Technology Overview

Compressed Air Energy Storage (CAES) is a mechanical energy storage technology that stores electricity by compressing air into high-pressure vessels or underground formations, and then releasing it to drive turbines for electricity generation when needed. A more advanced variant is Adiabatic CAES (A-CAES), where the heat generated during compression is stored and reused, improving round-trip efficiency.

Technical Characteristics

Two main technologies are considered: conventional CAES and A-CAES. Conventional CAES uses natural gas to compensate for thermal losses, resulting in CO₂ emissions, whereas A-CAES does not require fossil fuels and produces no emissions.

Advantages of CAES include large storage capacity at relatively low cost and fast start-up capability. However, disadvantages include CO₂ emissions (except for A-CAES) and dependence on suitable geological storage locations. The technology requires relatively low water consumption, but may have environmental impacts associated with fossil fuel use and underground construction.

A-CAES is currently under development and is expected to be commercialized within 10–15 years, with a round-trip efficiency of up to 70%.

Globally, only two conventional CAES plants are currently in commercial operation: one in Huntorf (Germany) and one in McIntosh (USA). The Huntorf plant has a round-trip efficiency of approximately 42% and a cost of 320 DM/kWel, while McIntosh has an efficiency of 52% and a cost of 591 USD/kWel.

Application in Vietnam

CAES has not yet been deployed in Vietnam. However, studies have identified storage potential in Dong Nai and Bien Hoa, where suitable sandstone formations exist. Investment costs for CAES projects are estimated at 400–500 USD/kWac (based on 2003 prices).