Nov 7 - McClatchy-Tribune Business News Formerly Knight Ridder/Tribune Business News - Alex Breitler The Record, Stockton, Calif.

Wood shavings left behind after construction of a new home could help keep its lights on in the future.

So could pine trees from the Sierra Nevada. Or branches pruned from a farmer's San Joaquin Valley orchard.

The Modesto Irrigation District, which serves thousands of homes and businesses in Ripon, Escalon and Mountain House as well as Stanislaus County, plans to tap a dormant biomass plant in the Sierra foothills for up to 5 percent of its future power supplies.

It is an effort, officials say, to reap renewable energy from an increasingly diverse number of sources -- wind, water, solar and, now, wood.

The move may help keep customers' rates stable if one energy source suddenly becomes unavailable.

"It's the smart thing to do for our customers and ratepayers," said district spokeswoman Kate Hora.

Biomass plants are the garbage disposals of power production. They gobble up dead trees, yard clippings, sawdust and bark, as well as leftover wood from construction projects, boxes or pallets.

The debris is chipped and burned in furnaces; the heat boils water and produces steam, which turns turbines to generate electricity.

At least 61 biomass plants have been built since the 1970s statewide, but many have turned off their furnaces because of the decline of the timber industry and deregulation of electric utilities.

Today there are 28 plants online, said Phil Reese, chairman of the California Biomass Energy Alliance. The Buena Vista plant near Ione may be the first to sell power to a municipal utility or irrigation district, he said.

"We applaud (Modesto Irrigation District) for doing this," Reese said.

Some details are still being worked out. If enough wood products can be found and transported to the plant, it could produce enough power for roughly 5,500 homes and businesses at a time.

The 15-year deal could cost the district up to $133 million, according to staff reports.

Diversification of energy sources became a priority in the 1970s, when droughts caused a spike in rates. The district at the time was heavily dependent on hydroelectric power from Don Pedro Dam east of Modesto.

Since then, officials have added wind power in Solano County, solar power and now biomass. Nearly one-fifth of the district's total power comes from renewable sources, edging Modesto officials closer to meeting a state mandate of 20 percent.

Pacific Gas and Electric Co. is also relying on biomass for about 5 percent of its energy, a company spokeswoman said.

The Buena Vista plant originally burned lignite, a form of coal that yielded an oil used in now-obsolete carbon paper. The plant was converted to biomass in the 1990s but hasn't operated since 2000.

Washington-based National Energy Systems, which runs several biomass plants in the Pacific Northwest, is retooling the plant near Ione. It could be operational by December 2007, said Vice President Larry Becker.

The California Energy Commission says biomass burning can reduce global warming. Carbon dioxide that is released when the material is burned can be captured by new crops or trees, the commission says.

Plants such as the one near Ione could produce enough power for 2 million homes if they burned all 60 million dry tons of biomass in California.

Right now, only about 5 million tons are burned statewide.