Israeli energy storage developer Airengy and real estate and energy firm Hagag Europe have announced plans to develop a large-scale compressed-air energy storage facility in Romania, targeting a total capacity of 5 GWh and a commercial launch as early as 2028.

Co-Development Agreement

The two companies have signed a co-development agreement to advance the project, which will deploy Airengy's proprietary long-duration energy storage platform, known as AirBattery technology. The partnership brings together Airengy's storage expertise and Hagag Europe's regional presence to pursue what would become one of the more significant long-duration storage installations in southeastern Europe.

Underground Salt Caverns as the Storage Medium

Central to the project's design is the use of underground salt caverns, which serve as the physical reservoirs for storing compressed air. Salt cavern formations are considered well-suited for compressed-air energy storage applications due to their natural pressure-retention characteristics and geological stability. The Romanian site's subsurface geology is expected to support the gradual buildout toward the 5 GWh target capacity, though the project is described as reaching that figure eventually, suggesting a phased development approach rather than a single construction phase.

Timeline and Commercial Outlook

Airengy has indicated to industry media that commercial operations are likely to commence in early 2028. That timeline places the project within a broader wave of long-duration energy storage developments across Europe, as grid operators and policymakers seek storage solutions capable of balancing intermittent renewable generation over periods longer than the two- to four-hour window typical of lithium-ion battery systems. Compressed-air energy storage, particularly when paired with existing geological formations, has attracted renewed interest as a cost-competitive alternative for multi-hour and potentially multi-day storage needs.

Romania's Emerging Storage Landscape

Romania has been expanding its renewable energy capacity in recent years, with wind and solar generation playing an increasingly prominent role in the country's electricity mix. That growth has sharpened the need for flexible storage assets capable of absorbing surplus generation and dispatching power during periods of high demand or low wind and solar output. A 5 GWh compressed-air facility, if completed as described, would represent a substantial addition to the country's grid balancing infrastructure and could support broader regional energy security goals within southeastern Europe.