Design of a Modular Solid-Based Thermal Energy Storage for a Hybrid Compressed Air Energy Storage System

The share of renewable energy sources in the power grid is showing an increasing trend world-wide. Most of the renewable energy sources are intermittent and have generation peaks that do not correlate with peak demand. The stability of the power grid is highly dependent on the balance between power generation and demand. Compressed Air Energy Storage (CAES) systems have been utilized to receive and store the electrical energy from the grid during off-peak hours and play the role of an auxiliary power plant during peak hours. Using Thermal Energy Storage (TES) systems with CAES technology is shown to increase the efficiency and reduce the cost of generated power. In this study, a modular solid-based TES system is designed to store thermal energy converted from grid power. The TES system stores the energy in the form of internal energy of the storage medium up to 900 K. A three-dimensional computational study using commercial software (ANSYS Fluent) was completed to test the performance of the modular design of the TES. It was shown that solid-state TES, using conventional concrete and an array of circular fins with embedded heaters, can be used for storing heat for a high temperature hybrid CAES (HTH-CAES) system.