Introduction

Hydropower, or Hydroelectric power, is the harnessing of the energy of moving water to create electricity. The force of falling water turns a wheel, or turbine. This creates electricity by turning a generator.

How a hydropower plant works

Hydropower, or Hydroelectric power, contains 6 major parts.

1. A Dam

   This controls flow of water and increases elevation for a higher water wall. Moving water, by power of gravity, is created by making a reservoir above the turbines. This dam contains floodgates which it can open and close to vary the amount of water entering the penstock.

2. A Penstock

   A penstock is a large pipe that channels water from the dam to the turbines.

3. Turbines

   These are turned by the force of the moving water pushing against large blades attached to a cylinder.

4. Generators

   These generators are connected to the turbines. As the turbines rotate, they move giant magnets around coiled copper wire to get the electrons moving, thus creating electricity.

5. Inducters

   These convert the electricity from AC to DC (alternating current to direct current). This changes the form of electricity to one that we can use.

6. Transmission lines

   These transport the energy into your home or business.

Pumped storage systems

Another types of hydroplant is a pumped storage system. This system is used to store energy when it is not needed.

How it works

A pumped storage system pumps water through a pipe from a lower reservoir (called a "tailpond" or "afterbay") to an upper reservoir (called a "headpond" or "forebay"). This allows electricity made a night, when not many people want it, to move the water up to the headpond, so that it can be sent down to the tailpond when additional power is needed. This water, then it goes down, passes through a turbine, generator, transformer, and to transmission lines just like in a hydropower plant.

How hydropower is used

Hydropower can be used in any one of three power usage capacities: Primary Source, Reserve Source, or Start Up Source

1. Primary

   This is the main energy supplier for a city or town, requiring a large body of water with a very high base flow of water and a lot of rain.

2. Reserve

   This acts as a secondary source of power when extra power is needed during peak hours (from 11:30 to 3:00). Usually it supports a nuclear power plant or a coal power plant. This is the most common type of hydropower source.

3. Start Up Source

   Because a hydropower plant can start without any outside energy, also called a black start, it can be used to start up other power plants, most of which require energy for lights, electronic monitering equipment, etc.

The future or hydropower

There are thousands of sites all over the world that would be suitable for hydropower plants.  With the great increase in power need as we approach the new millenium, we will need more clean energy sources.

Advantages of hydropower

• It is a clean and safe source of energy
• They are self sustaining
• They create habitat for more types of fish
• They can act as a flood controller
• They are the most efficient energy source running from 90-95% efficiency

Hydropower's effect on the environment

Hydropower is a clean source of energy. There are no problems with air pollution, chemical runoff, toxic waste or the like.

Hydropower plants also create recreation areas and animal habitat. Because of the change in water location, wide areas after the dam become great for water edge species of animals.  And the large reservoir is good for many types of large fish. Boating areas are created in the reservoir too, as well as bird watching sites downstream of the dam.

Some problems may still occur though., but through careful planning these can be eliminated almost completely.

• Temporary disruption in the ecology to build the dam, but afterwards this cleared land can be used to make animal habitat.
• downstream of the dam, water flow may be significantly reduced, but careful monitoring of the land downstream of the dam can give operators enough information to allow more water to pass through the dam.
• Catadramous fish (fish that live in salt water and spawn in fresh water) migration may be interupted- but fish ladders and fish elevators may be installed to eliminate this problem. Anadromous (fish that live in fresh water and spawn in salt water) fish do not have this problem, because they can go right through the turbines which only spin at 81.8 rpms.
• Flooding of land upstream of the dam can be a problem, but careful monitoring of the land upstream of the dam can give operators enough information to allow more water to run through the dam to compensate for this problem.

Other forms of Hydropower

• Tidal power: electricity generated by turbines moved by the tides. This is still in experimental stages.
• Ocean thermal power: power generated by the thermal expansion of the ocean. This can only be used in a location like the Gulf stream.
• Geothermal power: natural steam is used underground to turn turbines. This is limited to location which have these phenomenon.

Bibliography