Power System Energy Storage Technologies

Paul Breeze

• Publisher: Academic Press
• Year: 2018
• Print ISBN: 9780128129029
• eBook ISBN: 9780128129036
• Topic: Physical Sciences
• Subtopic: Energy

Power System Energy Storage Technologies provides a comprehensive analysis of the various technologies used to store electrical energy on both a small and large scale. Although expensive to implement, energy storage plants can offer significant benefits for the generation, distribution and use of electrical power. This is particularly important in renewable energy, which is intermittent in its supply. This book provides coverage of major technologies, such as sections on Pumped Storage Hydropower, Compressed-Air Energy Storage, Large Scale Batteries and Superconducting Magnetic Energy Storage, each of which is presented with discussions of their operation, performance, efficiency and the costs associated with implementation and management.- Provides a description and analysis of various storage technologies, such as Pumped Storage Hydropower, Compressed-Air Energy Storage, Large Scale Batteries and Superconducting Magnetic Energy Storage- Breaks down each storage type and analyzes their operation, performance, efficiency and costs- Considers how each energy storage plant benefits the generation distribution and use of electric power

Chapter 1

An Introduction to Energy Storage Technologies

Abstract

Energy storage plants take energy from generating stations and store it for later use. Large storage plants can operate at the transmission grid level while the smallest can offer storage services to small commercial and residential consumers. The plants can be used to supply grid support and stability services and they can provide support to intermittent renewable energy sources such as wind and solar power. Electrical energy is ephemeral and usually has to be utilised as soon as it is produced. Most energy storage technologies operate by converting the electrical energy into another form of energy, which must then be converted back into electrical power for use. Energy storage technologies include large-scale pumped storage hydropower plants, batteries, and energy storage flywheels.

Keywords

Energy storage; load leveling; energy arbitrage; grid support; renewable support; pumped storage hydropower; battery storage; flywheel

Energy storage technologies comprise a range of different systems that can take up and store electrical energy, holding it securely and making it available for delivery at a later time. These systems vary in the amount of energy they can hold and in the time over which they can store the energy without significant loss. They can operate at the grid level, absorbing surplus energy from the grid and then delivering it back when grid demand rises, or they can operate at the individual consumer level, balancing local supply and demand. In either case the storage system will reduce peaks and troughs in demand from the grid and help stabilize the supply.

Electrical storage technologies are also capable of offering a range of vital grid services, particularly in the support of grids that absorb large volumes of renewable energy from intermittent sources such as wind and solar power. This makes them increasingly attractive as the use of these renewable technologies grows. In the past, the availability of energy storage technology has been limited, often because capacity has been considered too expensive to build.

The earliest type of energy storage technology for grid use was pumped storage hydropower and this continues to be the most important in terms of absolute capacity. New technologies including batteries and flywheels provide smaller scale storage units but with the advantage of faster response. Advances, particularly among batteries, are making these technologies cheaper and more widely accessible and this could lead to a transformation over the next two to three decades in the way grids operate.

An Energy Storage Overview

While the storage of electrical energy is still relatively rare, other forms of energy storage play a vital part in the modern global economy. At a national level, oil and gas are regularly stored by both utilities and by governments while at a smaller scale petrol stations store gasoline and all cars carry a storage tank to provide them with the ability to travel a significant distance between refueling stops. Domestic storage of hot water is also usual in modern homes. Yet when it comes to electrical energy, storage on anything but a small scale, in batteries, is still uncommon.

Part of the reason for this is that storage of electricity, although it can be achieved in a number of ways, is far from straightforward. In most storage technologies, the electricity must be converted into some other form of energy before it can be stored. For example, in a battery it is converted into chemical energy while in a pumped storage hydropower plant the electrical energy is turned into the potential energy contained within an elevated mass of water. Energy conversion makes the storage process complex and the conversion itself is often inefficient. These and other factors help to make energy storage system costly.

In spite of such obstacles, large-scale energy storage plants have been built in many countries. By far the largest part of these, in terms of installed capacity is provided by pumped storage hydropower plants, often built to capture and store power from base-load nuclear power plants during off-peak periods. Many of these storage plants were built in the 1960s, 1970s, and 1980s. More recently there has been renewed interest in technologies such as pumped storage for grid support, particularly in European countries that are installing large capacities of renewable capacity such as wind and solar power. However the economics of energy storage often makes construction difficult to justify in liberalized electricity market. New tariffs that encourage energy arbitrage and grid support services may offer better economic incentives in the future.

While economics may not always favor their construction, energy storage plants offer significant benefits for the generation, distribution, and use of electric power. At the utility level, for example, a large energy storage facility can be used to store electricity generated during off-peak periods—typically overnight—and this energy can be delivered during peak periods of demand when the marginal cost of generating additional power can be several times the off-peak cost. Energy arbitrage of this type is potentially a lucrative source of revenue for storage plant operators and is how most pumped storage plants operate.

At a smaller scale, energy storage plants can supply emergency backup, as well as other grid support features, helping to maintain grid stability. Small, fast-operating storage units can be employed in factories or offices to take over in case of a grid supply failure. Indeed, in a critical facility such as a computer server facility where an instantaneous response to loss of power is needed, a storage technology that can take over within the space of a single cycle of the grid supply may be the only way to ensure complete reliability.

Energy storage also has an important role to play in the efficient use of electricity from renewable energy. Many renewable sources of energy such as solar, wind, and tidal energy are intermittent and so incapable of supplying electrical power continuously. Combining a renewable energy source with some form of energy storage helps remove this uncertainty and increases the value of the electricity generated. It also allows all the renewable energy available from these sources to be used. Today the shedding of excess renewable power when demand does not exist for it, or when the grid cannot cope with it, is becoming common on some grid systems with high renewable capacity.

While there are many types of electrical energy storage system, pumped storage hydropower plants account for virtually all grid storage capacity available today with perhaps 183 GW of generating capacity in operation, based on estimates by the US Department of Energy. This was effectively the only large-scale energy storage technology available until the late 1970s but in the past 30–40 years interest has been stimulated in a range of other technologies. These vary in size so that some are suitable for transmission system level storage while others are more suited to the distribution grid or even for small microgrids. They include a range of battery storage systems, compressed air-energy storage (CAES), large storage capacitors and flywheels, superconducting magnetic energy storage, and systems designed to generate hydrogen as an energy storage medium. The widespread adoption of electric vehicles that use battery energy storage could potentially offer a major new means of storing grid electricity too.

If deployed widely, these technologies could potentially transform the way the grid-based delivery of electrical energy is managed by eliminating the need for expensive peaking power plants while at the same time fully integrating the range of renewable generation technologies now available. This would, in turn, eliminate the vulnerability of electricity production to the economic vagaries of the global fossil fuel markets, creating more stable economic conditions everywhere. There is no consensus on how much storage capacity would be required to achieve this on a mature national grid but it could be equivalent to around 10%–15% of the available generating capacity. In principle, with much larger grid storage capacity, the use of energy storage might eliminate the need for fossil fuel power plants altogether, and with them one of the largest global sources of greenhouse gas emissions.

In spite of the apparent advantages offered by energy storage, widespread adoption remains slow. Cost appears to be the main obstacle although developments are slowly bringing costs down. At the same time, the growth of distributed generation is offering new opportunities for small-scale energy storage facilities.

The History of Energy Storage Systems

The early history of electricity storage is based entirely on the development and use of pumped storage hydropower. Opinions seem to differ as to when the first pumped storage plant was built but it was probably in Switzerland, either toward the end of the 19th century or at the beginning of the 20th century. Italy also adopted the technology at an early stage. These first plants used a turbine to generate...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Chapter 1. An Introduction to Energy Storage Technologies
• Chapter 2. Pumped Storage Hydropower
• Chapter 3. Compressed Air Energy Storage
• Chapter 4. Large-Scale Batteries
• Chapter 5. Superconducting Magnetic Energy Storage
• Chapter 6. Flywheels
• Chapter 7. Super-Capacitors
• Chapter 8. Hydrogen Energy Storage
• Chapter 9. The Environmental Impact of Energy Storage Technologies
• Chapter 10. The Cost and Economics of Energy Storage
• Index