Hydrogen dew point control in renewable energy systems using thermoelectric coolers

This paper describes a system, utilizing the Peltier effect, to reduce and control the dew point of hydrogen gas by water condensation and desublimation using thermoelectric coolers and water cooled heat sinks. The design is compared to a two-tube desiccant-drying system used in some commercial proton exchange membrane electrolyzer systems. The desiccant system in the water electrolyzer consumes roughly 0.2 kg per day of hydrogen product gas (corresponding to 3.4 kWh per kg of hydrogen based on the higher heating value) to maintain the two desiccant beds. Thermodynamic modeling was performed to determine the appropriate sizing for the thermoelectric coolers and water-cooled heat sinks for a 1 Nm 3 hr -1 hydrogen flow rate to obtain a theoretical dew point of -35 degC. The potential benefits and energy consumed by the thermoelectric approach (3.05 kWh per kg of hydrogen) is compared to the hydrogen loss of the desiccant system. The thermoelectric cooler-based system has the ability to control the dew point to match the variable flow rate of hydrogen in a renewable electrolysis system.