With his massive eyes and a gaping mouth, ‘Mr Trash Wheel’ and his compatriot, ‘Professor Trash Wheel’, wouldn’ t look amiss in a fun fair. But these cute, cartoonish-looking fellows have a serious job to do. From their perch on the Jones Falls River they are responsible for keeping litter from entering the harbour of Baltimore (US). The wheels rotate based on power drawn from the river’s current, and if there is not enough electricity generated from the river alone then they are boosted by solar energy. Most of the trash that ends up in the river comes from rain runoff that carries garbage overflow from within the city. The litter that the wheels pick up is either sorted into groups of recyclable material, or burned to provide electricity for the city. It is estimated that about 800,000 kg of trash has been prevented from entering Baltimore Harbour since the installation of the Trash Wheels in May 2014.