Lead–acid batteries have been used for energy storage in utility applications for many years but it has only been in recent years that the demand for battery energy storage has increased.
Improvements to lead battery technology have increased cycle life both in deep and shallow cycle applications. Li-ion and other battery types used for energy storage will be discussed to show that lead batteries are technically and economically effective. The sustainability of lead batteries is superior to other battery types.
Lead–acid batteries typically have coulombic (Ah) efficiencies of around 85% and energy (Wh) efficiencies of around 70% over most of the SoC range, as determined by the details of design and the duty cycle to which they are exposed. The lower the charge and discharge rates, the higher is the efficiency.
Batteries use 85% of the lead produced worldwide and recycled lead represents 60% of total lead production. Lead–acid batteries are easily broken so that lead-containing components may be separated from plastic containers and acid, all of which can be recovered.
Safety needs to be considered for all energy storage installations. Lead batteries provide a safe system with an aqueous electrolyte and active materials that are not flammable. In a fire, the battery cases will burn but the risk of this is low, especially if flame retardant materials are specified.
Lead–acid batteries may be flooded or sealed valve-regulated (VRLA) types and the grids may be in the form of flat pasted plates or tubular plates. The various constructions have different technical performance and can be adapted to particular duty cycles. Batteries with tubular plates offer long deep cycle lives.