Gravity is a great way to store energy.
Water can be stored behind dams and then released, turning turbines, creating electrical energy.
A hydroelectric power station does just that.
Dams, however, are damaging to the environment because large areas have to be flooded. Dams can also silt up over time.
Tidal power is similar to hydroelectric power in that water is stored.
Underwater turbines generate power as the tide goes in and out.
Disadvantages of tidal power include:
But the power is free and produces no carbon waste.
How hydroelectric works
How tidal power works