How does hydroelectric energy generate electricity?

• A. Water's force lifts water to a higher reservoir for storage
• B. Water's chemical energy powers a turbine
• C. Water's force heats water to create steam to drive a turbine
• D. Water's force spins a turbine connected to a generator

Answer: (D)

Hydroelectric power generates electricity by converting the energy of moving water into mechanical energy to drive a generator. Water released from a reservoir flows down, and gravity turns its potential energy into kinetic energy. That moving water spins a turbine, which is connected to a generator. Inside the generator, this mechanical energy is converted into electrical energy as coils and magnets interact. So the water’s force provides the motion that ultimately creates electricity. The other ideas don’t fit: lifting water to a higher reservoir is storage, not generation; chemical energy in water isn’t what powers the turbine; and heating water to steam describes a steam-cycle power plant, not hydroelectric use of flowing water.