Energy Storage, Grid Integration, Energy Economics, and the Environment

Radian Belu

• Publisher: CRC Press
• Year: 2019
• Print ISBN:
  9780367261405
• eBook ISBN:
  9781000449020
• Topic: Technology & Engineering
• Subtopic: Economic Theory
• Index: Technology & Engineering

The book covers energy storage systems, bioenergy and hydrogen economy, grid integration of renewable energy systems, distributed generation, economic analysis, and environmental impacts of renewable energy systems. The overall approaches are interdisciplinary and comprehensive, covering economic, environmental, and grid integration issues as well as the physical and engineering aspects. Core issues discussed include mechanical, electrical, and thermal energy storage systems, batteries, fuel cells, biomass and biofuels, hydrogen economy, distributed generation, a brief presentation of microgrids, and in-depth discussions of economic analysis and methods of renewable energy systems, environmental impacts, life-cycle analysis, and energy conservation issues. With several solved examples, holistic material presentation, in-depth subject matter discussions and self-content material presentation, this textbook will appeal strongly to students and professional and nonprofessional readers who wish to understand this fascinating subject. Readers are encouraged to solve the problems and questions, which are useful ways to understand and apply the concepts and the topics included.

1

Energy Storage Systems

1.1 Introduction, Energy Storage Overview

Electricity distribution systems have entered in a period of considerable change, driven by several interconnected factors, aging network, distributed generation, renewable energy integration, pollutant reduction requirements, regulatory incentives, demand side management and new technologies. In this climate, the use of energy storage has emerged as an area of considerable interest. The end of this period of transition will be signaled by the successful establishment of the technology and practices that must go together to create what is termed the smart grid. A smart grid as part of an electricity power system can intelligently integrate the actions of all users connected to it, generators, consumers and those that do both, in order to efficiently deliver sustainable, economic and secure electricity supplies. The end state of this transition is not yet known. Moreover, the transmission capabilities are not expanding enough to meet the growing needs, causing serious constraint problems, while as a result of the electrical grid aging, outages cost billions of dollars annually in the U.S. economy and elsewhere. Energy storage, designed to provide support for both long-term applications and dynamic performance enhancement, can provide better balancing between the energy demand and supply, allowing the increased asset utilization, facilitating the renewable energy penetration, and improving the flexibility, reliability and the overall grid efficiency. On the other hand, most of the renewable energy sources are characterized by generation variability, intermittency and discontinuity; the generation cannot be controlled by the system operator, making it more difficult to integrate it into the generation pool when compared with conventional electricity generators.

The most important enabling technology for the renewable energy use on the utility scale is the energy storage. It has been in existence for a long time and has been utilized in many forms and applications—from a flashlight to spacecraft systems. Today energy storage is used to make the electric power systems more reliable and resilient or to broaden the renewable energy use a reality. Energy storage systems (ESSs) are critical in enabling the renewable energy integration and usage, by providing the means to convert non-dispatchable energy system into a dispatchable one. To match power demands, in the context of the renewable energy intermittent and the fairly predictable electrical demands, the energy storage is critical, allowing de-coupling of generation from consumption, reducing the needs for constant energy demand monitoring and prediction. Energy storage also provides economic benefits by allowing a reduction of plant energy production to meet average demands rather than peak power demands. Transmission lines and equipment can also be sized for average power demand, instead of peak demands. The energy storage is enabling the power plants to run at higher capacities, ensuring that electrical demands are met all times, reducing the needs for peaking power plants that have lowest efficiency, higher harmful emissions, and highest operating costs. Even the entire peaking power plant concept could be dismissed if adequate energy storage is utilized. Moreover energy storage helps the utilities to provide the required power quality and reliability by the increasingly complex and sensitive equipment, while maximizing the electrical capacity use. Overall it can improve system responsiveness, reliability, resilience and flexibility, reducing capital and operating costs. Suppliers can use energy storage for transmission line stabilization, spinning reserve, and voltage control, while customers receive improved power quality and more reliable supply. Technologies such as ultra-capacitors, flywheels, batteries, fuel cells and superconducting magnetic energy storage can be used for power quality and reliability purposes. These applications require a large power output over very short timescales, typically from tenths of a second to a few minutes, while not requiring large amount of energy to be stored, because of the operations’ short timescales. ESSs can provide a wide array of solutions to key issues, affecting the power systems, such as spinning reserves, load leveling and shifting, load forecasting, frequency control, voltage regulation, relief of transmission line and system capacity, enhance power quality, more effective and efficient use of capital resources. Being able to store the excess available energy that has not been consumed not only helps with the variety of issues previously mentioned, but it also increases the overall power system efficiency.

There are several well-established electricity storage technologies, as well as a large number in process of development offering significant application potential. Economically viable storage of energy requires efficient conversion of electricity and storage in other energy form, which can be converted back to electricity when needed. All energy storage methods need to be feasible and environmentally safe. Energy storage technologies are separated into four major classes: mechanical-, electrical-, thermal- and chemical-based energy storage systems. Each class contains several types with specific characteristics and applications. Mechanical storage includes pumped hydro storage, compressed air energy storage and flywheels. Electrochemical storage includes all types of batteries, hydrogen-based energy storage and fuel cells. Here also is included thermochemical energy storage, such as solar hydrogen, solar metal, solar ammonia dissociation–recombination and solar methane dissociation–recombination. Electromagnetic energy storage includes super-capacitors and superconducting magnetic energy storage. Thermal energy storage includes two broad categories: (1) low temperature energy storage, such as aquiferous cold energy storage and cryogenic energy storage, and (2) high temperature energy storage, which is divided into sensible heat systems such as steam or hot water accumulators, graphite, hot rocks and concrete, and latent heat systems such as phase change materials. Figure 1.1 summarizes the most common energy storage technologies. Despite the opportunity offered by the energy storage systems to increased energy stability and reliability of the intermittent energy sources, there were only few energy storage technologies (batteries, pumped hydro energy storage, compressed air energy storage, and thermal storage) with a globally installed capacity exceeding 100 MW. There are several opportunities for significant improvement in energy storage, with the most appropriate technologies for application to power quality management, load shifting and energy management.

FIGURE 1.1
Classification of the major energy storage technologies.

In a weak power grid, the RES integration at remote connection points may generate unacceptable voltage variations due to power generation fluctuations. Upgrading the power transmission line to mitigate this problem is often very expensive, while the EES inclusion for power smoothing and voltage regulation at the connection point allows the weak grid operation, offering an economic alternative to transmission line upgrading. The current status shows that several drivers are emerging, spurring the growth in the energy storage demand, such as increase in the renewable energy usage, an increasingly strained transmission infrastructure as new lines lag well behind demand, the microgrid emergence as part of distributed grid architecture, and the increased needs for higher supply reliability and security. However, issues regarding the optimal active integration (operational, technical and market) of energy storage systems in the electric grid are still not fully developed, tested and standardized. The ESSs integration and further development of energy converting units including renewable energies must be based on the existing electric system infrastructure, requiring optimal integration of energy storage systems. Renewable energy systems with optimum energy storage can behave as conventional power plants, at least for short-time intervals, 1 hour to 1 day, depending on the energy storage system capacity. Renewable energy sources can rarely provide immediate response to demands as these sources do not deliver a supply easily adjustable to consumption, being in this regard low-inertia systems. Growth of decentralized power generation results in greater network load stability problems, requiring energy storage, as one of the potential solutions. Energy storage is crucial in the energy management from renewable energy sources, allowing energy to be released into the grid during peak hours when it is needed. In the conventional operation planning process of bulk power plants, normally a top-down strategy, coming from an energy consumption point of view down to a stepwise detailed description is used. In this strategy, the planning h...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• Acknowledgment
• Author
• 1. Energy Storage Systems
• 2. Batteries, Fuel Cells and Hydrogen Energy
• 3. Biomass, Biofuels, Waste-to-Energy Recovery
• 4. Electric Utility Integration of Renewable Energy Systems
• 5. Economics, Energy Management and Conservation
• 6. Distributed Generation and Microgrids
• 7. Renewable Energy Environmental Impacts
• Appendix A
• Appendix B
• Index