What can be used to make sustainable fuels?
There are many options, from cooking oil, to household waste and algae. They can also be produced synthetically (more on that later). Because there are so many possible sources, different materials can be used in different locations, depending on the local resources available. It also means that plants can supply the airports nearest to them, rather than needing to ship fuel around the world.
We believe that Sustainable Aviation Fuels need to satisfy three criteria to be viable:
Suitable: they meet the specifications of an aviation fuel.
Sustainable: they don’t compete with land use for food or habitation, or place significant demand on other natural resources such as fresh water.
Scalable: there’s potential to produce them at scale, with the right infrastructure in place.
Cooking oils: Along with animal fats, used cooking oils are the most common materials used to create Sustainable Aviation Fuels. Waste oil from vegetable oil production plants can be used, as well as inedible oils which are created as a by-product of ethanol. Waste cooking oil can even be collected from restaurants and other businesses, sent to refineries and used to fuel flights.
Synthetic fuels: These are produced by capturing CO2, such as directly from the air or from industrial processes, and creating the fuel using electricity. They are in the early stages of testing, but if they can be commercialised and made using zero carbon electricity, such as from a small modular nuclear reactor, they are a promising source of energy for the aviation industry.
Waste: Fuels can be made from municipal or household waste that would otherwise end up in landfill. Using rubbish has added benefits; firstly landfill waste can be a source of methane emissions which have a warming effect far greater than CO2, so by not burying rubbish, we avoid extra emissions. Secondly, any plastics in the waste, once broken down into their constituent components, represent a valuable energy source in the finished fuel.
Crops: Plant or animal materials such as wood, wheat or algae can be used. As these materials grow, carbon is removed from the atmosphere through photosynthesis, converted into fuel and released via combustion. When using crops, broader sustainability impacts must be taken into account, such as not competing with the food supply, limiting the use of fresh water, and avoiding deforestation. For that reason we believe fuels created from waste feedstocks or synthetically using low carbon energy are the most attractive for aviation.