Abstract: A system and method to store and retrieve energy includes a heat source or an energy consumer thermally connected to a fluid. The fluid is transported through a first well fluidically connected to a second well. A slot is sawed into a rock below the earth's surface and a cable and tubing connect the first well to the second well. The cable and the tubing are partially encapsulated by casing, wherein the cable stores heat. A plurality of materials is filled into the slot. A first hole is disposed beneath a first rig and surrounds the first well. A second hole is disposed beneath a second rig and surrounds the second well. The first hole and the second hole are configured to be vertical or slanted.