The worlds largest system is in China, in Fengning, and can discharge power of 3,600 MW for a little over 11 hours, for an energy storage capacity of about 40,000 MWh or 144 TJ (10 12 Joules, or equivalently 0. How much electricity can energy storage devices store at most? 1. The capacity of these devices is influenced by the type of technology used, such as lithium-ion. Energy from fossil or nuclear power plants and renewable sources is stored for use by customers. The first battery, Volta's cell, was developed in 1800. In a BESS, power determines how quickly the system can charge or discharge.