A quantum well thermoelectric module providing very high conversion of heat energy in to electrical energy. In prefered embodiments the module provides electric power for monitoring, measuring or detecting any of a variety of things (such as temperature, smoke, other pollution, flow, fluid level and vibration) and a transmitter for transmitting information measured or detected. In a preferred embodiment wireless monitor systems are utilized to monitor conditions at various locations aboard a ship and to wirelessly transmit information about those conditions to a central location. Preferably, a finned unit is provided to efficiently transfer heat from a module surface to the environment. A preferred quantum well choice is p type B.sub.9C/B.sub.4C and n-type Si/SiGe legs. Another preferred choice is n-doped Si/SiGe for the n-legs and p-doped Si/SiGe for the p-legs. At higher temperatures the preferred quantum well legs are alternating layers of silicon and silicon carbide for the n-legs and for the p-legs alternating layers of different stoichiometric forms of B-C.