What is Sustainable Aviation Fuel and How is it Made?
Aviation is critical to the world economy. As demand for air travel and transport continues to grow, so does the need for innovative energy solutions in aviation. The US biofuels industry provides an answer with sustainable aviation fuel (SAF). Sustainable aviation fuel refers to jet fuel made from materials like used cooking oil and agricultural and industrial waste. SAF can be dropped into existing aircraft engines and infrastructure, so there is no need for expensive retrofitting or new designs. World Energy’s SAF is currently approved at a 50/50 blend level with conventional jet fuel for commercial use.
Delivering both economic and environmental benefits, SAF is good for our air, good for farmers, and good for business. SAF is good for our air because it releases fewer particulates when it burns and has the potential to reduce emissions by up to 94% depending on the technology pathway used to produce it. It’s good for farmers because it provides a revenue stream through feedstock production, and it’s good for business because it supports our bioenergy sector and adds to the abundance of our domestic energy supply.
SAF might sound like a new technology, but it’s already been used in hundreds of thousands of flights around the world. Still, there’s a lot of room for growth in its production and use. Understanding what SAF is, how it’s made, and the various production challenges and opportunities involved can help aviation leaders make informed decisions about biofuels like SAF.
SAF Production Methods
As many as nine SAF production “pathways” are recognized by the American Society for Testing and Materials (ASTM). However, three technologies are the main methods for producing SAF currently or in the near future.
Hydroprocessed esters and fatty acids (HEFA) SAF uses hydrogen to turn agricultural products such as soybean, corn, and canola oil; waste oils and fats like used cooking oil; and animal fats into SAF via hydrodeoxygenation.
HEFA SAF has an estimated emissions reduction potential of 74%–84%, depending on the feedstocks used and where those feedstocks come from.
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 emissions from corn ethanol have decreased significantly over the past 15 years. Some have estimated that ATJ has the potential to reduce life-cycle emissions by up to 94% compared with traditional jet fuel. However, additional factors may come into play with the use of corn ethanol in the ATJ pathway, such as upstream emissions and land use change. Some models show that these factors could increase the life-cycle carbon intensity of ATJ SAF to be as high as that of conventional jet fuel.
Although commercial availability of ATJ SAF has been limited, the world’s first production plant for ATJ was unveiled in 2024, with plans to produce 9 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 CO2 in the fuel equals what is captured during processing. This exciting technology is very new, however, and unlocking its full potential will require significant advances on several fronts, including technology, infrastructure, and funding. Its cost — up to eight times more than traditional jet fuel — is another obstacle to large-scale production and use.
HEFA – The Leading SAF Technology
At World Energy, we’re focused on the HEFA pathway because it’s currently the most mature and reliable way to produce SAF. HEFA is the only technology consistently producing large volumes of sustainable aviation fuel, and it is the fuel type used in the vast majority of all SAF-powered flights today. HEFA technology is also the easiest to implement, since existing equipment can be adapted to produce SAF. For example, World Energy has converted a legacy petroleum refinery in Paramount, California, to produce sustainable aviation fuel through the HEFA process.
Another advantage of HEFA is that it’s flexible in terms of feedstocks. HEFA SAF can be produced from a variety of feedstocks, including low-quality waste fats, oils, and greases. This helps make HEFA SAF more affordable than other types of sustainable aviation fuel. HEFA also supports the development of cover crops like carinata and camelina, which have high oil yields, improve soil health, and don’t compete with food sources.
HEFA SAF produced with advanced feedstocks is projected to remain the primary source of SAF through about 2045. In addition to being a foundational SAF technology, HEFA is also a critical building block for continued growth and innovation in the sustainable aviation fuel industry. For instance, co-locating HEFA and PtL facilities can help lower the carbon intensity of SAF even further by using the CO2 by-product of the HEFA process as a feedstock for the PtL process. This is an innovation World Energy is exploring for our California and Gulf Coast facilities.
World Energy and the Future of SAF
We’re constantly exploring new and emerging technology pathways for SAF production. We stand out for aggressively driving down the carbon intensity of our SAF with innovations in our HEFA process and feedstock sourcing. We’re also excited to begin exploring PtL production at our Houston facility, which could begin making this type of SAF by 2030.
Sustainable aviation fuel has an important role to play for our environment, for the US economy, and for leading corporations dedicated to responsible growth. With our leadership and experience, World Energy is a trusted partner in helping the domestic biofuels industry expand and develop new technologies, today and for the future.
