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Home » IIR announces new informatory note: Thermal energy storage systems

IIR announces new informatory note: Thermal energy storage systems

Energy demand is seldom steady, and this variation often requires oversizing energy conversion systems to satisfy peak demand. This latest IIR informatory note illustrates the possible benefits of equipping a heating or cooling plant with a thermal energy storage system, describing the many technologies available with different capacity, cost, size and performance characteristics.

IIR informatory note on thermal energy storage systems. Image credit: International Institute of Refrigeration

IIR informatory note on thermal energy storage systems. Image credit: International Institute of Refrigeration

The frequent variation in energy demand in many applications that requires such oversizing energy conversion equipment compared to average values, results in high investment costs and reduced performance.

Renewable energies seldom ensure a steady energy supply. In the case of solar energy, a plant must face not only the obvious day-night alternation, but also the strong variations due to meteorology from one day to another and over the year.

Thermal energy storage systems offer a fundamental aid to mitigate the above-mentioned undesirable effects and allow renewable energy plants to increasingly meet the energy demand. Many choices are possible.

The storage can be based on a liquid, typically water, or on a solid such as rock or concrete; this is called sensible storage. Recently, the use of phase change materials (PCMs), referred to as latent storage, allows stable temperatures to be achieved with a significant volume reduction compared to liquid or solid storage systems, for the same service.

A storage system can smooth out peak demand, as with a domestic hot water tank, by satisfying the demand for a few hours and then smoothing out the request to the energy converter, for example a boiler or a heat pump. It can store energy during periods of high insolation in a solar heating/cooling plant, supplying energy at night or in bad weather or low insolation days.

Cold can also be stored, usually in the form of chilled water or ice. Storing cold thermal energy allows for economical savings, using night-time electricity tariffs, by operating the refrigeration equipment mainly at night. Most importantly, it reduces the cooling capacity of the plant, which should otherwise be sized for peak demand, with high equipment costs and contracts with electricity suppliers.

A general benefit arises from the reduction in the electrical power required when the electricity grid is overcharged in the daytime. Recent developments aim to achieve seasonal storage for both heating and cooling capacity, and there is particular interest in harnessing solar energy throughout the year for heating in winter and cooling in summer.

This informatory note is available by free download for IIR members. A complementary summary for policymakers is free to access.

This is an extract from the document as per the free summary for policy makers. The document can be accessed here.