Compressed Air Energy Storage: Companies, Startups & Research

Hydrostor, Siemens AG and Corre Energy are among the organizations working on compressed air energy storage. Hydrostor develops advanced adiabatic projects using underground cavities and water-based pressure compensation. Corre Energy develops grid-scale underground storage and has patented a hybrid CAES system. Siemens AG appears among the organizations active in the field, including in diabatic systems.

Corre Energy and Power8 are the startups with CAES-specific descriptions in FACTS. Corre Energy develops grid-scale underground energy storage and has patented a hybrid CAES system. Power8’s patent describes converting a compressed-air storage system into a hydroelectric power-storage system. These entries identify activity, but do not establish which startup is most commercially promising.

University of Chinese Academy of Sciences, Chinese Academy of Sciences CAS and Tsinghua University are among the leading research organizations in the recent activity data. Their work includes isothermal and adiabatic systems, porous-media storage, thermal management and control. Xi'an Jiaotong University and North China Electric Power University also have substantial research activity in the field.

FACTS reports $31,456,605 in grants across 21 awards since 2020 and $12,165,606,193 across 15 funding rounds. The grant total and round total are different funding categories. The listed rounds include financing for infrastructure and corporate activity that may not directly fund CAES, so the round total is not a clean measure of investment in the technology.

Hitachi Ltd. is the leading patent holder in FACTS, with 6 patents in the holder data. Pratt & Whitney Canada, the UNIVERSITY OF VIRGINIA PATENT FOUNDATIN and Siemens Energy Global GmbH & each have 3 listed patents. These figures identify recorded holders, not necessarily the full patent portfolios of those organizations.

No: FACTS reports 96 patents in the defined window and a patent growth rate of -31.6%. Publication activity moved in the opposite direction, with 470 publications in the last year and 1.1% growth. The contrast suggests that recent research activity has remained comparatively steady while patenting has declined over the measured period.

In March 2026, the Huai’an Salt Cavern CAES project in Jiangsu entered full operation. Recent research also examines adiabatic systems coupled with deep-borehole technology, storage in porous media, low-cost expansion devices and control strategies for large-scale systems. These developments address deployment, thermal performance, equipment costs and operation under changing grid conditions.

The main approaches are diabatic, adiabatic, isothermal, liquid-piston and underwater systems. Diabatic systems add heat during discharge, while adiabatic systems store compression heat for later use. Isothermal designs seek to limit temperature changes. Liquid pistons improve heat transfer through a liquid medium, and underwater designs use water pressure to help contain air.

FACTS identifies renewable energy integration (322 documents), grid balancing and peak shifting (222), and utility-scale long-duration storage (254) as applications. It also lists industrial cogeneration and microgrids and remote power. These uses rely on storing electricity for later dispatch, supporting renewable supply, grid operations or local power needs.