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New material harvests the sun's heat for cheaper electricity

Washington, Oct. 21, Researchers have developed a material that can be used to harvest electricity from the sun's heat, which…

Washington, Oct. 21, Researchers have developed a material that can be used to harvest electricity from the sun’s heat, which weighs the way to generate less expensive solar power during cloudy days and at night.

Innovation is an important step for solar thermal power generation in direct cost competition with fossil fuels, researchers say.

“Storage of solar energy as heat can already be cheaper than saving energy through batteries, so the next step is to reduce the cost of generating electricity from the sun’s heat with the added benefit of greenhouse gas emissions,” says Kenneth Sandhage, a professor at Purdue University in the United States.

Concentrated solar power plants convert solar energy to electricity using mirrors or lenses to concentrate a lot of light on a small area, generating heat transferred to a molten salt.

Heat from the molten salt is then transferred to a “working” liquid, supercritical carbon dioxide, which expands and works to rotate a turbine to generate electricity.

To make solar powered electricity cheaper, the turbine unit should generate even more electricity for the same amount of heat, which means the engine needs to run hotter.

The problem is that heat exchangers that transfer heat from the hot melt salt to the working fluid are currently made of stainless steel or nickel-based alloys that become too soft at the desired higher temperatures and at the high pressure of supercritical carbon dioxide.

Scientists thought of a ceramic zirconium carbide and metal tungsten composite for more robust heat exchanger.

They made ceramic metal composite plates. The plates are customizable channels to customize heat exchange.

Mechanical tests and corrosion tests showed that the composite material could be tailored to meet the high temperature high-pressure supercritical carbon dioxide needed to generate electricity more efficiently than today’s heat exchanger.

An economic analysis also showed that the upgraded manufacturing of these heat exchangers could be performed at comparable or lower cost than for stainless steel or nickel-based.

“In the end, with continued development, this technology would allow large-scale penetration of renewable solar energy into the grid,” said Sandhage.

“This would mean dramatic reductions in human CO2 emissions from power generation,” he said. MHN

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