This $1.5 billion startup promised to ship clear fuels as low cost as gasoline. Specialists are deeply skeptical.

The method

The method breaks down into 4 principal phases, based on Prometheus’s investor supplies. 

In the 1st step, industrial followers attract air and blow it by means of a mixture of water and different compounds, which McGinnis says might embody sodium carbonate. That then readily reacts with carbon dioxide molecules within the air, shifting a lot of the carbonate to bicarbonate.

The ensuing answer then strikes right into a battery-like cell with a membrane within the center and electrodes on both finish, which makes use of electrical energy to spark a collection of chemical reactions that produce complicated alcohols. It’s geared up with a catalyst based mostly on expertise licensed from Oak Ridge Nationwide Laboratory. In an earlier description, that lab mentioned it had developed a catalyst made out of tiny carbon spikes embedded with copper nanoparticles. When a voltage was utilized, it transformed carbon dioxide dissolved in water into ethanol “with a yield of 63%.”

Prometheus’s carbon nanotube membranes come into play in step three, separating the alcohols from the water. 

And in a ultimate step, totally different catalysts are used to mix the alcohols and convert them into artificial gasoline, diesel, or jet gas. In 2020, Prometheus licensed separate expertise from the Oak Ridge lab that can be utilized to supply jet gas from ethanol, by means of a multistep course of that depends on a novel although unspecified catalyst. 

The general course of is considerably totally different from the one different firms changing captured carbon into fuels are taking. As McGinnis defined in a Joule commentary, the Prometheus programs can function underneath customary atmospheric strain and at room temperature. The expertise additionally avoids the warmth vitality wanted to supply concentrated carbon dioxide in addition to the capital prices of an electrolyzer devoted to producing hydrogen. As an alternative, the corporate claims, it might probably synthesize alcohols straight from carbon dioxide dissolved in water, after which convert these into customary fuels.

In the event that they’ve certainly discovered how to do that, it “might result in important vitality and price financial savings,” says Evan David Sherwin, a postdoctoral researcher at Stanford who produced the Environmental Science & Know-how examine.

One of many final slides within the investor supplies reveals a Prometheus-branded gas station, with a pink neon “Zero Web Carbon” signal promoting gasoline costs of $3.50 a gallon and diesel at $3.75, nicely under present common US costs.