In the class of API-166 in Kennedy school, we have learned a lot of about the deregulation of electricity markets. One of the direct result of the deregulation is the price fluctuation. This has provide an economic opportunity for the energy storage technologies to take an arbitrage in the deregulated electricity market. Moreover, more and more solar and wind energy has been installed all through the world and such unstable electricity sources would further increase the instability of electricity price. Intuitively, the more solar and wind, the more instability of the electricity price, and thus the more economic value for the installation of energy storage devices. In this work, such intuition has been proved.