Thermal Energy Storage vs. Compressed Air Energy Storage

May 10, 2022

Thermal Energy Storage vs. Compressed Air Energy Storage: A Battle for the Ages

When it comes to energy storage, two innovative technologies that have gained popularity in recent times are Thermal Energy Storage (TES) and Compressed Air Energy Storage (CAES). While both technologies aim to provide a sustainable solution to energy storage, they are inherently different in terms of their applications, efficiency, and cost.

Let’s have a closer look at both technologies:

Thermal Energy Storage

As the name suggests, Thermal Energy Storage (TES) stores energy in the form of heat by capturing and storing excess thermal energy generated during the day, to be used during peak periods of energy demand.

TES technology can be classified into two types: Sensible Heat Storage and Latent Heat Storage:

Sensible Heat Storage: In sensible heat storage, energy is stored by heating or cooling a substance like water, rocks, or ceramic bricks. When the stored energy is needed, the heated or cooled substance is passed through a heat exchanger to create steam, which can be used for power generation.
Latent Heat Storage: In latent heat storage, energy is stored by changing the phase of a material, usually from solid to liquid. This change of phase requires a large amount of energy, which is stored in the material. When needed, the material is passed through a heat exchanger to release the stored energy.

TES system efficiency is usually measured in terms of Round Trip Efficiency (RTE), which is the ratio of the energy output to the energy input. The typical RTE for Sensible Heat Storage ranges between 60-85%, while the RTE for Latent Heat Storage ranges between 85-95%.

TES is a proven technology that has been in use for several decades, and its reliability has been well established. It is a flexible, scalable, and cost-effective technology that can be integrated with a variety of energy sources such as solar, wind, and hydroelectricity.

Compressed Air Energy Storage

Compressed Air Energy Storage (CAES) technology utilizes excess electricity generated during off-peak periods to compress air and store it in underground reservoirs such as depleted natural gas fields or salt caverns. When electricity demand is high, the compressed air is released and used to generate electricity.

The efficiency of a CAES system is measured in terms of Energy Efficiency and Round Trip Efficiency (RTE). The Energy Efficiency of a typical CAES system ranges from 40-60%, while the RTE ranges from 70-75%.

CAES is a relatively new technology and has shown great potential for large-scale energy storage. While it requires significant upfront investment, it has the advantage of being scalable to meet the highest demand periods, making it a viable option for utility-scale applications.

Which One is Better?

Both thermal energy storage and compressed air energy storage technologies have their specific advantages and disadvantages. In low-temperature applications, TES has the advantage of being more efficient and cost-effective, while CAES is better suited for high-demand applications and has the advantage of being more scalable.

It is challenging to make a direct comparison as the choice of technology will depend on the specific use-case and the priorities of the stakeholders involved.

However, both technologies have shown great potential in meeting energy storage needs while reducing the dependency on fossil fuels and combating climate change.

Thermal Energy Storage vs. Compressed Air Energy Storage: A Battle for the Ages

Thermal Energy Storage

Compressed Air Energy Storage

Which One is Better?

References