Thermoelectric Power Generation Based on Waste Heat
Conversion of heat energy into electricity is based on electric potential difference which is caused by temperature differences at both sides of thermoelectric elements. Around 70% of total energy provided in Japan is wasted through its emission into the atmosphere, making thermoelectric power generation a viable method for utilization of this vast untapped energy coming form different sources, including incinerators, automobiles, ships and industrial equipment, while at the same time it will contribute in reduction of CO2 emission. Up to now, development of thermoelectric power generation has been done on the low temperature range between 100 to 300 degrees Celsius involving hot springs and diesel engines. Based on this, Showa Denko (SDK) and Plantec have made an announcement on full scale demonstration of thermoelectric power generation based on waste heat using SDK thermoelectric conversion modules in a waste incinerator built by Plantec.
The SDK’s thermoelectric elements and modules have achieved world’s highest level conversion output in the medium operational temperature range of 300 to 600 degrees Celsius. The constructed modules consists of thermoelectric element which has been arranged in form of plates or cylinders. In order to achieve high power output, it is essential to ensure high electrical conductivity and low heat conductivity of materials being used as thermoelectric elements. SDK has developed a high performance thermoelectric elements by applying its advanced quick cooling technology for the production of sintered magnetic alloys. Through use of technology, materials for thermoelectric elements are quickly cooled and solidified for efficient formation of filled skutterudites (a structure with properties of semiconductor), and then sintered. In addition to this, SDK has used its proprietary bonding technology in the production of modules, resulting in high output of around 500 degrees Celsius. In the laboratory testing, where temperature at hot side is 600 degrees Celsius and temperature at cold side is 50 degrees Celsius, SDK has achieved a conversion efficiency of 6.2% and power density of 2.4 W/cm2. Furthermore, the company has achieved a maximum output of 216.6 W, highest level in the world for thermoelectric modules.