Now, engineers from Columbia University are developing a "solar fuels rig" that floats on the ocean, captures energy through a solar cell and uses it to harvest hydrogen from the water beneath it.
The rig produces hydrogen through water electrolysis, a technique where H2 and O2 gases are separated out of water by passing an electric current through the liquid. Most of the time, these devices require a membrane to separate the two electrodes, but these membranes are fragile and require very pure water, which limits their practical applications.
The device developed at Columbia can split water into hydrogen and oxygen without needing a membrane. That means it can be deployed on seawater, which would normally degrade a membrane thanks to the impurities and micro-organisms that call it home.
"Being able to safely demonstrate a device that can perform electrolysis without a membrane brings us another step closer to making seawater electrolysis possible," says Jack Davis, the first author of a paper describing the device. "These solar fuels generators are essentially artificial photosynthesis systems, doing the same thing that plants do with photosynthesis, so our device may open up all kinds of opportunities to generate clean, renewable energy."