ESCONDIDO -- Preliminary emission test results show that the Palomar Energy power plant in western Escondido meets state standards for its generation of nitrogen oxides, key ingredients of smog.

The test results were released this week by the San Diego Air Pollution Control District at the request of the North County Times. The 550-megawatt power plant is scheduled to start full operations next week.

Last week, the California Energy Commission approved the transfer of the $420 million plant from Palomar Energy, a unit of Sempra Energy, to San Diego Gas & Electric Co., also owned by Sempra.

SDG&E spokesman Ed Van Herik said the company expects to begin operating fully next week. The plant was running at 300 megawatts Friday and is ramping up "very quickly," Van Herik said.

The utility is planning to hold open houses with public tours in the middle of the month.

When the natural gas-fueled Palomar Energy plant was approved by the California Energy Commission in 2003, it was allowed to emit 104 tons of nitrogen oxides per year. However, SDG&E is predicting that it will need to emit more in a few years.

Nitrogen oxides are byproducts of burning both natural gas to drive steam turbines and burning gasoline in car engines.

Their emissions are monitored because when they mix with volatile organic compounds -- also produced by combustion engines -- in the presence of sunlight, they create ozone, the main lung irritant in smog.

Cars and trucks are by far the largest sources of nitrogen oxides in San Diego County, producing more than 170 tons a day.

In an "advice letter" to the state Public Utility Commission sent Feb. 28 and posted online, SDG&E says Palomar Energy will emit between 55 tons and 66 tons of nitrogen oxides this year and up to 147 tons in 2010. The plant will emit more nitrogen oxides than expected by 2010 because of periodic start-ups of the energy-producing turbines.

SDG&E will have to pay about $2 million extra for "offsets" or permits for the extra pollution, the advice letter says. The government-issued permits will be bought from other industrial facilities that aren't producing close to their limits, company spokesman Van Herik said.

One hundred tons of nitrogen oxides is roughly the equivalent of what would be produced by 3,000 cars and trucks driving 15,000 miles per year around the neighborhood of the power plant, according to figures compiled by the state Air Resources Board.

In comparison, the largest power plant in the state, at Moss Landing north of Monterey, emits over 400 tons of nitrogen oxides per year, and several California oil refineries each emit more than 2,000 tons a year.

"Newer power plants are much cleaner than older power plants," said Jan Cortez, an environmental analyst with the American Lung Association in San Diego. "But 40 more tons of air pollution is not insignificant."

Cortez said that the company should have installed additional pollution control equipment rather than buying offsets.

The San Diego Air Pollution Control District supervised several tests on samples of the exhaust produced by the plant in late January, senior district chemist Suzanne Blackburn said.

Palomar's two exhaust stacks have monitoring equipment that continuously measure nitrogen oxides, carbon monoxide and oxygen, and those were certified in January, she said.

In three separate runs at around a third of maximum power, the plant's two exhaust stacks produced nitrogen oxides at levels between 1.76 and 1.91 parts per million. The California Energy Commission's limit is 2 parts per million.

Particulate matter, dust that can also irritate the lungs, produced by one natural gas-burning unit was above the state limit of 14 pounds per hour in one run, but the average of three runs was just below the limit, the data showed.

District officials said the information was preliminary and needed to be checked again, and that may take several weeks. The plant has permission to begin operating while the data are checked, officials said.

The district has also tested the exhaust for volatile organic compounds, benzenes and aldehydes but the data on those compounds are still incomplete, Blackburn said.

Contact staff writer Quinn Eastman at (760) 740-5412 or qeastman@nctimes.com.

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