From ash to property: Seattle’s Mast proves that biomass buried in wildfires can support forest recovery

For landowners, it’s heartbreaking to lose acres of forest to a wildfire – and then there’s the challenge of what comes next.

Mast Reforestation has an answer that helps to restore the burned area and prevent additional carbon emissions that warm the planet while generating income: it is called biomass burial.

The Seattle startup has developed a solution that permanently disposes of burned trees, locking in their carbon and methane that would otherwise be released into the atmosphere. The company announced today that its first tree funeral has performed as designed and has sold 80% of the carbon produced as a result.

Under normal circumstances, “the maintenance of that land is really expensive,” Maria Huyer, head of product at Mast, told GeekWire. “And this is a simple solution to the removal of carbon dioxide that has the potential to support such a big challenge.”

Burying biomass

After a wildfire, landowners have limited strategies for removing burned vegetation and replanting. They can burn down dead trees, sell their wood, find a mill to take damaged wood, or turn it into environmentally friendly biochar – but that requires special equipment and is difficult to do with mobile units.

Because of the remote location, landowners of the destroyed forest in southern Montana had the option of burning the remaining wood. Then came the collaboration with Mast.

The project produced more than 4,500 tons of biomass that was buried in a mud-sealed area that prevents the wood from getting wet, rotting and outgassing. The pit is carefully covered with a layer of clay, geoengineered fabric, stones and organic matter. Native grasses are planted on top.

Sensors inside the vault monitor changes in temperature and humidity that indicate decay, allowing the team to take action and stop the process. Ground-based sensors operate continuously and can detect elevated levels of carbon dioxide and methane that are monitored remotely.

The startup has committed resources to continue monitoring for 100 years.

Some of the revenue generated from the sale of carbon credits pays for the reforestation of Montana’s forest, which was burned by the 2021 Poverty Flats Fire. That work will begin this spring.

Companies, organizations and institutions buy carbon credits to reduce their climate impacts. Buyers of Montana credits include Royal Bank of Canada, carbon credit marketplace CNaught, and Muir AI, a Seattle startup that tackles supply chain costs.

The project generated 4,277 carbon offset credits that were independently verified and registered with an organization called Puro.earth. Huyer did not disclose how much they cost, but he said they are more expensive than the environmental credits created by forest conservation and are about in line with the cost of biochar.

A growing strategy for carbon removal

There are other efforts to bury biomass, including Graphyte, which turns plant and wood waste into bricks that are dumped in landfills, and Carbon Lockdown in Maryland, which uses a strategy similar to Mast’s, among others.

The use of wood walls for carbon sequestration is gaining interest, according to experts. But there are concerns about ensuring the best use of wood waste. Depending on the situation, biomass can be used for continuous jet fuel production and other applications. Huyer said the company looks at these alternatives when evaluating a project.

Mast first launched in 2015 as Droneseed, which used drones to map and replant burned areas. It has expanded and changed focus since then. It now owns Silvaseed, the largest independent seed supplier in western Colorado; seedling supplier Cal Forest Nurseries; and seed supplier and processor Siskiyou Seed.

The company, which just raised $25 million from investors last year, still repairs forests with the help of drones, but it plants by hand to improve the trees.

Mast’s goal is to increase its burial of burned wood to contain about 20,000 metric tons of biomass. It aims to build a pipeline of projects of up to 150,000 tonnes each year. There is no shortage or waste to be had.

“In Montana alone there’s 2.8 million tons of biomass burned,” Huyer said. “And this is a broader and broader challenge.”