Energy Storage Technologies in Grid Modernization E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 472

Veröffentlichungsjahr: 2023

Beschreibung

ENERGY STORAGE TECHNOLOGIES IN GRID MODERNIZATION Written and edited by a team of experts, this exciting new volume discusses the various types of energy storage technologies, the applications of energy storage systems, their role in the real-time operation of power markets, and the operational issues of modern power systems, including renewable-based generating sources. The worldwide energy sector, specifically power generation, has undergone a huge transformation in recent years, and the focus is to make it sustainable, environmentally friendly, reliable, and highly efficient. As a result, a significant share of highly intermittent but clean renewable sources is being integrated into the power system using advanced technological components. The higher penetration level of renewable energy sources (RESs) has increased the active power generation share in the grid but reduced the total rotating system inertia. This high reduction in inertia brings new challenges and technical issues to the operators of modern power systems and impacts the stability and security of the grid. The stochasticity of these renewable sources also poses a big challenge to the efficient operation of the power system. Electrical energy storage systems help to manage such issues and challenges that occur due to the intermittent nature of RES and can play a big role in the smooth and reliable operation of the power system. The applications and opportunities to use storage on the grid are growing due to the improvements in energy storage technologies, and flexible regulatory frameworks. Technological developments have made it possible to use batteries and other Energy Storage Systems (ESSs) for managing the operation of the power system. This book aims to illustrate the potential of energy storage systems in different applications of the modern power system considering recent advances and research trends in storage technologies. These areas are going to play a very significant role in future smart grid operations. This book discusses the various types of energy storage technologies and promotes the applications of ESSs in the performance improvement of modern power systems. Whether for the veteran engineer, new hire, or student, it is a must-have for any library.

Leseprobe

Table of Contents

Cover

Series Page

Title Page

Copyright Page

Preface

1 Overview of Current Development and Research Trends in Energy Storage Technologies

1.1 Introduction

1.2 The Technology of Energy Storage

1.3 Energy Storage and Smart Grids

1.4 Energy Storage and Micro-Grids

1.5 Energy Storage Policy Recommendations

1.6 Energy Storage: Challenges and Opportunities

1.7 Practical Implementations of Energy Storage Technologies

1.8 Conclusions

References

2 A Comprehensive Review of the Li-Ion Batteries Fast-Charging Protocols

2.1 Introduction

2.2 The Literature Review

2.3 Materials and Methods

2.4 Discussion

2.5 Conclusion

Acknowledgements

References

3 Development of Sustainable High‑Performance Supercapacitor Electrodes from Biochar-Based Material

3.1 Introduction

3.2 Role of Energy Storage Systems in Grid Modernization

3.3 Overview of Current Developments of Supercapacitor-Based Electrical Energy Storage Technologies

3.4 Potential of Biochar as High-Performance Sustainable Material

3.5 Overview of Recent Developments in Biochar-Based EDLC Supercapacitor

3.6 Current Challenges and Future Potential of Biochar-Based Supercapacitor

3.7 Conclusion

References

4 Energy Storage Units for Frequency Management in Nuclear Generators-Based Power System

4.1 Introduction

4.2 Investigated System Modeling

4.3 Controller and Cost Function

4.4 Optimization Methodology

4.5 Impact Analysis of Energy Storage Units

4.6 Result and Discussion

4.7 Conclusion

Appendix

References

5 Detailed Comparative Analysis and Performance of Fuel Cells

5.1 Introduction

5.2 Classification of Fuel Cells

5.3 Cost of Different Fuel Cell Technologies

5.4 Conclusion

References

6 Machine Learning–Based SoC Estimation: A Recent Advancement in Battery Energy Storage System

6.1 Introduction

6.2 SoC Estimation Techniques

6.3 BESS Description

6.4 Results and Discussion

6.5 Conclusion

References

7 Dual-Energy Storage System for Optimal Operation of Grid‑Connected Microgrid System

7.1 Introduction

7.2 System Mathematical Modelling

7.3 Objective Function and Problem Formulations

7.4 Simulation Results and Discussion

7.5 Conclusion

References

8 Applications of Energy Storage in Modern Power System through Demand-Side Management

8.1 Introduction to Demand-Side Management

8.2 Operational Aspects of DR

8.3 DSM Challenges

8.4 Demand Response Resources

8.5 Role of Battery Energy Storage in DSM

8.6 Conclusion

References

9 Impact of Battery Energy Storage Systems and Demand Response Program on Locational Marginal Prices in Distribution System

9.1 Introduction

9.2 Problem Formulation and Solution Using GAMS

9.3 Case Study: Numerical Computation

9.4 Results and Discussions

9.5 Conclusions

References

10 Cost-Benefit Analysis with Optimal DG Allocation and Energy Storage System Incorporating Demand Response Technique

10.1 Introduction

10.2 Distribution Generation and Energy Storage System

10.3 Grey Wolf Optimization

10.4 Numerical Simulation and Results

10.5 Conclusions

References

11 Energy Storage Systems and Charging Stations Mechanism for Electric Vehicles

11.1 Introduction to Electric Vehicles

11.2 Introduction to Electric Vehicle Charging Station

11.3 Modern System Efficient Approches

11.4 Battery Charging Techniques

11.5 Indian Scenario

11.6 Energy Storage System Evaluation for EV Applications

11.7 ESS Concerns and Experiments in EV Solicitations

11.8 Conclusion

References

Index

Also of Interest

End User License Agreement

List of Tables

Chapter 2

Table 2.1 Comparison of different charging protocols.

Table 2.2 The effect of extreme temperatures on Li-Ion batteries.

Table 2.3 The root causes and consequences of Li-Ion degradation.

Table 2.4 The causes of the degradation mechanism in the Li-Ion battery.

Table 2.5 The degradation mechanism and its effect on the Li-Ion battery.

Table 2.6 The physical parameters for each battery.

Chapter 3

Table 3.1 Techno-economic parameters of various energy storage devices [9].

Re

...

Table 3.2 Wood & plant residues as biochar precursor for supercapacitor applic...

Table 3.3 Waste biomass as biochar precursor for supercapacitor application [7...

Chapter 4

Table 4.1 Summary of literature review.

Table 4.2 ACO technique optimized proposed controller gain parameters.

Table 4.3 Time domain-specific parameters of del F1 & F2 of proposed system wi...

Table 4.4 Time domain-specific parameters of del F1 & F2 of proposed system with...

Table 4.5 Time domain-specific parameters of del F1 & F2 of the proposed system ...

Table 4.6 Time domain-specific parameters of del F1&F2 of proposed system with...

Table 4.7 Time domain-specific parameters of del F1&F2 of proposed system with...

Table 4.8 Time domain-specific parameters of del F1&F2 of proposed system with...

Chapter 5

Table 5.1 Categorisation of direct fuel cells.

Chapter 6

Table 6.1 Battery configuration.

Table 6.2 Performance evaluation of different methods based on performance ind...

Chapter 7

Table 7.1 Literature summary of the present and previous studies.

Table 7.2 Cost coefficients of the power generating units of MG.

Table 7.3 Characteristics of the power generating units of MG.

Table 7.4 Data of shiftable and controllable loads.

Table 7.5 Costs associated with the scheduling of the microgrid operating unde...

Chapter 8

Table 8.1 Different DSM approaches and their objectives.

Table 8.2 Battery specifications [25].

Chapter 9

Table 9.1 Generator power constraints and cost co-efficient data.

Table 9.2 Line data.

Table 9.3 Load at peak hour at each bus.

Table 9.4 ESS/BESS data [17].

Table 9.5 Result comparison of all cases at off-peak load.

Table 9.6 Result comparison for all the cases at peak load.

Chapter 10

Table 10.1 Types of DGs and their performance parameters.

Table 10.2 PVDG unit specification.

Table 10.3 WTDG unit specification.

Table 10.4 Load modeling parameters.

Table 10.5 Cost-benefit analysis of various cases.

Chapter 11

Table 11.1 Description of different EV chargers and charging levels.

Table 11.2 Vehicle time of chargers.

Table 11.3 Different types of EV chargers.

List of Illustrations

Chapter 1

Figure 1.1 Global installed renewable energy capacity.

Figure 1.2 Classification of energy storage technologies.

Figure 1.3 Schematic of a large-scale diabatic in-ground cavern CAES system [1...

Figure 1.4 Basic structure of a GES [11].

Figure 1.5 Components of a flywheel storage system [12].

Figure 1.6 Doubled layer supercapacitor [13].

Figure 1.7 Schematic of a SMES [14].

Figure 1.8 Schematic of a TES [16].

Chapter 2

Figure 2.1 The energy densities and specific energies of several rechargeable ...

Figure 2.2 Cardiac pacemakers. Source: Adapted from [2].

Figure 2.3 Li-Ion batteries used in the international space station. Source: A...

Figure 2.4 Basic battery working principle during discharge/charge.

Figure 2.5 The volumetric and gravimetric energy densities for various batteri...

Figure 2.6 Lithium in the periodic table.

Figure 2.7 Li-Ion battery during charging.

Figure 2.8 Li-Ion battery during discharging.

Figure 2.9 Illustration of the electrochemical process in a Li-Ion battery [12...

Figure 2.10 Scanning electron microscope image shows the SEI layer’s morpholog...

Figure 2.11 Constant current-constant voltage protocol.

Figure 2.12 Multi-stage constant current (MSCC) charging.

Figure 2.13 Pulse charging (PC).

Figure 2.14 The main stages in the capacity fade vs. time.

Figure 2.15 Battery capacity vs. the time curve.

Figure 2.16 Number of cycles vs. capacity at different rates.

Figure 2.17 SEI build-up with the increasing numbers of cycles.

Figure 2.18 An overview of the main degradation mechanisms in the Li-Ion batte...

Figure 2.19 The breakdown of the weight percentage by the components of a comm...

Figure 2.20 Degradation mechanisms on the anode material.

Figure 2.21 Degradation mechanisms that affect cathode materials.

Figure 2.22 Typical battery management system.

Figure 2.23 Schematic of Li-Ion cell structure with embedded Ni foil.

Figure 2.24 Lithium deposition increase with increasing the charge rate from l...

Chapter 3

Figure 3.1 Various energy storage technologies.

Figure 3.2 Types of supercapacitors.

Figure 3.3 Advantages of carbon material for electrochemical energy storage.

Figure 3.4 Preparation of modified activated carbon electrode [27]. Reprinted ...

Figure 3.5 Mechanism of EDLC supercapacitors (a) the charging process, (b) EDL...

Figure 3.6 Galvanostatic charge–discharge performances of (a) all samples at d...

Figure 3.7 SEM Images showing surface morphology of carbonized leather waste b...

Figure 3.8 Charge-discharge curve of CF electrode [18]. Reprinted with the per...

Figure 3.9 Galvanostatic charge/discharge of a supercapacitor built from carbo...

Figure 3.10 SEM images of modified carbon samples, Source: [20] (a) F400 (coal...

Figure 3.11 Changes of the high temperature biochar electrode as a function of...

Chapter 4

Figure 4.1a Proposed Simulink model of power system.

Figure 4.1b Isolated model of nuclear power plant.

Figure 4.2a Proposed power system model with BESS.

Figure 4.2b Transfer function model of BESS.

Figure 4.3 Proposed power system model with FC.

Figure 4.4a Proposed power system model with RFB.

Figure 4.4b Transfer function model of RFB.

Figure 4.5a Proposed power system model with PEM-FC.

Figure 4.5b Transfer function model of PEM-FC.

Figure 4.6a Proposed power system model with UC.

Figure 4.6b Transfer function model of UC.

Figure 4.7a Proposed power system model with SCES.

Figure 4.7b Transfer function model of the SCES.

Figure 4.8 Simple structure of PID controller.

Figure 4.9a delF1 comparison of with/without BESS.

Figure 4.9b delF2 comparison of with/without BESS.

Figure 4.10a delF1 comparison of with/without FC.

Figure 4.10b delF2 comparison of with/without FC.

Figure 4.11a delF1 comparison of with/without RFB.

Figure 4.11b delF2 comparison of with/without RFB.

Figure 4.12a delF1 comparison of with/without PEM-FC.

Figure 4.12b delF2 comparison of with/without PEM-FC.

Figure 4.13a delF1 comparison of with/without UC.

Figure 4.13b delF2 comparison of with/without UC.

Figure 4.14a delF1 comparison of with/without SCES.

Figure 4.14b delF2 comparison of with/without SCES.

Figure 4.15a delF1 comparison of with/without ESU.

Figure 4.15b delF2 comparison of with/without ESU.

Figure 4.15c Assessment of tie line power deviation with/without ESU.

Figure 4.15d Bar chart comparison of the settling time of various ESUs.

Chapter 5

Figure 5.1 Working of regenerative FC in fuel cell mode.

Figure 5.2 Working of RFC in reverse mode.

Figure 5.3 Indirect fuel cell operation (Source: iconspng.com).

Figure 5.4 SOFC (Source: Fuel cell Store).

Figure 5.5 A PEM fuel cell (Source: World Fuel Cell Council).

Figure 5.6 Liquid fuel cells using Methanol (Source: Fuel Cell Store).

Figure 5.7 Proton exchange membrane fuel cell (Source: researchgate.net).

Figure 5.8 Direct methanol (Source: researchgate.net).

Figure 5.9 Alkaline fuel cell (Source: researchgate.net).

Figure 5.10 Phosphoric acid fuel cell (Source: researchgate.net).

Figure 5.11 Molten carbonate fuel cell (Source: researchgate.net).

Figure 5.12 Solid Oxide Fuel cell (Source: researchgate.net).

Chapter 6

Figure 6.1 Centralized control of a microgrid.

Figure 6.2 Layout of an energy management system.

Figure 6.3 Classification of SoC estimation techniques.

Figure 6.4 Thevenin equivalent model.

Figure 6.5 Basic structure of ANN.

Figure 6.6 Basic structure of SVR.

Figure 6.7 Structure of ELM.

Figure 6.8 Original voltage, current, and SoC dataset at temperature (a) 25°C,...

Figure 6.9 SoC estimation using linear SVR, quadratic SVR, Gaussian SVR, ELM, ...

Figure 6.10 Graphical representation of the comparative analysis based on (a) ...

Chapter 7

Figure 7.1 Electrical and thermal load demand of the microgrid system.

Figure 7.2 Day-ahead electricity market price.

Figure 7.3 Solar, wind and net renewable power of the microgrid system.

Figure 7.4 Power exchange between the grid and the microgrid.

Figure 7.5 State of charge battery and pump hydro storage for single and dual ...

Figure 7.6 Power generation from diesel generators.

Figure 7.7 Charging/motoring and discharging/generating mode power of battery ...

Figure 7.8 Adjustable load scheduling.

Chapter 8

Figure 8.1 Demand-side management techniques.

Figure 8.2 DR operational aspects.

Figure 8.3 Different DR resources.

Figure 8.4 Effect of DR on the net load profile.

Figure 8.5 Battery charging/discharging cycles over the day.

Figure 8.6 Comparison of forecasted and actual net load curves.

Figure 8.7 Net load variations with/without DR and BESS power exchange.

Figure 8.8 Net actual load curve with and without DR.

Chapter 9

Figure 9.1 Electricity Market Structure for 5-bus system.

Figure 9.2 Single Line diagram of IEEE 5 bus system.

Figure 9.3 Load profile.

Figure 9.4a Case 1: Active and reactive power demand and generation.

Figure 9.4b

Case 1:

Active and reactive power loss.

Figure 9.4c Case 1: Voltage profile.

Figure 9.4d Case 1: LMPs of active and reactive power at different buses.

Figure 9.4e Case1: Generator economics: Cost and profit.

Figure 9.5a Case 2: Active and reactive power demand and generation.

Figure 9.5b Case 2: Active and reactive power loss.

Figure 9.5c Case 2: Voltage profile.

Figure 9.5d Case 2: LMPs of active and reactive power at different buses.

Figure 9.5e Case 2: Generator economics: cost and profit.

Figure 9.6a Case 3: Active and reactive power demand and generation and capaci...

Figure 9.6b Case 3: Active and reactive power loss.

Figure 9.6c Case 3: Voltage profile.

Figure 9.6d Case 3: Capacitor size and cost vs. time.

Figure 9.6e Case 3: LMPs of active and reactive power at different buses.

Figure 9.6f Case 3: Generator economics: cost and profit.

Figure 9.7a Case 4: Active and reactive power demand and generation and capaci...

Figure 9.7b Case 4: Active and reactive power loss.

Figure 9.7c Case 4: Voltage profile.

Figure 9.7d Case 4: ESS/BESS: SOC, discharging and charging power.

Figure 9.7e Case 4: Capacitor size and cost vs time.

Figure 9.7f Case 4: LMPs of active and reactive power at different buses.

Figure 9.7g Case 4: Generator economics: cost and profit.

Figure 9.8a Case 5: Active and reactive power demand and generation and capaci...

Figure 9.8b Case 5: Active power demand: without DR and with DR.

Figure 9.8c Case 5: Load curtailment and incentive payment.

Figure 9.8d Case 5: Active and reactive power loss.

Figure 9.8e Case 5: voltage profile.

Figure 9.8f Case 5: ESS/BESS: SOC, discharging and charging power.

Figure 9.8g Case 5: capacitor size and cost vs. time.

Figure 9.8h Case 5: LMPs of active and reactive power at different buses.

Figure 9.8i Case 5: comparison of active power LMP of case 4 and case 5.

Figure 9.8j Case 5: generator economics: cost and profit.

Chapter 10

Figure 10.1 Indian renewable energy sector. [Source: Ministry of New and Renew...

Figure 10.2 PVDG generation profile.

Figure 10.3 WTDG generation profile.

Figure 10.4 Load variation profile of a day.

Figure 10.5 Real time pricing.

Figure 10.6 Variation in load curve due to RTP DR.

Figure 10.7 EV charging profile.

Figure 10.8 Variation in location marginal pricing owing to RTP-DR.

Figure 10.9 Variation in generation from thermal DG for various cases.

Figure 10.10 Variation in voltage profile without DG & demand response.

Figure 10.11 Variation in voltage profile with DG.

Figure 10.12 Variation in voltage profile with DG and RTP-DR.

Figure 10.13 Battery performance of single battery without DR.

Figure 10.14 Battery performance of single battery with DR.

Figure 10.15 Battery performance of 1

st

battery without DR.

Figure 10.16 Battery performance of 1

st

battery with DR.

Figure 10.17 Battery performance of 2

nd

battery without DR.

Figure 10.18 Battery performance of 2

nd

battery with DR.

Chapter 11

Figure 11.1 Battery-powered electric vehicle architecture.

Figure 11.2 Series parallel configuration of HEV.

Figure 11.3 Organization of different energy storage technologies.

Figure 11.4 Different technologies associated to energy storage.

Figure 11.5 Efficiency distribution of different energy storage technologies.

Guide

Cover Page

Series Page

Title Page

Copyright Page

Preface

Table of Contents

Begin Reading

Index

Also of Interest

WILEY END USER LICENSE AGREEMENT

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Scrivener Publishing100 Cummings Center, Suite 541JBeverly, MA 01915-6106

Publishers at ScrivenerMartin Scrivener ([email protected])Phillip Carmical ([email protected])

Energy Storage Technologies in Grid Modernization

Edited by

Sandeep DhundharaYajvender Pal Verma

and

Ashwani Kumar

This edition first published 2023 by John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USA and Scrivener Publishing LLC, 100 Cummings Center, Suite 541J, Beverly, MA 01915, USA© 2023 Scrivener Publishing LLCFor more information about Scrivener publications please visit www.scrivenerpublishing.com.

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Library of Congress Cataloging-in-Publication Data

ISBN 9781119872115

Front cover images supplied by Pixabay.comCover design by Russell Richardson

Preface

The electrical infrastructure of the grid is aging and there is a need to modernize the existing grid meeting the challenges of the 21st century power sector operation with the penetration of renewable energy sources. Modernization of the grid by incorporating smart grid technologies and moving towards grid digitization will make the power grid resilient to avoid power outages under extreme weather conditions and climatic changes. Energy storage technologies have emerged as a promising solution to address the challenges of grid modernization. These technologies have gained significant attention in recent years due to their potential to enable the integration of renewable energy sources and enhance the resilience, reliability, and flexibility of the electric grid. With the increasing adoption of intermittent renewable energy sources, the need for energy storage technologies has become more critical, as they can help mitigate the variability and uncertainty of these sources and enable their integration into the grid. These technologies enable the efficient and reliable storage of excess energy during times of low demand and the discharge of that energy during times of high demand. Energy storage technologies will act as an ancillary services to the grid for frequency regulation, voltage support, and providing black start capabilities.

This book provides a comprehensive overview of the various energy storage technologies, their applications in grid modernization, and the simulation-based case studies showing their implementation in modern power systems. It covers the overview of current development and research trends and various applications of energy storage technologies and their role in enabling a more sustainable and resilient energy system. The book contains eleven chapters that cover the specific aspect of energy storage technologies in grid modernization. The chapters provide a clear and concise explanation of the key concepts, illustrated by real-world examples and case studies.

In chapter 1, an overview of energy storage technologies, recent trends, role of energy storage in smart/micro grids is presented. The chapter provides opportunities and challenges in energy storage, policy recommendations and practical applications of ESS. Chapter 2 provides comprehensive overview of Li-ion batteries, its materials, operation, charging protocols and fast charging strategies. Chapter 3 deals with an overview of current developments of Super-capacitor-based electrical energy storage technologies. Recent Developments in Biochar-Based EDLC Supercapacitor, Carbon-Based Supercapacitors and current challenges and future potential is discussed.

Chapter 4, deals with the role of energy storage technology in frequency regaultion services. The impact on frequency regulation due to battery energy storage systems, fuel cell, Supercapacitor Energy Storage, and ultra capacitors are analyzed. Chapter 5 provides detailed comparative analysis and performance of Fuel Cells. Chapter 6 described the Machine Learning–Based SoC estimation and recent advances in Battery Energy Storage System techniology. Electrical equivalent and electrochemical model of the BESS are discussed and Machine Learning–Based methods as Support Vector Regression (SVR) and Ridged Extreme Learning Machine (RELM) are applied to SoC estimation. In the chapter 7, dual-energy storage system for optimal operation of grid-connected Microgrid System is analyzed. The modeling of different renewable energy sources are described and role of storage technology on power transfer capability is presented. Chapter 8 deals with the applications of energy storage in modern power system using demand-side management for peak load management, minimizing load variations, and energy storage dispatching. The case studies are provided to show the impact of energy storage technology on the load management. Chapter 9 presents impact of battery energy storage and demand response program on locational marginal prices in distribution system. Five different case studies have been analyzed to show the impact of energy storage systems on the active and reactive power cost in a distribution system. Chapter 10 gives cost-benefit analysis with optimal DG allocation and energy storage system considering the role of demand response technique. The impact of distributed generation from solar PV and wind power generators on system operation and locational marginal prices have been analyzed considering the electrical vehicles in the network. Chapter 11 discusses energy storage systems and charging stations mechanism for Electric Vehicles. The role of energy storage system and its evaluation for EV applications are presented in the context of Indian scenario.

This book is intended for a broad audience, including researchers, engineers, policymakers, and industry professionals working in the field of energy storage technologies and grid modernization. It provides a comprehensive and up-to-date reference for understanding the current state of the art, the challenges and opportunities, key role of energy storage technology in operation and management of smart/micro grids. It provides the potential platform for an innovation and deployment of energy storage technologies in the electric power grid.

We are extremely thankful to all the authors who have contributed their chapters to this book. We sincerely thank all excellent reviewers to give their valuable time providing their crtical evaluation, suggestions and comments for the improvement of the chapters. We sincerely acknowledge their support in the review process and bringing the book to the final stage.

Sandeep Dhundhara

Yajvender Pal Verma

Ashwani Kumar

1Overview of Current Development and Research Trends in Energy Storage Technologies

O. Apata

Department of Electrical Engineering, Independent Institute of Education, IIEMSA, Roodepoort, South Africa

Abstract

The role of energy storage in ensuring grid flexibility and security of energy supply cannot be over-emphasized. Energy storage technologies harvest the available intermittent power from renewable energy sources in times of excess to be redistributed during scarcity by decoupling energy supply and demand, therefore improving grid flexibility, resiliency, and reliability. Different types of energy storage technologies have been proposed for grid integration of renewable energy sources. This chapter presents an overview of the various storage technologies, providing a comparative analysis of the different energy technologies and their application to smart grids, paying attention to the pros and cons of each of these technologies. This chapter also presents discussions around current developments and trends in this ever-evolving research area. It is important to state that environmental benefits can be provided indirectly by energy storage technologies. It is therefore pertinent to also understand the net environmental impact of the different energy storage technologies.

Keywords: Energy storage, renewable energy sources, smart grid, micro-grid

1.1 Introduction

Over the last decade, there has been a rapid growth in population and urbanization which has led to a corresponding exponential demand for energy. The exponential demand for energy across the globe has also raised concerns about greenhouse gas (GHG) emissions and their impact on climate change. To address the rising concern of climate change and greenhouse gas emissions, the United Nations through its climate action plan came up with a strategy in 2015, known as the Paris Agreement [1, 2]. This action plan seeks to substantially reduce GHG, especially from fossil fuels. Governments all over the world are therefore embracing renewable energy solutions as alternatives to conventional fossil fuel plants to meet the rising energy demand. In its 2021 report, the International Energy Agency (IEA), indicated global installations of new renewable energy power increased to 290 GW compared to 280 GW in 2020, representing a 3% growth in renewable energy installations globally [3]. Figure 1.1 below shows the growth in the use of renewable energy sources in the last eight years.

However, a significant concern of renewable energy sources, wind and solar, for energy generation is the intermittency of these renewable energy sources and power fluctuations, increasing the complexities associated with planning and operation of the grid. This has been the focal point of argument for those who are against a transition to alternative/ renewable energy sources. However, the concerns of energy intermittency from renewable energy sources can be solved by different solutions such as load shifting by demand management, electric energy storage, interconnection with external grids, and a few others. Energy storage systems (ESS) have been identified as a promising approach to the challenges associated with different renewable energy sources. ESS can help in the mitigation of power variations, enabling the storage and dispatch of electrical energy generated from renewable energy sources and ultimately improving the system flexibility.

Figure 1.1 Global installed renewable energy capacity.

Electric energy storage entails converting electrical energy into a storable form, and reserving it in different mediums, converting the stored energy back into electrical energy when needed. The integration of ESS into renewable energy systems not only helps to alleviate the intermittency of the renewable source but also reduces energy import during periods of peak demand and provides time-varying energy management. The concept of energy storage for bulk power supply has been in existence as far back as the 1930s when batteries were used in stabilizing and providing support to the power system in different German cities, especially at night [4]. The Electric storage batteries at that time provided the energy needs and emergency capacity during the peak periods when the dynamos, which generated direct current, were out of service.

The International Energy Agency (IEA) in its 2021 report [5] projected a 56% expansion in the global installed energy storage capacity in the next five years, reaching over 270 GW in 2026 with utility-scale batteries projected to experience significant growth in energy storage capacity worldwide. In the study carried out in [6], the report projected that by the end of 2030, the total cumulative installed energy storage capacity would be 741 GWh representing an exponential 31% compound annual growth rate (CAGR) of globally installed energy storage capacity. This is a pointer to the importance of EES to the modern-day power system. The rapid scaling up of energy storage systems is therefore of great importance to address the variability of renewable energy sources as their share of generation increases on the road to a net-zero carbon emission by 2050.

The different services which can be obtained from the integration of ESS include but are not limited to customer energy management services, ancillary services, bulk energy services, transmission infrastructure services and off-grid applications. The integration of EES in both isolated and grid-connected scenarios has multiple advantages ranging from the improvement of power quality to off-grid services such as electric vehicles (EV) and micro-grid stability. With ESS, an opportunity is presented for peak load demand shaving and demand-side management (DSM) ultimately reducing the burden associated with the installation of new generation capacity. EVs are mobile EES and complement the storage capacity of the grid while plug-in-electric (PEV) and smart electric parks have the potential to reduce the peak-to-average ratio and the overall electricity cost in real-time pricing by participation in energy trading of DSM.

The rest of this chapter discusses the different aspects of electric energy storage.

1.2 The Technology of Energy Storage

An ideal energy storage technology should be cost-effective and have a short start-up time, have high roundtrip efficiency, be able to operate at the level of the electric grid with a minimal power rating, and must have an appropriate capacity over power ratio for load shifting. It is important to note that none of the currently existing technologies for ESS has all of the above-mentioned characteristics at once, therefore a trade-off is required depending on need. The choice of storage technology adopted is dependent on factors such as storage duration, end application, the type of energy production, charging and discharging rate, and the depth of the chosen system [7].

Figure 1.2 presents a classification of the different energy storage technologies based on energy usage in a specific form. Each system has its distinguishable characteristic in wattage rating, life cycle, energy density, discharge time, and discharge loss. These characteristics are important to determine the suitability of each storage technology in providing the different services described in Section 1.1.

A. Mechanical energy storage

This storage technology is advantageous because of the flexibility it provides in converting between mechanical and electrical energy forms. Using the principle of potential and kinetic energy, and in some instances, pressurized gas, during off-peak periods electric energy is converted into mechanical energy when energy demand is low and converted back into electrical energy during peak demand for electrical energy. The most commonly available mechanical energy storage are: gravity energy storage systems, compressed air energy storage, flywheel energy storage system, and pumped hydro storage.

Figure 1.2 Classification of energy storage technologies.

1. Compressed air energy storage (CAES)

The CAES operates on the principle of operation of gas turbine systems. In this energy storage system, energy is stored either as mechanical energy or a combination of thermal and mechanical energy. By compressing air and storing it in an underground space such as a cavern underground, the storage of energy is achieved. Electricity is produced when there is an expansion of the modified gas to rotate the turbine. During off-peak power demand, by utilizing the available excess power, a generator unit or reversible motor is driven. This in turn injects air into the storage unit by running a chain of compressors. The compressed air is released and heated by a heat source during low power generation for load demand before being transferred to the turbine where a recuperation unit recycles the waste heat energy.

Figure 1.3 Schematic of a large-scale diabatic in-ground cavern CAES system [10].

CAES systems are ideal for small- to large-scale power capacity; however, they can be deployed for large-scale applications involving peak shaving, voltage control, frequency control, and load shifting [8]. CAES can be further classified into diabatic, adiabatic, and isothermal storage [9] based on endothermic and exothermic processes that take place in the compression and expansion of air and heat exchange. System flexibility and high power density are two important characteristics of the Diabatic CAES system that make them the most commercially implemented CAES system. The CAES system can maintain the required system temperature by using external power sources in the heating and cooling of the air as shown in Figure 1.3; this makes them highly efficient. Adiabatic and isothermal CAES systems are well positioned for systems requiring small power density.

CAES systems are highly efficient thermodynamic systems due to the continuous subtraction and addition of heat during compression and expansion, respectively, keeping the air at ambient values. In addition to the ability to smoothen the power output of renewable energy plants, CAES has a high response time. However, a major challenge associated with CAES systems is the selection of a suitable geographical location for such a project.

2. Gravity energy storage (GES) systems

This is an emerging field in energy storage systems that has become a popular alternative to CAES and pumped hydro systems for large-scale power systems. The basic structure of a GES is represented in Figure 1.4. This is a closed system consisting of a piston, generator, reversible turbine/pump, and a container with a returned pipe.

When energy demand is high, water is pushed to flow into the container by the piston to drive the pump/turbine. The kinetic energy of water is then converted into mechanical energy by the turbine, spinning the generator to drive the turbine to produce electricity. A reverse mechanism is initiated during off-peak demand by supplying the excess energy to the motor. The piston is driven to the top of the container by the generated kinetic energy, and the mechanical energy is stored. The GES storage system overcomes the geographical limitation associated with the CAES system.

3. Pumped hydro storage (PHS)

The principle of operation of the PHS is based on storing electrical energy as a form of potential energy by pumping water from the lower side of a reservoir to its higher side when energy demand is lower and vice versa during high energy demand. The performance of a PHS system is generally dependent on the volume and height of available water. Energy storage using PHS is achieved by pumping water uphill using off-peak electricity and then allowing the water to flow downhill, driving the generator to produce electricity for the power grid when the need arises. It is mostly applied in storing and generating electricity using two water reservoirs at different elevations, recompensing high-peak demand. PHS is a commercially available technology representing about 99% of installed EES capacity.

Figure 1.4 Basic structure of a GES [11].

A typical PHS system consists of a generator, upper reservoir, lower reservoir, an inlet valve, penstock valve, motor, and pump. Energy storage time in the PHS is prolonged since the application process is subdivided into a 24-hour scale. The power rating of a PHS varies between 1 MW to 3000 MW at an operating efficiency of 76-85% with practically unlimited life cycles and an operating life span of about 50 years. PHS can be subdivided into three major classifications:

Open PHS system: This is a pump back system that allows water to continuously flow through the upper and lower reservoir.

Semi-open PHS: This is made up of one modified lake with continuous through flow and one modified or artificial reservoir.

Closed loop PHS: This system comprises two non-connected reservoirs and is split by a vertical span.

A significant advantage of the PHS is its remarkable fast response time, which is typically less than a minute, enabling the PHS system to become an important component controlling electrical network frequency in the provision of reserve generation. PHS can act as a stabilizer for power systems consisting of renewable energy sources through its flexible control. The main drawback of the PHS is the constraint of geographical availability.

4. Flywheel energy storage (FES) system

This energy storage system is made of a large cylinder fixed on a stator by magnetic glide bearings that serve as the main component of the FES systems as shown in Figure 1.5. The storage of energy in the FES is a mechanically executed process because the kinetic energy of the rotor mass spins at very high speeds. Through torque control, the energy stored in the flywheel can be reused by reducing the speed of the flywheel while the kinetic energy returns to the electrical motor, functioning as an electric generator. The energy produced by the FES is dependent on the moment of inertia of the rotor and the speed at which it is rotated along its tensile strength and stress restrictions.

FES can be generally classified into low- and high-speed FES systems. Low-speed FES are generally used in power quality applications requiring high power for short durations with a high number of charge-discharge cycles. The high-speed FES system on the other hand has a high energy density in the range of 200 Wh/kg with a high-power density. In contrast to the low-speed FES, which is cheap and commercialized, the high-speed FES is not economical because of the high cost associated with high-speed composite materials, making their use limited to specific longer storage systems.

Figure 1.5 Components of a flywheel storage system [12].

Some merits of the FES include a performance rate of about 90% and a longer cycle life (some FES have a capability of over 100 000 full discharge cycle depth), operating at varying temperature conditions with the ability to sustain high power levels. However, a major drawback of the FES is the “flywheel explosion”. This is a scenario where the flywheel tensile strength is exceeded causing the flywheel to shatter, and consequently releasing all of its stored energy at one go.

B. Electrical energy storage (EES) systems

These storage systems can store electrical energy for the production of electric energy and supply the same to the load for use when required. By modifying the magnetic or electric fields using superconducting magnets or capacitors, energy is stored. Since power systems face numerous challenges in the integration of renewable energy sources into the transmission and distribution systems, EES systems have been proposed as an appropriate technology to mitigate these challenges due to its different operating features such as the ability to support micro-grids, reduction of electrical energy import during peak demand period, load balancing and improving power quality. An ultra-capacitor also referred to as a super-capacitor and the super magnetic energy storage are typical examples of an EES.

An ultra-capacitor (UC) stores electrical energy between two conducting electrodes, as shown in Figure 1.6. An advantage of this technology is the absence of any chemical reactions, making it an alternative to the typical capacitor used in general batteries and different electronic applications. The UC operates with a large surface area and molecule thin layer of electrolyte. The UC also has a high peak power output with a high-power density. In comparison to a conventional battery, the UC has a longer calendar life cycle. In power systems applications, there is a possibility of having pulse load, causing severe thermal and power disturbances in the power system and also in micro-grid applications. The UC, because of its fast response to power balancing and leveling with an appropriate control system in place, can help in overcoming these challenges. A major drawback of the UC is its high self-discharge rate and cost.

The operation of the super magnetic energy storage (SMES) is based on the principle of electrodynamics. By circulating current in the superconducting coil while in charging mode, energy is stored in the magnetic field of the SMES device, therefore reducing the superconductivity at low temperatures. The superconducting material present in the SMES is cryogenically cooled. The implication of this is that stored energy can be released back to the network by discharging the coil (discharging mode). A major concern of this storage technology is heat generated by ohmic losses thereby causing thermal instability. The high cost of installation is also a drawback of this technology.

Figure 1.6 Doubled layer supercapacitor [13].

C. Thermal storage systems

The thermal energy storage (TES) systems store energy as either heat or ice, which can be released later when needed. It is an alternative technology to replacing the usage of fossil fuels and meeting the demand for sustainable energy regulations. TES can also be used for applications such as heating or cooling systems in industrial and residential sectors, power generation, and load shifting.

TES consists of a thermal storage tank, a heat transfer medium, and a containment control system. Using distinctive technology, heat is stored and kept in an insulated reservoir. Figure 1.7 depicts a diagrammatic representation of a thermal energy storage system. Stored heat energy is initially transferred and then transformed into electricity using a heat engine cycle [15]. The containment control system is required for the general operation of the reservoir and to monitor the heat transfer medium. It is important to note that TES systems have a very low cycle efficiency in the range of 30-30%; however, this storage technology has a high daily self-discharge and energy rate, environmental friendliness, and the low-cost initial capital, which are some of the advantages of the TES. The schematic of a TES is shown in Figure 1.8 below.

Figure 1.7 Schematic of a SMES [14].

TES systems are broadly classified into two groups based on operating temperature. These are low-temperature TES and high-temperature TES. Low-temperature TES systems are made of cryogenic energy storage and auriferous low-temperature storage typically operating at temperatures below 200 degrees Celsius and find their applications in water heating and solar cooking [17]. The high-temperature TES can be further subdivided into three categories, namely: latent heat system (LHS), absorption and adsorption system (AAS), and sensible heat (SHS). The schematic of a TES is shown in Figure 1.8.

Latent heat storage systems (LHS) cannot be sensed by a change in temperature. An important feature of the LHS is thermal conductivity, improved with metal fillers, metal matrix structures, aluminium shavings, and paraffin. The enthalpy and density of the system is a determinant factor of its storage capacity while the medium of storage can be organic, inorganic, or bio-based.

Figure 1.8 Schematic of a TES [16].

The absorption and adsorption system (AAS) is based on a physico-chemical process. This is also referred to as a thermo-chemical storage system. With this storage technology, heat is not stored directly. High energy density is the main advantage of the AAS.

The sensible heat (SHS) can regulate the mass medium and specific heat capacity used for determining the capacity of the storage system during the storage operation processes. The medium of storage used for SHS can be categorized into different forms such as liquid (thermal oil, molten salt, and water), liquid with solid filter material (stone/molten salt), and solid (concrete, metal, and ground). A main drawback of the SHS is the size requirement.

D. Chemical energy storage (CES)

This energy storage system is suitable for storing significant amounts of energy for long periods. In this system, the energy is stored in the chemical bonds between molecules and atoms that are released through the transfer of electrons to directly produce electricity. The most popular sources of chemical fuels for generating electricity and energy transportation systems are coal, ethanol, propane, hydrogen, gasoline, diesel, and liquefied petroleum gas (LPG). The focus of the CES system is hydrogen technology because of its remarkable ability to act as fuel and also store large amounts of electrical energy.

Hydrogen fuel cell (HFC) is a promising alternative for emission-free electricity generation, and its application can be extended to distributed generation and the automobile industry. In comparison to other hydrocarbon fuels, it releases only water vapor into the environment when burned, though it burns faster and contains considerable chemical energy per mass. Its high energy density by weight and low energy density by volume as well as the environmental friendliness of hydrogen has made it become a focus for an energy storage solution. HFC as a medium of energy storage is also very cost-effective considering that hydrogen is readily available.

The application of hydrogen to energy storage systems can be divided into four categories, namely: hydrogen liquefaction, hydrogen adsorption on carbon nanofibers, metal hydrides absorption, and hydrogen pressurization. The pressurization of hydrogen is dependent on the high permeability of materials. A pressure of about 200-250 bars can be stored in a steel tank. However, this is only possible when the ratio of stored hydrogen per unit weight is low since the storage efficiency depends on the increase in temperature. Metal hydride energy storage systems are dependent on the properties of hydrogen absorption of the chemical compounds present. The advantages of this storage system include compatibility and low pressure since most hydrides have higher rates of absorption equivalent to the volume of hydrogen stored to the volume of metal used.

Hydrogen storage technology is preferred for load-shifting applications; however, this technique is costly and its efficiency is the most critical criterion to develop this technology [18].

E. Electrochemical energy storage

In electrochemical storage systems, chemical energy is converted into electrical energy. The process of energy conversion is completed by chemical reactions, while the energy is stored as an electric current for a specific voltage and time. Electrochemical energy storage solutions are the largest group of energy storage devices available. Conventional flow and rechargeable batteries are two technologies for storing energy in electrochemical form. Though there is minimal maintenance needed for batteries, the life expectancy and energy are reduced as a result of a chemical reaction.

Electrochemical storage devices have the advantage of being readily available in different sizes. Examples of the different electrochemical storage devices include lithium-ion, sodium-sulphur, nickel-cadmium, Lead-acid, and flow batteries.

F. Hybrid energy storage

As the name implies, a hybrid energy storage system integrates two or more energy storage technologies, capitalizing on the advantages each of them provides to obtain an excellent solution for a particular application. Since it is practically impossible for single storage technology to have all the advantages, hybrid energy storage is becoming more appealing for modern-day applications such as in micro-grids.

Fast response at high rates for a short duration can be obtained by implementing high-power ESS, while slow response applications for an extended time are achieved with high-energy devices. Micro-grids and power systems need an energy storage solution that can combine the characteristics of a high power and high energy storage system to reduce the problems associated with power quality and improve the stability of the power system. Hybrid energy storage solutions have more complicated control structures than those of single energy storage systems. Some of the possible configurations for hybrid energy storage solutions include the following:

CAES + SMES

CAES + FES

CAES + UC

CAES + Battery

Pumped hydro + battery

Pumped hydro + UC

Pumped hydro + SMES

Battery + SMES

Battery + UC

1.3 Energy Storage and Smart Grids

With the ever-increasing growth in the global population comes a corresponding incremental demand for electrical energy. This has become a challenge not only for the generation of electrical energy but also for its distribution. The growing demand for electrical energy has increased the complexities associated with power grids by increasing the requirements for greater reliability, security, efficiency, and environmental and energy sustainability concerns.

Renewable energy sources (RES) have been proposed as suitable alternatives to conventional fossil power plants in meeting the rising demand for electrical energy. The integration of RES into the power grid has been a source of concern for system operators. This is because of the intermittent nature of such RES and their impact on grid flexibility and balance.

Grid flexibility is the ability of the power system to quickly respond to conditions of unpredicted variations. With conventional power plants, this requirement is made possible by managing the power plant output by rapidly ramping up and down to match the variable and non-predictable electric load. However, with grid integration of RES, the unpredictability of the power system has shifted from the demand side to the generation side and in response to adjustment, flexibility agents have conversely migrated to the demand side. Nevertheless, the current power systems can still make room for flexibility by managing the output of the power plants; with RES this translates into curtailment, therefore, losing clean energy.

To improve power systems and grid flexibility, especially with the grid integration of RES, the concept of smart grids has been introduced. A smart grid is simply a grid that uses modern communication technologies to integrate various elements of an energy system, such as generation and demand, thereby ensuring a balance on both sides. Smart grids ensure that RES can be adequately and optimally fed into the grid. Such a grid can digitally gather, distribute and use provided information on all participants such as suppliers and consumers to improve the reliability, efficiency, and economics of the electricity services [19].

The development of a smart grid comes with the difficult challenge of ensuring a balance between the various variables in connection with dynamic load control powered by the ever-increasing penetration of RES. Installing energy storage solutions can help in achieving the balance between these variables. Energy storage is a very important component of a smart grid and the different ESS available have been well documented in Section 1.2 of this chapter. The choice of ESS for a smart grid is dependent on the number of charging/discharging cycles and the duration of such operations.

ESS plays a complementary role in meeting the goals of an efficient smart grid. The benefits of a smart grid to the power system include less costly interruptions, improved reliability of the power system, an increase in efficiency of power delivery with lower losses in distribution as well as deferred capital expenditure on transmission and generation assets. Energy storage helps the smart grid actualize these merits by negating the need for extra peaking generation by deferring load transmission and distribution upgrades, reducing the transmission congestion fees in deregulated markets by the addition of energy storage to distribution substations, and provision of load capabilities that can help in improving the intermittency of renewable energy sources.

ESS incorporated into the smart grid can also bring cost-saving benefits to the residential consumer from cost savings from peak load management and energy efficiency. On the other hand, the smart grid also provides an opportunity for dispatch of storage units and load control, making RES more valuable to the grid.

A major advantage of a smart grid is the allowance for a wider range of technologies. The use of a fast response ESS such as a flywheel in a smart grid can potentially improve the overall power quality and reliability of the grid by quickly responding to intermittency issues.

Though ESS can facilitate improving power quality and the overall reliability of the grid, it is practically impossible for the ESS to deliver these advantages at every given time. Therefore, the smart grid makes a “smart decision” on the most technical benefit to the grid at any given time, co-optimizing between revenue streams such as ancillary markets and arbitrage [20].

1.4 Energy Storage and Micro-Grids

Micro-grids (MG) are symbols of controllable electric entities containing different loads of distributed energy sources. All typical micro-grids produce electricity from two or more sources, and at least one of such sources is a renewable energy source. Micro-grids are also susceptible to stability and power balance, hence the integration of ESS with a micro-grid is of great benefit to the micro-grid, operating either in an islanded mode or grid-connected mode.

An ESS can be added at various positions in the MG depending on the purpose. The ESS can undertake peak shifting and load leveling functions while acting as a load, supporting peak demand. With the integration of RES, fluctuation mitigation can be performed by the ESS. For an MG with solar photovoltaic and wind power generation, the ESS can enhance the low voltage ride-through capability. It is important to note that the configuration of an ESS in a MG is dependent on the application. For MGs with renewable energy penetration, the ESS can be configured as a distributed ESS or an aggregated ESS.

1. Distributed ESS

In the distributed ESS configuration, the ESS units are coupled directly to the individual distributed generators with different interfaces. Distributed ESS for micro-grids can be further configured to be positioned either on the generator side or the load side of the MG. The ESS positioned on the generator side helps in the generation of smooth output power while on the load side, it helps in the reduction of load variation and energy management. For the generator side distributed ESS, it is usually connected to the DC link of the renewable energy generation unit. A major advantage of the distributed ESS is easy maintenance, optimized cost, and efficiency.