ONCE a technological marvel, concentrated solar power (CSP) seems to have died a rather sudden death, with the announcement in the past two weeks of the imminent shutdown of one of the world’s largest CSP facilities in California, and the beginning of the wind-down of the company that tried to pioneer the concept in Australia. The unfortunate developments are an illustrative tale, and perhaps even a cautionary one, about how a good idea at a certain point in time can be quickly undone by excessive optimism, complexity and technical evolution.
Unlike solar photovoltaic (PV) power, in which an electrical current is produced directly by sunlight falling on a solar panel, CSP uses large mirrors called heliostats to focus sunlight on a heat exchanger to boil water and produce steam that can spin a generator, much like a conventional power plant. The mirrors can be arranged in a circular pattern to focus the sunlight on a tower with the heat exchanger mounted at the top of it, or in rows where the sunlight is focused on pipes that carry the heat to a boiler system.
The Ivanpah Solar Energy Generating System in California is of the first configuration, containing 173,500 heliostats arranged in circles around three 140-meter-tall solar power towers; the facility covers about 1,400 hectares (14 square kilometers) of land in the Mojave Desert near the border with Nevada. Originally designed for a nameplate capacity of 440 megawatts (MW), it was scaled back to about 387 MW to avoid disturbing the habitat of the endangered desert tortoise. At the time it was commissioned in 2014, it was the world’s largest CSP facility, although it has since been surpassed by plants in Morocco and the UAE. The Ivanpah facility cost approximately $2.18 billion to build, $300 million of that coming from a company called NRG Energy, the largest shareholder, and $168 million from Google. Another $90 million came through the EB-5 Investor Immigration program, mostly from foreign nationals working in California’s tech sector, and the US government, through the Department of Energy, provided $1.6 billion in loan guarantees.
There were three basic problems that undid the Ivanpah project. First, at the time it was planned and designed, solar PV power was expensive. By the time construction started in 2010, the price of solar PV was already dropping rapidly, and it was for this reason that Google announced in 2011 that it would not invest any more in the plant. Second, the plant struggled to meet its supply contract obligations, running only at about 40 percent of its expected capacity. Two-thirds of its output was to go to Pacific Gas and Electric (PG&E), the biggest utility in California, with the remainder to Southern California Edison (SCE), but it took until 2017 until it was able to supply the contracted 640 and 336 gigawatt-hours (GWh) per year, respectively. The announcement at the beginning of this year that PG&E was seeking regulatory approval to cancel its contract with Ivanpah (something that is apparently still being argued between the utility and the regulator, apparently) led to the announcement that at least two of the three units would be closed down this coming year. SCE has also indicated it will pull out if PG&E is able to cancel its contract, and so the process to shut Ivanpah down completely and find something else to do with the land has already started; by 2027, it will likely be gone.
Finally, and somewhat ironically for a renewable energy plant, the third factor in Ivanpah’s undoing is natural gas. The plant’s design does not allow a black start using solar power alone; it would take more than the available sunlight hours in a day for solar heat alone to bring the steam up to operating temperature. Thus, the plant relied on gas-fired boilers to maintain system temperature; this is a feature of any CSP system, one that its proponents would rather the public didn’t notice. The original design called for the gas boilers to be run for about an hour before sunrise each day, but in practice, they had to be operated much more than that. As a consequence, about 120 GWh per year of Ivanpah’s output was attributable to gas generation, with emissions actually being higher than the limit under California’s emissions cap for power plants.
The recent flop of the CSP concept in Australia involved even more complex and expensive technology, one in which concentrated sunlight would be used to heat molten salt, which would serve as heat storage that could be used in a second stage to generate electricity, or as the company behind it planned, also be used in methane production. Vast Renewables, an energy startup owned by Sydney’s oligarch Kahlbetzer family, had no trouble initially securing funding, having listed on the Nasdaq in 2023 (it has since been delisted) and collecting nearly $300 million in government subsidies, and as a result, actually built most of its flagship storage facility in Port Augusta, Queensland.
However, the same sort of technical difficulties that plagued Ivanpah in the US had not been overcome; Vast Renewables ran into obstacles in securing energy offtake agreements, which led to difficulties in securing additional funding to complete its projects. After racking up about $450 million in losses, including about $79 million in delinquent debt — something that seems to infuriate some Australian commentators, given the large subsidies Vast was given — the company went into “voluntary receivership” (“bankruptcy” for those of us who don’t speak Australian) in mid-November. Despite optimistic announcements from the company that the receivership would allow it to come to terms with its creditors and find fresh funding, the receivership isn’t buying it; at last report, the process of setting up the liquidation of Vast’s assets has been started.
I think the big lesson here is that when it comes to renewable energy, simpler is better, and something with too many moving parts that takes too long to develop is almost certain to fail. Nobody really did anything wrong in either of these two cases; it was just that their reach exceeded their grasp. It should be something for energy developers and policymakers fascinated by “next generation” technology simply because it exists in well-produced PowerPoint presentations to think about.
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Bluesky: @benkritz.bsky.social

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