This startup is about to conduct the biggest real-world test of aluminum as a zero-carbon fuel

The initial pilot will use the engine to supply hot steam and hydrogen. But the energy released in the reactor can be used in several ways across a range of temperatures, according to Godart. Hot steam could turn a turbine to produce electricity, or hydrogen could produce electricity in a fuel cell. By burning the hydrogen contained within the steam, the engine can produce superheated steam of up to 1,300 degrees Celsius, which can be used to generate electricity more efficiently or refine chemicals. Burning hydrogen alone can generate temperatures of up to 2,400 degrees Celsius, hot enough to make steel.

Pick up scrap

Godart says he and his colleagues hope the engine will eventually power many different industrial processes, but the initial target is the aluminum refining and recycling industry itself, as it already deals with scrap metal and aluminum oxide supply chains. “Aluminum recyclers come to us and ask us to take their aluminum waste, which is difficult to recycle, and then turn it into clean heat that they can use to remelt other aluminum,” he says. “They are begging us to do this for them.”

Citing nondisclosure agreements, he doesn’t name any of the companies that supply the non-recyclable aluminum, which he says is a “dirty secret” for an industry that’s supposed to recycle everything it collects. But the International Aluminum Institute, an industry group, estimates that just over 3 million metric tons of aluminum collected for recycling globally is not recycled each year; Another 9 million metric tons are not collected for recycling at all or are incinerated with other waste. Together, this represents just under a third of the estimated 43 million metric tons of aluminum scrap that is currently recycled each year.

Even if all that unused fuel scrap was recovered, it would only provide a small portion of the total industrial demand for heat, let alone the total industrial demand for energy. But the plan doesn’t have to be limited to available scrap. Ultimately, Godart says, the hope is to “recharge” the aluminum hydroxide that exits the reactor with clean electricity to turn it back into aluminum metal and react again. According to the company’s estimates, this “closed-loop” approach could meet all of the world’s industrial heat demand by using and reusing approximately 300 million metric tons of aluminum — about 4% of Earth’s abundant aluminum reserves.

However, all this recharging requires a lot of energy. “If you do that, [aluminum fuel] “It’s an energy storage technology, not an energy saving technology,” says Jeffrey Reisman, who studies industrial decarbonization at Energy Innovation, a research center in California. As with other forms of energy storage such as thermal batteries or green hydrogen, this may still make sense if the fuel can be recharged using low-cost, clean electricity, Reisman says, but this will be increasingly difficult to achieve amid the scramble for clean energy for everything from AI data centers to heating. pumps.

Despite these obstacles, Godart is confident that his company will find a way to make it work. The current engine may actually be able to extract more power from aluminum than expected. “We actually think this could produce half a megawatt,” he says. “We haven’t completely throttled it.”

James Deneen A science and environmental journalist based in New York City.