A thermal battery includes a heat sink material that remains solid across an operating temperature range (i.e., for all operating modes) of the battery, and a heat conductive material in direct heat transfer relationship with the solid heat sink material. The heat conductive material has a melting point below that of the heat sink material so that in use the heat conductive material is a fluid, for example molten when the heat conductive material is a metal, in the operating temperature range of the battery.

A heat storage device includes a ceramic part having a closed space therein, a latent heat storage provided inside the closed space, an electric heater provided inside the ceramic part and configured to heat the latent heat storage, a heat insulating member covering the ceramic part, and a power supply part configured to supply electric power to the electric heater.

A heat absorption and radiation system uses a heat medium containing a rubidium-manganese-iron cyano complex, and is configured to release heat from the heat medium by applying a pressure to the heat medium and causing phase transition of the rubidium-manganese-iron cyano complex from a high-temperature phase to a low-temperature phase, absorb heat into the heat medium by releasing the pressure applied to the heat medium and causing phase transition of the rubidium-manganese-iron cyano complex from the low-temperature phase to the high-temperature phase, and repeat application of the pressure to and release of the pressure from the heat medium. Thus, it is possible to efficiently absorb and release heat through effective utilization of the characteristics of the rubidium-manganese-iron cyano complex.

A fireplace system includes a fireplace, a thermal energy storage system (TESS) implemented with the fireplace and including one or more heat storing materials in which thermal energy is stored, and a control system comprising one or more controllers operatively coupled with the fireplace and the TESS. The control system is operable to control operation of the fireplace and the TESS to release the stored thermal energy from the one or more heat storing materials into a surrounding environment based on one or more inputs.

A thermal battery includes a heat sink material that remains solid across an operating temperature range (i.e., for all operating modes) of the battery, and a heat conductive material in direct heat transfer relationship with the solid heat sink material. The heat conductive material has a melting point below that of the heat sink material so that in use the heat conductive material is a fluid, for example molten when the heat conductive material is a metal, in the operating temperature range of the battery.