Cutting CO2 transportation emissions is feasible, says report

By midcentury, a combination of new policies and technologies could lower greenhouse gas emissions from the US transportation sector by 65% of 2010 levels, according to a new report, Reducing Greenhouse Gas Emissions from U.S. Transportation from the Pew Center on Global Climate Change . Improved vehicle fuel efficiency, adoption of electric and fuel-cell drives and biofuels, and changes in travel behavior all lessen carbon dioxide emissions, but the extent to which that will happen depends on the public’s willingness to change and on the federal government’s willingness to enact policies that promote mitigation.

The many path approach

No single technology or policy can produce reductions of 65%, the Pew report asserts. Instead, the US would also need to enact new land-use policies that promote high-density development and adopt ride sharing, car sharing, and “eco-driving” practices such as anticipating traffic situations and maintaining adequate spacing between vehicles to avoid unnecessary braking and acceleration. Without further policy interventions, CO₂ emissions from the US transportation sector will rise 28% from 2010 to 2035, even assuming substantial increases in the use of renewable fuels, according to the US Department of Energy’s Energy Information Administration . But, given the austere budget climate and political resistance to regulation, Pew Center president Eileen Claussen warned that further emissions reductions will be an uphill fight. “If we have no money to spend and no mandates, it’s unclear what sort of policies we can have.”

Steven Plotkin , a researcher at Argonne National Laboratory who coauthored the report, said many of the technologies for lowering CO₂ emissions are already available from the same manufacturers that had once declared them to be impossible. Turbocharged four-cylinder engines, for example, are able to replace six-cylinder power plants; with no decline in performance and with reduced emissions. Lithium ion cathode technology licensed from Argonne is being used to improve the performance and increase the safety of the batteries being manufactured by South Korea’s LG Chem for the Chevrolet Volt.

A multiple-path approach would work best because of uncertainty about which technology will provide the biggest payoffs in emissions reductions. Game changers such as the lithium-air battery chemistry being pursued by Argonne could give electric vehicles the same sort of range between charges as conventional gasoline-powered cars have.

One piece of the puzzle

But coauthor David Greene , of the Howard H Baker Jr Center for Public Policy, said the gains in light-vehicle efficiency have yet to be reflected in other modes of transportation. Little progress has been made on alternative fuels and fuel efficiency in commercial air transport, trains, or heavy-duty trucks. The comprehensive approach is unlikely to be followed until the public is convinced that global warming is a reality.

Public policies such as a tax on carbon emissions are needed to provide market signals, Plotkin noted. He said that the price of gasoline will become considerably less important to the owners of cars getting 75 or more miles per gallon than to the drivers of existing generation vehicles. And it will be cars at the more efficient end of that scale that will be competing against electric or fuel-cell vehicles.