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Concentrating Solar Power

Rare earths pose no threat for CSP – but silver does

There's one renewable energy technology that might just withstand the export restrictions that China is imposing on vital renewables component rare earth metals, according to a report from Sweden-based Chalmers University of Technology – concentrating solar power.

"The prospects for strong growth for CSP over the next few decades seem good," says Dr. Erik Pihl, lead author.

Built mainly on more common materials like steel and glass, concentrating solar power could cover at least five times the current global electricity demand, the report says.

Of course, Mr. Pihl says, CSP does have its own problems that would case "a stir on the global commodity markets." The good part is that that, too, can be solved.

He says one component, silver, would cause that "stir." Extensively used in the technology for reflecting surfaces, the material could face a supply shortage even before the CSP industry booms and increase demand.

"CSP mirror manufacturers might have to look at other reflective surface materials, such as aluminum, to secure cost competitiveness," the report said.

In a scenario, from a group led by Greenpeace, where the technology reaches 8,000 terawatt-hours per year in 2050, solar plants would consume up to 50 to 120 percent of the current yearly nitrate salt production, and 5 to 15 percent of several common materials such as glass, nickel, magnesium, and molybdenum.

With this data, they suggest using aluminum and stainless steel-made small heliostat towers for the plants instead of concrete and iron-based parabolic trough models, which is more widely used.

"The common design of a parabolic trough plant requires more molten salt per megawatt than a salt-receiver tower plant, even when the former has fewer storage hours," said Mr. Pihl. "That means that trough plants appear slightly more sensitive than tower plants to possible salt production bottlenecks, unless other storage techniques can be employed."

If these were the case, material demand for plants would decrease, plus efficiency rates would go up, he said.

"There might be enough for CSP alone, but there are many other uses", says Mr. Pihl. "That could be a problem in the more distant future. In the short term, substituting silver and increasing nitrate salt production should be the first priority." – EcoSeed Staff

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