They've been using Prometheus Fuels (a YC-backed company with further investment from US DOE and BMW i Ventures) thus far, starting with a 2019 deal. It will pr

They've been using Prometheus Fuels (a YC-backed company with further investment from US DOE and BMW i Ventures) thus far, starting with a 2019 deal. It will probably be up to United as to how they fuel the aircraft once in service, but they are basically touting that it is using a carbon-neutral fuel source all through R&D and Prometheus is using Boom to show that it can produce A1 (or possibly JP-8 with additives) in some new ways starting with ethanol and renewable energy sources. https://www.globenewswire.com/news-release/2019/06/18/1870486/0/en/Boom-Supersonic-Partners-with-Prometheus-Fuels-to-Supply-Carbon-Neutral-Fuel-for-XB-1-its-Mach-2-2-Demonstrator-Aircraft.html https://www.globenewswire.com/news-release/2019/06/18/187048... https://www.greencarcongress.com/2020/09/20200916-prometheus.html https://www.greencarcongress.com/2020/09/20200916-prometheus...