Thermal energy storage in district heating and cooling systems: A review

Thermal storage facilities ensure a heat reservoir for optimally tackling dynamic characteristics of district heating systems: heat and electricity demand evolution, changes of energy prices, intermittent nature of renewable sources, extreme wheatear conditions, malfunctions in the systems. The present review paper explores the implementation of thermal energy storage in district heating and cooling systems. Both short-term and long-term storages are considered highlighting their potential in combination with district heating. Connections of sensible, latent (phase change material) and chemical heat storage are analyzed taking into account the research maturity of each type technology. The transition of current energy systems towards next generation district heating, and sustainable multi energy networks is considered. Performance assessment by using proper thermodynamic indicators and costs are investigated. Further addressed topics include the use of heat capacity of the network and the buildings connected to the system to store energy. The main issues currently limiting the diffusion of daily and seasonal thermal storage and the main research paths are discussed.