Projecting a deficit in its energy supply by 2010, Avista Utilities is looking for additional sources of renewable energy.

On Wednesday, the Spokane energy company announced it is seeking proposals from renewable energy suppliers to provide 35 megawatts of power by the end of 2007. That's enough to supply about 23,000 homes.

"I think wind is the most likely, but there are other things out there," said Hugh Imhof, a company spokesman. "Who knows what the market has to offer?"

It's a sign of changing times for the company founded as Washington Water Power 116 years ago to produce power from the flow of the region's rivers. Within the next 20 years, hydropower will make up only one-quarter of the power Avista provides to its customers, Imhof said.

The change is due mostly to a growing population. Avista won't be producing less hydropower, but as demand for energy grows with the population, it will become a smaller percentage of the power supplied.

Avista customers currently demand about 1,000 megawatts of power - enough for about 650,000 homes - and about 54 percent of that comes from hydropower, the company said in a news release. By 2027, the company anticipates that demand will grow 70 percent to 1,745 megawatts, enough for 1.1 million homes.

By 2010, Avista anticipates that demand for power in its service territory will outstrip its supply by 40 megawatts. Those deficits rise to 360 megawatts by 2016 and to 640 megawatts by 2026.

The company projects that it will meet more than half of the additional demand for power with conservation, plant upgrades and renewable energy resources, such as wind and solar power, the news release said.

Responses to Avista's request for proposals are due on Feb. 1.

"Later this year, we will also be looking for proposals to implement additional effective conservation programs," said Dick Storro, Avista's director of power supply, in a prepared statement.

Renewable energy sources are gaining support nationally and regionally. The federal energy bill provides tax credits for utilities that meet certain renewable energy requirements by 2007, Imhof said. In addition, the Washington state Legislature passed legislation last year supporting the use of renewable energy.

Business writer Alison Boggs can be reached at (509) 459-5491 or by e-mail at alisonb@spokesman.com