On the edge of the Mojave Desert in Lancaster, California, hundreds of mirrors beam sunlight onto a molten-hot tower. Cameras paired with high-processing-power software control the huge field of mirrors in real time, as the sun moves, making tiny adjustments so that the mirrors can always reflect the most light onto a small receiver that heats up to more than 1,800 degrees.
This is the demonstration plant for a startup called Heliogen—the winner of the energy category in Fast Company’s 2020 World Changing Ideas Awards—that wants to solve one of the biggest challenges for renewable energy: creating the soaring temperatures needed to make steel or cement and other industrial products that typically create ultra-high emissions. The system uses mirrors like a huge magnifying glass. While concentrated solar power isn’t new, “the breakthrough that we’ve come up with is the way we control those mirrors to be so accurate and so inexpensive,” says Bill Gross, Heliogen’s CEO.
“The price of electricity from solar cells has come down dramatically and now is lower cost than fossil fuel electricity,” says Gross. “But there is no solution with electricity for the intense needs of the heavy industrial processes that produce all of our built materials in the world, whether it’s cement or steel or aluminum. . . . We wanted to find a way to make high-intensity, high-concentrated solar heat to bring renewable energy to those industries.”
In the sunny areas where the technology is viable, it’s less expensive than current processes that make heat by burning huge amounts of fossil fuels. The energy is stored in high-temperature bricks—like a giant version of a pizza stone—so that it can keep factories running at night when the sun isn’t shining. (Unlike batteries for storing solar electricity, which are expensive, storing heat is affordable.)
Some factories plan to use it to make high-temperature steam; a pasta company is interested in using it to dry pasta. An agricultural company wants to use it instead of natural gas in a process to dry produce. A mining company that uses steam to extract minerals wants to use the technology to replace coal. The mining company is indifferent to the source of energy, Gross says, but they’re interested in switching because the new solar tech can beat the price of coal.
In cement manufacturing—one of the most polluting industries—the technology can help both by replacing heavily polluting fuels such as petroleum “coke” and by making it possible to capture emissions that are a separate part of the process of making cement. When limestone is heated up to make cement, it releases large amounts of CO2. When plants burn fossil fuels for heat, the stream of emissions is so dirty that capturing the CO2 isn’t really feasible, but in a plant using solar energy, the CO2 will be released in a pure stream that can easily be reused elsewhere. Some cement companies are working on new types of cement that actually store CO2, meaning that the end product can be carbon negative if it’s made with renewable energy. Right now, 3 to 4 billion metric tons of CO2 are emitted from cement production every year, and that will grow as the number of buildings in the world is expected to double by the middle of the century.
Heliogen appeared as if by stealth in late 2019 and was quickly deluged by requests from more than 1,000 manufacturers. “Up until we announced, people didn’t even know this was possible,” Gross says. “Now that they know it’s possible they want to do it.” Perhaps half of the cement plants in the world are in areas where there’s enough sunshine for the technology to make sense. But Gross believes that others will begin to locate to sunny areas. “One, having lower carbon is getting more and more important as time goes on,” he says. “The awareness has gone up dramatically. But it also just saves money—the economics of these plants matters greatly. Basically, if you’re going to build a new cement plant, where are you going to put it? Are you going to put it where you have to burn fossil fuel, or are you going to put it where you have free sun? I think it’s going to shift people’s thinking.”