Credit: Illustration from Purdue University / Raymond Hassan.

Sunlight enables solar panels to generate electricity. It can be used to heat a material or object to extremely high temperatures. This is what makes the concentration of solar thermal energy possible. According to a report by Daily Science, “Concentrating solar power plants convert solar energy into electricity using mirrors or lenses to concentrate a large amount of light in a small area, generating heat that is transferred to the molten salt. The heat of the molten salt is transferred to an “operating” fluid, supercritical carbon dioxide, which expands and spins a turbine to generate electricity“.

Heat exchanger for CSP.

Critical elements of this process are the heat exchangers used to transfer the heat stored in the molten salt to the supercritical fluid. If the whole process could operate at even higher temperatures, CSP systems could produce more electricity from a given amount of sunlight.

“Storing solar energy as heat may already be cheaper than storing energy in batteries, so the next step is to reduce the cost of producing electricity from the sun’s heat with the added benefit of zero greenhouse gas emissions. says Kenneth Sandhage, professor of materials engineering at Purdue University.

Currently, these heat exchangers are made of stainless steel or nickel base alloys, but they get too soft at the higher temperatures we want to achieve, and the high pressure of supercritical carbon dioxide. Professor Sandhage has collaborated with researchers at the Georgia Institute of Technology, the University of Wisconsin – Madison and the Oak Ridge National Laboratory to develop new materials that can be used in heat exchangers operating at these higher temperatures. The results of his research were recently published in the Nature magazine.

Scientists analyzed the materials used to make solid fuel rocket engine nozzles and created new heat exchangers in zirconium carbide and tungsten They can withstand the high temperatures and supercritical pressures of carbon dioxide needed to generate electricity more efficiently. An economic analysis conducted by researchers at Georgia Tech and Purdue also showed that large-scale manufacturing of these heat exchangers can be achieved at a cost comparable to or less than that of stainless steel or nickel alloys.

Ultimately, with continued development, this technology would enable large-scale penetration of renewable solar energy into the power grid, ”says Sandhage. This would mean drastic reductions in man-made carbon dioxide emissions from power generation.

How ironic that carbon dioxide – the molecule responsible for most of global warming – can be used to help reduce carbon emissions in the production of renewable energy. You can watch the video below to learn more about this groundbreaking research.


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