It is cheaper than molten salt and causes less damage to heat tank walls than packed rocks, say engineering researchers at the University of Arkansas, who have developed concrete layers as a means of capturing heat from solar energy. Phys.org reports
that the concrete plates conduct heat with an efficiency of 93.9%.
Although this is slightly less efficient than the packed rock method, the specially developed concrete avoids the stress caused to tank walls because of the expansion and contraction of storage tanks during thermal cycling. In addition, energy storage using the new technique costs only USD$0.78 per kilowatt-hour, far below the US Department of Energy’s benchmark figure of $15 per kilowatt-hour.