https://www.siliconvalley.com/2021/06/25/sfos-sustainability-chief-erin-cooke-fuels-cleaner-flights/ > Erin Cooke, San Francisco International Airport’s director of sustainability, says she found her professional “sweet-spot” at the juncture of environmental advocacy, public service and capitalism. > As environmental chief of the state’s second largest airport, Cooke has become a national proponent of sustainable aviation fuel, or SAF, an alternative energy source derived from tallow, fats and vegetable matter that burns cleaner, is more expensive to produce and is, thus, less common than conventional jet fuel.