WASHINGTON — Scientists said on Wednesday they have developed a new way to make liquid ethanol efficiently without using corn or other crops needed in the conventional method for producing the biofuel.
The scientists said their process turns carbon monoxide gas into liquid ethanol with the help of an electrode made of a form of copper. They said the new technique may be more environmentally friendly and efficient than the current method.
Critics say that growing crops for biofuels is energy-intensive and takes up vast tracts of nonagricultural land, using too much water and fertilizer. They also say diverting corn and sugar to make biofuels pushes up food prices
The United States leads the world in ethanol production, with 13.3 billion gallons in 2013, followed by Brazil's 6.3 billion gallons, according to the Washington-based Renewable Fuels Association, which represents the U.S. ethanol industry.
A group of scientists led by Stanford University chemist Matthew Kanan described the new method in research published in the journal Nature. Kanan said a prototype device could be ready in two to three years, enabling an assessment on whether the process can become commercially viable.
"I emphasize that these are just laboratory experiments today. We haven't built a device," Kanan said. "But it demonstrates the feasibility of using electricity that you could get from a renewable energy source to power fuel synthesis — in this case ethanol. There are some real advantages to doing that relative to using biomass to produce ethanol." Ethanol fuel generally is produced at high-temperature fermentation facilities that chemically transform corn, sugarcane and other plants into liquid fuel.
Kanan and his colleagues built an electrochemical cell — a device consisting of two electrodes that were put in water saturated with carbon monoxide gas. One of the electrodes was made of a material they call "oxide-derived copper." When voltage was applied across the electrodes, the carbon monoxide gas was converted into ethanol, they said.
The researchers hope to take carbon dioxide from the atmosphere and convert it to carbon monoxide, which then would be fed into the copper-oxide catalyst. The researchers hope the catalytic cell would be powered by a renewable energy source such as solar or wind.
Chemist Aaron Appel of the Pacific Northwest National Laboratory, a U.S. Department of Energy government research lab, said that the work from Kanan's group demonstrates "a remarkable improvement in selectivity and energy efficiency" for the production of ethanol from carbon monoxide.
Appel was not part of the study but wrote a commentary in Nature on the findings.
Advocates call ethanol a green energy source that, compared to gasoline, reduces greenhouse gas emissions that contribute to climate change. Ethanol last year directly supported more than 86,000 U.S. jobs in fuel production and agriculture, the Renewable Fuels Association said.
Last November, the U.S. Environmental Protection Agency proposed cutting the amount of ethanol required to be mixed with the gasoline supply, responding to pressure from the petroleum industry. It marked the first planned cut to renewable fuel targets written into a 2007 U.S. law.