A heat conduction system including modular pipes housing a solid heat conductor made of a combination of carbon foam glass and grapheme and, for conductors, insulated from the outermost pipe by an insulating layer and with an annular gas purging gap for high-temperature applications. Also included in the system are thermal valves, manifolds, and heat exchangers to route and use the thermal energy. In an exemplary use, a down-hole heat exchanger, thermally coupled to a string of heat conduction modules, brings geothermal heat up from abandoned oil wells to operate a boiler and steam turbine. In another exemplary use, waste heat is conducted out of slag for conversion into useful energy. In yet another exemplary use, waste heat is conducted away from a nuclear reactor.