Sustainable Aviation Fuels: How Do They Fit into Our Climate Goals?

When you think of greenhouse gas emissions, what sources do you think of? The energy sector, cars, and airplanes might be some of the industries that come to mind first. And you’d be right! Transportation as a sector makes up 28% of all greenhouse gas emissions and air travel alone makes up 11.5% of these emissions. Unlike small vehicles like cars, there is no way to electrify the aviation industry. This has big implications for countries trying to reduce greenhouse gas emissions in order to reach their climate goals.

Luckily, companies across the U.S. and beyond have been studying and producing Sustainable Aviation Fuels at a small scale for decades.

But what are Sustainable Aviation Fuels? (Referred to as SAF.) They are a class of fuels that are not made from petroleum while still meeting all of the safety and efficiency standards to power an aircraft. Crucially, SAF must also emit at least 50% fewer greenhouse gas emissions as compared to traditional fuel. These emissions must include all the emissions it takes to produce the fuel, as well as emissions that are released when the fuel is combusted.

SAF is primarily made from vegetable oils like soy, palm, and canola as well as waste cooking oil or tallow from livestock processing. However aviation is a huge industry, and the U.S. does not produce enough of these crop based biofuels to meet the demand for jet fuel production. 

It’s important to consider the ecological impacts of using crop-based biofuels. If demand for SAF continues to grow, as is projected, demand for the crops that are used to create the fuel will increase. At the same time, the existing demand for soy and corn from food markets will continue.

Farmers would then need additional land for farming more of these crops that otherwise could have been grasslands or forested land. Whenever possible it is important to preserve grassland and forest ecosystems to provide habitats for wildlife and to prevent additional soil carbon loss that contributes to climate change. 

Luckily there is an alternative option for farmers! Farmers can rotate crops seasonally and meet the existing demand for soy and corn during the summer and fall while growing cover crops during the winter and spring that can be turned into sustainable aviation fuels. These alternative crops are currently being developed and refined to maximize output, and starting to be deployed in various places around the world.

Outside of crop-based SAF, there are several chemical processes available to produce jet fuel from other sources like hydrogen and CO₂. Water and clean energy flow into a hydrolyzer which creates hydrogen that when combined with waste CO₂ from industrial sources or the air can be turned into SAF. 

It’s important to note that these new synthetic processes have not been proven cost-effective at scale, and there are additional considerations around clean energy demand and water availability that should be taken into account. 

Given the scale of the aviation industry, sustainable aviation fuels will have to play a role in reducing emissions from air travel. However as we have learned there are still gaps in research and development that need to be addressed before SAF can reach its full potential. With smart and strategic government policy, financial investment, and incentives, SAF can play a meaningful role in meeting the needs of the aviation industry while also meeting our climate goals.