Electric cars run on coal, partly

Nov 19 - McClatchy-Tribune Regional News - Purva Patel Houston Chronicle

Environmental groups and power companies are touting the benefits of emissions-free electric vehicles as a way to cut pollution in Texas.

But do electric vehicles, especially in Texas where much electricity is generated with coal, simply move emissions from the tailpipe to the smokestack?

"The electricity grid is a mix of generation technologies, some dirty and some clean. With electricity generation that tends toward dirtier feedstocks (like coal), you get fewer emissions benefits from electric vehicles," said Luke Tonachel, senior analyst at the Natural Resources Defense Council.

About 37 percent of Texas power comes from coal, according to July data from the Electric Reliability Council of Texas, the state's grid operator.

But even charged with power from dirtier sources, electric cars are cleaner than today's average vehicle and on par with the cleanest hybrids, Tonachel said.

Hybrids use a combination of electric and gasoline power.

Those pushing electric cars in Texas argue the vehicles offer an effective long-term tool for cutting auto pollution and potentially helping big cities such as Houston meet federal clean air standards.

Wind power

But that's assuming that drivers will charge their cars overnight, when wind power generation peaks. That could decrease pollution.

On Thursday, power generator NRG Energy announced plans to develop a network of electric vehicle charging stations in Houston and Dallas and later in cooperation with city-owned utilities in Austin and San Antonio.

Glen Stancil, NRG vice president, told state lawmakers earlier this year that electric cars exchange daytime tailpipe emissions in densely populated areas for night-time generation emissions in less populated areas.

Time of day

That depends, though, on when consumers charge their cars. During the day, plants fueled by coal or natural gas are more likely to be feeding the grid.

But Stancil was optimistic in his assessment.

"Even in the worst-case scenario where 100 percent of that generation is from coal, there is still a net positive emissions trade-off," Stancil said. A 2007 study found that a plug-in hybrid electric vehicle charged with electricity from a coal plant would result in 25 percent less carbon dioxide emissions than a conventional gasoline vehicle, he said.

The study was conducted by Electrification Coalition, a trade group of which NRG is a member.

A study by Jan Kreider, founding director of the University of Colorado's Joint Center for Energy Management, found similar results.

Less pollution

Over a lifetime, from production to transportation, disposal and the energy used to power various cars, the electric and hybrid electric vehicles emitted less pollutants than conventional internal combustion engines. Kreider's study looked at carbon dioxide, sulfur oxide, nitrogen oxide and mercury levels emitted.

Cars running on natural gas, however, fared the best.

"A Prius (hybrid) is a lot better than a conventional car if we just focus on greenhouse gases, but then the question is, 'What's the best you can do?'?" Kreider said.

"The point about electric vehicles is they're not that clean. To do it really clean, you'd do compressed natural gas."

purva.patel@chron.com