This Small Business Technology Transfer (STTR) Phase I project will develop a new class of heat engines that can be used for electrical generation. These heat engines, which are based on thin films of pyroelectric materials, perform all the functions of conventional thermoelectrics, but are not constrained by the competition between thermal and electrical conductivity that has hampered the development of high-efficiency Peltier devices. These "post-Peltier thermoelectrics" or thin-film pyroelectric generators have the potential to improve the efficiency and lower the costs for harvesting electrical power from waste heat. The flexible, low-weight and durable thin-film format opens many new opportunities for exploiting a wide range of heat sources from sunlight to automobile engines. Additionally, similar devices can be used for energy efficient refrigeration and cooling. A thin-film pyroelectric generator has a layer of pyroelectric material sandwiched between two thin-film heat switches. The thin-film heat switches are an essential, new technology that is a major focus of this Phase I program. Switches with high-thermal-conductivity contrasts would enable thin-film pyroelectric generators to outperform conventional technologies that rely on the Peltier effect or on vapor compression.
The broader impact/commercial potential of this project is that its success would launch an entirely new approach to energy harvesting. While many technology sectors benefit from advanced materials and the use of information processing, progress in thermal management and the exploitation of waste heat lags far behind. Today's cooling devices, for example, largely rely on decades-old vapor compression systems or Peltier thermoelectric devices. Thin-film pyroelectric electrical generation is a new approach to heat engines that has the potential to far outperform conventional Peltier devices while capturing their advantages, such as being compact and having no moving parts. The thin-film format of these "post-Peltier thermoelectrics" allows low-cost manufacturing and engenders countless new applications that would be impossible with conventional devices. Ultimately, this technology could create substantial new industries, well-paying jobs, and huge economic and environmental savings. Carmakers could incorporate thin-film energy scavenging devices into automobile radiators, generating enough power to increase the overall efficiency by more than 5% and reducing our dependence on foreign oil by 100 million barrels each year. Electric power plants could extract extra electrical energy from hot wastewater, increasing total power production by about 1% and cutting our annual carbon emissions by 800 million tons.
The aim of ThermoDynamic Films (TDF) LLC’s research is to develop a new class of heat engines. These heat engines will harvest low-temperature waste heat, which is ubiquitous in industrial processes, and transform that heat into electrical power. This low-cost and environmentally-benign technology could engender countless new applications that would be impossible with conventional devices. For example, carmakers could incorporate them into automobile radiators, generating enough power to increase the overall efficiency by more than 5%. Likewise, significant savings could come from scavenging heat emitted by the water that cools power plants. In this capacity, TDF’s heat engines could save up to ~0.24 quads of electrical energy annually. These annual savings represent about $80B and a reduction of about 800 million tons of atmospheric CO2. One of the two key elements of these heat engines is a new innovation called a "heat switch". It is made from thin films of rod-shaped liquid crystals or other materials whose orientation can be controlled by applying a small electric field across the switch. When the liquid crystal molecules are aligned perpendicular to the surface, the thin film allows heat to pass through it. But when the electric field turns the molecules parallel to the surface, no heat is allowed to pass. These liquid crystals are commonly used in displays. During TDF’s Phase I project, the company, in collaboration with the University of New Mexico, demonstrated the first liquid-crystal-based thin-film heat switches. In future work, TDF will continue to develop heat engines but will also deploy these heat switches in a second application, the cooling of electronics. Removing heat from computers, notebook computers, smart phones, and light-emitting-diode lighting is a huge technological challenge. TDF’s heat switch-based device, called FLOWFIns, generates airflow without the use of moving parts, such as a fan. It costs less and requires less power and space than competing technologies.
