Forest Service begins making biochar at wildfire recovery site

03 December 2020

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USA- ESTACADA, Ore. — An excavator rumbled over a pile of dead tree branches, limbs and woody debris in the Mt. Hood National Forest east of Estacada, Ore., where the Riverside Fire began Sept. 8 and quickly enveloped 138,054 acres.

Next to the pile sat the Tigercat 6050 carbonator, a tank-like mobile machine designed to convert organic biomass such as forest brush and slash into biochar, a carbon-rich soil amendment with serious potential for Northwest farms.

“Black gold,” remarked Kraig Kidwell, regional timber contracting officer for the U.S. Forest Service, as he grabbed a handful of grainy, jet-black biochar. “We’re taking a waste product and creating something usable.”

Kidwell watched alongside Phil Monsanto, West Zone silviculturist for the national forest, as the excavator dropped several loads of slash into the open top of the carbonator, flames barely visible as they peeked out of the vessel.

To the best of anyone’s knowledge, it is the first time federal land managers have incorporated making biochar as part of a wildfire cleanup project.

“We have so much of this slash, we just wanted to find other ways to manage it,” Monsanto said.

The Riverside Fire, named for the nearby Clackamas River, was one of several large wildfires that ravaged Western Oregon after Labor Day, fueled by bone-dry conditions and ferocious winds. Firefighters now have the blaze mostly contained, though not before losing at least 57 homes.

In addition to property damage, the fire has left normally lush hillsides in the forest canyon dangerously barren and prone to landslides and rock slides.

Along the Clackamas River Highway, crews have been cutting down hazardous trees as part of the recovery effort. The logs may be sold for timber, though the smaller-diameter brush cannot be processed at local mills, leaving the Forest Service with few options for it.

Slash may be used to make wood chips, though with so much burned material the cost of production quickly outweighs any potential profits. Oftentimes it is simply burned in big piles, though that too has some drawbacks, such as emitting plumes of smoke into the air.

Biochar could offer a solution on both fronts.

The Tigercat 6050 works by burning the slash in an oxygen-free environment — a process known as pyrolosis — with a large air-blower recirculating air to trap emissions.

“I’ve been aware of the technology,” Monsanto said. “We were impressed by its potential.”

Monsanto estimated between 80% and 90% of carbon is sequestered in biochar. Studies show biochar also improves the water-holding capacity of coarse-textured soils.

Earlier this year, Elder Demolition, a commercial demolition contractor based in Portland, purchased a Tigercat 6050 carbonator as a way to recycle wood from homes and buildings.

Jeff Elder, the company’s vice president, said most of their recovered wood was previously sent to the WestRock paper mill in Newberg, which shut down permanently in 2016.

“Recycled wood is so hard to get rid of,” Elder said. “All these mills are shutting down, so nobody is taking it anymore.”

The Mt. Hood National Forest contracted with Elder for recovery services beginning in early November, with approval from the Oregon Department of Environmental Quality.

After starting at Timothy Lake near Mt. Hood, the Elder Demolition crew moved to a wood pile at a truck weigh station along the highway destroyed by the fire. The carbonator averages roughly 4% yield, meaning that for every 100 yards of brush it burns, it produces 4 yards of biochar.

Kidwell said the markets for biochar, admittedly, are still developing. While the product’s benefits are mostly understood, the issue boils down to basic economics — not many outfits are producing biochar, which in turn makes it cost-prohibitive for most farmers.

In 2019, the average price for biochar in the U.S. was $1.29 per pound. By comparison, nitrogen fertilizer costs 35-44 cents per pound.

Incorporating biochar into more forest fire rehabilitation projects could help boost supplies and make it more affordable, Kidwell said.

“If someone doesn’t start doing this, it’s not going to happen,” he said.

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