Biochar for carbon capture The City of Stockholm is using biochar made from waste Christmas trees and other garden waste to sequester carbon in soils: https://www.euronews.com/green/2021/06/14/how-is-the-3-billion-biochar-industry-transforming-green-energy-sweden Please note that the original modelling study, showing that biochar production could make a significant contribution to global carbon capture, was done by PhD student Dominic Woolf, at Swansea University, UK, and not by Cornell University in the US, where he works now: https://www.nature.com/articles/ncomms1053