The document discusses hydropower, which is a renewable energy source that harnesses the kinetic energy of moving water. Hydropower has been used for thousands of years to grind grain and generate electricity. Modern hydropower plants capture the potential energy of dammed water and convert it to electrical energy using turbines connected to generators. The amount of power generated depends on the height that water falls and the volume of water flow. Larger dams and rivers with greater water flow can produce more hydropower.