FYI, Good analysis. JBK

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Edward Mainland emainland@COMCAST.NET 7/30/2010 11:19 PM >>>

Grid sets electric cars' green standard David R. Baker, San Francisco Chronicle Staff Writer Monday, July 19, 2010

When you drive an electric car in California, you're not just driving on electricity - you're driving on natural gas, nuclear power, hydropower and coal.

Drive an electric car in, say, Georgia, and it's mostly coal and nuclear.

Public fascination with electric cars is growing, as people and politicians look for ways to fight global warming and wean America off oil. Palo Alto's Tesla Motors has developed a cult following for its pricey electric sports cars, and Nissan by year's end will start selling a less-expensive, all-electric sedan dubbed the Leaf.

The buzz tends to obscure a basic fact - electric cars are only as green as the power grid that supplies their juice. They don't burn fossil fuels or spew greenhouse gases into the air. But most of the power plants that generate their electricity do.

Many energy analysts, however, love them anyway. Even when power plant emissions are included, electric cars still pump far less carbon dioxide into the atmosphere than do their gasoline-burning brethren, analysts say.

"In California, you plug into the grid with an electric vehicle, and you're going to see a two-thirds reduction in your global warming pollution," said Roland Hwang, transportation program director for the Natural Resources Defense Council. "It's a big benefit."

Note that he mentioned California.

The amount of greenhouse gas emissions saved by electric cars varies widely from state to state. California's grid is relatively carbon-free, drawing 14.4 percent of its electricity in 2008 from nuclear plants, 11 percent from large hydroelectric dams and 10.6 percent from renewable sources such as geothermal plants and wind farms, according to the California Energy Commission. More than 45 percent of the state's electricity comes from burning natural gas, which produces less carbon dioxide than coal.

Many states in the Midwest or Southeast, however, rely heavily on coal. There, electric cars will still produce fewer emissions than gasoline vehicles, but the difference won't be as great.

"A Tesla in Georgia would give you about the same greenhouse gas emissions as a good Prius," Hwang said, referring to Toyota's popular hybrid car. "You're not going backward, but you're only doing as well as a Prius."

Different figures

Figuring out the greenhouse gas emissions associated with different kinds of cars and fuels has become something of a cottage industry, with many researchers coming up with their own estimates. Those estimates have taken on greater importance as state and federal officials wrestle with energy policy and climate change.

Researchers use an approach called "well to wheels," in which they study the greenhouse gas emissions generated by making fuel and delivering it to customers as well as burning it in a car. A well-to-wheels study of gasoline, for example, looks at the emissions produced by pumping crude oil from the ground, shipping it to refineries, processing it into gasoline, delivering the gas to stations and burning it while driving.

The Natural Resources Defense Council, using data from the U.S. Department of Energy and the California Air Resources Board, estimates that a typical gas-powered car produces 465 grams of carbon dioxide per mile. Electric cars feeding off of California's power grid produce 142 grams per mile. Electric cars plugged into the grid elsewhere in the country - drawing power from the nation's average mix of natural gas, coal and nuclear plants - produce 214 grams of carbon dioxide per mile.

A study for the California Energy Commission, which estimated greenhouse gas emissions from cars two years from now, yielded comparable results. Cars burning gasoline will produce 473 grams of carbon dioxide per mile, the study found, while electric cars in California will produce 123 grams.

Energy analysts say the benefits of electric cars will increase as the use of renewable power grows. It's far easier to "de-carbonize" the electricity grid than it is to cut the greenhouse gas emissions from millions of fuel-burning cars.

'Cleaner over time'

"Even if the grid is dirty now, we expect it to get cleaner over time," said Patricia Monahan, deputy director of the clean vehicles program at the Union of Concerned Scientists. "In the long run, by 2030, we really need to be on a path to electrification if we want deep greenhouse gas reductions."

Electric car owners tend to know exactly where their power comes from. Some even take steps to make that power greener.

Steve Casner of Sunnyvale stuck solar panels on his house. The software engineer owns both a Tesla and an electric Rav4, which Toyota sold from 1997 to 2003. (The Japanese automaker announced Friday that it would develop a new electric Rav4 with Tesla's help, with the vehicles hitting the market in 2012.)

"Some people would say to me that I was just diverting my pollution elsewhere, so I said, 'I can solve that problem,' " Casner said. "I can't make gasoline at my house, but I can make electricity."

Casner charges his cars at night, so they don't draw their electricity directly from the solar panels. But he usually generates more electricity in the afternoon than he can use, selling the excess back to the grid. He figures it all evens out.

"We treat the grid as a big battery," he said.

E-mail David R. Baker at dbaker@sfchronicle.com.

http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2010/07/19/BU0M1EF33T.DTL

This article appeared on page D - 1 of the San Francisco Chronicle

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