LA JOLLA —— San Diego Gas & Electric Co. announced plans Wednesday to stretch a major transmission line between North County and the Imperial Valley that could bring enough power to the area to light up more than 650,000 homes.

The new line, which will follow a wide track that will begin near El Centro and meander northwest to somewhere east or south of Escondido, could be the only way that SDG&E can meet its announced goal of using renewable energy sources, such as solar radiation, wind power or geothermal wells, to provide 20 percent of its energy supply by 2010.

The Sunrise Powerlink, as the utility is calling the new transmission line, has not been assigned to a specific route yet, and exactly where it will hook into SDG&E's existing electric system is unclear, but the company's president, Edwin Guiles, said that if it had been up and running last week, it might have spared 51,000 local customers from the brief blackouts that followed a transmission failure farther north.

"Last week's electric transmission emergency was a sharp reminder of just how fragile California's transmission grid is," Guiles said. "The Sunrise Powerlink will improve the reliability of our system, provide access to renewable energy resources, and help reduce costs for our customers."

The Imperial Valley area near El Centro is close to planned geothermal production units, which generate electricity using underground heat sources, and the route the transmission line is projected to follow —— actually a wide corridor that follows a shallow s-curve from the southeast corner of San Diego County to mid-North County —— passes near proposed wind-farm locations in East County.

Forecasts cited by SDG&E predict that, by 2010, demand for electricity in SDG&E's service territory will exceed the available supply that can be produced locally or imported on existing transmission lines.

Guiles said the utility is "going to be looking at routes that minimize the impact on the environment." It also will be routed away from the existing Southwest Transmission Line between southern Arizona and San Diego because of concerns that if the routes were too close to each other, both power lines could be compromised by a single wildfire.

Guiles would not estimate the cost of the project, which will differ from transmission lines built in the past because the extensive use of carbon fiber materials will allow the use of thinner cables and single-pole construction.

From first proposal to completion, a transmission line like the Sunset Powerlink usually takes five to seven years, according to SDG&E spokeswoman Stephanie Donovan.

Before the end of the year, Guiles said, the utility will apply to the California Public Utility Commission for permission to build it. The biggest hurdle the utility faces is lining up support from all the people affected by building the line, including property owners along the way, at so-called stakeholder meetings that have yet to be scheduled, Donovan said.

Among the factors contributing to potential problems is that the route must pass through a maze that includes the Cleveland National Forest, Anza-Borrego State Park, several American Indian reservations and Bureau of Land Management properties.

Contact staff writer Edmond Jacoby at (760) 739-6675 or ejacoby@nctimes.com.