Solar hydrogen production is a clean energy system that holds great potential to bolster sustainability efforts across the globe. Unfortunately, it's also largely unfeasible due to the high costs associated with its production and operation.
Now, researchers from the Australian National University and the University of New South Wales have set a new world record in efficiency for the production of renewable hydrogen from solar energy using low-cost materials. The team of scientists achieved a solar-to-hydrogen conversion efficiency of greater than 20 percent.
The researchers focused on combining tandem solar cells with low-cost catalyst materials to split water into both hydrogen and oxygen through electrolysis.
Research co-author Dr. Siva Karuturi of Australian National University told RenewEconomy that his team's new approach of combining solar cells with hydrogen electrolyzers into a single unit could produce significant improvements in production efficiency and reductions in cost.
“In a centralized electrolyzer which usually runs on grid electricity, membrane and electrodes are stacked in multiple numbers – often hundreds of them – to achieve the desired production capacity which results in a complex system,” Karuturi said.
Karuturi added that in direct photovoltaic (PV)-electrolysis, a single unit of electrodes and membrane can be directly combined with PV cells into a simplified solar hydrogen module, getting rid of the need for power infrastructure and electrolyzers, and resulting in higher power conversion efficiency and lower costs.
The team speculates that their new design could lower the cost of renewable hydrogen production to $2.30 per kilogram. This would be in line with targets set by the United States Department of Energy.
This is welcome news as the world strives to achieve net zero emissions by 2050, a target that is the catalyst behind a number of green hydrogen projects. In 2017, another energy innovation used a floating solar rig to produce hydrogen fuel using seawater. However, that technology continues to be quite costly.