Solar hydrogen panel

A solar hydrogen panel is a device for artificial photosynthesis that produces hydrogen directly from sunlight and water vapor utilizing phytocatalytic water splitting and thus bypasses the conversion losses of the classical solar–hydrogen energy cycle where solar power is first harvested with solar panels and only then to converted to hydrogen with electrolysis plants.

Pictured molecular formula of conversion of water to hydrogen and oxygen.

In the solar hydrogen panel the hydrogen and oxygen evolution reactions are performed in the gas phase in cathode and anode compartments separated by a membrane. Anion exchange membranes provide an alkaline environment enabling the use of earth abundant materials as electrocatalysts.[1]

Scientists at KU Leuven's Center for Surface Chemistry and Catalysis in Belgium have managed to produce a solar hydrogen panel, which is able to directly convert no less than 15 per cent of sunlight into hydrogen gas, which according to them is a world record.[1][2][3] According to IEEE Spectrum in 2019 this is a giant leap from 0.1% efficiency 10 years earlier.[3]

Solar hydrogen panels seem very promising for the green hydrogen economy as this method of producing hydrogen fuel emits no CO2, unlike steam reforming from natural gas and then utilizing the water-gas shift reaction to produce hydrogen. As of 2015 the majority of H2 worldwide was produced via steam methane reforming, at prices down to $1 / kg H2.[4]

The power-to-gas process of producing methane from hydrogen and CO or CO2 is called methanation and produces substitute natural gas. Due to the challenges in hydrogen storage, other methods of energy storage and delivery may be useful, despite of the conversion losses in power-to-gas.