Helping the aviation industry advance it’s goal of reaching net-zero by 2050¹ will require innovative product solutions to produce Sustainable Aviation Fuel (SAF) at scale. Today, the renewable portion of SAF is manufactured from feedstocks such as used cooking oils and animal/vegetable fat wastes. While this is a necessary first step in helping the aviation industry begin its energy transition, the future of SAF will need to incorporate substantially greater amounts of fuels produced from alternative, more abundant feedstocks such as municipal solid waste, forestry and agricultural residues, biogenic CO2, and even atmospheric CO2. However, these alternative feedstocks require advanced technology to enable their conversion into valuable products. Fuels derived from these alternative feedstocks are often termed ‘synthetic’ and when utilizing renewable electricity as an energy input, may be referred to as Power to Liquid (PtL) or eFuels.
Synthetic fuels have been around for a long time. One of the earliest technologies to convert these feedstocks into fuels was developed during World War II and is called Fischer-Tropsch synthesis. With this technology, these feedstocks are first partially oxidized into a mixture of carbon monoxide and hydrogen. These two components are then combined together over a catalyst to produce synthetic crude oil. This technology has found limited application over the last few decades due to the expense of the Fischer-Tropsch synthetic process relative to petroleum refining. Additionally, the process suffers from a lack of selectivity to any specific product, which means that conversion into a useful fuel or lubricant requires significant additional capital expenditure. However, to date the Fischer- Tropsch process has been the only way to access these alternative feedstocks for the production of synthetic fuels.
That is all about to change.
ExxonMobil is working to engineer a new, proprietary process technology for the production of synthetic fuels from these alternative feedstocks. After first converting these feedstocks into methanol using commercially available 3rd party technology, the new ExxonMobil Methanol to Jet (MTJ) process converts this methanol with high selectivity into a synthetic jet fuel blending component.
So, what will it take to start making synthetic jet fuel utilizing the ExxonMobil MTJ process? Importantly, it will be necessary for industry to create the infrastructure to generate the alternative feedstocks needed to make renewable methanol.
Additionally, the methanol to jet fuel synthetic component must be evaluated and qualified according to an industry-accepted protocol to demonstrate that the fuel is fit for use in an aircraft. So what does this industry protocol entail?
New Fuel or fuel blending components are evaluated to ensure they perform as expected and safely in an aircraft engine. To facilitate this evaluation, the aviation fuel subcommittee of ASTM International developed the ASTM D4054 standard practice, which outlines the data the industry requires to effectively assess a candidate fuel’s composition and performance. This rigorous standard practice includes typical fuel specification testing, but also many non-standard tests that are used to comprehensively demonstrate that a new fuel is acceptable for use in an aircraft. After all the data has been generated, a research report is prepared for review by the broader ASTM fuels community. If the new fuel satisfies all requirements for use in an aircraft, it can be qualified with a new manufacturing specification.
ExxonMobil is spearheading the development of a new synthetic aviation fuel.
ExxonMobil has now begun producing synthetic jet fuel components utilizing MTJ technology at pilot plant scale at our Machelen research facility in Belgium². To date, we have produced over 100 gallons of this new synthetic jet fuel component that will be submitted in early 2023 for evaluation according to the ASTM D4054 criteria described above.
What does this ultimately mean for the aviation industry? Qualifying Methanol to Jet as a new synthetic jet fuel manufacturing pathway will help grow the much-needed supply of SAF. It opens the door to alternative fuel feedstocks that are difficult to access with today’s technology. As such, it presents an alternative to the existing Fischer-Tropsch process, providing more options to a growing industry. Finally, pursuit of synthetic fuels from alternative feedstocks can help the aviation industry transition to fuels having lower carbon intensity and strive towards its net zero ambitions.
At ExxonMobil, we are celebrating 120 years of supplying quality fuel for the aviation industry. Today, we are developing advanced technology product solutions that continue to propel the industry forward through our leadership and expertise in R&D, manufacturing, and supply chain logistics.
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2 Exxon Mobil Corporation has numerous affiliates, many with names that include ExxonMobil, Exxon, Esso and Mobil. For convenience and simplicity in this article, those terms and terms like corporation, company, our, we and its are sometimes used as abbreviated references to specific affiliates or affiliate groups. Abbreviated references describing global or regional operational organizations and global or regional business lines are also sometimes used for convenience and simplicity. Similarly, ExxonMobil has business relationships with thousands of customers, suppliers, governments, and others. For convenience and simplicity, words like venture, joint venture, partnership, co-venturer, and partner are used to indicate business relationships involving common activities and interests, and those words may not indicate precise legal relationships.