Buckthorn is one of the most difficult invasive plants to deal with in Minnesota and the solution usually involves removing it and burning the brush piles. But, for every pound of wood burned in an open pile, 1.82 pounds of carbon dioxide is released into the air, according to the Wood Products Council. A St. Paul nonprofit’s new wood-burning tool can put most of that CO2 into the ground. Great River Greening, an organization focused on land restoration and nature-based climate solutions, promotes a new way of burning wood and biomass to fight climate change by producing something called “biochar” instead of excessive CO2 and ash. The organization recently lit an inaugural fire at Lake Elmo Park Reserve, demonstrating the use of their new “Big Box Kiln,” which produces biochar, a charcoal-like substance that can be used to fortify the soil and lock in the carbon. “In the open-pile burns, all of that carbon was being released, so this is a huge, huge benefit for climate-smart practice,” executive director Kateri Routh said. An alternative to open-pile burns Great River Greening executive director Kateri Routh and conservation director Todd Rexine with the Big Box Kiln on Thursday, Dec. 5, 2024 at Lake Elmo Park Reserve. Great River Greening is launching a new mass wood-burning “Big Box” biochar kiln, which, along with the biochar material, is aimed at reducing the negative effects of climate change in the state. (Talia McWright / Pioneer Press) Open-pile burns, in which wood or biomass, like the invasive buckthorn plant, is stacked in a pile and then lit on fire, is a common practice among farmers and other land managers — one that conservation director Todd Rexine said he’s participated in himself. It was simply “a way to get rid of the wood,” he said. However, the damage open-pile burns cause the environment led him to learn about the biochar alternative. In cities, waste wood can be turned into energy such as in downtown St. Paul’s District Energy system. That’s not always practical for smaller burns in rural areas. “While you’re burning the stuff in biofuel plants, you’re producing energy and getting something out of it,” Rexine said. “When you go to do a full burn (open-pile burn), we’re just burning things down to ash and everything’s releasing into the atmosphere.” Related Articles Environment | ‘Gitmo’ in the Mojave: How the Marines are saving endangered desert tortoises Environment | F.D. Flam: Black spatula saga shows the danger of hyping science Environment | Neighbors oppose planned trash truck fueling station near St. Paul’s Randolph and West Seventh Environment | Drought, fires and deforestation battered Amazon rainforest in 2024 Environment | Bans on ‘junk fees,’ forever chemicals and binary triggers among new Minnesota laws as of Jan. 1 Great River Greening now has three wood-burning kilns ranging in size from small to medium, what they call the Oregon, Ring of Fire and their new, 10-foot-long Big Box Kiln. The process of lighting the kilns is unlike a campfire or brush pile, Rexine said. Instead of lighting the wood from the bottom, a fire is lit at the top. As the wood disintegrates and is then quenched with water, biochar is produced. “Keeping the fire at the top creates a low oxygen environment at the bottom where the biochar is being created,” Rexine said. “The process is called ‘pyrolysis.’” Biochar kilns are designed with specific air inflow and exhaust features that create a “flame-cap” effect, which helps maintain low oxygen levels and prevents fire from spreading downward, according to Rexine. It also allows water to be used for quenching the process and then released through a drain. What can biochar do? Biochar material, the product of Great River Greening kilns, is aimed at reducing the greenhouse gas emissions from brush-pile fires. (Talia McWright / Pioneer Press) Farmers can use biochar to “supercharge” soil by redistributing the carbon into the ground, Rexine said. It acts as a sponge and sucks in the nutrients, then releases them to growing organisms. Biochar can also be mixed with compost and used in gardening and land restoration. Not just any burn product qualifies as biochar, Routh said. Biochar needs to be at least 60% carbon to be up to standard. If not, it’s just ash. “Trying to do this without having the knowledge and skill set is not going to create the product that you want and the benefits you want,” Routh said. Rexine said biochar kilns are used in Oregon, Washington and California. The technology was developed to help combat wildfires, he said: Brush is turned into biochar to remove wood waste and reduce the potential for fast-spreading fires. Who gets to use it? CenterPoint Energy, the Minnesota Environment and Natural Resources Trust Fund and additional small family foundations funded Great River Greening’s development of its biochar kilns. The Big Box Kiln, which cost $15,000 to build, can turn 45 cubic yards of wood waste — about 20 pickup loads — into 9 cubic yards of biochar. While Great River Greening doesn’t have enough kilns available to rent out to individuals, they would like to be able to offer the service in the future. In the meantime, local environmental groups, counties and cities can use the kilns, and Great River Greening’s agricultural program is working with farmers to see how they can adopt biochar in agriculture. “We need to get to that next phase where we have a place to store the kilns in different locations throughout the state to make it more manageable for people to access it,” Routh said. Great River Greening Great River Greening works throughout the state of Minnesota in partnership with landowners; they do not own or manage any land themselves. “That makes us unique because every project we work on, we’re working directly with the community,” Routh said. Her team of ecologists specializes in prairie restoration, forest restoration, tree planting, working in parks across the state and in farm fields on regenerative agriculture practices. “We are driven to use science-based best practices in all that we do,” Routh said. Biochar is another initiative that the organization is hopeful can have a positive impact on the environment. Related Articles Environment | Listening House program that hires homeless, low-income workers to clean downtown streets expands Environment | Recent major fraud cases in Minnesota Environment | Twin Cities Habitat for Humanity to honor Jimmy Carter with messages from community Environment | Burnsville clinic that served underinsured closes after merger Environment | St. Paul free mental health clinic reached more than 100 visits since opening in October “We know buckthorns are a really big issue in our state right now, emerald ash borer is such a big issue and what do you do with all that waste product,” CenterPoint Energy program manager for community relations Rachel Molzahn said. “This seems like a really innovative and cool process to get rid of all that biowaste without creating some of the negative effects through emissions.” Molzahn said one of the things she loves about Minnesota is the outdoors. She said she thinks it’s important to find ways to sustain greenspaces and is excited about the prospect of biochar doing so. “The emissions thing is a really big deal,” Molzahn said. “I have a 4-year-old daughter and if she decides to have kids, then I want to make sure that they get to play outside, too.”