VSL:SCIENCE // A solar-power breakthrough

It’s a problem with solar power: There are times when the sun doesn’t shine. On such cloudy days (or during the night), expensive solar arrays are utterly useless, like a car engine without gas. Critics of alternative energy have long pointed to this failing as the main reason solar power will never account for a significant percentage of energy production.

But now, thanks to a breakthrough by MIT chemists, it appears that this technical problem is a thing of the past. The lab of Daniel Nocera has invented a cheap catalyst — a chemical substance that makes it easier for a particular chemical reaction to occur — that can break water molecules apart, allowing energy to be stored as hydrogen ions. When needed, this pure hydrogen can either be burned or be run through a fuel cell, thus producing energy even when the sun isn’t shining. Previous catalysts required large amounts of energy to perform the same task, but Nocera’s device can split water using the low voltages generated by a solar cell. Within five years or so, it’s possible that this technology could even find its way into car roofs, making it possible for an engine running on hydrogen to rely on the same raw materials as a plant: a little water and some sunlight.

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