The case for concrete energy storage

Is the EnergyNest concrete thermal energy storage system at Masdar Solar Hub, based on Heatcrete made with HeidelbergCement Group, a game changer? Photo: Masdar Institute

Is the EnergyNest concrete thermal energy storage system at Masdar Solar Hub, based on Heatcrete made with HeidelbergCement Group, a game changer? Photo: Masdar Institute

By Jason Deign

The Norwegian firm EnergyNest is expected to announce the outcome of a pilot of its concrete-based thermal energy storage (TES) product soon, potentially within days.

In September the company’s CEO, Christian Thiel, told SmartGridToday that the company was due to complete tests of the product, Heatcrete, “by next month.”

The company’s website, meanwhile, says a “first-of-its-kind” solid-state TES pilot at Masdar Institute’s Solar Platform in Abu Dhabi will deliver full validation of EnergyNest’s “potentially game-changing technology” at some point in 2015.

The Abu Dhabi pilot is part of a joint research project that has been underway since 2013. The 500kWh pilot itself began in May.

“The project will effectively demonstrate the operational and economic feasibility of concrete-based energy storage vis-à-vis other TES systems currently in the market,” says EnergyNest.

“EnergyNest and Masdar Institute aim to prove that incorporating this new technology into commercial solar thermal projects allows project developers to derive significant benefits and savings.”
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Concrete steps forward in thermal energy storage

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.