Toronto, Canada-based Hydrostor was founded in 2010 and is a leader in Advanced Compressed Air Energy Storage (A-CAES), a technology uniquely suited to enable the transition to a cleaner, more reliable electricity grid. Unlike utilizing lithium-ion energy storage batteries, compressed air energy storage (CAES)

is a way to store energy generated at one time for use at another time using compressed air. Basically, Hydrostor’s utility-scale storage systems pump large volumes of air into small underground shafts during off-peak hours and then releases it to run turbines when energy demand goes up.

How A-CAES Works

Hydrostor’s A-CAES system’s performance is very similar to other rotating generation equipment such as the type used in natural gas facilities, however, compared to competing technologies, Hydrostor A-CAES has many distinct advantages that lower life-cycle costs. Perhaps the biggest plus is that no fuel or chemicals are used in the technology and there are no emissions. And with a 50-plus year system life, the system has the lowest installed cost per kilowatt hour (kWh) for large-scale, long-duration energy storage (100+ MW). And we are talking about four to well over 24 hours worth of energy storage.

Agnas Zinc Mine before construction of Hydrostor A-CAES Project.

How the process works

Actually, the accompanying video is very easy to understand, but basically, off-peak or surplus electricity from the grid or a renewable source is used to operate a compressor that produces heated compressed air. In Hydrostor’s patented fuel-free adiabatic process, the heat is extracted and stored in a proprietary thermal storage unit. A specially-built storage cavern is also used to store air. Hydrostatic compensation is used to maintain the system at a constant pressure during operation. When electricity is needed, hydrostatic pressure forces the air to the surface where it is recombined with the heat and expanded through a turbine to produce electricity.

Angas A-CAES Project Above Ground Infrastructure 3D Model

Now all this sounds simple enough. But what Hydrostor has done is figured out a way to repurpose coal-fired power plants and even old mines – turning them into utility-scale energy storage facilities. What’s the huge plus to doing this? The old facilities already have the

infrastructure in place to connect to the electric grid. Hydrostor has signed an AUS$30-million deal in Australia to build a demonstration facility at a disused zinc mine near Adelaide. Hydrostor will construct the 5 MW / 10 MWh fuel-free Advanced Compressed Air Energy Storage (A-CAES) facility which will re-purpose the Angas Zinc Mine in Strathalbyn, 60 kilometers southeast of Adelaide.

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