Opportunities for economies of scale with alkaline electrolyzers

•An initial chemical engineering based large-scale electrolyzers is presented.•We show that use of scaling leads to significant capital cost estimate reduction.•Compressors represent the most costly process equipment in electrolyzer systems.

Large alkaline electrolyzer installations are typically modular and do not exhibit significant economies of scale. Substantial capital cost reductions are possible if electrolyzer stacks utilize equipment common to each modular installation. This work analyzes the possible capital cost reduction arising from the use of common equipment. Established chemical engineering techniques are used to determine the capital cost curves for the major electrolyzer subsystems for installations ranging from one to fifty units. The major equipment found in large-scale alkaline electrolyzers – like those electrolyzers used in the DOE's Hydrogen Analysis (H2A) program – is reviewed and the associated cost scaling exponents are discussed. The common equipment is scaled up to meet the flow rates and processing requirements of large, multi-electrolyzer systems. The capital costs of the scaled electrolyzer systems are calculated and compared to standard modular systems. It is shown that scaling the compressors, the gas holding tanks, the transformers and the balance of plant equipment can reduce the capital costs by as much as 60% for the best-case scenario and 25% for the worst-case scenario. It was also found that simply using large compressors common to each electrolyzer has the greatest impact on capital cost reduction.