NRC releases report on energy efficiency in autos by 2050
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NRC releases report on energy efficiency in autos by 2050 www.nap.edu
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he National Research Council finds that by the year 2050, the United States may be able to reduce petroleum consumption and greenhouse gas emissions by 80% for cars and small trucks through a combination of more efficient vehicles; the use of alternative fuels like biofuels, electricity, and hydrogen; and strong government policies to overcome high costs and influence consumer choices. While achieving these goals will be difficult, improving technologies driven by strong and effective policies could make deep reductions possible. The Council details its findings in the report, “Transitions to Alternative Vehicles and Fuels.” “To reach the 2050 goals for reducing petroleum use and greenhouse gases, vehicles must become dramatically more efficient, regardless of how they are powered,” says Douglas M. Chapin, principal of MPR Associates, and chair of the committee that wrote the report. Improving the efficiency of conventional vehicles is, up to a point, the most economical and easiest-to-implement approach to saving fuel and lowering emissions, the report says. This approach includes reducing the work the engine must perform—reducing vehicle weight, aerodynamic resistance, rolling resistance, and accessories—plus improving the efficiency of the internal-combustion engine powertrain. Improved efficiency alone will not meet the 2050 goals, however. The average fuel economy of vehicles on the road would have to exceed 180 mpg, which, the report says, is extremely unlikely with current technologies. Therefore, the study committee also considered other alternatives for vehicles and fuels, including hybrid electric vehicles, plug-in hybrid electric vehicles, battery electric vehicles, hydrogen fuel-cell electric vehicles, and compressed natural-gas vehicles.
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VOLUME 38 • JUNE 2013
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Although driving costs per mile will be lower, especially for vehicles powered by natural gas or electricity, the high initial purchase cost is likely to be a significant barrier to widespread consumer acceptance, the report says. Additionally, particularly in the early years, the report predicts that some of the alternative vehicles will rely on fuels that are not readily available or have restricted travel range, and others may require bulky energy storage that will limit their cargo and passenger capacity. Strong policies and technology advances are critical in overcoming these challenges. The report identified several scenarios that could meet the more demanding 2050 greenhouse gas goal. Each combines highly efficient vehicles with at least one of three alternative power sources— biofuels, electricity, or hydrogen. While corn-grain ethanol and biodiesel are the only biofuels to have been produced in commercial quantities in the United States to date, the study committee found much greater potential in biofuels made from lignocellulosic biomass, which includes crop residues like wheat straw, switch grass, whole trees, and wood waste. This “drop-
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