A modular heating or cooling system includes a heating and/or cooling unit and a plurality of storage modules that may be releasably connected to the heating and/or cooling unit by a releasable coupling. The storage modules may include a heat exchanger having a thermal transfer bladder filled with eutectic fluid. The storage modules may include a hydroelectric generator and/or turbine assembly placed in-line in a circulation line for transporting heated or cooled fluid to and/or from the heat exchanger, the hydroelectric generator and/or turbine assembly operative to drive an electric light or a fan. A base station in the form of a movable cabinet is also disclosed for storing a plurality of the storage modules. The base station includes circulation lines that attach to fluid supply lines from a heating or refrigeration unit and may include terminals with releasable couplings for connecting to the storage modules stored therein.