Work

Grid-responsive hydrogen production: Capital utilization and current density vs. efficiency in variable electricity markets

Year: 2025

Type: article

Abstract: To achieve low-cost hydrogen production from water electrolyzers, grid tied electrolysis may need to operate dynamically to minimize the cost of supplying energy to the electrolyzer stack and produce hydrogen during low-cost hours and turn off/down during high-cost hours. Operating systems in this way can decrease capital utilization (capacity factor) and electricity costs. This strategy would shift the dominant cost drivers away from electricity (and thus efficiency) to the capital costs of the system, due to the underutilized capital when operating at low-capacity factors. Increasing the operational current density of the system could, in effect, reduce the capital cost of the system while producing hydrogen at a lower efficiency on a per unit energy basis. In the variable electricity cost profiles analyzed in this paper, increasing the current density for liquid alkaline from 0.5 A/cm2 to 1.5 Ac/m2 and proton exchange membrane electrolyzers from 2 A/cm2 to 4 A/cm2 resulted in substantial reductions in the levelized cost of hydrogen. Additionally, as capacity factors and electricity costs decrease, the optimal operating current density of the electrolyzer systems analyzed increases. These findings suggest R&D efforts should focus on increasing the operational current densities, reducing the turn down ratios, and understanding the durability implications of those strategies on low-temperature liquid alkaline and proton exchange membrane electrolyzers. • High current densities could reduce LCOH in variable electricity markets. • High current densities increase hydrogen production rate, lowering $/kW capex. • Turn down ratio economic impacts scale with electricity variability. • R&D efforts should prioritize understanding the stack effects of high current density.

Source: International Journal of Hydrogen Energy

DOI: 10.1016/j.ijhydene.2025.152576

Authors: Colby Smith, Joe Brauch, Meital Shviro, Bryan Pivovar, Alex Badgett

Institution: National Laboratory of the Rockies

Language: English

Topic: Hybrid Renewable Energy Systems

Subfield: Energy Engineering and Power Technology

Field: Energy

Domain: Physical Sciences

SDGs: Affordable and clean energy, Industry, innovation and infrastructure, Climate action

Open Access status: hybrid

Estimated APC paid: $3,730