According to Prometheus’ investor materials, the process is divided into four main stages.
In the first step, an industrial fan draws air and blows it through a mixture of water and other compounds, which McGinnis said may include sodium carbonate. It then easily reacts with carbon dioxide molecules in the air, converting most of the carbonate to bicarbonate.
The resulting solution then goes into a battery-like battery with a membrane in the middle and electrodes at both ends, which uses electricity to initiate a series of chemical reactions that produce complex alcohols. It is equipped with a catalyst based on technology licensed from Oak Ridge National Laboratory. In an earlier description, the lab said it had developed a catalyst made of tiny carbon spikes embedded with copper nanoparticles. When a voltage was applied, it converted carbon dioxide dissolved in water into ethanol “in 63 percent yield.”
Prometheus’ carbon nanotube membranes work in the third step, separating the alcohol from the water.
In the final step, different catalysts are used to combine the alcohols and convert them into synthetic gasoline, diesel or jet fuel. In 2020, Prometheus licensed a separate technology from Oak Ridge Labs that can be used to produce jet fuel from ethanol in a multi-step process that relies on a novel but unspecified catalyst.
The whole process is very different from how other companies turn captured carbon into fuel. As McGinnis explained in the Joule review, the Prometheus system can operate at standard atmospheric pressure and room temperature. The technology also avoids the thermal energy required to produce concentrated carbon dioxide and the capital costs of electrolyzers dedicated to producing hydrogen. Instead, the company claims, it can synthesize alcohol directly from carbon dioxide dissolved in water, which is then converted into standard fuel.
If they do figure out how to do this, it “could lead to significant energy and cost savings,” said Evan David Sherwin, a postdoctoral researcher at Stanford University who produced the Environmental Science and Technology study.
The final slide in investor materials shows a Prometheus-branded gas station with a red neon “Net Zero Carbon” sign advertising gasoline at $3.50 a gallon and diesel at $3.75, a far lower price. at current U.S. average prices.