Solar market is constantly searching for a low-cost energy storage solution. In Malaysia, off-grid solar systems are using battery to store the energy received during daytime. Battery is costly which make up 30% to 50% of the total system cost.
Researchers from University of Arkansas have developed an energy storage system to store the thermal energy (heat) absorbed by solar panels at a lower cost than conventional energy storage methods. The system utilizes the characteristic of thermocline.
So, what is thermocline? Thermocline is a thin but distinct layer in a large body of fluid in which temperature changes more rapidly with depth than it does in the layers above or below. In the ocean, the thermocline may be thought of as an invisible blanket which separates the upper mixed layer from the calm deep water below.
University of Arkansas researchers created a thermocline system with parallel plates of concrete and steel pipes running through them. The steel pipes will transfer heat absorbed by the solar panels into the concrete, which stores it until it is needed later to run a steam turbine or other heat-powered generators such as Stirling engines or thermoelectric modules.
The thermocline system is capable to withstand temperatures up to 600 degrees Celsius with efficiency of 93.9%. This provides a low cost energy storage solution. Table below demonstrates the price comparison of different storage methods.
Thermocline system has promised an effective solution for low-cost energy storage. I believe there are still in the research state and hopefully soon we could see the system be implemented at the utility scale solar-thermal power farm.