Design considerations for industrial water electrolyzer plants

The motivation of this work is to propose a shared balance of plant (BoP) and power supply (PS) design for industrial scale alkaline electrolyzer plant that has reduced CAPEX with a minimum loss in OPEX for variable load operation. Three important aspects are: a) flow-sheet -either shared or individual BoP and PS per stack, b) variable or constant lye flowrate per stack and c) sizing of cooling duty in the lye circulation loop. Steady-state optimization shows that individual BoP per stack (with higher CAPEX) is optimal when the plant is ex-pected to operate at high capacity. For shared BoP and PS, the hydrogen production is higher by 8-12% when operated with variable lye flowrate compared to fixed lye flowrate. Our results further suggest that lye cooling duty should be designed based on the cooling requirements of the degraded electrolyzer stacks at end of life. (c) 2021 The Author(s). Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC. This is an open access article under the CC BY license (http://creativecommons.org/ licenses/by/4.0/).

Automated summary

This work proposes a shared balance of plant and power supply design for industrial scale alkaline electrolyzer plant to reduce CAPEX and minimize OPEX losses during variable load operation. The study shows that the design of individual balance of plant per stack is optimal for high capacity operation, while shared balance and power supply can increase hydrogen production by 8-12% when operated with variable lye flowrate. Cooling duty in the lye circulation loop should be based on the cooling requirements of degraded electrolyzer stacks at the end of life.