A new steam-fed electrolyzer aims to bridge the gap between liquid-water electrolyzers, many of which require exotic materials and intricate membranes, and solid-oxide electrolyzers, which require superheated steam and temperatures as high as 800°C. This ‘symbiotic’ electrolyzer, developed by Advanced Ionics (Milwaukee, Wis.; www.advanced-ionics.com), is designed for operation at intermediate temperatures, so it can utilize onsite process and waste heat at temperatures of 100°C and up. “We don’t think there has been another electrolyzer specifically developed to operate at typical industrial heat temperatures, which enables close synergy with industrial processes that use H2,” says Chad Mason, CEO and founder of Advanced Ionics. The ability to operate with steam and tap into existing process heat can reduce the electricity expenditure to as low as 30–35 kWh per kg of H2, whereas other electrolyzer configurations typically require 40–50 kWh/kg. The efficiency gains from using existing process heat means that the electrolyzers are suitable for installation both within existing plants and for greenfield construction. “We know there are sites that do not want to wholesale switch out their steam methane reformer, but they might need to add 10 to 20% green H2 to capture some incentives, or mitigate carbon taxes. We can provide those marginal capacity additions to append onto an existing installation,” says Mason.
“And in a greenfield ammonia plant, for instance, the Advanced Ionics electrolyzers could take that the steam off of the Haber-Bosch reactor and from some of the other heat-generating locations at the site. We’re designing the units to work with many thermal-transfer mediums,” he adds.
Advanced Ionics’ electrolyzer is constructed mainly of commodity materials, such as stainless steel. “We don’t use any platinum-group metals or perfluorinated membranes, so from a cost and supply chain perspective, as well as recyclability, it’s a very friendly architecture,” explains Mason. And unlike other electrolyzers, no deionized water is required — the steam feed just undergoes reverse osmosis. Thus far, the electrolyzer has been operated at the laboratory scale, but a scaleup endeavor is underway, with the expectation that gigawatt-scale capacity could be achievable in five years.