Reaching 1,000°C with solar energy is the crazy bet of this start-up

On November 18, the top investors from Silicon Valley gathered at an industrial site near Lancaster, California, to witness a demonstration of a revolutionary technology: reaching temperatures of 1,000°C with the sun. It is enough to decarbonize the world’s most polluting industries and generate green electricity on a large scale.

Heliogen is based on a technology known since ancient times, namely thermodynamically concentrated solar energy. This system uses thousands of parabolic mirrors (called heliostats) to converge the sun’s rays into a tower containing a heat transfer fluid (usually water) that will turn a turbine using heat. There are already several such plants in Andalusia, Dubai, and California.

Decarbonize concrete and steel manufacturing

Reaching temperatures as high as 1,000°C naturally provides an advantage for electricity production: the more water is heated, the higher the power injected into the turbine. The stored heat could also be used as a night storage device. But the start-up is mainly aimed at industrial uses, in particular, the production of steel and concrete. These two activities are very greenhouse gas emitters because they require temperatures close to 1,500 °C to heat coke or the mixture of clay and limestone. Concrete production alone is responsible for 8% of global CO2 emissions. According to the start-up, these companies could reduce their fossil fuel consumption by 60% by using the electricity supplied by its system.

Mirrors that constantly adjust their position

But where current thermodynamic power plants reach a maximum temperature of 560°, Heliogen promises to exceed 1,000°C or even 1,500°C. Rather than building more and more mirrors, the start-up is betting on artificial intelligence to optimize heat concentration by changing the orientation of the panels in real-time.

 To solve this problem, Heliotrop has installed cameras that precisely measure the position of each mirror by taking equidistant points around it (the camera cannot directly observe the mirror without which it would melt due to the intensity of the light). Thus, the alignment of each mirror allows the light to converge more efficiently on a given point, about 50 cm in diameter.

Green “hydrogen” at will

Another promising market is hydrogen, a potential fuel for the cars of the future. Currently, hydrogen production is mainly based on the reforming of natural gas with water vapor, a process that is not very environmentally friendly. It is also possible to use electrolysis to obtain hydrogen, but this method is very inefficient and requires a lot of energy. The very high temperatures of Heliogen’s thermodynamic solar energy would theoretically make it possible to obtain from this famous “green” hydrogen, the Grail of industrialists.

A reduced version of this solar concentration system with 70 mirrors has apparently been successfully tested. A “normal” scale deployment would cover about 8,000 square meters, about the equivalent of a football field. Much less than these conventional power plants, the largest of which, in the Mojave Desert in the United States, extends over 14 km2 with its 173,500 heliostat mirrors.