Like charcoal, but made from organic waste

Biochar is one way that Minneapolis hopes to build a healthier and more cyclical city ecosystem

biochar after
Biochar was used in a soil regeneration project near the Linden Hills trolley path off York Avenue. Recent demonstrations showed gardens with biochar had production yields averaging 20%–30% greater than those without the charcoal-like substance. Photos courtesy of Ginny Halloran

It is rare to leave a presentation about climate change feeling a sense of optimism. But optimism was in the air as Southwest residents, urban gardeners and sustainability advocates filed out of Mayflower Church in Tangletown following a recent city presentation on biochar.

Biochar is a charcoal-like substance made from organic waste. It has many benefits but the one that gets the most buzz is its carbon sequestration capacity: It acts as a long-term container for carbon that would otherwise be released into the atmosphere or ocean and contribute to climate change. This is what makes biochar a “carbon-negative” technology.

In her piece “Poetry is Not a Luxury,” the essayist, black feminist and cultural critic Audre Lorde writes “there are no new ideas still waiting in the wings to save us as women, as human. There are only old and forgotten ones, new combinations, extrapolations and recognitions from within ourselves, along with the renewed courage to try them out.”

In Lorde’s tradition, biochar is not a new idea. But Minneapolis is poised to figure out how it can be an idea adapted to the city’s current political and ecological context.

In June, the City Council passed a resolution entitled Recognizing Regenerative Agriculture and Biochar to codify the city’s support of biochar as an effective agricultural and climate mitigation strategy.

The resolution, sponsored by Council Member Jeremy Schroeder, came after years of testing in partnership between the city and the Shakopee Mdewakanton Sioux Community (SCMC). Using compost produced at an SCMC-operated organics recycling facility, they opened five demonstration sites to test the impact of biochar-compost mixtures on urban agricultural production. The demonstration gardens with biochar had production yields averaging 20%–30% greater than those without.

biochar before
The above area before the use of biochar.

The studies both deepened fine-grain understanding of how biochar techniques could be implemented locally while confirming what many communities and scientists around the world already know: Biochar is an effective sustainable agriculture tactic.

Biochar is also receiving increasing international support as a climate mitigation strategy. The Intergovernmental Panel on Climate Change included biochar as a climate resiliency recommendation in its 2018 Special Report. Other co-benefits of biochar include stormwater management and soil remediation.

Linnea Champ is finishing up her summer graduate internship with the Department of Environmental Services in the Health Department. Champ has taken the lead in researching the potential benefits and best practices for biochar use in Minneapolis — all with an eye toward how the ecological and the human interconnect.

Talking about the relationship between environment and health is important, Champ explained, because “people tend to be more motivated when things feel imminent and personal, and health is one of those things.” When it comes to biochar, it is through co-benefits like food growth and pollution remediation that the human stake becomes startlingly apparent.

There is fervent agreement across city agencies from the Park Board to Public Works that biochar is a good idea. According to Patrick Hanlon, director of environmental programs for the Health Department, the issue is about scaling up.

Part of scaling up is figuring out production. For its test cases, Minneapolis has been importing biochar from a facility in Missouri. Yet in order to truly have a self-sustaining and ecologically viable biochar program, the city wants to produce it in house.

But biochar production is not simple. It is made through a process called pyrolysis in which organic materials are heated to very high temperatures in an oxygen-limited environment. The temperatures needed to produce biochar must be exact and vary from one organic material to the next. If produced incorrectly, biochar can mess with soil pH and actually reduce plant productivity. These production specifications add to both machinery and operational costs.

The other roadblock to scaling up is bureaucratic.

Given that biochar touches on areas from public health to sustainability to infrastructure, effective implementation will require aligning communication and processes across many city departments and existing programs. “Biochar works best in combination with a lot of our other climate-change-combatting strategies,” Schroeder explained. “But cities move slowly.”

On the upside, Minneapolis has access to a huge supply of biochar-ready organic waste from local compost to municipal ash tree removal. “For me the most exciting part about something like biochar is that it takes something that’s currently waste … and turns it into something that can be used,” Champ said. “It’s a step toward a more circular economy as opposed to a linear one.”

And while local residents may have trouble speeding up production capacity and bureaucratic procedures, the public education around biochar is a powerful means to change how people understand human actions as intertwined with ecological systems. Biochar, Schroeder argued, is a tool to help us tangibly envision this paradigm shift in practice. It is about living in a world of climate change beyond simply surviving it.

“We need to be looking toward finding a different way to live,” Schroeder said. “We should be looking for solutions that are going to preview what that world is.”

Mira Klein is a Minneapolis-based writer and environmental justice activist. You can reach her at mira.r.klein@gmail.com.

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