Thermal energy storage has the potential to be an essential brick in building a fossil-free energy system. Approximately half of the world’s energy consumption is in the form of heat, from heating the built environment to a range of industrial processes and more. By combining thermal energy storage with renewable electricity production, many applications that currently use fossil fuels to produce heat can be decarbonized.
As with any other energy storage solution, thermal energy storage can make use of overproduction of renewable energy sources; in this case to charge a thermal storage. Heat can be stored in the form of sensible heat (increasing the temperature of a material), as latent heat (using the energy associated with a phase change) or thermochemically (where a chemical reaction absorbs and releases heat). Heat storages can be coupled to waste heat sources or high temperature heat pumps to increase their efficiency. The heat from the thermal storage can be used directly in e.g. district heating or in industrial processes, or it can be converted to electricity. Both power-to-power and power-to-heat have the potential to be important implementations of thermal energy storages.
At DTU Energy, we study materials, model thermal energy storage systems and test prototype systems for a range of thermal energy storage technologies. We currently focus on rock bed thermal energy storage (where we have a 1 MWh pilot plant in operation), as well as on thermochemical energy storage and liquid air energy storage. We make use of the thermal analysis lab at DTU Energy to measure material properties such as specific heat and thermal expansion as well as study storage material structure and degradation. Our modelling activities cover detailed models of specific components to system-level models of e.g. a power-to-power thermal storage system.