On the opposite finish of the spectrum, some crop-based biofuels can really produce extra carbon dioxide emissions total than fossil fuels, Pavlenko says. That’s regularly the case for biofuels constituted of palm oil, since rising that crop can decimate rainforests. Even artificial e-fuels can strategy the influence of jet gas in the event that they’re produced utilizing electrical energy from fossil fuels.
Today, most commercially out there different jet fuels are constituted of fat, oils, and greases. If they’re derived from waste sources like used cooking oils, these fuels cut back carbon dioxide emissions by roughly 70% to 80% in contrast with fossil fuels.
It’s price noting that whereas SAFs can strategy net-zero carbon dioxide emissions, burning the fuels nonetheless produces different sorts of air pollution, together with different greenhouse gases and particulate matter. The fuels may also contribute to formation of contrails, which lure warmth within the environment.
What’s subsequent for SAFs?
There are a number of different applied sciences on the desk for slicing local weather impacts in aviation, together with hydrogen– and battery-powered planes. However, with out additional technical progress, these choices could also be restricted to smaller planes flying shorter routes, and most international carbon dioxide emissions at the moment come from flights over about 900 miles (1,500 kilometers). That’s the place SAFs may assist. Alternative fuels are enticing for the aviation trade as a result of they’re a drop-in resolution, requiring little adjustment of plane and airport infrastructure. (Planes may want small changes to run on 100% SAFs sooner or later, relying on the combo of chemical substances within the gas.)
Many aviation net-zero plans, just like the one printed by the International Air Transport Association, assume that SAFs will make up nearly all of the trade’s local weather progress within the coming a long time. Over the previous 12 months, a number of take a look at flights powered by 100% SAFs have taken off. However, different fuels made up lower than 0.2% of the worldwide jet gas provide in 2022. So there’s plenty of progress wanted to produce different fuels which are really useful for the local weather.
One of the primary challenges to getting SAFs into the skies is increasing the availability. While fat, oils, and greases are the idea of most commercially out there SAFs at the moment, the world doesn’t eat sufficient french fries for used cooking oils to fulfill international jet gas demand alone. In truth, even with elevated assortment, waste fat, oils, and greases in all probability received’t present greater than 5% of world jet gas provide, Pavlenko says.
Some new biofuels, like these constituted of agricultural residue, municipal stable waste, and hardy crops like switchgrass, are beginning to enter the market; a number of amenities are underneath building or producing jet gas from these sources worldwide, and the carbon dioxide emission financial savings they obtain can vary from 50% to 90%.
Recent coverage strikes in each the US and the European Union are aimed toward boosting the marketplace for different fuels. RefuelEU Aviation, a deal finalized in April, requires that gas provide at EU airports embody 2% SAFs by 2025 and 70% by 2050. The EU rule will solely depend SAFs from waste sources, superior biofuels, and e-fuels, not crop-derived fuels. It additionally has a particular goal for e-fuels that’s aimed toward boosting their manufacturing.
The US, alternatively, not too long ago handed new tax credit for different fuels, aimed toward serving to costly choices attain value parity with fossil fuels. The tax credit final till 2027 and apply to any gas that reduces carbon dioxide emissions by not less than 50% in contrast with fossil fuels, although the main points on how reductions are calculated haven’t been launched but.
Ultimately, different fuels current one of the easy pathways to slicing the local weather impacts from aviation, however solely sure sorts will find yourself benefiting the local weather. “SAFs are a solution, but they need to be very properly done,” Mirolo says. Otherwise, they danger turning into “a cure that’s worse than the disease.”