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.

Paving the way for clean energy to power the future, a team of researchers have created a synthetic material that will make solar energy a more cost-effective, efficient and reliable source of power. Their findings were published in Nature, a leading multidisciplinary science journal.

Dr. Dorrin Jarrahbashi, assistant professor in the J. Mike Walker ’66 Department of Mechanical Engineering at Texas A&M University, led the thermal-hydraulic design simulations and performance analysis for the project.

Absorbing energy

Unlike the solar panels attached to hybrid cars or residential rooftops, the ones found in solar power plants are massive and many. 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, a liquid version of carbon dioxide known as supercritical CO2 acts as the medium in the energy conversion. The hotter the fluid gets, the more electricity that can be produced.

Still a novel technology, using supercritical CO2 as the medium fluid lowers electricity and manufacturing costs and promises greater efficiency for future power plants.

However, Jarrahbashi said that the current metal materials used to construct heat exchangers in supercritical CO2 energy cycles are only stable up to 550 degrees Celsius. If the heat rises above that, the components begin to rapidly break down and lose effectiveness – ultimately needing replacement.

To combat this, the 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.

An important step

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,” said 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.

“I am very pleased that my contribution to this research has an impact on the future clean energy,” Jarrahbashi said. “Through this project, I enjoyed exploring new areas of research and developed the leadership skills required for directing interdisciplinary research initiatives.”

The team included Dr. Devesh Ranjan, associate professor at the Georgia Institute of Technology; Dr. Asegun Henry, associate professor and Noyce Career Development Professor at the Massachusetts Institute of Technology; and Dr. Mark Anderson, professor at the University of Wisconsin-Madison. Dr. Kenneth Sandhage, professor at Purdue University, headed the project.

The study, conducted in collaboration with Oak Ridge National Laboratory, was funded by the Department of Energy’s Sunshot Initiative.