To get through the darkness of night and cloudy or even windless days, a grid that runs primarily on wind and solar, as part of the future that clean energy proponents are aiming toward, will require a lot of long-duration energy storage.
Hydrostor, a Canadian business, has submitted applications with California regulators in the last week to build two reactors using “compressed air energy storage” to supply some of that demand. Compressed air would be pumped into deep caverns, then released to power a turbine and generate electricity.
With no fossil fuels and also no greenhouse gas emissions, the stored energy may create hundreds of megawatts (MWs) of the electric power for up to 8 hours at a time. Long-duration storage refers to systems that can discharge electricity for 8 hours or longer, as compared to the lithium-ion battery storage, which only lasts four hours.
This project and technology could have a significant impact on the race to create long-term energy storage. However, the crucial word here is “possibly,” because there are a lot of companies and technologies competing for a piece of this fast-growing energy market, and the outcomes thus far have been nothing more than study results and hoopla.
In general, Mike Gravely, who is a manager of energy systems research for California Energy Commission, stated of CAES, “Their technology is not unduly difficult.” “The principle of compressed air is extremely basic.” The key problem, as with many other renewable energy technologies, is to bring the costs down to the point where many of the plants can be built.
Hydrostor, a Toronto-based company launched in 2010, has completed two minor facilities in the Toronto region, including one with a 1.75-megawatt storage facility that can run for up to six hours.
The company’s system starts with a large-scale air compressor which runs on energy and draws air from the surrounding environment. The technology takes the heat produced by air compression and stores it in the thermal storage vessel. Meanwhile, compressed air is pumped into the cavern over 1,000 feet beneath the surface via a conduit. Rather than using natural caverns for storage, the cavern would just be excavated for the project.
The device releases water into the cavern to discharge the energy, forcing the air to the surface, where it combines with the heat which had been stored. The heated air is then circulated through turbines, which generate power. Last, Hydrostor submitted an application for a plant dubbed Pecho Energy Storage Center in San Luis Obispo County that would cost $800 million. It would have a 400-megawatt producing capacity and a runtime of up to 8 hours.