Israeli company Augwind Energy is planning to build the world’s first commercial-scale ‘air battery’ in Germany, using underground salt caverns to store compressed air for electricity generation. Commissioning is scheduled for 2027–2028. The facility will be the first operational installation at scale of Augwind’s ‘AirBattery’ hydraulic compressed air energy storage (CAES) system designed specifically for grid-scale energy storage for up to months at a time.
Germany has over 400 caverns suitable for AirBattery, and geological potential for storing 330 TWh in total. AirBattery is said to be highly cost-effective at 10-15 USD per kWh, and environmentally friendly, with almost no hardware degradation (over the 40 years lifetime). In addition, it uses locally sourced materials as opposed to the critical and non-local minerals needed for lithium-ion batteries
The AirBattery system combines two well-established technologies: it merges pumped hydroelectric principles with compressed air storage, circulating water between underground chambers to compress and decompress air at vast scales. Excess energy is used to compress air to pressures from 50 bar all the way to above 200 bar, depending on the demand and geomorphic structure of the cavern, and feed the pressurised air into vast underground caverns. A typical cavern has the potential to store enough compressed air to generate 3-8 GWh of electricity.
Energy is recovered from the system by returning the high-pressure air back through the water filled chambers, streaming the water to spin a turbine. Augwind has already reached a 47% AC-to-AC round-trip efficiency at its AirBattery demonstration facility in Israel, and anticipates that commercial installations will exceed 60%.
Or Yogev, founder and CEO of Augwind said: “This is more than a project; it’s a milestone for achieving net zero. With the AirBattery, we’re introducing a storage solution that finally matches the scale and rhythm of renewable energy.”
Augwind is now working with local cavern owners, utilities, energy traders and industrial off takers to secure permitting and finalise the system design. The project will showcase the techno-economic viability of Augwind’s hydraulic CAES but also, it is hoped, lay the groundwork for broader deployment across Europe by 2030.
Huntorf CAES
An air battery storage system that uses large scale CAES but recovers its energy via a different system has been running in Huntorf, Germany, since it was commissioned in 1978. Huntorf was the first commercial scale CAES plant in the world, at a rating of 320MW.
During off-peak load periods, air is compressed and stored in underground salt caverns. During peak load periods, the process is reversed and the compressed air is mixed with natural gas and combusted to produce electricity. A gas turbine normally uses up to 2/3 of its power output for compressing the combustion air, so when the compressor is supplied from the stored compressed air and separated from the expander, the power rating can be up to three times greater for the same consumption of natural gas per kWh compared to a conventional combustion turbine.
