Efficient use of fossil fuels, such as petroleum and natural gas is in everyone’s agenda, more so for Japan that relies heavily on imports for very much most of its primary energy supplies. This dependency is making Japan as well many other countries with substantial energy dependency to focus on power generation using recovery waste heat as a method in increasing energy utilization efficiency. However, recovering waste heat involves many issues including high recovery costs as well as developing new technology to facilitate the recovery to begin with. One technology that has been gaining in popularity for its capability in waste-heat-recovery power generation is thermoelectric power generation, due to its simple system configuration suitable for downsizing. But use of this technology involves improving the performance of thermoelectric materials to achieve electrical conductivity as high as of a metal and thermal conductivity as low as glass. Based on this researchers at AIST has successfully developed a thermoelectric power generation module that can withstand temperature as high as 300 degrees Celsius.The module uses new thermoelectric materials such barium, gallium and thin which is available in abundance. The module has achieved a power-generation efficiency of about 4% which is equivalent to the modules with conventional materials. The new compound which is mix of Ba, Ga, and Sn, form a compound semiconductor with a cage-shaped crystalline structure. The compound which is commonly known as clathrates, is expected to have a higher performance than traditional bismuth telluride-based thermoelectric materials. Furthermore, the Ba-Ga-Sn-based clathrate can be used as either a p-type or n-type thermoelectric material by slightly changing the basic composition ration. Both p-type and n-type Ba-Ga-Sn polycrystals were surface treated to prevent diffusion. This prototype model has a dimension of 28.0 mm x 28.0 mm x 5.5 mm and it weighs around 15 grams, which includes the substrate. The module is still sometimes away to be used commercially, and further steps need to be taken to improve its performance. The new technology will be targeted for efficient use of unused waste heat from homes, buildings, factories as well as vehicles.
