Clean fuels: The future of aviation.

One day, airplanes will fly without fuel, using a steady stream of fats, starches, sugars, garbage, and other exotic fuels. This is the plan of American, Delta, and United, airlines that have set ambitious goals to reduce carbon emissions by 2050.

General trend

Last year, Virgin Atlantic successfully completed a transatlantic flight using entirely synthetic fuel derived from plant fats and sugars. This breakthrough opens up a future for sustainable aviation fuel (SAF). SAF is a general term for aviation fuels that emit less carbon than conventional jet fuel, produced from resources such as biodiesel, agricultural by-products, etc.

Virgin Atlantic has received permission from the UK Civil Aviation Authority to operate a transatlantic flight as part of its long-term plan to use 100% sustainable aviation fuel (SAF). Photo: VIRGIN ATLANTIC

The Boeing 787 aircraft used by Virgin Atlantic on the aforementioned flight used a type of fuel oil (SAF) that emits 70% less carbon than synthetic aviation fuel derived from petroleum. Previously, an Airbus A380 passenger plane also conducted its first three-hour test flight using fuel primarily made from cooking oil and waste fat. To date, no one has designed a battery that is both lightweight and powerful enough to power commercial aircraft. Therefore, the most practical way to reduce aviation emissions is to require aircraft to use SAF.

However, reducing aircraft carbon emissions will depend on finding suitable fuel sources, as none of the potential sources can meet all fuel needs. Although the administration of U.S. President Joe Biden has set a goal of increasing the aviation industry's sustainable fuel supply to 100% by 2050, last year the U.S. only produced enough sustainable fuel to meet less than 0.2% of its aviation fuel consumption.

Find suppliers

Almost all sustainable aviation fuel to date has been made from some form of fat, including used cooking oil, vegetable oil, and animal fat, but supply doesn't meet demand. The U.S. and Europe currently rely almost entirely on their domestic supply of used cooking oil and import additional waste fats from Asia to produce biofuels for aircraft, cars, and trucks.

The next generation of sustainable jet fuels set to enter the US market in the near future could be produced from corn and sugarcane. Previously, refineries fermented the starch and sugars in these crops into ethanol, which was then blended into gasoline and diesel. LanzaJet – an alternative fuel startup – has opened the world's first plant producing jet fuel using ethanol derived from US corn, Brazilian sugarcane, and other sources.

One limitation is that fuels made from food crops may not be as sustainable as fuels made from waste. Agricultural land is limited, and expanding the area of biofuel crops could lead to negative environmental consequences such as excessive water use and deforestation, releasing more carbon into the atmosphere. To meet the entire fuel needs of the US aviation industry with corn ethanol, the country would have to plant 114 million acres of corn – an area larger than the state of California. According to the Washington Post, this is why European regulations do not consider most food crop-based biofuels to be “sustainable,” and jet fuel made from corn ethanol may not qualify for preferential tax treatment under the US definition.

As an alternative, manufacturers are developing methods for producing jet fuel from cellulose-based cover crops, a type of grass commonly grown on farms between normal growing seasons to keep the soil healthy. Because they grow out of season, these crops will not compete for agricultural land with food crops, making them more sustainable.

Several companies are turning waste into jet fuel. Among them is the US refinery Fulcrum Bioenergy, which opened a waste-to-fuel plant in 2022. But not all waste is good for fuel; it needs to be sorted. There are also other forms of waste that are more suitable, such as agricultural waste, including: stems, leaves, and unharvested produce, or husks and leftover shells from food processing. Branches and bark left over from logging, sawdust, and wood chips can also be sources of fuel. Green hydrogen fuel is also highly regarded.

According to SkyNRG, a sustainable aviation fuel producer, while hydrogen-based jet fuel production is not yet fully developed, once production begins to increase, green hydrogen will quickly become one of the largest sustainable fuel sources.

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