A thermal reservoir for storing heat energy that can convert water to steam and thus power steam driven machines and vehicles is enclosed. The thermal reservoir converts electrical energy to heat energy using electrical resistance heating coils and the heat energy is stored with a thermal storage substance consisting primarily of lithium fluoride. Heat loss is minimized with a specially designed insulation layer that surrounds the thermal storage compartment. The thermal reservoir is charged and discharged via a heat exchanging system comprised of nested cylinders and a plurality of heat conducting fins that innervate the thermal storage compartment.