over millions of years.

“[Liquid biofuels] will always be inefficient,” Searchinger said in an interview. “It’s probably not the intelligent way to spend money today.”

Searchinger said that earlier studies, some of which he helped conduct, looked only at the benefits of liquid biofuels.

He explained that the amount of carbon dioxide released by burning biofuels such as corn theoretically matches the amount the plants sequester from the air during their short lives. Biofuels should therefore release less greenhouse gases than fossil fuels, which emit carbon dioxide that has not been in the atmosphere for millions of years, he said.

“Most analyses found corn ethanol reduced emissions relative to gasoline by 20 percent,” Searchinger noted.

There are many hidden costs, however, to using greater tracts of land for biofuels, Searchinger said.

“Land is not free. It’s a tremendous asset,” Searchinger explained. Clearing new land to grow biofuel crops often necessitates cutting into extant forests, he added, noting also that forests play an essential environmental role in preventing carbon dioxide from entering the atmosphere.

“Take an acre of forest,” Searchinger explained. “You cut it down, you burn it. You lose all the carbon that is stored in the trunks. You also lose the carbon in the roots. You lose on the order of 25 percent of the carbon in the soil is also lost to the atmosphere.”

The loss of forests in the face of the growing biofuel industry is significant, Searchinger said, yet the dangers of biofuels go even further because lands used for producing biofuels often were devoted to food production.

“If we don’t replace this food, we’ll have hunger, which is worse,” he explained. As forests and prairies are cleared, air-cleansing plants are lost, Searchinger added, noting that the process emits even more greenhouse gases and threatens biodiversity.

Critics have taken issue with this “acre for acre” argument.

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Robert Brown, an Iowa State University engineering professor, wrote in a column for The Des Moines Register last year that the biofuels industry in the United States has not been the primary drive behind deforestation.

“Something else is responsible for the epidemic of deforestation,” Brown noted.

Though Searchinger said he acknowledges Brown’s point, he also said he considers the argument illogical, as no one can deny the link between biofuels and deforestation.

“There are additional sources of deforestation. So what?” Searchinger said, adding that the United States has already suffered from land-use change, with more prairies being plowed up earlier for ethanol production.

Searchinger also explained that, as ethanol prices rise and biofuel production becomes more efficient, the tendency to cut down forests for new farmland may subside further. This will not completely eliminate deforestation, he added.

Searchinger also questioned how critics have invoked the uncertainties in his models. He said these uncertainties exist, but he added that for many reasons, the model he used might actually underestimate his numbers.

“Uncertainty cuts both ways, so emissions can be much lower but they can also be much higher,” he said.

A greener alternative to liquid biofuels may simply involve recycling used plant material, Searchinger said. Using spare plant matter, such as leftover corn stalks, to generate electricity for electric cars is a far more viable option than using liquid biofuel, he noted.

This energy-production process, Searchinger explained, is both cleaner and more efficient than liquid biofuel. “You take half the energy in the plant to turn the remaining half into liquid fuel, [and] you save more greenhouse gas emissions per ton of biomass and also per dollar,” he said.

Operations research professor Alain Kornhauser GS ’71, director of the Program in Transportation, said that he finds the idea of recycling plant matter appealing, though he would prefer to reuse material not already devoted to food use.

“If it is corn, it is one thing. If it is switchgrass or refuse (garbage), it is another,” Kornhauser said in an e-mail.

Mechanical and aerospace engineering professor Robert Socolow, co-director of the Princeton Environmental Institute’s Carbon Mitigation Initiative, said he appreciated how Searchinger has helped shape the study of biofuels.

“Tim Searchinger has added significantly to the world’s understanding of biofuels by identifying a relatively unexplored issue: the ‘indirect’ effects of producing biomass in Place A that take the form of changes in land use in Place B,” Socolow said in an e-mail.

“This is a big idea,” he added.