Aviation accounts for 12% of CO2 emissions from transportation and 2% of all CO2 emissions globally. Sustainable aviation fuel (SAF) is fuel made not from petroleum hydrocarbons, but from other sources of carbon and hydrogen. These non-fossil hydrocarbons include waste oils, plant-derived oils, and more complex sources like woody biomass and municipal solid waste; even CO2 can serve as a source of carbon to make hydrocarbons. Derived from all of these sources and more, approximately 160 mil...