Sustainable aviation fuels (SAFs) are a type of biofuel used to power aircrafts that are produced from renewable sources and have lower greenhouse gas emissions than traditional fossil fuels. They are a promising solution for reducing the carbon footprint of the aviation industry, which is a significant contributor to global greenhouse gas emissions. SAFs can be produced from a variety of feedstocks, including agricultural crops, waste oils and fats, and algae. They are chemically similar to traditional jet fuel, and can be used in existing aircraft engines without modification. However, SAF still has to be blended with traditional aviation fuel, which is made from fossil fuels. Current rules state that SAF can make up a maximum of 50% of the mixture, but there are hopes that airlines will be able to use 100% SAF by 2030.