RUSSELL, Mass. The push for more power from renewable fuels has renewed interest in one of the oldest energy sources: wood.

While airwaves have been permeated by advertisements for solar and wind power, wood generated more net electricity in the U.S. last year than those two up-and-comers combined. New wood-burning electricity plants are again being proposed from Massachusetts to New Mexico as the nation finds itself in another energy shock.

That developers are again looking to forests for fuel has many worried.

"We don't want to mine our forest for energy," said Bryan Bird of WildEarth Guardians, a Santa Fe, N.M., environmental group.

There were 196 wood-burning electricity plants in the country as of January 2007, including 72 with 40-megawatt capacity or larger, according to the Department of Energy. The bulk of today's wood power comes from plants that mainly serve the on-site lumber or paper mills that supply their fuel.

Developers say they wouldn't need to cut down trees for power plants because of the current wood surplus. Many proposed plants plan to use wood left over by routine activities such utility-line clearing or from existing timber companies. Wood is also found on forest floors.

"There is a tremendous resource," said Neil Rossmeissl, a technology manager at the Department of Energy.

Bird and other environmentalists challenge that mindset.

"A forest doesn't waste anything," he said. "That's the next generation of soil and nutrients in a forest ecosystem."

Last month, Duke Energy Corp., one of the nation's largest electric power companies, and the French nuclear engineering company Areva announced plans to build up to 12 wood-electricity plants with roughly 50-megawatt capacity on the Eastern seaboard in the next six years. (A 1-megawatt plant can supply up to 1,000 homes with power).

At least eight more wood-burning electricity plants of 40-megawatt capacity or larger have been proposed around the country, according to New Energy Finance, which provides information to investors in renewable energy markets.

Wood-energy projects benefit from federal subsidies that developers say are essential. New mandates in many states to increase renewable power use has led to additional incentives.

But wood has far less stored energy than fossil fuels and coal, so more must be gathered, trucked and burned to produce the same power. Higher transportation costs mean wood plants must gather their fuel nearby, limiting where plants can be located. The issue of carbon neutrality is also a point of contention.

And like any power plant, local opposition can be fierce.

-- The Associated Press