Clean energy is at a crossroads. To become a viable replacement for fossil fuels, solar power plants must first improve their efficiency to match the electrical output of nonrenewable energy sources. This relies heavily upon the innovation and development of new products that absorb and exchange heat at higher temperatures.
Unlike the solar panels on hybrid cars or residential rooftops, the ones found in solar power plants are massive and numerous. They absorb as much thermal energy from the sun as they possibly can and channel that heat into a fluid-filled converter called the heat exchanger.
There, supercritical CO2, a liquid version of carbon dioxide, acts as the medium in the energy conversion. The hotter the fluid gets, the more electricity that can be produced.
Still a new technology, using supercritical CO2 as the medium fluid lowers electricity and manufacturing costs and promises greater efficiency for future power plants, researchers say.
However, the current metal materials used to construct heat exchangers in supercritical CO2 energy cycles are only stable up to 550 degrees Celsius, according to Dorrin Jarrahbashi, an assistant professor in the mechanical engineering department at Texas A&M University. If the heat rises above that, the components begin to rapidly break down and lose effectiveness—and ultimately need replacement.
To combat this, researchers created a new composite material from a combination of ceramic and tungsten, a refractory metal, that can withstand temperatures over 750 degrees Celsius. This leap in heat absorption could increase the efficiency of generating electricity in integrated solar and supercritical CO2 power plants by 20 percent.
Taking on fossil fuels
Along with enhancing energy output, the composite’s durability and low production cost will help cut down the expense of constructing and maintaining power plants.
“Using this material for manufacturing heat exchangers is an important step towards direct competition with fossil fuel power plants and a large reduction in greenhouse gas emissions,” says Jarrahbashi.
With its unique chemical, mechanical, and thermal characteristics, the applications for the composite are numerous. From safely upgrading nuclear power plants to constructing rocket nozzles, the implications of this innovation stretch far into the future of research and industry.
Their findings appear in Nature.
Additional researchers are from Georgia Institute of Technology, Massachusetts Institute of Technology, the University of Wisconsin-Madison, and Purdue University. The Department of Energy’s Sunshot Initiative funded the study, which researchers conducted in collaboration with Oak Ridge National Laboratory.
Source: Hannah Conrad for Texas A&M University