This new technology could make affordable green hydrogen

On a former golf course in Lancaster, California, sitting on holes #1 and #2, there’s now a massive array of mirrors, and the former clubhouse is now a manufacturing plant. Heliogen, a renewable energy startup, is using the site to test its new solar technology, which makes both electricity and steam from sunlight.

[Photo: courtesy Heliogen/Bloom Energy]

The latest demonstration, done in collaboration with the fuel cell company Bloom Energy, shows a new way to make “green” hydrogen (so-called when the electricity used in the process comes from renewable energy). The technology could eventually make that hydrogen cheaper than natural gas, and help make the fuel viable for uses from powering airplanes and cargo ships to heating houses.

In the field of mirrors at the Heliogen demonstration site, “those mirrors are acting like a large, computer-controlled magnifying glass,” says Bill Gross, founder and CEO of Heliogen. Directed by artificial intelligence, the mirrors reflect light to the top of a tower that the company calls a “Sunlight Refinery,” creating extremely high temperatures and sending hot air down to a tank of rocks on the ground that store the heat. The system solves one of the challenges of traditional solar power—the fact that the sun doesn’t shine 24 hours a day, and batteries are still relatively expensive—by making it affordable to store solar power. But because the technology also produces low-cost steam, it makes it possible to make hydrogen in a new way.

[Photo: courtesy Heliogen/Bloom Energy]

Hydrogen has huge potential, since if hydrogen fuel is used in a truck or a jet, it doesn’t release greenhouse gas emissions when it burns. “Scientists and climate experts across the globe have sliced and diced every possible scenario that would enable a carbon neutral world by 2050, which nearly 70 countries are aiming for,” says Venkat Venkataraman, CTO at Bloom Energy. “And the consensus is clear: There is no way to get to a net zero future without hydrogen.”

But right now, most hydrogen is made from natural gas through a process that releases CO2 as the hydrogen atoms are pulled from that gas. Extracting the gas in the first place also emits methane. “Green” hydrogen, made by splitting water with renewable electricity, doesn’t emit pollution, but uses so much energy that it has been too expensive, so far, to widely use.

“We’re splitting water with a combination of electricity and this high temperature steam,” Gross says. “And that’s what leads to a breakthrough in efficiency, and that leads to an eventual breakthrough in price.” Because the technology uses steam, it can use less electricity, making it as much as 45% more efficient. Since it also can run throughout the night, “we can amortize the cost of the electrolyzer over 24 hours, instead of over 6 hours a day,” he says. “And that four-to-one better amortization leads to lower cost hydrogen.”

[Image: courtesy Heliogen/Bloom Energy]

Bloom’s high-efficiency electrolyzer, the machine that splits water into hydrogen and oxygen, is designed to use both electricity and steam as it works. Bloom says that it can be used in other settings, such as at nuclear power plants, which also produce steam. (Hydrogen made with nuclear power is called “pink” instead of green, in the color spectrum used in industry jargon.) The company also plans to continue using fossil-based hydrogen, saying that its carbon capture and separation technology makes carbon neutral generation possible, and arguing that it’s necessary to produce hydrogen from a variety of sources to scale up. But using concentrated solar power can help meet the quickly growing demand for green hydrogen.

The next step will be getting the technology ready to go to early customers, such as Woodside Energy, a natural gas producer in Australia that currently ships gas to countries like Japan. Green hydrogen “is a molecule, so you can put it on ships,” says Gross. “You can’t put electrons on a ship—you can’t make solar energy in the desert in Australia and move those electrons to Japan.” Green hydrogen, he says, will finally make it possible to make renewable energy transportable.

Green hydrogen can be produced in the most ideal locations for solar power, such as Australia or Arizona, and shipped to other places with less sunlight. “That is what we really need to power the Earth,” he says. “Because not everyone has sunshine, like California, or Australia or Morocco. But everyone has train lines and shipping lines. That’s how we move our fuel around now.”

Making the technology cost-competitive with natural gas is just a matter of scaling up over time, Gross says. After the small demonstration in Lancaster, which covers two acres, the next site will be a full-size 100-acre module. “Building that repeatedly will make that economically okay,” he says.

That would make it possible for green hydrogen to become widespread. While batteries are better for some applications, like electric cars, they aren’t yet viable for long-distance transportation in heavy vehicles like ships or planes. Green hydrogen could also be used at steel and cement plants to shrink the carbon footprint of production. “As the price of hydrogen comes down to someday be cheaper than natural gas, you can use it to power everything,” Gross says.