A secretive start-up with Bill Gates as one of its investors has just come out of stealth mode.

Heliogen is their name, and extreme heat generation is their game.

I think we all agree that at a first glance this sounds pretty boring and unimportant. So before we all doze off—yours truly included—here’s why it matters:

“…cement and steel rely on large amounts of continuous high-temperature heat, and […] there are very few viable low-carbon sources of such heat. Collectively, these industrial processes represent around 20 percent of global carbon emissions”.

So where does Heliogen come in?

“Heliogen’s technology is based on concentrating solar power (CSP). That’s where hundreds of mirrors in a field are all angled to reflect sunlight onto a tower, inside of which is a steam turbine. The heat from the sunlight turns fluid (usually water) to steam, which runs the turbine, which generates power”.

This CSP stuff mostly died out in the 2010s because solar panels got cheaper, faster.

Also, it could only get up to temperatures of around 560°C.

That’s hot enough to make electricity, but not hot enough to help directly produce concrete and steel.

Heliogen has started to get heat over 1000°C using fairly awesome trickery.

How did they do it?

It’s pretty damn cool. They found a way to make sure that all of the mirrors are always pointing at exactly the same spot on the tower, thus concentrating the heat better.

They did it by putting four cameras on the tower and measuring the intensity of the light halo at four equidistant points around each mirror. If the four values are the same, the mirror is pointing in the right direction. Otherwise, the mirror is ever so slightly tilted, in real-time, to fix it.

This is continuously being done to all of the mirrors at the same time. Very, very cool. Apparently the computational power to do it wasn’t even available five years ago. (We’ll let slide what energy is powering the computers for today—is some electricity siphoned off from the tower?)

Right, so that’s what they’re doing. But why the hell is it such a game changer?

First, this kind of heat (1000°C and up) can be used to produce cement and steel, and is also useful in the chemical industry. Imagine if you could get this heat with little or no CO2 emissions.

Game changer.

But it gets crazier still.

If Heliogen can get the temperature up to 1500°C—which is their goal—it gets epic. They will be able to directly generate liquid fuels to be used in the place of fossil fuels. What the what?!

“This is a relatively new engineering development, being perfected by Swedish researchers as we speak. It goes like this: a new, state-of-the-art material called ceria (CeO2) is heated to about 1,500° C, at which point it releases a pure stream of oxygen. Then, at about 1,000° C, water and carbon dioxide are introduced. The ceria wants its oxygen back, so it breaks the water and carbon dioxide up into hydrogen, carbon monoxide, and oxygen, and absorbs the oxygen. What’s left is a mix of hydrogen and carbon monoxide, otherwise known as “syngas.”
“Basically, you start with H2O + CO2 and you end up with a mix of H + CO. As it happens, every hydrocarbon (fossil) fuel in the world, from kerosene to gasoline, from boat fuel to jet fuel, is built around some combination of H and CO, which means synfuel can be refined into any fuel, for any purpose. If the CO2 that feeds into the process is drawn from the ambient air via direct air capture (DAC), which is still a big if for now, then the resulting fuels can be said to be carbon-neutral, a huge improvement on the carbon-intensive fuels now in use”.

So that’s the remaining catch for the fuel generation application. Getting enough CO2 out of the air in a low-carbon way to fuel the process to make the fuel, which when burned just puts the CO2 that was in the atmosphere already back into the atmosphere: carbon neutral. Got it? Else: read again!

And let’s not forget that Heliogen is going to need a way to store the intense heat for days or times when the sun ain’t shining. They say they’re working on it.

Still, big news like this doesn’t come through every day, and it sure feels like a nice change from watching Australia burn to the ground while simultaneously constructing its new coal mine.

[All of the quotes above come from this magnificent article by David Roberts at Vox.]