Inspired by Stockholm’s success, a U.S. city goes big on biochar

Minneapolis is already using biochar to bolster urban agriculture. After three city leaders visited Stockholm in May, Minneapolis is considering new uses for the carbon-capturing soil additive.

Biochar is nothing new in Minneapolis. The city has, for years, bought truckloads of the charcoal-like material from a plant in Missouri and used the dusty black nuggets for a well-known use: to enrich soil for urban agriculture and bolster the local bounty of fruits and vegetables to harvest.

But then three city leaders visited Stockholm in May. And now Minneapolis is starting to think even more expansively about how this carbon-catching soil conditioner might help the city address a number of emerging concerns — from climate change to stormwater management.

The Minneapolis team visited the tidy plant in Stockholm’s public-works yard, where the city turns tree limbs into biochar — and simultaneously kicks off energy to heat buildings. And they went to one of the new super-sustainable neighborhoods Stockholm is known for, where biochar helps sponge up and filter stormwater while helping street trees thrive. (See the infographic at the bottom of this page for more on how biochar is made and used.)

They were blown away by Stockholm’s holistic approach to turning its abundance of yard waste into a recycled resource with so many applications — all while taking advantage of biochar’s signature benefit as a carbon sink that helps mitigate climate change.

“It was a lot simpler than I imagined it to be,” said Robin Hutcheson, Minneapolis’ public works director and a member of the Minneapolis delegation. “I think I had imagined biochar as something that was chemical and complicated and difficult to produce and difficult to use. What I learned is that it is actually simple to produce and able to be used in a variety of settings.”

Participants in the Stockholm convening visited the plant where the city turns yard waste into biochar.

The Stockholm trip was part of a Bloomberg Philanthropies event meant to showcase and aid replication of Stockholm’s success with biochar. After winning €1 million through the foundation’s Mayors Challenge, Stockholm opened its small biochar plant two years ago and is now looking at scaling up production. At the convening, city leaders behind the Stockholm effort shared their lessons learned with the Minneapolis team, as well as…