The utility with the most renewable power sources in the country is about to get a little greener.

Southern California Edison has signed a contract with an energy company to build a 909-megawatt wind farm in north-central Oregon, which would provide enough electricity for about 600,000 homes, according to Vanessa McGrady, a spokeswoman for the utility.

The utility already gets about 16 percent of its energy from renewable sources and has signed contracts that will soon move that number to 20 percent, officials said.

"We produce more renewable energy than any other state, obviously, besides California," McGrady said.

While the 20-year contract to build 303 wind turbines will initially be costly, wind energy costs are stable will save cash in the long run, said Stuart Hemphill, SCE's vice president of renewable and alternative power.

"The beauty of renewable projects is they are not tied to natural gas," he said, noting that natural gas prices can change quickly.

Currenly, more than half the utility's energy comes from natural gas, he said.

The wind energy will be provided by an affiliate of Caithness Energy, which is scheduled to build the first phase of the farm - called Caithness Shepherd's Flat - by June 2011. The second phase is expected to be finished a year later. Transmission lines for the energy are already in place, a fact that will get the energy to customers faster than is normal for such a large project, Hemphill said.

Right now, about 2300 megawatts of wind energy are produced in California, and the state has potential to produce about 20,000 megawatts, said Nancy Rader of the California Wind Energy Association.

"We've just barely scratched the surface," she said.

But many utilities are looking out of state where regulations are not as stringent, she said.

SCE is the largest electric utility in California, serving a population of more than 13 million in Central, Coastal and Southern California, according to a statement from the company.