Conditions west of Tracy make the area a magnet for power companies that have proposed building electricity plants that could spew nearly 3,000 tons of pollution a year into the skies.

Cheap land and proximity to major electrical substations, gas lines and water sources have attracted Calpine Corp., Florida Power & Light and Pacific Gas and Electric Co. to the swath of land west of Mountain House on the far eastern edge of Alameda County. The area is centrally located, too, said Jim Swaney, permits manager for the San Joaquin Valley Air Pollution Control District.

“It’s between that Bay Area, Sacramento and Stockton-Tracy-Modesto area,” Swaney said. “There’s just less distance to the customers who use that energy.”

The companies have each applied for state permits to build a power plant, including two that would be among the largest energy suppliers in the state, according to the California Energy Commission.

The Mariposa Energy Project, Tesla Power Plant and East Altamont Energy Center range in size from 200 to more than 1,100 megawatts. A megawatt powers roughly 750 to 1,000 homes, according to the California Independent System Operator, which runs the state electrical grid.

Add to those the fourth full-fledged power plant slated for the area, the GWF Tracy Combined Cycle Power Plant.

GWF Energy LLC — corporate owner of the 7-year-old Tracy Peaker Plant — is poised to begin construction in 2012 to expand from a 169-megawatt station to one with a second turbine that could feed 314 megawatts into the grid.

Together and at maximum permitted capacity, the proposed plants would release more than 700 tons of nitrogen oxide every year, among other pollutants. The combined plants would release about 1,500 tons a year of carbon monoxide, 157 tons of organic emissions, 455 tons of small particulates and nearly 60 tons of sulfur dioxide.

Excluding the GWF Energy expansion project, the proposed power plants would sit in a sparsely populated stretch of Alameda County, which would reap the benefit of millions more dollars in property taxes every year.

But because the prevailing winds blow east, according to the National Weather Service, San Joaquin County residents would bear the brunt of the impacts in the form of thousands more tons of pollution every year, especially over Tracy and Mountain House.

Also, San Joaquin County officials have little control over the Mariposa, Tesla and East Altamont project approvals, because the plants would be in another county’s jurisdiction. Though a Tracy-area irrigation district could turn some profit from their construction by selling recycled water to cool the energy-generating turbines.

Powering up and down

The power plants would likely run at much less than their full annual capacity, according to the state energy commission. And though all the power companies applied for the permits to build around Tracy, some might not follow through with those plans.

Calpine, which filed for bankruptcy in 2005, halted construction last year on 33 plants nationwide, including the East Altamont Energy Center poised to sit on 44 acres bordered by Kelso, Mountain House and Byron roads.

In October 2008 year, the state granted Calpine a five-year extension on a 2003 permit to build the 1,100-megawatt energy center. A company spokeswoman contacted this week refused to publicly comment on the project, because plans have yet to be finalized.

Tesla also got a five-year permit extension this year, so it can delay construction until the company is in better financial shape.

GWF Energy has made the most progress in its plans to construct a full-fledged electricity plant on its land a few miles southwest of Tracy. Because it already owns 40 acres on which a part-time, single-turbine power plant sits, it has a little more momentum, according to GWF vice president Doug Wheeler.

The only thing left for GWF Energy to do before construction begins is to work out a few details, like how to use landscaping to disguise the facility from immediate neighbors without violating the California Fish and Game’s restriction on planting trees, because they could attract raptors that prey on the endangered kit fox.

The energy company also has to get its plans in closer alignment to the Clean Air Act’s provisions on carbon offsets, according to the U.S. Environmental Protection Agency. A final report about the peaker plant’s expansion plans is set to be released sometime in late summer or early fall.

Once that’s approved, the state would hold evidentiary hearings on the project before it could finally grant a permit to build. GWF Energy spokesman Riley Jones said he expects that to happen early next year.

The Mariposa project is the newest among those proposed for the land west of Tracy. The single-turbine, 200-megawatt peaker plant would lie about 7 miles northwest of Tracy and 2½ miles west of Mountain House on a 10-acre chunk of a 160-acre parcel just south of a PG&E substation. The land is on the very eastern edge of Alameda County at the intersection of Bruns and Kelso roads.

PG&E just applied for the state permit to build Mariposa in June, so construction is at least three years away, according to company officials. Of all the proposed plants, San Joaquin County Supervisor Leroy Ornellas said he thinks Mariposa is moving along the fastest.

“The other two, we’re not sure we’ll ever see those,” he said.

To build Mariposa would require a new 580-foot natural gas pipeline and a new 1.8-mile canal to supply water to the plant from the nearby Byron-Bethany Irrigation District.

Tracy activist Bob Sarvey, who keeps a close eye on Bay Area and San Joaquin Valley energy projects, said he worries that the area west of Tracy seems destined to become a corridor for massive power plants.

“The ironic part is that all this power plant development is being licensed in an area known for its renewable energy potential, with massive wind farms dominating the skylines,” he pointed out.

• Contact Tracy Press reporter Jennifer Wadsworth at 830-4225 or jwadsworth@tracypress.com.