Increased annual energy production at significantly lower cost is the promise that engineering researchers at the University of Arkansas give to solar power plant managers. This will be achieved if the new thermal energy storage system developed by the scientists is incorporated in the operation of the facilities.
Currently, the available conductors of heat inside energy storage tanks are expensive or destructive. The cheapest and most efficient available conductor on the market, the packed rock, causes thermal “ratcheting” as a result of the thermal cycling that triggers expansion and contraction of the tanks.
According to Panneer Selvam, professor of civil engineering, although this method satisfies the needs of the US consumers, the material used inside the tanks could lead to their rapture. To prevent this, Selvam and his doctoral student Matt Strasser, looked for alternative storage systems.
They designed a structured thermocline system that uses concrete plates inside the tank. The mixture that forms the plates was developed by Micah Hale, associate professor of civil engineering, and it is resistant to temperatures as high as 600 degrees Celsius. The heat collected in the solar panels is transferred to the concrete through steel pipes, and it is stored until needed.
The efficiency of the design is estimated to reach 93.9% which is slightly less than the most efficient method, however still higher than the goal of the Department of Energy. The concrete layers were found to be completely harmless to the tanks, while storing energy for as little as $0.78 per kWh.
As Selvam states, the proposed alternative thermal energy storage is comparable with the existing thermocline system in terms of efficiency, but at a much lower production cost and without causing damage, which should decrease expenses and increase solar energy production.