What is Sustainable Aviation Fuel and How is it Made?
Aviation is critical to the world economy. But it also has a troubling environmental impact: air travel accounts for 2.5% of global carbon emissions every year.
The aviation industry has a goal of net-zero carbon emissions by 2050. To get there, it is exploring solutions including efficient routes and better aircraft designs. There are also promising innovations like electric and hydrogen-fueled aircraft, but those technologies are decades away.
Most aviation emissions come from burning petroleum-based jet fuel, making alternative fuels the main focus of sustainability efforts. Sustainable aviation fuel (SAF) refers to biofuel made from materials like used cooking oil and agricultural and industrial waste. These green fuels can be dropped into existing aircraft engines and infrastructure, so there is no need for expensive retrofitting or new designs. Overall, they have the potential to reduce greenhouse gases by up to 94%, depending on the technology pathway
SAF is also the only option available at a commercial scale. It has already been used in hundreds of thousands of flights around the world.
Still, there’s a lot of room for growth. Understanding what SAF is, how it’s made, and the various production challenges and opportunities can help aviation leaders make informed decisions about green fuels.
SAF Production Methods
There are currently three main methods for producing SAF.
Hydrotreated esters and fatty acid (HEFA) SAF is refined from vegetable oils (such as soybean, corn, and canola oil), waste oils (like used cooking oil), and animal fats via a process that uses hydrogen (hydrodeoxygenation).
Carbon intensity varies widely based on the feedstocks used and their origin. However, potential emission savings are estimated at 74 to 84% compared to fossil-based jet fuel.
Right now, HEFA is the only method that can produce commercial-scale volumes of SAF, and it is used for the vast majority (95%) of all SAF-powered flights. World Energy focuses on this production method since the technology is more mature and reliable. It is also the easiest to implement because existing equipment can be adapted: we are currently converting a petroleum refinery in California for SAF production instead of building an entirely new facility.
As the most economical and only commercially available form of SAF at scale, HEFA continues to be the most effective and efficient route to decarbonize the aviation industry. It is projected to meet the majority of the aviation’s demand for sustainable fuel for the next couple decades, even as other pathways gain momentum. More infrastructure, new policy, and increased investment in HEFA SAF will also help bring prices down.
Alcohol to jet (AtJ) SAF is mainly made from ethanol sourced from corn, related crops, or waste. The technology to derive ethanol from corn is well-established, and in fact greenhouse gas emissions from corn ethanol have significantly decreased over the past 15 years. SAF produced by this method is has an emissions reduction potential of 85 to 94%.
However, there are challenges with increases to the carbon intensity during the conversion process. In addition, restrictions in Europe require ethanol to be waste-based instead of crop-based, which could pose further obstacles to commercial production.
Commercial availability of AtJ SAF has been limited. However, the world’s first production plant for AtJ was unveiled in 2024, with plans to produce nine million gallons in its first year.
Power to Liquid (PtL) SAF does away with concerns about feedstock quantity and availability by capturing carbon dioxide and synthesizing it with renewable hydrogen to form liquid fuel. Unlike the other types of SAF, Ptl is carbon-neutral, since the carbon burned equals what is captured.
However, this exciting technology is very new, and unlocking its full potential will require significant advances on several fronts, including technology, infrastructure, and funding. Its cost— five to eight times more than petroleum-based jet fuel—is another obstacle to large-scale production and use.
World Energy and the Future of SAF
We’re constantly exploring new and emerging technology pathways for SAF production. That includes being one of the few SAF producers to constantly make improvements and add novel technologies to our HEFA process that further reduce the carbon intensity of our SAF. For example, we plan to use low-carbon hydrogen electric heaters to reduce the processing intensity in our facility in Paramount, CA, an initiative we hope to start as soon as next year.
We’re also very excited to begin implementing PtL production at our Houston facility, which could begin producing this type of SAF by 2030.
The aviation industry has already taken significant steps toward incorporating alternative fuels, but there is much more to do. As technologies evolve and the biofuel sector expands, World Energy will be there to help secure a greener future for air travel.
