The malevolently incompetent Commander-in-Chief who occupies the Oval Office promised the moon to his pals in the fossil energy industry. However, the renewable energy writing is on the wall, particularly in regards to the US solar industry, which keeps finding new ways to insert itself into the nation’s energy profile. For the first time in years, concentrating solar power technology may even have an opportunity to break into the mainstream.
What’s The Matter With Concentrating Solar Power?
A concentrating solar rebirth in the US would be news indeed. Unlike solar panels, which generate electricity on the spot, concentrating solar power plants rely on fields of specialized mirrors to focus sunlight on a centralized point, where it heats up a liquid solution, typically composed of molten salt although some systems deploy an oil-based solution. The hot solution is then shunted to a generating station, where it boils water to produce steam to run a turbine, and then finally the electricity comes out.
If that sounds complicated, it is. During the Obama administration, the US Department of Energy made a mighty attempt to showcase concentrating systems but the idea never caught on here in the US, although other nations have adopted the technology.
Despite the lack of investor interest, the Energy Department continued to support innovations in the concentrating solar power field during the first Trump administration. In November of 2017, for example, the agency posted an article under the title, “Concentrating Solar Power Could Provide the Flexibility and Reliability the U.S. Electric Grid Needs.“
The emphasis on flexibility and reliability means that concentrating solar power plants could do the same job as gas “peaker” plants, which grid operators deploy to deliver a fresh burst of electricity during periods of peak demand.
As the Energy Department explained, a “50-megawatt (MW) CSP plant can be configured as a type of peaker plant with less than six hours’ worth of energy storage.”
“This plant can be used to supplement baseload generation when there’s a sudden, high spike in energy demand,” DOE elaborated (note: the original link defaults to the current Energy Department website).
Where Are The Concentrating Solar Power Investors?
Replacing gas peaker plants with concentrating solar systems was just for starters. In a concentrating system, the heated solution acts as a built-in energy storage platform. With larger fields of mirrors and a larger volume of solution, concentrating solar power plants could hit the level of long duration energy storage systems, enabling them to do the same job as baseload coal power plants, which DOE was happy to point out.
“That same plant can also be used with more than 12 hours of storage and a much larger mirror field to generate baseload power—allowing the plant to provide solar electricity throughout the day and night.”
DOE also observed that a concentrating solar system can behave just like a conventional baseload power plant that supports “spinning reserve” to generate electricity at any time, without the commodity price spikes suffered by gas and coal power plants.
“Because the ‘fuel’ is free, costs are predictable over the lifetime of a plant operation and its maintenance costs,” DOE emphasized.
“In addition, more than 60% of the cost to operate a CSP power plant happens in the first year, enabling investors to have a better long-term understanding of costs and the return on their investment,” the agency added, though the pitch to investors fell flat.
Or…did it?
The Heliogen Thermal Energy Solution
Back in 2019 CleanTechnica took note of the startup Heliogen, a concentrating solar venture backed by Bill Gates. Instead of focusing exclusively on electricity generation, Heliogen zeroed in on the potential for concentrating solar systems to produce the high level of heat needed for certain industrial processes like steel and cement making. Depending on the user’s needs, the system can also generate electricity or produce green hydrogen, too. The company also markets lower-temperature systems for food processing and other operations.
Heliogen notes that conventional concentrating solar systems only reached temperatures around 565 degrees Celsius (about 1,049 degrees Fahrenheit), sufficient for generation steam. In contrast, Heliogen targets up to 1,500 degrees Fahrenheit, with a funding assist from the Energy Department.
Heliogen’s other contribution to the field is a modular, transportable system for ease of installation at a range of sites, and that’s where things get interesting.
Zeo Meets Heliogen…Where’s The Concentrating Solar Power?
Heliogen fell off the CleanTechnica radar after 2023 but a SPAC (special purpose acquisition company) called ESGEN was keeping an eye on things. ESGEN combined with the Florida-based solar firm Sunergy Renewables last year and changed its name to Zeo Energy, retaining the Sunergy senior management team.
On May 29, Zeo announced a plan to merge with Heliogen in a transaction to be completed before the end of this year. Leaving aside the financial details, Zeo plans establish an entire new division to promote its newly acquired technology for commercial and industrial facilities, particularly in the rich area of energy solutions for data centers.
“The transaction unites Zeo’s existing residential solar and storage footprint with Heliogen’s long-duration energy storage expertise,” Zeo explained in a press statement.
“Heliogen’s commercial and utility-scale thermal storage solutions address mission-critical power quality and energy capacity issues faced by AI and cloud computing data centers, while concurrently aiding grid stability,” Zeo noted.
Zeo CEO Tim Bridgewater also chipped in his two cents, stating that the company “will be able to accelerate our vision of serving energy consumers across the spectrum – from residential rooftops to larger-scale industrial solar and storage applications to build an energy platform at scale.”
Heliogen CEO Christiana Obiaya also put the energy storage angle front and center, describing Heliogen systems as “practical, dispatchable clean energy solutions.”
If you’re wondering why nobody mentioned concentrating solar power by name, that’s a good question. On its website, Heliogen provides plenty of details about its concentrating solar technology. However, the company also notes that the average renewable capacity factor of its concentrating system is 90%. Customers aiming to get closer to 100% can exercise an “option to hybridize for full availability.”
Capacity factor refers to the amount of time an energy system is used compared to its technical capacity on paper, so 90% is pretty impressive. The capacity factor of a typical gas peaker plant, for example, can get down to a lowly 10-15% range, reflecting its pattern of sporadic deployment.
As for what Heliogen means by “hybridize,” that’s a good question. The Zeo team could be considering any number of options on the long duration energy storage side, with or without the concentrating solar angle. If you have any guesses, drop a note in the comment thread. Meanwhile, I’ve reached out to Zeo for clarification.
Photo (cropped): Heliogen’s concentrating solar power system integrates long duration energy storage to achieve an average renewable capacity factor of 90% (courtesy of Heliogen).
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