The technology behind a new wood-fired power plant being built in north Eugene has been touted as Oregon’s piece of the green-power economy. It has been championed by Gov. Ted Kulongoski and endorsed by Eugene Mayor Kitty Piercy – not to mention encouraged with up to $24 million in state and federal tax incentives.

But, since construction on the Seneca Sustainable Energy plant got under way this year, critics across the country have raised questions about the amounts of carbon dioxide that such plants pump into the air, and the supposed impact on global warming.

Their questions were pointed enough to derail plans for plants in Fresno County, Calif., and Traverse City, Mich., during the past month, according to news reports.

And Massachusetts stopped issuing permits for such “biomass” burning plants in December.

The Environmental Protection Agency recently declined to extend a blanket rating of “carbon neutral” to biomass plants – a move that left members of the Oregon congressional delegation flabbergasted. A carbon neutral rating means an industrial process doesn’t put more greenhouse gases into the atmosphere than it absorbs.

If the agency’s decision stands, it will smother the infant biomass energy industry with excessive costs, said U.S. Rep. Kurt Schrader, D-Ore. That’s because industries that aren’t carbon neutral eventually will have to pay penalties for the excess carbon they put out of their smokestacks.

“It will literally bankrupt the western timber community,” he said. “Rural America will not be able to participate in the energy independence and climate change (solutions) that we keep talking about.”

Regulators and researchers are wrestling with a set of related questions about biomass. Is burning wood an alternative to coal and natural gas that will help stop the accumulation of greenhouse gases linked to global warming, and simultaneously create a whole new set of green jobs?

Or is biomass a misguided attempt to elevate an old boiler-based technology that could contribute to global warming, in order to satisfy the political imperative to add jobs?

The not-very-satisfying answer to these questions is a qualified “It depends.”

Accounting for the greenhouse gases emitted by any kind of fuel – be it solar, wind or fossil – is a devilishly complicated endeavor that scientists and regulators are just now learning.

“And nothing is more complicated than biomass. These are not easy issues. It’s really complex. It’s legitimately complex,” said Gregory Morris, director of the Green Power Institute in Berkeley.

The impact of burning wood for energy depends on where you draw a line.

Draw the line at the smokestack, analyze the output, and the conclusion is a slam dunk: Burning wood produces more carbon dioxide than burning coal.

“If you just look at the smokestack, it is a fact that you’ll get more carbon dioxide per kilowatt hour out of a biomass plant than you do out of a coal plant. That’s true and it’s always been true,” Morris said.

The 98-foot smokestack at Seneca Sustainable Energy will release about 200,000 tons of carbon dioxide a year, according to the Lane Regional Air Protection Agency.

At the point of combustion, carbon dioxide is carbon dioxide, regardless of what you burn to get it, said Joshua Skov, principal with Good Company in Eugene, which performed an analysis on the Seneca plant.

“The atmosphere doesn’t really care where carbon dioxide comes from. It just cares that it’s carbon dioxide,” he said.

But if you draw the line wider to take in the source of the fuel and compare this to coal or oil, you get a different answer.

Treetops and limbs can regrow as the forest is replanted and grows. And the new wood begins to reabsorb the carbon that was released when the previous limbs and treetops were burned.

“This is not adding carbon to the natural cycles out there. It’s already there. It’s either in the trees or it’s in the air or it’s in the soil or in animals, or somewhere in between,” Skov said.

Oil and coal, on the other hand, are stored underground for millions of years, until a company digs them up, burns them and releases previously stored carbon into the atmosphere.

“When you dig stuff out of the ground, like coal, that is not part of the natural cycle, you are adding to the problem. In that sense, biomass is definitely preferable,” Skov said.

If the biomass plant is using tree limbs and tree tops that would have been burned as slash in the forest, most everyone agrees that that isn’t increasing greenhouse gases within the natural cycle.

The biomass plant may even decrease greenhouse gases if the heat generated by the boiler also is used, for example, to warm buildings, instead of using coal or natural gas.

A wood-fired plant, however, that burns whole logs harvested just to fuel the plant would not be carbon neutral – or at least not in any reasonable time frame because it takes so long to regrow the trees.

That was one finding of a recent study by the Manomet Center for Conservation Sciences in Massachusetts that rocked the biomass industry – and spread confusion nationwide – because some readers misinterpreted the study to mean that biomass plants contribute to global warming by adding carbon dioxide to the atmosphere.

The study was misleading, Morris said, because it would not pay companies to burn whole trees to power a biomass boiler. Companies get a lot more money out of the logs by making 2-by-4s, he said.

“That’s the key: You will never (cut down trees) for the express purpose of making fuel anywhere in the United States, for sure,” he said.

Skov and others say that eventually regulators will have to draw the widest possible circle to take in the smokestack, the woodpile and the forest that supplies the plant when they evaluate biomass.

“If you’re going to say biomass is carbon neutral, then you have to be concerned about the way we manage land,” Skov said. “You have to manage the land so it actually ends up growing trees.”

While the government policy on biomass is unsettled, the Environmental Protection Agency will begin regulating greenhouse gases in January. It’s unclear whether biomass will be seen as part of the solution to be encouraged or part of the problem to be regulated.

Oregon has adopted “renewable energy standards” that require utilities to buy green power – 20 percent of electricity must come from new, homegrown sources by 2025.

If biomass is considered by the federal government as part of the problem, plants such as Seneca’s may not be able to get the government incentives that make the plants profitable to operate.

In Oregon, the politics of biomass are complicated by decades of mistrust. Most of the power plants are built and owned by timber companies. Many of the opponents of biomass are environmentalists who have resisted logging in federal forests by private timber companies.

Today, the controversy centers on how thinning projects in the federal forest can feed biomass plants.

“Are you going back door into the woods to get a commercial harvest out of thinning? That’s where you get into a little bit gray area with some environmentalists. The issues aren’t trivial,” Morris said.

Some environmentalists won’t believe that timber companies absolutely will not burn whole trees in their biomass plants, Skov said.

“The interesting point that did not come across on the Seneca (biomass) issue is that people would accuse Seneca – which frankly hasn’t done a lot to earn the trust of environmentalists – of planning to burn whole trees: Planning to log, to bring trees back and throw them into this energy plant,” Skov said.

With a little more effort, the company could have demonstrated that it doesn’t make financial sense to burn whole trees, Skov said.

The wood products industry, as a whole, has not done a good job of explaining its business plan to the public, Seneca attorney Dale Riddle said, including the fact that it doesn’t want to cut down and burn whole trees to produce electricity.

“There can’t be anybody on the West Coast burning trees,” said Rick Re, sawmill general manager.

“It’s absurd,” he added.

In Morris’ view, operations at the Seneca Sustainable Energy plant, as planned, are carbon neutral, meaning it won’t add greenhouse gases.

At 18.8 megawatts, the plant is of modest size, compared with other plants in the works around the country at 47, 65 or 100 megawatts. When it’s completed early next year, the plant will sell enough electricity to the Eugene Water and Electric Board to power 13,000 houses.

Seneca will need 132,000 bone dry tons of wood byproducts to feed the plant each year.

Seneca chose the plant size based on the company’s ability to fuel the plant exclusively from mill wastes and forest residue from the 165,000 acres of timberland the company owns in Lane and Douglas counties – so it wouldn’t ever have to rely on wood from federal timberland, Riddle said.

“They’re not going to cut down trees for the biomass plant,” Morris said. “They’re going to cut down trees to manage their commercial forest. They would do that anyway, and they would burn the residue in the field.”

Seneca manages its forest in accordance with the Oregon Forest Practices Act, which requires replanting clear-cut areas within two years and re-establishing a healthy, freely growing stand by the sixth year.

The Seneca plant is likely to burn tree tops and limbs for other nearby timberland owners or the slash from an occasional federal logging contract. In the future, the plant also may burn waste straw from grass seed growers or, perhaps, hazelnut shells from orchardists, Riddle said.

And Seneca gets a carbon bonus because it will use heat – a byproduct of burning – to dry lumber in its kilns.