Generating renewable solar energy is just one side of the coin with the other being the availability of an efficient way to store excess energy for use when more energy is not being generated. Conventional methods to store solar thermal energy in molten salts, oils or beds of packed rocks do the trick, but they are either too expensive or cause damage to the storage tanks.
The use of packed rocks to store thermal energy is definitely an efficient way to store energy, but the expansion and contraction of storage tanks due to thermal cycling leads to thermal “ratcheting”, which creates uncalculated inefficiencies and could eventually lead to a catastrophic rupture of the energy storage tank. Researchers at the University of Arkansas have developed a thermal energy storage system, which combines the efficiency of the packed rock method, while ensuring that no damage is done to the tank walls.
The team here has tested a structured thermocline system that makes use of parallel plates of concrete instead of packed rock inside the storage tank. Made using a special mix of concrete, the system can handle temperatures of up to 600 degrees Celsius and can conduct heat with an efficiency of 93.9 percent. The storage process stores heat until it can be transferred to a generator to produce electricity. Tests also confirmed that the method doesn’t cause any damage to the materials used for storage and energy storage would cost just $0.78 per kilowatt-hour. The team believes that the innovative storage system would increase solar production and decrease operating expenses to reduce the overall cost of solar generated electricity.