The Potential of Plug-in Hybrids
(Page 2 of 3)
October/November 2005
By Bill Moore
COAL CONSIDERATIONS
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The concept of electric plug-in hybrids has been around for about a decade. Andy Frank and his students at the University of California at Davis have built a number of prototypes based on sedans and sport utility vehicles. Electric companies are attracted to the idea because it would enable them to sell more of their surplus overnight power. Carmakers, which have started to shift their position on this issue lately, historically have tended to denigrate both electric cars and the plug-in hybrid concept as contributing to global warming. They point out that most utilities currently generate electricity from coal, and because gasoline burns cleaner than coal, the argument is that a shift to electric cars would generate more air pollution, not lessen it.
But it turns out that this argument is not correct. Plug-in hybrids actually will contribute less climate-altering carbon dioxide (CO2) than gasoline. Here’s why: A conventional gas vehicle releases about 24 pounds of CO2 and travels about 24 miles on 1 gallon of gas. It would take about 6 pounds of coal, creating just 12 pounds of CO2, to produce enough electricity to travel the same distance in a plug-in hybrid. What’s more, not all our electricity comes from coal; roughly 30 percent of the grid electricity that would be used by plug-ins comes from non-CO2-producing or CO2-neutral sources, including nuclear and hydroelectric plants, biomass and renewables such as wind and solar energy. This means that plug-ins would produce only about 8 pounds of CO2, or about one-third as much as a conventional 24-mpg gasoline engine. Burning coal gives off other pollutants, including mercury, particulates and sulfur, but these either are captured, or soon will be captured, using advances in technology at newer power plants.
BETTER BIOFUELS
The emergence of biofuels — such as ethanol and biodiesel — to power the internal-combustion engine makes the potential for plug-ins even more compelling. Proponents such as James Woolsey, the former director of the CIA, argue that burning E85 (85-percent ethanol; 15-percent gasoline) would further reduce the amount of gasoline the “flexible-fuel plug-in hybrid” would consume. If Energy CS’s 160-mpg Prius were refitted to burn E85, it could consume only 15 percent as much gasoline, resulting in the equivalent of a conventional car getting 1,000 mpg for the first 60 miles — at least theoretically. After 60 miles, the fuel efficiency would drop back to 333-mpg gasoline equivalent.
