(Phys.org) —Making cars more fuel-efficient is great for reducing greenhouse gas emissions, but rather than promoting sales of electric and other alternative-fuel vehicles, policymakers should turn their focus to cutting emissions in other energy sectors—from oil wells and power plants to farms and forests affected by biofuels production—says a University of Michigan researcher.
"While the rush to get alternative fuels on the road has become dogma in many policy circles, such haste cannot be justified by careful analysis," said John DeCicco, a research professor at the U-M Energy Institute and professor of practice at the School of Natural Resources and Environment.
Alternative fuel vehicles have been promoted for decades—plug-in electric cars as well as those powered by ethanol, natural gas, hydrogen or other nonpetroleum fuels. Federal tax credits for electric vehicles range up to $7,500 per car and many other alternative fuels are also subsidized.
A new study by DeCicco affirms that research and development are important to create better options for the future. But at least for reasons of climate protection, moving beyond R&D into public subsidies, mandates and other costly programs to prop up alternative fuel sales "is not warranted on the basis of current data," he says.
The study, appearing online in Energy Policy, examines expected increases in driving for both the U.S. and China. It compares those projections to data on the carbon emissions associated with different fuels and the efficiency gains in vehicles that still burn liquid fuels (including hybrids that don't plug in).
"Gasoline vehicle efficiency is already improving by nearly 4 percent per year, while emissions from U.S. electric power generation are not even declining by 1 percent per year," DeCicco said.
"If you think that electric cars will be needed someday, you first have to greatly cut carbon emissions from power generation. If you think that biofuels are going to be important, then you need to remove more carbon from the air at farms or forests than we're already doing today."
DeCicco's research shows that as long as carbon emissions in those other locations remain poorly controlled, there are no compelling climate advantages to alternative fuels and cars that use them. The most effective approaches, he says, are steadily improving vehicle efficiency and limiting travel demand.
"Higher fuel economy—that's one good track the country is already on, and we should stay the course on that," he said. "Reducing the demand for car travel makes sense in urban areas, where policymakers can do more to encourage efficient land use, better mass transit and making it easier to walk and bike or otherwise minimize traffic congestion."
Beyond transportation efficiency, the next priorities lie outside the transportation sector, DeCicco says.
"The missing link for really cleaning up cars is not about the car at all," he said. "It's about limiting net carbon impacts in the energy and natural resource sectors that supply motor fuel, whatever form that fuel may take."
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More information: www.sciencedirect.com/science/… ii/S0301421513002309