What is Hydroelectric Power

History

People have been using the movement of water to their advantage for a very long time. One of the earliest applications of hydro power was 2000 years ago when the Greeks used a water wheel to grind grains and wheat into flour. They found that this job could be accomplished much easier by letting gravity and water do this hard work which gave people more time to focus on things such as farming and irrigation.

Although hydro power has been used for such a long time, it was only in the 1880's that the first hydroelectric generator was invented and installed in the United States. This generator was installed in Appleton, Wisconsin and it was able to produce about 12.5 kW of power. During the next twenty years hydroelectricity boomed and there were 300 additional power plants installed in the United States.

Hydroelectric power is still widely used today. It is estimated that roughly 10% of all power in the United States still comes from dams which is a considerably large portion. And while dam construction in the US has virtually come to a halt, countries around the world including China, Argentina, and Pakistan continue to build large dams that produce as much as 18,000 MW (Gorges dam in China).

Hydroelectric dam in Ontario, Canada

How Hydroelectricity Works

As previously stated, hydro power comes using the movement of water to create energy. Hydroelectricity is most commonly produced in a dam which generates electric power from the mechanical energy that is taken from the water.

Water enters a dam through a gate when the gate opens, allowing the water to pass through and continue down the penstock. When the water reaches the turbine at the bottom it is moving very fast and has a lot of pressure behind it. It is large pressure that is the result of more water in the penstock above that spins the blade of the turbines.

The spinning turbine receives the mechanical energy from the moving water and transfers it up to the generator using a coil of wires and a large magnet. This spinning apparatus induces a current which allows the energy to transfer from mechanical to electrical and then be moved through the transformers and directly onto the electrical grid.

How a dam works.

Hydroelectric Power Around the World

Some of the biggest dams in the world produce enough electrical power to provide for up to a few million people. Dam technology has not changed very much over the past few decades, but their construction has become large and capable of generating increasingly large amounts of power. Here is a list of some of the largest dams in the world:

Damn Country
Three Gorges China
Samara Russia
Tarbela Pakistan
Fort Peck United States
Lower Usuma Nigeria

The Three Gorges Dam

The largest dam in the world, the Three Gorges in China, has a total of 26 generators, each with a maximum capacity of 700 MW. This dam is by far the largest ever built and will be finally completed in 2011 after multiple setbacks have delayed its debut. Construction of this massive dam began in 1994, and has taken over 17 years to build (assuming it opens in 2011). And while some people have condemned the Three Gorges Dam as a "disaster waiting to happen", China is eager to get the facility online as it will increase their nation's overall power output by around 10%.

Three Gorges Dam, China

The Future of Hydroelectric Power

While the United States has not increased it's own stake in hydro power over the last few decades, the rest of the world continues to look at hydroelectricity as a very viable renewable resource. Many countries around the globe are building or planning to build large dams that will dramatically increase their power output. And while there are disadvantages to hydroelectric power such as large scale human and wildlife displacement, this form of renewable energy has a lot to offer while other renewable forms of energy such as wind and solar continue to become more widely developed.