Mechanical and thermal energy storage

Different technologies can be used to capture and store energy.

We will briefly describe some of them here and in the next step.

Mechanical energy storage

Mechanical energy storage is one of the oldest and most widely used methods for storing energy. It accounts for nearly 99% of global energy storage capacity, which is over 1500 gigawatts (GW).

One common type of mechanical energy storage system is pumped hydroelectric storage, which stores energy by using the gravitational potential energy of water. This technology stores and generates energy by pumping seawater between two reservoirs with distinct altitudes (located at different heights). When energy is needed, the water is released from the higher reservoir, flowing down to the lower one and generating electricity as it moves. This method is quite efficient, with 70–85% of the energy being successfully stored and later retrieved. However, some energy is lost due to air resistance.

_{Adapted from Physik Druck Höhe Oberbecken Unterbecken einfach by Pedalito, CC0 1.0}

While mechanical energy storage is reliable and long-lasting, it does have some downsides. These include high initial costs, potential environmental impacts, and the need for specific geographical conditions to set up the system (Steinmann, 2021).

Thermal energy storage

Thermal energy storage (TES) refers to systems that store thermal energy (heat) from high-temperature sources such as sun collectors or industrial processes. The captured energy from these hot resources can be stored in materials like ice, water or molten salts within a TES system, and then used when energy is needed.

_{Workers construct one of a dozen molten salt tanks at Abengoa’s Solana Plant. The molten salt tanks will generate clean, renewable electricity with conventional steam turbines. U.S. Department of Energy; public domain}

TES systems have a wide range of applications across industrial sectors and residential areas. However, one challenge with TES is that it can lose some of the stored heat over time, which can reduce its efficiency (Sharma et al., 2009).

_{Thermal energy storage tower in Bozen-Bolzano, South Tyrol, Italy. Bartleby08; CC BY-SA 4.0}

Research and share

Research other examples of mechanical or thermal energy storage. Share what you’ve learned about one of them in the comments below.

References

Sharma, A., Tyagi, V. V., Chen, C. R., & Buddhi, D. (2009). Review on thermal energy storage with phase change materials and applications. Renewable and Sustainable energy reviews, 13(2), 318-345.

Steinmann, W. D. (2021). Overview of the Section on Mechanical Energy Storage. Encyclopedia of Energy Storage, 3, 1-4.

Adam Beck Complex. Ontario Power Generation; CC BY 2.0