Compressed air energy storage works by using excess electricity during off-peak hours to drive compressors that press air into underground storage caverns. When power demand rises, the compressed air is released to generate electricity.

As a form of physical energy storage, the technology can help balance supply and demand in the power grid and support the large-scale integration of renewable energy. Unlike fossil-fuel-based peaking plants, salt cavern compressed air energy storage does not rely on combustion, making it a low-carbon and environmentally friendly option.

The Jintan project makes use of deep salt caverns, which are regarded as ideal storage spaces because salt formations are dense and highly impermeable, reducing the risk of air leakage.

During periods of low electricity demand, surplus grid power is used to compress air to more than 130 atmospheres before injecting it into the salt caverns. During peak demand, the stored high-pressure air is released to drive turbines and generate electricity.

China has a growing number of salt cavern energy storage projects, but this facility stands out for both scale and technical complexity.

This is awesome. In other countries old salt caverns are used to store nuclear waste or are turned into tourist attractions (which is not a bad thing per se…if you have never visited a big salt mine i highly recommend you do at least once in your life, it is quite impressive being in such huge halls so deep underground), it’s nice to see that China can also use them to help with the integration of renewable energies.

According to CCTV News, the project also features Asia’s largest single-set thermal storage water tank matrix in the compressed-air storage sector. The system includes 16 spherical water tanks, each capable of holding 3,500 cubic meters of water, with a total volume of 56,000 cubic meters — roughly equivalent to 22 standard swimming pools.

These thermal storage tanks play a key role in the process by capturing heat generated during air compression and reusing it later to warm the released compressed air, improving efficiency and reducing energy loss.

This is exactly what I was hoping to read. One of my main concerns with compressed air energy storage as opposed to pumped hydro storage solutions is that the compression and expansion cycles necessarily involve a release of heat (physics makes this unavoidable) which means a loss of a percentage of the stored energy with each cycle.

If a part of that waste heat can be captured and recycled that’s great. I wonder though how the efficiency compares with pumped water reservoirs for energy storage. My intuition says the latter is probably still better.