Hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator. Another variation is to make use of water's kinetic energy or undammed sources such as tidal power. Hydro power works by harnessing the gravitational descent of a river that is compressed from a long run to a single location with a dam or a flume. This creates a location where concentrated pressure and flow of water can be used to turn turbines or water wheels. These can then drive an electric generator. This can be compared to past days when a water wheel would drive a mill. Electric generators powered by hydro power can be run backwards as a motor to pump water back up for later use.
Pros
- Water can be accumulated above the dam and released to coincide with peaks in demand. So, unlike other types of power stations, hydroelectric power stations can promptly increase to full capacity.
- Electricity can be generated constantly, because there are no outside forces, unlike other forms of alternative energy, which affect the availability of water.
- Hydroelectric power produces no waste or pollution since there is no chemical reaction to produce power.
- Water used for hydro power can be reused.
Cons
- Dams can be very expensive to build.
- There needs to be a sufficient, and powerful enough, supply of water in the area to produce energy.