(Invited) The Design, Fabrication, and Operation of a MW-Scale Low-Temperature Electrolyzer System to Support Industry and the U.S. Dept. of Energy

Abstract

Over the last 15 years the National Renewable Energy Laboratory (NREL) has supported industry and the U.S. Department of Energy by providing independent evaluation and performance validation of next generation electrolyzer stacks. Designated a U.S. Department of Energy user facility, the Energy Systems Integration Facility (ESIF) houses a comprehensive balance-of-plant infrastructure designed to support a wide range of drop-in electrolyzer stacks with capacities of up to 1 MW direct current (DC) electrical power. This NREL designed and fabricated infrastructure includes four individual power supplies (250V, 4000A Total), high-quality and high-flow deionized water (DIW) supply (up to 300 GPM), water polishing and particulate filters to achieve better than 10MΩ-cm resistive water, heat rejection via a plate heat exchanger and facility chilled water, gas/liquid phase separation of hydrogen and oxygen from water, and a hydrogen dryer bed to reduce water vapor content to less than 5 parts per million by volume to enable compression, storage and use in a wide variety of applications including light- and heavy-duty fueling, onsite fuel cell research and development (R&D), and biological and thermochemical processes requiring hydrogen. Safety, monitoring, data archiving, and control of the electrolyzer and balance of system are achieved using custom controls programmed specifically to achieve a safe and flexible architecture.Robust and redundant safety systems ensure safe and reliable long-duration, unattended operation of the electrolyzer with downstream compression equipment and systems consuming the product gas directly from the stack. Working with a small business, NREL is working to develop a low-cost individual cell voltage (iCVM) monitoring system capable of monitoring 100’s of cell voltages in the 2 – 3V range at a rate of 1 sample per second. The presentation will highlight critical safety considerations including reliable hydrogen-in-oxygen monitoring, lessons learned, and performance date taken over last 15 years of designing, building, and operating lab- and megawatt-scale low-temperature water electrolyzer systems.