A Warming Trend for Putting Wood Waste to Work as Fuel

Climate Concerns Spur New Interest In 'Bio-Oil' Efforts

A plant to produce "bio-oil," under construction in Guelph, Ontario, will vaporize sawdust derived from the scrap lumber and wood chips now piled beside it. (Photos By Doug Struck -- The Washington Post)

GUELPH, Ontario -- A mountain of wood -- broken rafters, studs and floorboards recovered from demolished houses -- rises on a lot here. In a few million years, geologic forces could make it oil. Entrepreneurs are hoping to do it this month.

The pile of debris is growing as welders join the last pieces of machinery to convert wood scraps into "bio-oil" that can replace conventional heating oil. The new fuel is one of a widening variety of long-delayed petroleum alternatives moving closer to commercial production as concern over global warming makes them more attractive.

"There's going to be a mix of fuels in the future," said Andrew Kingston, head of Dynamotive Energy Systems, the company building the plant. "You can think of each one of these plants as an oil well."

President Bush has set an ambitious goal of 35 billion gallons of alternative fuels produced annually by 2017. The most recognized biofuel now is ethanol, a gasoline substitute brewed from corn and other grains, which promoters say will significantly reduce the greenhouse gases pumped into the air from petroleum-based fuel.

But when the energy required to grow corn is counted, the advantage of ethanol is marginal, and using a food source to power cars remains troubling to some. Researchers are looking at other methods to convert cellulose such as grass or weeds or discarded lumber into fuels. Some have focused on using enzymes for that conversion, others on chemical or mechanical treatments.

"I don't think there's going to be a silver bullet," said Gregory Kats, managing director of Capital E, an energy consulting firm in Washington. "I think it's clear there is a lot of opportunity. There is going to be a lot of innovation, and this is a case where letting a thousand flowers bloom is a good idea."

The plant rising in Guelph, 40 miles west of Toronto, is being built by one of at least three Canadian companies using variations of pyrolysis, an update of a technique used for years to produce charcoal.

The wood debris is cleaned and ground into sawdust, then injected into a heated, airless chamber with nitrogen. In a flash, the sawdust vaporizes into three forms: oil that is drawn off and sold, gases that are re-burned, and char that can be mixed with the oil or used as a fertilizer.

The process is considered "carbon neutral" because it uses carbon that is in the wood and that through natural decay would one day contribute to carbon dioxide emissions anyway. With petroleum fuel, in contrast, crude oil is brought to the surface to emit atmospheric carbon that would otherwise have remained trapped underground. In addition, the new fuels are low in sulfur, which adds to smog.

"We are not using anything that can be used as a food source. We take residual waste -- forestry debris, scrap wood, construction demolition wood," Kingston said in an interview at the company headquarters in Vancouver, B.C. "Residual biomass has little or no value, so the cost structure means you can compete."

While the process works in a laboratory, there are pitfalls to making it successful on a scale large enough to be commercially profitable, researchers acknowledge. A pilot plant by Dynamotive at West Lorne, Ontario, was heavily subsidized by government agencies, recorded large losses and never did achieve large-scale bio-oil production, a worrisome precursor to the plant being built in Guelph.

There were "mechanical and design difficulties," Kingston said, "but we are confident we have resolved them."