The NEDO/Cardiff thermoelectric project to economically recover low temperature waste heat

Since the Summer of 1994, a research project sponsored by the Japanese New Energy and Technology Development Organisation (NEDO) has been underway at the NEDO Centre for Thermoelectric Engineering, Cardiff University, to economically convert low temperature waste heat into electrical power using thermoelectric technology. A series of WATT (Waste heat Alternative Thermoelectric Technology) thermoelectric generators have been constructed and the latest, WATT-100, which produces 100W(e), successfully operated continuously for more than a year. The generator uses water at around 90C as a source of heat, and operates at a power generating density (PGD) which is close to the theoretical value of 18.5 kW per m(3) achievable using existing module technology. The use of modules assembled at Cardiff, whose thermoelement geometry has been optimised for power generation, will result in almost a doubling of the PGD. A further increase will accompany the use of modules with thermoelements fabricated from new materials with substantially improved electrical power factors which are under development at the Centre. A crucial aspect in economic waste heat recovery is the break-even-time, BET, (generating time required to produce electricity at a cost which matches that of commercial utilities). The use of improved modules with optimised geometry will reduce the break-even-time from the present seven years to around two years. In this paper an overview is given of the NEDO/Cardiff thermoelectric project and progress in improving the performance of modules, thermoelement materials and generating systems reviewed. It is concluded that thermoelectrics is an economically viable method of converting low temperature heat into electrical power.