Sustainable and secure energy distribution
Distributed generation and storage systems that use renewable energy play an important role in the electric power distribution system. To control the output from such power sources or match it with the demand is difficult. Conventional battery systems have a relatively short discharge time. Flow batteries based on zinc–air are suitable for storing renewable energy overnight since they can store relatively large amounts and have low self-discharge rates. The EU-funded project 'Zinc-air flow batteries for electrical power distribution networks' (POWAIR) is developing a new electrical energy storage system with high energy density, modularity, fast responses and low costs. To achieve these aims, POWAIR is radically extending the zinc–air battery performance from small-scale single primary cells to rechargeable redox flow battery modules. At production scales, these batteries can be stacked, yielding powers of 10 kW to several megawatts with several hours of storage. POWAIR technology allows large capacities of electrical energy to be stored indefinitely, and transmitted or distributed as and when required. The battery system can be charged directly from the grid for peak-saving applications or from renewable energy installations. It thus provides stability to the grid and eliminates the need for fossil-fuel–powered peaking plants. The project team collaborated to design new energy storage technologies, together with an accompanying modular power converter and system controller. The novel modular power converter is suitable for integration in the grid while allowing flexible expansion and reconfiguration. The rechargeable zinc–air battery developed uses an air electrode for one half-cell reaction, which increases energy density, and an alkali electrolyte in which the metal is highly soluble. The innovative catalyst system comes at a low cost and is stable, with performance exceeding that of precious metal systems. Work is under way to scale the air electrodes as well as optimise and scale the battery unit cells and integrate them into short battery stacks. POWAIR's legacy should be an energy storage system mainly for renewable energy integration, tested against worldwide grid connection standards and ready for industrialisation.
Keywords
Energy distribution, energy storage, renewable energy, electric power distribution, battery systems, zinc–air, zinc-air flow batteries, energy density, redox flow battery, electrical energy, power converter, air electrode, alkali electrolyte
