Scaling artificial photosynthesis: Economic and operational triumphs of photoelectrochemical-enriched solar hydrogen plants

Abstract

Photoelectrochemical (PEC) hydrogen production has long been recognized as a promising pathway for coupling solar energy with green hydrogen generation. This study reviews the development of scale-up PEC hydrogen production, from laboratory prototypes to potential scale-up deployment. Most previous studies focused on stand-alone PEC reactors or idealized solar conditions, leaving system-level integration and real-world performance largely unexplored. To address this, we develop a mixed-integer nonlinear programming (MINLP) model using hourly solar irradiance data from northern China. Three PEC architectures, Single, Side-by-Side, and Stacked, are systematically evaluated under two operational demand scenarios: a H-2-only demand scenario and a co-demand scenario considering both H-2 and electricity. The results show that Stacked PEC achieves the lowest levelized cost of hydrogen (LCOH, similar to$11/kg), reducing costs by 5-10% compared to a traditional photovoltaic-driven electrolyzer (PV-EC) system and improving both economic performance and system resilience. The co-demand scenario considering both H-2 and electricity mode further enhances renewable energy utilization (5-15%), though it introduces additional dispatch complexity. PEC dominates daytime supply, while battery and hydrogen tank storage buffer night-time and short-term volatility. Sensitivity analysis identifies H-2 demand certainty and PV-EC capital cost as the most influential economic factors, with PEC, battery, and electricity price having secondary effects. Overall, this study offers a system-level blueprint for the practical deployment of PEC-enriched hybrid energy systems. PEC-enriched system improves energy matching, reduces dependence on PV-EC system, and provides a scalable, resilient, and cost-effective pathway for green hydrogen production.