(338e) Fabrication of Photovoltaic Thermal Water Electrolyzer for Hydrogen Production

Solar energy is often harnessed by using a photovoltaic/thermal (PVT) collector, where a photovoltaic (PV) module and a thermal collector convert solar energy into electricity and heat, respectively. The heat energy has been conventionally used for hot water and/or room heating; it is, however, highly desirable to convert the released energy into alternative storable forms. Hydrogen is environmentally friendly and a sustainable energy carrier that can be stored. Currently the PV-assisted water electrolyzers available on the market have PV conversion efficiencies of only 15%. The energy that is not transformed into electricity is just dissipated. To this end, we have developed a new integrated system – so-called “photovoltaic thermal water electrolyzer” – which consists of PV cells positioned on top of a planar micro water electrolyzer. Herein, we provide the design, fabrication and characterization of a planar micro water electrolyzer for hydrogen production. The heat that is released from the system is used to raise the temperature of the electrolyte solution, thereby increasing the efficiency of the hydrogen production.

Analysis of the proposed design is performed using the COMSOL Multiphysics software package. Platinum black electrodes are deposited on a glass substrate and polydimethylsiloxane (PDMS) is used as the material for the electrolyzer chamber. An insulated flexible heater is attached to the top of the device and a constant temperature is applied in order to achieve the desired temperature of the electrolyte solution. Electrochemical characterizations are performed in 1 M H₂SO₄ solution at up to 70^oC under applied voltages of 1.8 V and 2 V. Enhanced gas separation and management are also investigated in the chamber in order to increase hydrogen evolution. This approach produces hydrogen and oxygen gases at least four times faster relative to room temperature operation. In summary, this new integrated approach brings advantages over current systems such as utilization of wasted heat into efficient hydrogen production, a smaller spatial footprint with architectural uniformity that is scalable to all types of PV modules, and can lead to reduced installation costs.