Energy storage technologies, including storage types, categorizations and comparisons, are critically reviewed. Most energy storage technologies are considered, including electrochemical and battery energy storage, thermal energy storage, thermochemical energy storage, flywheel energy storage, compressed air energy storage, pumped energy storage, magnetic energy storage, chemical and hydrogen energy storage. Recent research on. Energy storage technologies, including storage types, categorizations and comparisons, are critically reviewed. Most energy storage technologies are considered, including electrochemical and battery energy storage, thermal energy storage, thermochemical energy storage, flywheel energy storage, compressed air energy storage, pumped energy storage, magnetic energy storage, chemical and hydrogen energy storage. Recent research on new energy storage types as well as important advances and developments in energy storage, are also included throughout.••ATESaquifer thermal energy storageCAEScompressed air energy storageEES••A broad and recent review of various energy storage types is provided.••Applications of various energy storage types in utility, building, and transportation sectors are mentioned and compared.••Technical specifications of various energy storage types are included and compared.••Costs of various energy storage types are compared.••Advantages. Energy systems play a key role in harvesting energy from various sources and converting it to the energy forms required for applications in various sectors, e.g., utility, industry, building and transportation. Energy sources like fossil fuels can be used to provide energy according to customer demand, i.e. they are readily storable when not required. But other sources such as solar and wind energy need to be harvested when available and stored until needed. Applying energy storage can provide several advantages for energy systems, such as permitting increased penetration of renewable energy and better economic performance. Also, energy storage is important to electrical systems, allowing for load leveling and peak shaving, frequency regulation, damping energy oscillations, and improving power quality and reliability.Energy storage systems have been used for centuries and undergone continual improvements to reach their present levels of development, which for many storage types is mature. Many types of energy storage systems exist, and they can be categorized in various ways. For example, storage characteristics of electrochemical energy storage types, in terms of specific energy and specific power, are often presented in a 'Ragone plot', which helps identify the potentials of each storage type and contrast them for applications requiring varying energy storage capacities and on-demand energy extraction rates. Th. The various types of energy storage can be divided into many categories, and here most energy storage types are categorized as electrochemical and battery energy storage, thermal energy storage, thermochemical energy storage, flywheel energy storage, compressed air energy storage, pumped energy storage, magnetic energy storage, chemical and hydroge. Energy storage is an enabling technology for various applications such as power peak shaving, renewable energy utilization, enhanced building energy systems, and advanced transportation. Energy storage systems can be categorized according to application. Hybrid energy storage (combining two or more energy storage types) is sometimes used, usually when no single energy storage technology can satisfy all application requirements effectively. Storage mass is often an important parameter in applications due to weight and cost limitations, while storage volume is important when the system is in a space-restricted or costly area such as an urban core. Energy storage applications are continuously expanding, often necessitating the design of versatile energy storage and energy source systems with a wide range of energy and power densities. In this section, we focus on various applications of energy storage such as utilities, renewable energy utilization, buildings and communities and transportation. Table 2 provides examples of energy storage systems currently in operation or under construction and includes some of the features of such storage systems.Table 2. Examples of current energy storage systems in operation or under development.1.