Researchers at the University of North Carolina at Chapel Hill (UNC) have built a system that converts the sun’s energy not into electricity but hydrogen fuel and stores it for later use, allowing us to power our devices long after the sun goes down.
Solar energy has long been used as a clean alternative to fossil fuels such as coal and oil, but it could only be harnessed during the day when the sun’s rays were strongest. The UNC invention offers a solution inspired by natural photosynthesis. Tom Meyer at the Energy Frontier Research Center at UNC calls the new findings “a last major piece of puzzle for a new way to store the sun’s energy.”
In one hour, the sun puts out enough energy to power every vehicle, factory and device on the planet for an entire year. Solar panels can harness that energy to generate electricity during the day. But the problem with the sun is that it goes down at night—and with it the ability to power our homes and cars. If solar energy is going to have a shot at being a clean source for powering the planet, scientists had to figure out how to store it for night-time use.
The new system designed by Meyer and colleagues at UNC and with Greg Parsons’ group at North Carolina State University does exactly that. It is known as a dye-sensitised photoelectrosynthesis cell, or DSPEC, and it generates hydrogen fuel by using the sun’s energy to split water into its component parts. After the split, hydrogen is sequestered and stored, while the by-product, oxygen, is released into the air.
The new system needs almost no external power to operate and releases no greenhouse gases. What’s more, the infrastructure to install these sunlight-to-fuel converters based on existing technology. A next target is to use the same approach to reduce carbon dioxide, a greenhouse gas, to a carbon-based fuel such as formate or methanol.
“When you talk about powering a planet with energy stored in batteries, it’s just not practical,” said Meyer. “It turns out that the most energy dense way to store energy is in the chemical bonds of molecules. And that’s what we did – we found an answer through chemistry.”
