Stockholm’s Biochar Project aims to reduce carbon emissions by enabling citizens to be part of carbon sequestration. Residents will provide plant waste to the city, which will produce biochar – a charcoal-like product that can sequester carbon in soil for thousands of years. Biochar, when placed in plant beds, improves soil structure, encourages plant growth, and helps to purify stormwater runoff. Additionally, a by-product of the biochar production process is pyrolysis gas, which will be used to generate energy for the city’s district heating system. While there are examples of biochar use across Europe, Stockholm is implementing the first large-scale collaboration between local authorities and citizens in the generation of the product. Stockholm’s first physical biochar plant opened in March 2017—and four more are planned to be completed by the end of 2018. The City anticipates these five plants will produce 7,000 tons of biochar by 2020, sequestering 25,200 tons of CO2 (the equivalent of taking 3,500 cars off the road) and producing a corresponding 25,200-megawatt hours of energy. This project has the potential to take citizen engagement to a new and self-perpetuating level. That’s because citizens won’t only contribute to the process (as they traditionally have with recycling), they will also reap the benefits by taking home garden-boosting biochar.