The most efficient solar powered devices on Earth are the plants around us, which convert sunlight into chemicals that can be transported to wherever they are needed. Researchers have been attempting to replicate this process for some time with solar cells that pull hydrogen out of water. Now those at the Helmholtz Sentrum Berlin and Delft University of Technology have built a new device to achieve this that could revolutionize the field.
Artificial photosynthesis devices work by putting the electricity converted from sunlight into a material that reacts with water to release the hydrogen from it, sometimes with a catalyst to help. How this new device differs is that it uses a simpler solar cell design than that of other systems, making it cheaper, but not less efficient. Instead of relying on special semiconductors or amorphous silicon, the cell utilizes a relatively cheap metal oxide and catalyst to store 5% of sunlight as hydrogen. Potentially 100 square meters of such a cell could store 3 kilowatt hours of energy in hydrogen in just one hour of sunshine.
An advantage to using an artificial photosynthesis system like this, as opposed to more direct solar power, is that hydrogen can be stored like a chemical battery, discharged when needed instead of just when the sunlight is available. The researchers' next challenge is figuring out how to scale up the system so it can produce a useful amount of hydrogen.