Introduction

In my previous book, Large-Scale Solar Power System Construction and Economics, I covered large-scale electrical energy storage technologies such as foam lead-acid, lithium-ion, and sodium sulfur and flow battery technologies. For more information on those technologies, I encourage you to review that book. This book discusses available energy storage technologies or those currently under development for storing large amounts of electrical energy for peak power delivery to power grid systems.

Forms of Energy Storage

All forms of energy are either potential energy such as gravitational, electrical energy, temperature differential, latent heat, or kinetic energy, such as momentum. Energy storage is classified as either short-term or long-term. Energy storage is a natural process within the universe which is manifested as stored potential in stars such as the sun. We use this energy directly in the form of solar heat or indirectly by its conversion into electricity in solar cells, which is discussed in Chapter 1.

The ancient Romans harvested and stored energy by impounding and channeling water in the form of waterways to drive water mills for processing grain or powering machinery.

Nowadays, modern technologies use various forms of energies such as gas, wind, and solar power and store it in a reservoir such as in rechargeable batteries and hydroelectric dams, which store energy as gravitational potential energy.

In this chapter, we will discuss some of the most prevalent electrical energy forms used in renewable electrical energy production, such as solar and wind power technologies, which unlike conventional energy production technologies require special treatment to smooth out sporadic power output transitions, which otherwise are unsuitable for connection to power grid systems.

Importance of Grid Energy Storage

Grid energy storage or large-scale energy storage technologies currently under development allow energy producers to transfer excess electricity over the electricity transmission grid to temporary electricity storage sites that subsequently can be used to generate electricity during peak demand hours. Grid energy storage is particularly important for providing electrical power to the grid to facilitate supply and demand over a 24-hour period of time.

A proposed variant of grid energy storage is called the vehicle-to-grid energy storage system, where modern electric vehicles that are plugged into the energy grid can release the stored electrical energy in their batteries back into the grid when needed.