On the other hand, some crop-based biofuels can actually produce more carbon dioxide emissions than fossil fuels, Pavlenko said. That is often the case for biofuels made from palm oil, as the cultivation of this crop can devastate the rainforest. Even synthetic e-fuels can approach the effects of jet fuels if they are produced with electricity from fossil fuels.
Today, most of the alternative jet fuels available on the market are made from fats, oils and greases. If they come from waste sources such as used cooking oil, then these fuels will reduce carbon dioxide emissions by about 70% to 80% compared to fossil fuels.
It is worth noting that although SAF can reach net zero carbon dioxide emissions, the burning of fuel still produces other types of pollution, including other greenhouse gases and particulate matter. The fuels can also contribute to the formation of streaks, trapping heat in the atmosphere.
What’s next for the SAF?
There are a few other technologies on the table to cut climate impact in the aviation industry, including hydrogen– And battery powered airplane. However, without further technical progress, these options may be limited to smaller aircraft that fly shorter routes and most of today’s global carbon dioxide emissions come from flights over about 900 miles (1,500 km). That’s where the SAF can help. Alternative fuels are attractive to the aviation industry because they are an easy-to-use solution that requires little modification of aircraft and airport infrastructure. (Aircraft may need minor adjustments to run on 100% SAF in the future, depending on the chemical mix in the fuel.)
Many aviation net-zero plans, like the one announced by International Air Transport Association, assuming that SAF will account for the bulk of the sector’s climate progress in the coming decades. In the past year, some test flights provided by 100% SAF took off. However, less alternative fuels are produced 0.2% of global jet fuel supply by 2022. So there’s a lot of progress needed to provide really useful alternative fuels for the climate.
One of the main challenges to getting SAF into the sky is expanding the supply. Although fats, oils, and greases form the basis of most commercial SAFs today, the world doesn’t eat enough chips for used cooking oil to just meet global jet fuel demand. In fact, even with increased collection, waste, oil and grease likely won’t provide more than 5% of the global jet fuel supply, Pavlenko said.
A number of new biofuels, such as fuels made from agricultural waste, municipal solid waste and tough crops like switchgrass, are starting to enter the market; several facilities are being built or produce jet fuel from these sources worldwide, and the carbon dioxide emissions savings they achieve can range from 50% to 90%.
Recent policy moves in both the United States and the European Union are aimed at boosting the alternative fuel market. EU Aviation refueling, an agreement finalized in April, requires fuel supplies at EU airports to include 2% SAF by 2025 and 70% by 2050. EU rules will only calculate SAF from sources waste, advanced biofuels and e-fuels, not fuels derived from crops. It also has a specific target for e-fuels aimed at boosting their production.
On the other hand, the United States recently adopted new tax credit for alternative fuels, to help expensive options reach fossil fuel prices. Tax credits extended until 2027 and applies to any fuel that reduces carbon dioxide emissions by at least 50% compared to fossil fuels, although details on how the reductions are calculated have yet to be released.
Ultimately, alternative fuels are one of the simplest avenues to cut climate impacts from the aviation industry, but only certain types will ultimately benefit the climate. “SAFs are a solution, but they need to be done the right way,” says Mirolo. Otherwise, they run the risk of becoming “a cure for worse than a disease.”