Energy storage systems for wind energy integration. Technology, applications, and benefit analysis

Abstract

The aim of this thesis is to study energy storage technologies that are suitable for wind energy integration services. Energy storage can make wind energy more reliable and economically more attractive in an environmentally responsible way. Chapter 1 provides an analysis of the energy challenges faced and highlights the interest for renewable energy, especially wind energy. The particularities of wind generation and wind energy grid integration are analyzed. The need for and roles of energy storage and the drivers that led to the increasing interest in this area are presented. The chapter concludes with the identification of the possible energy storage applications to help wind energy integration. Through the strategic utilization of storage the use of renewable energy and more specifically the use of wind energy can in fact be improved. In Chapter 2 a comprehensive review of the existing research work related to wind energy storage has been made. The organizations involved in the promotion and research of wind energy storage have been also identified in this chapter. Some of the most important existing renewable energy storage projects and their characteristics are presented. The chapter ends with the presentation of the current state of wind energy storage development regarding the issues related to energy storage as renewable energy enabler, values obtained through the integration of energy storage technologies with renewable energy generation, modeling and analysis tools to assess the value of energy storage combined with renewable energy, state of the art of renewable energy storage and test and demonstration projects of renewable energy storage. Chapter 3 includes an energy storage technology overview. The forms and characteristics of energy storage are presented. The energy storage applications and their operational requirements are identified according to the duration and frequency of discharge. More specific services that energy storage could provide are also identified. The chapter ends with the study of the possible value streams of energy storage including flexible capacity, energy arbitrage, system balancing and ancillary services, congestion management, renewable time shifting, forecast hedging, emissions and power quality. Energy storage allows for the improved management of energy supply and demand and can provide multiple valuable energy and power sources. The relation between wind energy and demand curve has been studied in Chapter 4. Wind is more similar to load than to conventional generation, wind and most loads are nondispatchable resources, they have cycling behaviour, and they depend on weather conditions and sometimes deviate from the forecast. Wind power curtailment including the curtailment reasons and strategies to mitigate curtailment have also been analysed. Energy storage can effectively be used to mitigate wind power curtailment. The chapter concludes with the analysis of wind power and electricity demand in Spain. The price of electricity (�/MWh) is lower when demand is lower which gives an opportunity for economic benefits by storing wind energy when demand is low and selling it during peak demand when prices are higher. The technical characteristics and performance parameters, system costs, benefits and drawbacks, environmental impact, and commercial status of pumped hydro storage, compressed air energy storage, hydrogen fuel cell storage systems, flywheel energy storage systems and batteries and ultracapacitors have been studied in Chapters 5, 7, 8 and 9. Several battery energy storage technologies including lead acid, nickel cadmium, nickel metal hydride, lithium?ion, sodium sulphur, vanadium redox flow, zinc bromide, zinc chlorine, iron redox, sodium nickel chloride and nickel iron have been compared in Chapter 9. The results of this study have been presented in Chapter 10. The power rating, discharge time, energy and power density, efficiency, life time and cycle life, environmental impact and capital cost of the energy storage technologies studied in Chapters 5, 6, 7, 8 and 9 have been compared. The technical and ecomonical suitability of the different energy storage technologies for certain services and applications based on their specific technical requirements is determined. Besides, the time shift of 1 MWh of energy storage for a duration of 1 to 9 hours has been simulated using energy storage technologies. According to the results, on a day with high wind energy levels the gain obtained by time shifting wind energy from low to high demand hours could reach 67,8%. On a day with low wind energy levels, the gain obtained by time shifing wind energy could reach 19,17%.