For flotation, the machine has four little stabilizers. To move, there are two paddles in the middle of its body, which have flexible flipper joints to make sure they move efficiently and minimize drag. Powering the row-bot is a bacteria-filled fuel cell. In the cell, bacteria digest organic waste, and produce carbon dioxide as a by-product, as well as the protons and electrons needed to get the electrical circuit in the cell flowing. In this design, the row-bot generated more energy than it needed to keep refueling itself. That’s huge, and it means in the future, the answer to waste in the water might be sprinkling robots into the stream, and waiting until they eat all the garbage.