The world’s most relied-upon renewable energy source isn’t wind or sunlight, but water. Last year, the world’s hydropower capacity reached a record 1,308 gigawatts (to put this number in perspective, just one gigawatt is equivalent to the power produced by 1.3 million race horses or 2,000 speeding Corvettes). Utilities throughout the globe rely upon hydropower to generate electricity because it is cheap, easily stored and dispatched, and produced with no fuel combustion, meaning it won’t release carbon dioxide or pollutants the way power plants burning fossil fuels such as coal or natural gas do.