WASHINGTON —- Simpson Tacoma Kraft would seem like one of thegreener power plants. It boils water by burning sawdust, bark andwood shavings from saw mills and pulp mills, funneling theresulting high-pressure steam into a turbine to generateelectricity.
Such power produced from biomass —- tree trimmings, scraplumber and other plant material —- is a small but growing part ofthe nation’s quest for renewable energy. The goal is to curb demandfor imported oil by supplanting coal, natural gas and other fossilfuels and to reduce greenhouse-gas emissions blamed for alteringthe climate.
The technology enjoys wide political support and publicsubsidies at least in part because of the belief that it is carbonneutral. That is, carbon dioxide released from burning wood isequivalent to the amount of carbon absorbed during the tree’sgrowth.
But new, sophisticated calculations are casting doubts on themerits of biomass-produced power. Some researchers have concludedthat, when it comes to carbon dioxide, biomass could be morepolluting —- at least in the short term —- than coal, and muchworse than natural gas. Burning biomass is dirtier at the outset,they argue, and recouping that higher initial release of carboncould take years or even decades of forest growth.
“It’s hard to imagine a more polluting and less efficientalternative source of energy than biomass,” said Richard Wiles,former co-founder of Environmental Working Group, a research andadvocacy group in Washington, D.C.
Biomass supporters dismiss that contention, noting wood emitsthe same amount of carbon whether it’s burned or left to decay inthe forest. The net change in atmospheric carbon dioxide, they say,is zero.
Yet, doubts about carbon neutrality could well alter the futureof the biomass industry in Washington state and elsewhere. Thanksto its forests, the state is among the nation’s largest producersof biomass power, generating enough to meet electricity demands ofTacoma and Spokane.
A dozen plants, all located in Western Washington except fortwo, produce power from wood byproducts from mills and forestwaste. Four proposed projects are waiting to join the grid —-provided they can overcome regulatory hurdles and legal oppositionfrom environmentalists.
Challenges to biomass’s “clean” credentials also could posepolicy repercussions. Since taking office in 2009, state PublicLands Commissioner Peter Goldmark has made pursuit of biomassenergy a signature initiative. Gov. Chris Gregoire and DemocraticSens. Maria Cantwell and Patty Murray also are strongproponents.
Taxpayers, too, hold a stake. That’s by virtue of hundreds ofmillions of dollars in subsidies and federal grants for biomassprojects, along with an estimated 14,000 biomass jobs across thenation.
Although carbon math is complex, critics level two main strikesagainst biomass.
First, because of its high moisture, wood yields less energycompared with more efficient fuels. Generating the same amount ofelectricity from biomass emits 45 percent more carbon dioxide thancoal and almost 300 percent more than an efficient natural-gaspower plant, according to a 2010 study by the Manomet Center forConservation Sciences, a nonprofit environmental researchorganization. The study was commissioned by the MassachusettsDepartment of Energy Resources.
Second, burning biomass releases carbon dioxide instantly, whilerepaying that carbon debt through new tree growth takes years. Justhow long depends on many factors, including the biomass source,what was done with it before and the fossil fuel it displaces.
Replacing coal-fired electricity by burning tree tops and otherwood waste, for instance, might take 10 years to recoup the carbon,said Thomas Walker, a resource economist and team leader of theManomet study. But if whole trees were harvested for feedstock –something the industry says it doesn’t do — and the resultingelectricity replaced cleaner-burning natural gas, Walker said,payback might take a century.
The timing matters because the nation has pledged to reducegreenhouse gas emissions by 17 percent from 2005 levels by 2020 anddramatically more in subsequent decades.
“The interesting question is how much bioenergy do you want topromote from systems that have greater short-term potential toincrease greenhouse gases?” Walker said.
The clashing views on biomass went on display in January whenthe Environmental Protection Agency decided to punt on the questionof whether biomass boilers would be required to account for theircarbon emissions the same way as other polluters. The agencydecided to exempt biomass for three years, reversing its positionfrom a year earlier.
Some health groups, in addition, worry about other gases andchemicals emitted from burning biomass, including sulfur oxides,carbon monoxide and dioxin.
Rick Gustafson, a professor at the University of Washington’sSchool of Forest Resources, criticized the EPA’s earlier decisionto treat biomass and fossil fuels under the same emissionsrules.
Gustafson acknowledges carbon benefits of biomass could takeyears to accrue. Yet, carbon from biomass fundamentally pays foritself as long as standing trees aren’t being depleted, hesaid.
“If the forest is growing,” Gustafson said, “it has to be carbonneutral.”
But Mark Harmon, a climate researcher at Oregon StateUniversity, said forests in the Northern Hemisphere on balance arealways expanding. So crediting biomass for carbon sequestered innew trees amounts to double counting, he contends.
Harmon said he believes biomass has the potential to worsenclimate change for years before it helps. While some debris fromlogging is burned deliberately, much of it is left to decomposeslowly.
“If your investment doesn’t pay off in your lifetime,” Harmonsaid, “that really isn’t helping very much. We need to solve thisin the next 20 years. Fifty years will be too late.”
As an alternative to fossil fuels, biomass enjoys heavy publicsubsidies.
Federal tax credits, for instance, cover 30 percent of theeligible cost of a new project. And biomass harvesters inWashington receive a state business tax credit of $3 per ton.That’s slated to go up to $5 per ton in July 2013.
Bob Cleaves, president of the Biomass Power Association, a tradegroup, called the subsidies critical, adding he does not know ifthe industry could sustain itself without public assistance.
For Simpson Tacoma Kraft, the federal tax credit alone covered$17 million of the company’s $90 million-plus tab to convert theplant to produce biomass electricity.
Simpson has been burning biomass since the 1920s, generatingsteam to manufacture shipping boxes and containers. Thanks to the2009 expansion, Simpson now takes that steam and generates 40megawatts of electricity, allowing the plant to become largelyenergy self-sufficient, said Dave McEntee, vice president ofSimpson Investment, a privately held Tacoma firm that owns themill.
But because biomass power fetches a premium in the open market,where many utilities must meet quotas on using renewable energy,Simpson sells its electricity to California and replaces it withlower-cost power from the city of Tacoma.
McEntee said Simpson would not have converted the plant withoutthe reliable supply of wood waste from its adjacent saw mill andother operators around Tacoma. That, coupled with tax credits andmarket premiums for biomass power, has proved Simpson’s investmenta smart bet, McEntee said.
“In my view, what we do is biomass done right,” he said.
