Hydro energy can be stored when in the form of hydroelectricity. This method of storage revolves around the usage of excess electricity during periods where it is less needed so water is pumped to a high reservoir. As demand increases, more water is released to create electricity.
Other renewables (wind, solar power, etc.) are subject to change based on their conversions. While they cannot be directly stored for later use, they can be converted to different forms of energy that can be stored. These renewables also can produce hydrogen through a process called electrolysis, which also serves as a fuel source.
Energy storage matters because (1) it can stabilize the ratio of supply and demand, (2) it makes the overall power supply more resilient, (3) it brings more renewable energy to the grid rather than fossil fuels (coal, petroleum, etc.), and (4) it helps for the energy to be used at an appropriate time.
Energy storage overall can benefit our environment and save money; it’s a win-win!