Use of wood waste has environmental, business benefits

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Wood waste-chips, bark, etc.-was once considered a residue of the sawmill industry, with little value or use. Industry advances over the past decade, however, have transformed the organic scraps into valuable commodities in their own right, useful for generating steam, heat and electricity. Weyerhaeuser's Prince Albert pulp and paper mill has adapted to these changes by converting one of its existing recovery boilers into a wood waste boiler to take advantage of these potential benefits.

"What used to be seen as waste is now seen as a resource, an opportunity," said Wayne Roznowsky, Weyerhaeuser's public affairs manager for Saskatchewan. "We've been burning wood waste to create energy for better than a year now."

The boiler conversion was part of a $315 million project, completed in 2000, which also included the construction of a new recovery boiler.

"There were two reasons for the project," explained Roznowsky. "One was to generate steam and electricity for the mill. The other was to clean up the air. By not burning as much natural gas, a fossil fuel, emissions have gone way down. What happens is you burn it [wood] to create steam, and the steam runs turbines that generate electricity. The steam then continues into the pulp mill to heat the facility and run the process."

The benefits of the costly project are also being felt by other nearby mills.

"Right next door to our pulp mill is the Wapawekka Lumber sawmill -that's a joint venture between Weyerhaeuser and three bands, the Lac La Ronge, Montreal Lake and Peter Ballantyne First Nations," Roznowsky said.

"Because of this project, we didn't need to build any wood waste burner when we built that sawmill. All the wood waste from Wapawekka is trucked to the Prince Albert mill, and that has really helped them in terms of their cost structure. We also get wood waste trucked in from the new sawmill at Big River - that was also built without a burner."

With the trucked-in wood waste and the stockpile that already exists at Prince Albert pulp and paper, the facility could potentially achieve additional revenue, cost savings and benefits. Company officials are currently looking at all options to determine what to do with the massive amount of wood waste at their disposal.

"The pulp mill opened in 1967, so they've basically been storing wood waste since then. There's about a million tonnes of it. Plus, we're getting more hauled in. We are eating into the stockpile, but not nearly at the pace we wanted to," noted Roznowsky.

"Right now, our bottleneck is how much steam we can use in the pulp mill, so that's why we're looking at other options. It really is an opportunity that we want to take advantage of more fully, but we have to determine what the best uses are."

Given the significant environmental advantages of burning wood waste over fossil fuels (emissions from the P.A. mill's new boiler are less than a tenth that of the older models), and the major cost savings of decreased fossil fuel reliance (natural gas usage at the mill is down 50 to 60 per cent), Weyerhaeuser is likely to find many parties interested in getting involved and sharing in these significant benefits.

"I like to describe it as natural gas sitting on the ground," Roznowsky laughed, "because every time we burn wood waste we're not buying natural gas."