Hydro Power – How it Works and What We Need
Part of the beauty of hydropower lies in its simplicity. Moving water (kinetic energy) spins a turbine or wheel (mechanical energy), which drives a generator (electrical energy). Archaeologists have found evidence of water storage dams in Jordan, Egypt and elsewhere in the Middle East that date back 5,000 years to 3000 BC. One of the earliest designers to document his plans was Vitruvius (c.70 BC-c.25 BC), a Roman architect and engineer, who described an undershot waterwheel that could generate power. The Romans built many waterwheels, with the most ambitious being the one is Barbegal, France, in the 4th Century AD. Connected to a large aqueduct system that fed water to the city of Arles, Barbegal was a massive flour mill with not one but sixteen waterwheels in two parallel rows. The water turned the first pair of wheels, then flowed downhill to the second pair, then downhill again and so on until it had flowed through and turned all eight sets, after which it ran into a runoff pool at the bottom of the hill.
Today hydropower generates about 15 percent of the world’s electricity (about 6 percent of the total energy supply). Rather than using waterwheels on a moving river or through a duct, most hydroelectric plants extract energy from the potential energy that comes from the vertical distance the water drops (the “head”). The water is channeled through a sluice or gate, or through enclosed pipes that funnel the water down to the turbines; these channels are called penstocks.