Rosie Barnes, engineer and founder of Pardalote Consulting, traces the history of compressed air from Victorian-era pneumatic tube networks to its modern revival as grid-scale energy storage.
Key insights:
Compressed air lost the race against electricity in the 1890s primarily because AC transmission achieved around 75% efficiency over long distances, far beyond what compressed air could manage.
Modern compressed air energy storage (CAES) works by compressing air into underground caverns during off-peak periods and releasing it through turbines during peak demand, with suitable geology such as salt caverns reducing capital costs by a factor of ten compared to above-ground pressure vessels.
The first-generation Huntorf plant in Germany achieved only 42% roundtrip efficiency because it burned natural gas to reheat air during discharge, while newer adiabatic systems that capture and reuse compression heat reach 60–70%.
Hydrostor’s $600 million Silver City project near Broken Hill, Australia uses a water-compensated hard rock cavern 600 meters underground to achieve 66% efficiency over a 12-hour charge and 8-hour discharge cycle
While CAES offers low self-discharge and long asset life, its future depends heavily on local geology and its ability to compete economically with lithium-ion batteries.