Abstract: An energy storage apparatus includes a first circuit containing a first phase change material, a second circuit containing a second phase change material, and a heat pump having a cold side heat exchanger thermally coupled to the first circuit and a hot side heat exchanger thermally coupled to the second circuit. The apparatus is operable in a charging mode, a storage mode, and a discharge mode. In the charging mode the heat pump is energized to cool the first phase change material and heat the second phase change material. In the storage mode the first phase change material is stored in a first storage vessel and the second phase change material is stored as a pressurized vapor in a second storage vessel. In the discharge mode vaporized first phase change material is expanded by a first expander, or the vaporized second phase change material is expanded by a second expander.

Abstract: A thermodynamic cycle apparatus is provided. The thermodynamic cycle apparatus includes: (i) a first reservoir containing a first storage medium; (ii) a second reservoir containing a second storage medium; (iii) a heat pump having a cold side thermally coupled to the first reservoir for cooling the first storage medium and a hot side thermally coupled to the second reservoir for heating the second storage medium; (iv) a first thermodynamic circuit of a first working fluid; (v) a second thermodynamic circuit of a second working fluid; (vi) an auxiliary heat input thermally connected to the first thermodynamic circuit so that auxiliary heat may contribute to the creation of the first pressurized vapor; and (vii) an auxiliary heat output thermally connected to the second thermodynamic circuit so that the second working fluid can lose heat to an auxiliary heat sink.