A research group from Utrecht University in the Netherlands has compared the two most promising solar-assisted hydrogen production technologies: the photo-electrochemical (PEC) systems that directly convert solar radiation to hydrogen, and off-grid, PV-powered electrolyzers (PV-E).
They presented their research in “Renewable hydrogen production: A techno-economic comparison of photo-electrochemical cells and photovoltaic-electrolysis,” which was recently published in the International Journal of Hydrogen Energy. They concluded that the potential techno-economic benefits of PEC over PV-E are uncertain and limited.
The scientists calculated the levelized cost of hydrogen (LCOH) for both technologies by considering standard PV-E designs and projected PEC designs for future large-scale applications.
“Despite intense and promising research during the last years on PEC technology, no system is yet commercially available,” the researchers said. “The present paper will analyze if, and under what conditions, PEC devices can outcompete solar hydrogen production through PV-electrolysis.”
The group calculated the LCOH of the technologies based on investment expenses, revenues, and costs throughout a plant’s lifetime, discounted to a reference date. The production rate of the two systems was set at 10 tons per day, while the time frame for hydrogen generation was 20 years.
They conducted the demonstration in Daggett, California, as it is a location with daily irradiance of 6.19 kilowatt-hours per square meter. Installations costs are assumed to be 20% of the capital costs for both systems.
“The installation of the PV-E systems requires more cabling and the installation of the electrolyzers,” the academics said. “The PEC system, on the other hand, requires more piping and in addition the installation of the compressors.”
The PV-E system was designed to counterbalance the high costs of the electrolyzer through the optimization between the scale of the photovoltaic unit and that of the electrolyzer. The demonstrated electrolyzer had an overall efficiency of 10.9%.