Compressed Air Energy Storage

The process is simple:

Compressed Air Energy Storage (CAES) is a scalable solution for medium- to long-duration energy storage that uses surplus electricity to compress air and later expanded through a turbine converting the stored air pressure into mechanical energy that drives an electrical generator.

It notes that system performance depends on multi-stage compression and expansion, thermal management and the characteristics of the storage reservoir. CAES as one of the most promising long-duration storage technologies expected to be deployed over the coming years.

System efficiency and performance depend heavily on the design choices made for compression, expansion, heat recovery and storage. In adiabatic configurations, compression heat is recovered and reused during discharge, enabling zero-emission operation.

Where is turbomachinery used?

  • Charging: High-performance compressors convert electrical energy into compressed air by increasing its pressure before storage.
  • Discharging: Expansion turbines convert the pressure energy of the stored air into mechanical power, driving an electrical generator to produce electricity.

Main configurations:

Diabatic CAES: heat is added before expansion, traditionally using fuel.

Adiabatic or advanced CAES: compression heat is captured and reused during discharge.

Geological CAES: air is stored in underground caverns, including salt caverns where available.

Engineered-vessel or hard-rock CAES: air is stored in purpose-built infrastructure.

Why is CAES important to support the Energy Transition?

CAES as one of the most promising long-duration storage technologies expected to be deployed over the coming years. In fact, CAES configurations are among the storage technologies that come closest to economic viability in Germany and Great Britain after 2040.

CAES offers:

  • Large power and energy ranges.
  • Storage durations ranging from hours to several days.
  • Mature and reliable component technologies.
  • Potential applications in energy shifting, balancing and congestion management.