The US Air Force is studying the feasibility of a process developed by tech company Twelve that could allow the manufacture of a carbon-neutral aviation fuel called E-Jet anywhere on Earth using only carbon dioxide from the air, water, and renewable energy.
Any air force that has evolved beyond gliders is tethered to the supply lines that transport and store the fuel needed to keep its machines in the air. This is not only expensive and complicated when it comes to refueling distant bases, it's also dangerous because such supply lines are prime targets for enemy forces. According to the US Air Force, attacks on fuel and water convoys in Afghanistan accounted for 30 percent of coalition casualties.
As an alternative, the USAF is looking for ways to make its bases at least partly independent of outside fuel sources by means of a deployable, scalable synthesis process that doesn't need a large number of specialists to operate.
The process developed by Twelve is referred to by the company as "industrial photosynthesis" and uses polymer electrolyte membrane electrolysis, which is a sort of inverted fuel cell, with a metal catalyst installed on a cathode to break down carbon dioxide and water into their component ions and then convert them into oxygen, hydrogen, and carbon monoxide.
These are then put through the Fischer-Tropsch process, which is a series of reactions developed in Germany in the 1920s that, in steps, turns them into methane and then increasingly complex organic molecules like polyethylene, ethanol, ethylene, methane, polypropylene, and, as of August 2021, jet fuel.
The current pilot phase is expected to be completed by December and the results will then be assessed. If the technology is practical for military applications, it will mean that the USAF will potentially be able to produce synthetic fuel onsite without the need for coal, natural gas, or biofuel. According to Twelve, it might even be possible to harvest not only the carbon dioxide from the air, but the water as well.
For the next step, the USAF will look into scaling up the process to produce practical supplies of the fuel, which can be blended with conventional fuel in ratios of up to 50 percent. However, there are still basic problems that need to be resolved – not the least of which is to find a renewable way to power the process.
"My office is looking at a number of initiatives to not only optimize aviation fuel use for improved combat capability, but to reduce the logistics burden as well," says Roberto Guerrero, deputy assistant secretary of the Air Force for operational energy. "We’re excited about the potential of carbon transformation to support this effort and Twelve’s technology – as one of the tools in our toolbox – could help us get there."
Source: US Air Force
