On the opposite finish of the spectrum, some crop-based biofuels can really produce extra carbon dioxide emissions general than fossil fuels, Pavlenko says. That’s continuously the case for biofuels constructed from palm oil, since rising that crop can decimate rainforests. Even artificial e-fuels can method the impression of jet gas in the event that they’re produced utilizing electrical energy from fossil fuels.
Immediately, most commercially out there different jet fuels are constructed from fat, oils, and greases. In the event that they’re derived from waste sources like used cooking oils, these fuels scale back carbon dioxide emissions by roughly 70% to 80% in contrast with fossil fuels.
It’s price noting that whereas SAFs can method net-zero carbon dioxide emissions, burning the fuels nonetheless produces different forms of air pollution, together with different greenhouse gases and particulate matter. The fuels can even contribute to formation of contrails, which entice warmth within the environment.
What’s subsequent for SAFs?
There are a couple of different applied sciences on the desk for reducing local weather impacts in aviation, together with hydrogen- and battery-powered planes. Nonetheless, with out additional technical progress, these choices could also be restricted to smaller planes flying shorter routes, and most world carbon dioxide emissions right this moment come from flights over about 900 miles (1,500 kilometers). That’s the place SAFs may assist. Different fuels are engaging for the aviation business as a result of they’re a drop-in answer, requiring little adjustment of plane and airport infrastructure. (Planes would possibly want small changes to run on 100% SAFs sooner or later, relying on the combo of chemical compounds within the gas.)
Many aviation net-zero plans, just like the one revealed by the Worldwide Air Transport Affiliation, assume that SAFs will make up nearly all of the business’s local weather progress within the coming a long time. Over the previous 12 months, a number of check flights powered by 100% SAFs have taken off. Nonetheless, different fuels made up lower than 0.2% of the worldwide jet gas provide in 2022. So there’s quite a lot of progress wanted to provide different fuels which can be really useful for the local weather.
One of many essential challenges to getting SAFs into the skies is increasing the provision. Whereas fat, oils, and greases are the idea of most commercially out there SAFs right this moment, the world doesn’t eat sufficient french fries for used cooking oils to fulfill world jet gas demand alone. In truth, even with elevated assortment, waste fat, oils, and greases most likely received’t present greater than 5% of world jet gas provide, Pavlenko says.
Some new biofuels, like these constructed from agricultural residue, municipal strong waste, and hardy crops like switchgrass, are beginning to enter the market; a couple of services are underneath development or producing jet gas from these sources worldwide, and the carbon dioxide emission financial savings they obtain can vary from 50% to 90%.
Current coverage strikes in each the US and the European Union are geared toward boosting the marketplace for different fuels. RefuelEU Aviation, a deal finalized in April, requires that gas provide at EU airports embrace 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 selected goal for e-fuels that’s geared toward boosting their manufacturing.
The US, however, not too long ago handed new tax credit for different fuels, geared toward serving to costly choices attain worth parity with fossil fuels. The tax credit final till 2027 and apply to any gas that reduces carbon dioxide emissions by at the least 50% in contrast with fossil fuels, although the small print on how reductions are calculated haven’t been launched but.
Finally, different fuels current probably the most easy pathways to reducing the local weather impacts from aviation, however solely sure varieties will find yourself benefiting the local weather. “SAFs are an answer, however they have to be very correctly finished,” Mirolo says. In any other case, they danger turning into “a remedy that’s worse than the illness.”