Pumped Thermal Electricity Storage or Pumped Heat Energy Storage is the last in-developing storage technology suitable for large-scale ES applications. PTES is based on a high temperature heat pump cycle, which transforms the off-peak electricity into thermal energy and stores it inside two man-made thermally isolated vessels: one hot and one cold.
In 2010, Desrues et al. were the first to present an investigation on a pumped thermal energy storage system for large scale electric applications based on Brayton cycle. The system works as a high temperature heat pump cycle during charging phase. It converts electricity into thermal energy and stores it inside two large man-made tanks.
As previously said, thermal energy storage or heat and cold storage, allows to store heat or cold for a later use. In order to retrieve the heat or cold after some time, the storing method needs to be reversible. The possible methods can be divided into chemical and physical processes.
The storage question is of central importance for the future use of solar thermal energy as a potential substitute for fossil primary energy sources. The storage of solar heat in thermal energy storage systems (TESS) depends very much on the application.
It is worth noting that using sensible and latent heat storage materials (SHSMs and phase change materials (PCMs)) for thermal energy storage mechanisms can meet requirements such as thermal comfort in buildings when selected correctly.
Sensible heat storage which employs solid media like concrete, rocks or sand is the most inexpensive, safety and easy way to store thermal energy. For this reason, in literature a large number of studies on this topic can be found , , , , , , , , , .