VanWalleghem said there is room for cost reductions as the company gains experience with these initial plants. The storage systems have an expected lifespan of about 50 years, which is an important data point compared to battery systems, which have a much shorter lifespan, he said.
Yiyi Zhou, an analyst at BloombergNEF, said Hydrostor is one of about 100 companies focused at least partially on developing long-term energy storage.
Hydrostor stands out, she said, because its technology is “relatively mature” and the company is also one of the most successful companies in the industry when it comes to raising money from investors.
BloombergNEF reported a total of 1.4 gigawatts and 8.2 gigawatt-hours of long-duration energy storage worldwide last September, excluding pumped storage power plants. The average duration, which you can calculate by dividing gigawatt-hours by gigawatts, was 5.9 hours.
To illustrate, the two Hydrostor projects under development have a total capacity of 0.9 gigawatts, more than half of the world’s total power currently online.
Compressed air storage and flow batteries are expected to be the fastest-adopting long-term storage technologies this year and next, according to BloombergNEF. (I wrote an explainer on flow batteries in 2022.)
I find it difficult to get a handle on this part of the clean energy economy because there is a big gap between what has been developed and what is at some stage of planning. There are many ways for projects to stall and fail along the way.
With this in mind, I will be monitoring whether Hydrostor can begin construction in Australia on schedule and whether the company can navigate the regulatory approval process for the California plant.
The California project has undergone some major changes. At one point, Hydrostor had two proposals in the state but dropped one due to difficulties in the permitting process, including some issues building on a site overseen by the California Coastal Commission. The remaining Willow Rock project also underwent design and site changes based on feedback from the local community and regulators.
The California Energy Commission paused its review of Willow Rock last fall to give Hydrostor time to provide details on its updated plan. The review process began again in March and could be completed by this time next year.
One thing to consider is that the California state government and the California Energy Commission have made it clear that they want to build long-term energy storage. The country estimates it will need 4 gigawatts of long-term energy storage capacity to reach its goal of 100 percent clean electricity by 2045.
Hydrostor and state officials want this project to get off the ground. If that happens, it could be a flagship project that could encourage the construction of many more projects.
“We’re just looking forward to growing, building these projects and then doing another five, 10 projects at a time,” VanWalleghem said.