Cigarette butts, styrofoam cups, plastic bottles, food wrappers, an old car tire – these are just some of the items collected by a solar-powered water wheel in Baltimore. It started churning in May and so far has collected 40 tons of trash. John Kellet invented the water wheel to help clean up the copious amounts of trash that wind up in Baltimore’s inner harbor. He overhead some tourists remarking with disgust about how much they could see in the water, so he tried to come up with a solution.

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A solar-powered water wheel sounds like a great invention and it has been doing a good job so far. “It looks sort of like a cross between a spaceship and a covered wagon and an old mill. It’s pretty unique in its look, but it’s also doing a really good job getting this trash out of the water,” he explained to NPR.

He’s right that his invention does resemble an old water wheel used for grinding grain like wheat or corn on one side of the device. The water wheel is turned by currrents in the bay which in then moves a conveyor belt to transport trash from the water up to a dumpster, where it falls in. Two booms in front of the conveyor belt stop and guide trash to it for transport. An automated raking system helps draw the trash to the front of the conveyor belt.

Above the belt is open air and a roof that resembles an old covered wagon. The roof covers part of the conveyor belt to prevent wind from blowing trash all over and to cover the trash dumpster in the rear. On the roof, there are a number of solar panels generating about 30 kilowatt hours on a sunny day, or about enough to power a typical Maryland home. Of course, this unusual device is unique enough to capture attention so it winds up functioning as a conversation starter and something of a learning aid.

There is no good reason for people to be throwing trash into the harbor or surrounding it. Prevention would seem like the most logical solution to the trash problem, but behavior change can be very difficult to start and reinforce.

It would not be surprising if Kellet could patent his invention and build more for cities with bodies of water that also need regular cleanings. For example, trash in Rio’s waterways have been identified as a problem to clean up before the Olympics.