Background of energy storage

The exponential growth of intermittent renewable energy sources, such as wind and solar, and the global energy efficiency decarbonization campaign, are mainly driving increased interest in the storage of electrical energy. Current global electrical grid networks, however, are not capable of managing mass convergence of intermittent energy sources without significant network interruptions. The grid network is also accepted that more than 20% of intermittent renewable penitence can be significantly destabilized. Naturally, large-scale electricity storage technology can reduce the many intrinsic failures and weaknesses of the grid system, help improve grid efficacy, fully integrate intermittent renewable resources, and efficiently manage energy production. Electric energy storage provides two more critical advantages. First, it decouples electricity generation from the load- or energy user and simplifies the management of supply and demands. Second, it allows distributed storage opportunities for local grids or microgrids which greatly improve grid security and thus energy safety. This chapter aims to provide an extensive overview of a wide portfolio of techniques, equipment, and systems for the storage of electrical energy, and to present the latest advancement and difficulties that have yet to be overcome. Moreover, the chapter describes the status of storage techniques for mechanical, thermal, electrochemical, and chemical energy. It also offers background data on basic values for the interested nonexpert, where applicable, at the tutorial level. This chapter is expected to be of interest to both uninitiated and active researchers and engineers involved in energy storage techniques, with specific emphasis on large-scale storage of electrical energy.