CHAPTER TWELVEEnergy Storage Technologies
In this chapter, I'm going to cover the current technologies used for energy storage. There are plenty of ways to store electrical energy besides lithium-ion batteries. I'll cover the most common ones before we delve into battery storage. Energy storage is defined as capturing energy produced in the present and storing it for use at a later time. When we think of storing electricity, we generally think of a battery. But stored energy comes in other forms, too.
The most common form and vast majority of energy storage in use today is pumped hydroelectricity. It comes from hydroelectric dams and the reservoirs behind them. The water represents gravitational potential energy. When it is released and allowed to flow through turbines connected to generators, that kinetic energy is transformed into electrical energy. In a pumped hydroelectric facility, there are generally two reservoirs involved. During periods of low electric use, giant pumps move water from the lower reservoir to the upper one. Then during periods of high electric demand, water is released from the upper reservoir and it passes through turbines and generators to generate power during peak demand times. Pumped hydro storage is an example of a system that provides relatively short-term energy storage, usually several hours to a few days. Most pumped hydro systems range in efficiency from 70 to 85 percent.1 But most hydroelectric generators can be dispatched in as little as ...