CASTRO VALLEY, CA — Pull a burning log out of a campfire and it will send a smoky plume of carbon and ash into the air. Place that log in a 1,500-degree fan-blown kiln and the carbon and ash will lock down inside the coal.
That’s the mechanical principle behind the Tigercat 6050 Carbonator being used by the fire fuel reduction team in the East Bay Regional Park District this year.
District fire officials unveiled the machine that creates “biochar” Tuesday ahead of the fuel reduction season.
Anthony Chabot Regional Park is the site of the largest eucalyptus reduction project in Northern California and is the largest in park district history. According to the district, the use of the new carbonator to break down biomass is directly benefitting the communities of Oakland and Castro Valley by reducing truck traffic as well as the risk of forest fire.
“If we were to dispose of that biomass traditionally, we would be trucking the timber all the way to a cogeneration facility near Sacramnto,” said Assistant Fire Chief Khari Helae with the park district. Instead, they can process the biomass on-site.
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Deep in the park, green felling machines slash, rip, rake and grab young eucalyptus trees and stack them in a staging area next to the idle container-sized carbonator. By November, the smokeless incinerator will be burning 60 to 80 tons of biomass every 12 hours.
In a process called pyrolysis, the wood is burned at extremely high temperatures, under a curtain of fanned wind in the absence of oxygen. The charred wood is cooled with water and mechanically crunched into bits of dense porous coal, about the size of construction gravel.
“We would have had seven semi-trucks at all times on these small park roads,” he said. “We’re able to reduce the truck traffic carbon by nearly 10 times, from 19 pounds to 2.1 pounds. So not only are we doing it in a new way that’s etter for the environment, but we took something that did not have much use, which was eucalyptus lumber, and we’ve turned it into something that has a benefit, biochar,” he said.
One of the most beneficial uses of biochar is its ability to retain water, said Helae. It can be mixed with soil to make it drought-resistant. It also filters contaminants from soil.
This fall’s 365-acre fuel reduction project follows a smaller pilot project done on 80 acres in January. In 2021, the district’s fire officials were spooked by the sudden death of over 1,500 acres of drought-stricken trees.
Non-native eucalyptus trees contain chemicals that easily ignite. They regrow quickly into impenetrable densities, and firefighters can’t reach a blaze to fight it. Because the park is near urban areas, they can’t just let a fire burn out.
They knew the forest had to be thinned to avoid the risk of disasters like the 1991 Oakland Tunnel Fire, which killed 23 people and destroyed 3,000 homes. After seeking xpertise from forestry labs at the University of California, Berkeley and the University of California, Davis, they dedicated $1 million from their own district budget and asked the California Coastal Conservancy for another million dollars to fund the pilot.
District general manager Sabrina Landreth thanked a list of supporters who helped direct $10 million in state funds to upscale the project this year.
The district now has a biochar utilization committee, which is working to find additional uses for biochar within the park district.
The biochar from the pilot was given to Ardenwood Historic Farm, where it’s being utilized to improve soils and crop yields, said Helae.
Another project where biochar is being used is in Wildcat Canyon.
“We had a landslide occur during the atmospheric rivers that took place last winter,” said Helae. “Biochar is being mixed with the soil to help the plants grow back quicker.”
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