Photo by Dawn Danby.

Tommy Mitchell wasn’t an Occupier, but when he visited Occupy Wall Street, he found out that OWSers were charging their cell phones at a hot dog vendor’s gas-guzzling generator, The New York Times reports.

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“I was like, ‘Well that’s awful,’” he said. That’s when he began thinking about inventing a device that could harness renewable electricity in a public space without outlets. “It’s so practical that you can see it,” he said.

So Mitchell whipped up a solar cellphone charger, then brought it back to Occupy, where everyone loved it and declared him a hero of the people.His gadget uses one solar panel, can charge eight phones at a time, and stores energy in a battery so that it can operate even when the sun’s not out. He’s still working on finding paying customers, but these things are so practical that you should expect to see them popping up very soon at festivals, sporting events, campgrounds, and basically any other outdoor event lasting more than three hours.