Many environmentalists believe that plug-in hybrid cars could be an effective tool in the fight against global warming. Plug-ins have the potential to lower greenhouse gas emissions because they run partly on electricity and thus get much better gas mileage than traditional hybrid vehicles. But some critics note that plug-ins aren't all that eco-conscious. They use electricity, after all, and many US power plants generate a lot of carbon dioxide. Recent studies, including one from UC Berkeley, resolve this controversy. They suggest that plug-in hybrids will indeed reduce greenhouse gas emissions — but only if you live in a state, like California, that doesn't rely on coal power.

One of the more recent studies, conducted by UC Berkeley researchers and published by the Brookings Institution, shows that plug-in hybrids can decrease greenhouse gas emissions in California by more than 60 percent in comparison to conventional cars and by nearly 50 percent when compared to traditional hybrids. California doesn't generate much energy from coal, so when you recharge a plug-in here, it doesn't produce a lot of CO2. "Coal is about as bad as you can get" in terms of greenhouse gas emissions, explained Derek Lemoine, a UC Berkeley doctoral student who was one of the study's authors.

In the Bay Area, plug-in hybrids will be especially effective in fighting global warming because Pacific Gas & Electric gets very little energy from coal power. In fact, coal only represented 4 percent of the total electric power that PG&E sold to its retail customers in 2007, according to the most recent data available from the utility. PG&E's largest supply of energy — 47 percent — came from natural-gas-powered plants, followed by nuclear power at 23 percent, hydroelectric power at 13 percent, and renewable energy sources, such as biomass, geothermal, and wind power, at 12 percent. Of those, only natural-gas-powered plants produce significant amounts of CO2, although still much less than coal plants do.

Even if California relied entirely on natural gas, then plug-ins would still make sense. Plug-in cars powered by electricity generated from natural gas produce 54 percent fewer greenhouse gas emissions than conventional cars and 40 percent fewer than traditional hybrid cars, the UC Berkeley study revealed.

By contrast, the study also showed that plug-in hybrids powered by coal plants end up producing 25 percent more greenhouse gas emissions than traditional hybrid cars. As result, buying a plug-in would actually contribute to global warming if you live in an area, such as the South, that relies heavily on coal power. In fact, Lemoine's data was based on greenhouse gas emissions from newer, cleaner coal plants. So the amount of CO2 that would be generated by widespread use of plug-in vehicles would be even worse than the study predicted in areas that depend heavily on older, less-efficient coal plants. "We were looking at efficient coal-fired plants," he explained. "But many existing coal-fired plants are less efficient."

Another problem for plug-ins, according to the UC Berkeley study, is that they're not yet cost-efficient for consumers, and won't be until the large batteries they use become cheaper and gasoline prices rise. However, many consumers may choose to buy plug-ins anyway because they're good for the environment — at least in California and other places not dependent on coal. Plus, if researchers can discover how to effectively sequester CO2 emissions, then plug-ins may end up making sense even in coal-powered states.

As the use of renewable energy sources rises, the effectiveness of plug-ins will rise with them. According to the UC Berkeley study, a plug-in powered by renewable energy produces 99 percent fewer greenhouse gases than both a conventional car and a traditional hybrid.

Wind energy may be the most effective source of renewable power for plug-ins. The reason is that most plug-in hybrid owners will recharge their cars' batteries at night, while they're sleeping. And it just so happens that wind energy is the best renewable at night, Lemoine noted, because that's when the wind blows hardest. Now, if we could only get the wind-power companies to start using turbines that don't kill so many birds, we'd be in business.

New Rules Will Still Harm Plug-ins

Earlier this year we published a story about how the California Air Resources Board was considering a set of strict new regulations that threatened to put many small plug-in start-up companies out of business, including 3Prong Power of Berkeley (see, "Who's Killing the Plug-In Hybrid," January 14, 2009). But after our story came out, the board ordered its staff to come up with a compromise measure. However, the "compromise" could go before the board later this month, and it's creating serious financial concerns for small companies like 3Prong.

Originally, the air board's staff wanted to force start-up companies to pay for expensive air emissions testing, because even though plug-ins can produce fewer greenhouse gases, staffers were concerned that they also could generate more air pollutants, such as unburned gasoline vapors. Plug-in conversion companies maintained that those fears were unfounded, claiming they had devised a simple fix that would make the plug-ins run cleaner than traditional hybrids. They also didn't object to the testing per se, but said the expense — the tests cost between $20,000 and $125,000 — would bankrupt them.

After studying the issue for a few months, the air board staff now recommends that small companies don't pay for the tests until they have converted at least ten traditional hybrids into plug-ins. But Daniel Sherwood, co-owner of 3Prong, says that his company won't be able to generate enough profit from selling ten conversion kits to pay for the tests. The conversions sell for about $6,700, including installation. So the new rules will have the same effect as the old ones — they'll put small companies like 3Prong out of business. Sherwood plans to urge the air board to allow small companies to sell 50 conversion kits before having to pay for the tests, allowing business owners to generate enough revenue to cover the costs.

Tom Bates and Pacific Steel Casting

Two weeks ago, Eco Watch told you about how the Bay Area Air Quality Management District had conspired with a longtime Berkeley polluter, Pacific Steel Casting, to withhold vital public documents. At the time, we weren't sure of the role played by Berkeley Mayor Tom Bates, who had requested a copy of Pacific Steel Casting's "Odor Management Plan," which details the company's proposal to limit noxious emissions. But Bates also sits on the air district's board of directors, so it wasn't clear whether he knew that his request would result in district staffers inviting Pacific Steel Casting to sue the district so that they wouldn't have to release the odor management documents to the public.

But then last week, Bates called Eco Watch and said that he hadn't received the two phone messages left with his staffers seeking comment for the story. Bates said he wasn't attempting to duck questions, and maintained that he had nothing to do with the air district staff's actions. He said that after Pacific Steel Casting produced the odor management plan last October, he requested a copy, and that district staff gave him one that was highly redacted.

Bates said he then showed the redacted document to a toxics expert on the city payroll, who said the air district had no right to blacken so much of the document. The air district had maintained that the redacted portions represented Pacific Steel Casting's trade secrets. But Bates said he told the air district staff that he wanted the whole document, calling the redacted version "unacceptable." Soon after, Pacific Steel Casting sued to stop its release, he said. But when Eco Watch asked for a copy of the redacted document, Bates said he "threw it away."