As the Sierra Pacific Industries mill west of Burlington turns Douglas fir and hemlock trees into lumber, the facility also produces more electricity than it needs to power its operations.

Puget Sound Energy announced this week that it will purchase that excess power, called renewable biomass energy, starting in 2021. Other electricity providers have purchased that power from Sierra Pacific in the past.

“This is another step in our journey to acquire clean sources of energy for our customers,” PSE Senior Vice President of Energy and Supply David Mills said in a news release.

The energy is produced at the mill by the burning of byproducts, including bark and sawdust. Sierra Pacific spokesperson Andrea Howell said that as the material is burned, it creates steam that turns turbines.

That’s considered a clean energy source because ash and emissions are contained instead of released into the atmosphere.

A statement from PSE says “an air pollution controlling device filters out fine particles and other emissions from the burning wood so that what is released into the atmosphere comes out clean.”

While a fire blazed in the mill’s boiler room Wednesday, operator Rusty Raasch kept a watchful eye on video screens showing incoming sawdust, popping embers and billowing flames.

Outside, a worker driving a front loader mixed dry and wet bark and sawdust to ensure effective burning.

“They’re mixing that just like cake batter,” said Tony Minor, safety and environmental compliance officer at the mill. “They have to get that batter just right to equalize the moisture.”

Water recaptured from steam goes into a neighboring facility, ready to be recirculated through the mill’s system.

“What water we don’t lose through evaporation they’re going to collect and run back through the system,” Minor said.

This process of generating steam-powered electricity is used at Sierra Pacific mills in Washington and California. At the Skagit County facility, about 24 megawatts of energy are produced each hour. About 7 megawatts are used to power the facility.

The remaining 17 megawatts are what Puget Sound Energy will soon add to its mix of energy sources.

The power company, which provides electricity to about 1 million homes in Washington, expects that new source will meet the needs of about 14,000 homes.

PSE spokesperson Andrew Padula said it will add to the company’s renewable energy portfolio, which the company is working to grow in order to move away from coal power and meet the goals of the state’s Clean Energy Transformation Act.

That act, signed into law May 7, 2019, calls for electric companies to be coal free by 2025 and carbon neutral by 2030.

In 2018, coal accounted for 36% of PSE’s power mix, while renewable biomass accounted for less than 1%. Data for 2019 has not been released yet, but Padula said the company is working to move the needle on renewable power contributions.

“We’re slowly moving that up and changing things around since we are trying to get out of coal,” Padula said.

From 2016 to 2018, the amount of energy produced by renewable sources for PSE grew from 1.9 million to 2.3 million megawatt hours. The contribution of Sierra Pacific Industries’ excess energy will help boost those numbers.

Howell said the company values making use of all components of the logs it shapes into lumber.

“We are experts at turning round things into square things, and what we can’t we sell as residuals or turn into energy,” Howell said.

— Reporter Kimberly Cauvel: 360-416-2199,, Twitter: @Kimberly_SVH,

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