The $1.5 billion startup promises to provide clean fuel as cheap as gas. Experts are extremely skeptical.

Process

The process is broken down into four main stages, according to Prometheus investor documentation.

In step one, industrial fans draw air in and blow through a mixture of water and other compounds, which McGinnis says may include sodium carbonate. The substance then readily reacts with carbon dioxide molecules in the air, converting most of the carbonate to bicarbonate.

The resulting solution then moves into a battery-like cell with a membrane in the middle and electrodes at the ends, using electricity to trigger a series of complex alcohol-producing chemical reactions. It is equipped with a catalyst based on licensed technology from Oak Ridge National Laboratory. In one previously described, that lab says it has developed a catalyst made of tiny carbon spikes embedded with copper nanoparticles. When a voltage is applied, it converts water-soluble carbon dioxide into ethanol “with an efficiency of 63%.”

Prometheus’ carbon nanotube membrane comes into play in step three, separating the alcohol from the water.

And 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 separate technology from the Oak Ridge lab could be used to make jet fuel from ethanol, through a multi-step process based on a new, though unidentified, catalyst.

The overall process is fundamentally different from the process by which other companies convert the carbon captured into the fuel they are using. As McGinnis explained in a Joule’s comment, the Prometheus system can operate under standard atmospheric pressure and at room temperature. The technology also avoids the thermal energy required to produce concentrated carbon dioxide as well as the capital costs of an electrolyzer that specializes in hydrogen production. Instead, the company claims, it can synthesize alcohol directly from carbon dioxide dissolved in water, and then convert them into a standard fuel.

Evan David Sherwin, a postdoctoral researcher at Stanford who conducts Environmental Science & Technology research, said if they actually figure out how to do this, it “could lead to energy savings and significant cost.

One of the last slides in the investor brochure shows a Prometheus-branded fuel station, with a neon red “Zero Net Carbon” sign advertising gas prices of $3.50 a gallon and diesel at $3.75, much lower than now US average price.