Storing Energy

with Special Reference to Renewable Energy Sources

Trevor Letcher, Trevor M. Letcher

• Publisher: Elsevier
• Year: 2016
• eBook ISBN: 9780128034491
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Energy Storage discusses the needs of the world's future energy and climate change policies, covering the various types of renewable energy storage in one comprehensive volume that allows readers to conveniently compare the different technologies and find the best process that suits their particularly needs. Each chapter is written by an expert working in the field and includes copious references for those wishing to study the subject further. Various systems are discussed, including mechanical/kinetic, thermal, electrochemical and other chemical, as well as other emerging technologies. Incorporating the advancements in storing energy as described in this book will help the people of the world further overcome the problems related to future energy and climate change. - Covers most types of energy storage that is being considered today, and allows comparisons to be made - Each chapter is written by a world expert in the field, providing the latest developments is this fast moving and vital field - Covers technical, environmental, social and political aspects related to the storing of energy and in particular renewable energy

Part B

Electrical Energy Storage Techniques Gravitational/Mechanical/Thermomechanical

Chapter 2: Pumped Hydroelectric Storage

Chapter 3: Novel Hydroelectric Storage Concepts

Chapter 4: Advanced Rail Energy Storage: Green Energy Storage for Green Energy

Chapter 5: Compressed Air Energy Storage

Chapter 6: Compressed Air Energy Storage in Underground Formations

Chapter 7: Underwater Compressed Air Energy Storage

Chapter 8: A Novel Pumped Hydro Combined with Compressed Air Energy

Chapter 9: Liquid Air Energy Storage

Chapter 10: Flywheels

Chapter 2

Pumped Hydroelectric Storage

Chi-Jen Yang Center on Global Change, Duke University, Durham, NC, United States

Abstract

Pumped hydroelectric storage (PHES) is the most established technology for utility-scale electricity storage and has been commercially deployed since the 1890s. Since the 2000s, there has been revived interest in developing PHES facilities worldwide. Because most low-carbon electricity resources (e.g., wind, solar, and nuclear) cannot flexibly adjust their output to match fluctuating power demands, there is an increasing need for bulk electricity storage due to the increasing adoption of renewable energy. PHES has been the traditional way of storing energy. This chapter introduces PHES technology, its pros and cons, its historical developments, and its prospects.

Keywords

pumped hydroelectric storage

closed-loop

pumpback

peak shaving

1. Introduction

Pumped hydroelectric storage (PHES) is the most widely adopted utility-scale electricity storage technology. Furthermore, PHES provides the most mature and commercially available solution to bulk electricity storage. It serves to stabilize the electricity grid through peak shaving, load balancing, frequency regulation, and reserve generation.

Japan currently has the largest installed PHES capacity in the world [1], followed by China [2] and the United States [3]. China currently has the most aggressive plan to expand PHES installation, with over 27-GW capacity under construction as of December 2015, and much more planned. China is expected to surpass Japan in installed PHES capacity by 2018. Table 2.1 shows the installed PHES capacities in major countries [2–5].

Table 2.1

Installed Pumped Hydroelectric Storage (PHES) Capacities

Country	Installed PHES capacity/MW
Japan	27 438
China	21 545
United States	20 858
Italy	7 071
Spain	6 889
Germany	6 388
France	5 894
India	5 072
Austria	4 808
Korea, South	4 700
United Kingdom	2 828
Switzerland	2 687
Taiwan	2 608
Australia	2 542
Poland	1 745
Portugal	1 592
South Africa	1 580
Thailand	1 391
Belgium	1 307
Russia	1 246
Czech Republic	1 145
Luxembourg	1 096
Bulgaria	1 052
Iran	1 040
Slovakia	1 017
Argentina	974
Norway	967
Ukraine	905
Lithuania	900
Philippines	709
Greece	699
Serbia	614
Morocco	465
Ireland	292
Croatia	282
Slovenia	185
Canada	174
Romania	53
Chile	31
Brazil	20

A PHES facility is typically equipped with pumps and generators connecting an upper and a lower reservoir (Fig. 2.1). The pumps utilize relatively cheap electricity from the power grid during off-peak hours to move water from the lower reservoir to the upper one to store energy. During periods of high electricity demand (peak hours and when electricity is expensive), water is released from the upper reservoir to generate power at a higher price.

Figure 2.1 Pumped hydroelectric storage diagram.

There are two main types of PHES facilities: (1) pure or off-stream PHES, which rely entirely on water that was previously pumped into an upper reservoir as the source of energy; (2) combined, hybrid, or pumpback PHES, which use both pumped water and natural stream flow water to generate power [4]. Off-stream PHES is sometimes also referred to as “closed-loop” systems. However, some may define closed-loop systems more strictly as being entirely isolated from natural ecosystems. The US Federal Energy Regulatory Commission defines closed-loop pumped storage as projects that are not continuously connected to a naturally flowing water feature [5].

The efficiency of PHES varies quite significantly due to the long history of the technology and the long life of a facility. The roundtrip efficiency (electricity generated divided by the electricity used to pump water) of facilities with older designs may be lower than 60%, while a state-of-the-art PHES system may achieve over 80% efficiency.

2. Pros and cons

By storing electricity, PHES facilities can protect the power system from outages. Coupled with advanced power electronics, PHES systems can also reduce harmonic distortions and eliminate voltage sags and surges. Of all ...

Table of contents

• Cover
• Title page
• Table of Contents
• Copyright
• List of Contributors
• Preface
• Part A: Introduction
• Part B: Electrical Energy Storage Techniques Gravitational/Mechanical/Thermomechanical
• Part C: Electrochemical
• Part D: Thermal
• Part E: Chemical
• Part F: Integration
• Part G: International Issues and the Politics of Introducing Renewable Energy Schemes
• Subject Index