Hydrogen energy storage system in a Multi‒Technology Microgrid:technical features and performance

The features and performance of a hydrogen energy storage system included in the microgrid powering a plant for advanced green technologies is presented. The microgrid is powered by a 730–kW photovoltaic source and four energy storage systems. The hydrogen storage system consists of a water demineralizer, a 22.3–kW alkaline electrolyzer generating hydrogen, its AC–DC power supply, 99.9998% hydrogen purifier, 200–bar compressor, 200–L gas storage cylinders, a 33–kW proton–exchange–membrane fuel cell running on hydrogen, its DC–AC power conditioning system. The whole system is housed in three containers provided with anti–salt filters to remove brine. The whole system is controlled by the microgrid system supervisor. Operative tests at nominal power show that the round-trip efficiency of the hydrogen energy storage system, is 8.7% with in pure electric operation and about 20.1% in a heat cogeneration operation.