A frequent critique aimed at electric vehicles is that while they produce zero tailpipe emissions, the electricity fueling them often originates from carbon-heavy sources such as coal. Even within advanced renewable energy frameworks like the one found in the UK, grid reliability fluctuates during periods lacking sufficient wind and solar generation. Addressing this intermittent power supply requires robust long-duration energy storage solutions, and subterranean salt caverns historically used for gas storage could provide the ideal answer. Airengy's innovative AirBattery technology converts these massive underground spaces into compressed-air reservoirs, storing renewable power until it is required by the electrical grid. Company leaders explain how this engineering breakthrough could fundamentally alter energy storage.

Electric vehicles already profit from ongoing grid decarbonization. Estimates from the ICCT indicate that electric cars sold throughout the European Union in 2025 will yield 73 percent lower lifetime greenhouse gas emissions compared to equivalent gasoline models, factoring in forecasted electricity generation mixes over their operational lifespans. Maximizing renewable energy output can amplify this environmental edge further. Daniel Seroussi, who directs business operations at Airengy, notes that the target market focuses exclusively on extended storage windows rather than short-duration reserves, often spanning hundreds of hours.

Airengy Transforms Gas Caverns Into Power Plants

Initially, the firm aimed to rival lithium-ion batteries by constructing artificial underground chambers. However, connecting their proprietary conversion technology to much larger, pre-existing geological caverns dramatically shifted their commercial potential. Ido Ben-Yehuda, Airengy's head of marketing, explains that integrating their hydroelectric conversion system with existing subterranean salt caverns drastically reduces the cost per kilowatt-hour stored by an order of magnitude.

Ben-Yehuda notes that the strategic pivot transitioned the concept from a localized AirBattery storage unit to a comprehensive compressed-air power plant driven by the same foundational technology. This leverages existing gas storage infrastructure to supply both geological capacity and prospective industry partners, though individual caverns still demand thorough technical evaluations and regional permits before repurposing.

While oil storage caverns and alternative facilities could technically be adapted, Ben-Yehuda points out that gas storage caverns represent the most straightforward path, requiring minimal delay and investment for compressed-air conversion.

How Airengy’s AirBattery Stores Electricity

The mechanics behind Airengy's system are remarkably straightforward. Manufactured chambers positioned near the surface handle the conversion between water flow and compressed air, while the deep geological cavern supplies the storage volume for the pressurized air. Ben-Yehuda compares the mechanism to pumped hydroelectric storage contained within a box, where water circulates between compact subterranean chambers rather than massive surface reservoirs.

When a sealed chamber receives pumped water, the rising fluid level gradually compresses the trapped air. Excess renewable energy powers this pumping cycle, transferring water from a full chamber to an empty one. Once a predetermined pressure is reached, a valve opens to divert a portion of the compressed air into the deep storage cavern.

Naturally sealed salt caverns provide the repository, though operating pressure limits are strictly dictated by local geology. During the discharge phase, the process reverses to regenerate electricity. Releasing pressurized air from the cavern back into the water-filled chamber forces the liquid through pumps and a turbine, successfully converting stored potential energy back into electrical current.

Thermal management remains a core component of the design. Compression naturally heats air, while expansion cools it. Airengy utilizes a water-based process to achieve a near-isothermal environment through continuous heat exchange, eliminating the need for external thermal storage or supplementary fuel burning. This enables continuous long-duration operation limited only by the massive volume of the cavern.

The Efficiency Tradeoff For Airengy’s Technology

Despite near-isothermal operations, energy losses still occur, though the company plans to optimize performance beyond initial demonstration models. Ben-Yehuda reports that their current facility at Yahel—a 1 megawatt-hour energy storage demonstration system located on an Israeli kibbutz—achieves a 45.5 percent round-rate efficiency, with commercial targets set to exceed 60 percent.

Although less than half of the input electricity currently returns to the grid during early demonstrations, Airengy compensates through inexpensive capacity and strategic charging tailored for extended storage durations, such as a multi-week Dunkelflaute where wind and solar outputs plummet.

Seroussi emphasizes that the business model relies on energy arbitrage. By drawing power when wholesale grid prices drop near zero, charging efficiency becomes secondary to maximizing the generation of reliable electricity from the stored air during high-demand periods.

Beyond wholesale pricing, long-term economic viability benefits from exceptional equipment durability. Seroussi highlights that hydro turbines typically endure for 50 years, mirroring the multi-decade stability of salt caverns. Unlike lithium-ion batteries that require frequent replacements within a 10-to-15-year window, Airengy's electromechanical setup promises a far lower total cost of ownership under proper maintenance protocols.

From Demonstration To Airengy Deployment

Commercial interest is rapidly scaling, evidenced by four European collaboration agreements secured by Airengy. Notable partnerships, such as Nobian's feasibility assessments in Denmark, highlight the pathway toward future operating power plants.

Ben-Yehuda outlines global ambitions beginning in Europe and extending to the United States, Australia, and eventually Asia, supported by extensive geological mapping. Seroussi identifies cavern capacity and grid connectivity as the two primary constraints, noting that sites like SEFE's facilities in Germany offer multi-gigawatt-hour potential.

Utility-scale projects target grid connections exceeding 50 megawatts to rival traditional natural gas plants. Ultimately, this modular technology aims to guarantee that EV drivers draw continuous renewable energy, realizing a truly zero-emission transportation network backed by competitive economics.