Things You'll Need
Small plastic cups or hollow plastic balls
Water turbine generators can be built at home with minimal materials. Moving water is the prime driving force to turn the turbine and generate electricity. Using bicycle parts and an older automotive generator, several water turbines can be employed to gain any desired level of voltage and strength. The average backyard engineer can build a water turbine in about a day.
Remove the front wheel from the bike. Turning the axle nut in a counterclockwise direction will loosen it for removal.
Remove the chain from the bicycle's pedals. Rotating the chain while pushing it off center will accomplish this.
Weld or mount the car generator or alternator to the underside of the pedals, so that when the chain is wrapped around the alternator's pulley, it is centered. Replace the pulley with one of the pedal's gear sprockets, or weld the sprocket into place on top of the pulley, being sure to center it and checking its gear-teeth clearances. When the chain is wrapped around the sprocket, the alternator should turn with the rear wheel.
Raise the bike's seat all the way up. Usually it has a screw plate that can be loosened and adjusted.
Saw several dozen plastic balls into halves.
Screw the plastic ball halves or small plastic cups onto the bicycle's rear wheel, spaced about two inches apart, and all in the same direction. The "cups" should go in a clockwise direction to match the alternator.
Place the bike into a creek or source of moving water upside down so that the seat is in the water. The cups should be facing the water current so that they push the wheel. If the water current is strong enough, the wheel will keep turning and will generate 12 volts of electricity at a few amps. Wire the alternator to charge batteries on shore or to power equipment.
Hard plastic ball halves will withstand stronger water currents than drinking cups.
Do not let the alternator become submerged. Once the bike is in the water upside down, the alternator should be above the water line.
Eli Laurens is a ninth-grade physics teacher as well as a computer programmer and writer. He studied electrical engineering and architecture at Southern Polytechnic University in Marietta, Ga., and now lives in Colorado.