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In a single hour, more energy from the sun hits the Earth than all the energy used by humankind in an entire year. Imagine if the sun's energy could be harnessed to power energy needs on Earth, and done in a way that is economical, scalable, and environmentally responsible. Researchers have long seen this as one of the grand challenges of the 21st century.

Daniel Esposito, assistant professor of chemical engineering at Columbia Engineering, has been studying water electrolysis?the splitting of water into oxygen (O2) and hydrogen (H2) fuel?as a way to convert electricity from solar photovoltaics (PVs) into storable hydrogen fuel. Hydrogen is a clean fuel that is currently used to propel rockets in NASA's space program and is widely expected to play an important role in a sustainable energy future. The vast majority of today's hydrogen is produced from natural gas through a process called steam methane reforming that simultaneously releases CO2, but water electrolysis using electricity from solar PV offers a promising route to produce H2 without any associated CO2 emissions.

Esposito's team has now developed a novel photovoltaic-powered electrolysis device that can operate as a stand-alone platform that floats on open water. His floating PV-electrolyzer can be thought of as a "solar fuels rig" that bears some resemblance to deep-sea oil rigs, except that it would produce hydrogen fuel from sunlight and water instead of extracting petroleum from beneath the sea floor.

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Category: Science