Study assesses material constraints for concentrating solar power

PARIS – Concentrating Solar Power (CSP) is largely unrestricted by materials availability. Theoretically, enough solar plants could be built to cover at least five times the current global electricity demand, according to a study by Chalmers University of Technology in Sweden.

The report provides an assessment of potential material restrictions for a large-scale application of CSP technology using data from an existing parabolic trough plant and one prospective state-of-the-art tower plant.

In general, most of the materials needed for CSP are commonplace. There are, however, some issues that the industry needs to take into consideration, the study stated. A key concern is that silver, now used for reflecting surfaces, will be in short supply in the coming decades even without demand from a growing CSP industry. CSP mirror manufacturers may have to examine other reflective surface materials, including aluminium, to guarantee cost competitiveness.

The need for nitrate salts (NaNO3 and KNO3) and steel alloys (Nb, Ni and Mo) would also be significant if CSP grows to be a major global electricity supply. Based on a high adoption scenario where CSP reaches 8000 TWh/year in 2050, the study indeed outlined that the solar plants would consume up to 50-120 percent of today’s annual nitrate salt production, and 5-15 percent of several common materials such as glass, nickel, magnesium and molybdenum.

“Parabolic trough plants tend to use a lot of concrete and iron, while the concept of small heliostat tower plants has a higher use of aluminium and stainless steel,” declared Dr Erik Pihl, at the Chalmers University of Technology. “The common design of a parabolic trough plant also requires more molten salt per MW than a salt-receiver tower plant, even when the former has fewer storage hours. That means that trough plants appear slightly more sensitive than tower plants to possible salt production bottlenecks, unless other storage techniques can be employed.”

Pihl said he expects that material demands for plants will decline as we move for higher steam temperatures and increased plant efficiency. And, in the short term, the priority is to replace silver in mirrors and increase nitrate salt production.