A St. Paul bookkeeper bought the store he balanced the books for, plastered his family's name on it, and left it to all nine of his kids. Three generations later, they still won't sell.
Carba is a Minneapolis-area climate-tech company that turns low-value waste biomass - dead trees, yard waste, and other biogenic scraps - into a stable, charcoal-like material called biocarbon (biochar). Using a patent-pending autothermal pyrolysis reactor and an anoxic (oxygen-starved) burial method, Carba locks carbon away for a certified 1,000+ years, most notably inside existing landfills where the material can also filter pollutants. The company sells the resulting permanent carbon-removal credits - including a five-year, 44,000-tonne deal with Microsoft - and aims to remove a billion tons of CO2 by 2035.