This part of IEC 62933 defines the requirements for evaluating and reporting of the negative impact on the environment caused by the failure of a cell, flow cell, battery or flow battery in the accumulation subsystem of the battery energy storage system (BESS). The mainstream batteries currently used in BESS are classified in this document according to the type of their electrolyte. These electrolyte types are aqueous, non – aqueous or solid. In flow batteries, the aqueous electrolyte contains additionally the dissolved electrochemically active species and recirculates from external storage volumes through the flow cells. The environmental impacts directly caused by the failure of other components of the BESS are not within the scope of this standard. IEC TS 62933-4-1 outlines notions concerning environmental issues pertaining to electrical energy storage systems. These notions relate to product life cycle, system aspects and the nature of electrical energy storage technology.