Last summer, investors gathered in the parking lot of a converted warehouse in Santa Cruz, California.

Rob McGinnis, the founder and chief executive of Prometheus Fuels, was ready to show off his “Maxwell Core.” The pipe-shaped device is packed with a membrane riddled with carbon nanotubes, forming pores that separate alcohols from water. 

That day, it was connected to a tank filled with both. As McGinnis explained how the technology worked, his staff used it to fill the tank of a Harley-Davidson motorcycle. The alcohol seeped through the membrane, concentrating it enough to power the vehicle, which had been converted to run on the fuel, he says.

Attendees were then invited to take the Harley for a spin.

It was a theatrical demonstration of the technology key to McGinnis’s beguiling pitch: Prometheus will transform the global fuel sector by drawing greenhouse gas out of the air and converting it into carbon-neutral fuels that are as cheap as dirty, conventional ones.

Investors have thrown money at the company. Prometheus says it has raised more than $50 million from BMW’s investment arm, shipping giant Maersk, Y Combinator, and others. The startup has already struck deals to sell millions of gallons of its fuels to American Airlines and other aviation companies. It earned a shoutout in a Biden administration announcement detailing US efforts to shift toward sustainable aviation fuels. And after closing its venture round last September, the company announced that it was valued at more than $1.5 billion. 

The only problem? There is little available evidence it can actually live up to its lofty claims. 

McGinnis and his staff have built a prototype that combines the nanotube membrane with a device that sucks down carbon dioxide and a novel electrochemical cell. The system converts the captured carbon into alcohols and then concentrates them, avoiding what would otherwise be an expensive and energy-intensive distillation step as well as other costs.

A commercial-scale version would run on renewable power and add a final stage: converting those alcohols into synthetic forms of gasoline, diesel, and jet fuel. McGinnis has claimed that the resulting fuels will be “price competitive” with those derived from fossil fuels and won’t emit any more greenhouse gas than the process removes from the air.

The technology would look nothing like the huge refineries that the world depends on for its transportation fuels. They would be modular units that could be built anywhere, relatively cheaply. Last April, Prometheus announced it expects to have half a million of these plants operating by 2030. Those could collectively produce about 50 billion gallons of fuel per year and suck down nearly 7 billion tons of carbon dioxide by the end of the decade. 

If these fuels could be produced at the costs and on the scales claimed, Prometheus might well overhaul the global energy marketplace. It would offer a simple way to neutralize the emissions of the cars and trucks already on the road, as well as the world’s fleets of ships and planes. And it would reduce the pressure to continue extracting fossil fuels and building oil refineries, easing the grip of petrostates and the world’s addiction to petroleum.

But Prometheus’s assertions have raised eyebrows among researchers, entrepreneurs, and venture capitalists. Several experts who have reviewed an investor presentation obtained by MIT Technology Review are dubious that the company can achieve the claimed costs.

“It’s laughable,” says Eric McFarland, a professor of chemical engineering at the University of California, Santa Barbara. “It’s the tech bubble again,” he added later. “People are putting money into lots of things that ultimately won’t ever work, and this is one of them.”

To support MIT Technology Review’s journalism, please consider becoming a subscriber.

Others are skeptical that a small startup has quietly integrated leading-edge chemistry, novel catalysts, and a breakthrough membrane into a single cost-effective package that will easily scale to commercial levels. They note that the company hasn’t publicly demonstrated a fully working system, submitted the process to peer review, or provided more detailed information on how it works, even to some potential investors.

The fact that the company widely missed its own targets for delivering synthetic fuels to the market has raised further doubts. McGinnis originally said that Prometheus would sell its alternative gas for $3 a gallon by sometime in 2020, undercutting fuel sold at the pump. Instead, two years later, the company has yet to piece together an integrated device that generates fuels that could power standard vehicles today.

All of this has created a perception among some that McGinnis, a theater major and playwright before he earned a doctorate in

Read More


By: James Temple
Title: This $1.5 billion startup promised to deliver clean fuels as cheap as gas. Experts are deeply skeptical.
Sourced From:
Published Date: Mon, 25 Apr 2022 10:00:00 +0000