Hydro electricity is another term for power generated by harnessing the power of moving water. Not necessarily falling water, just moving water. There are many famous such generating stations in the world, not the least of them at Niagara Falls, Grand Coulee and Boulder Dam. These are just a few of the many examples of energy produced by falling water. On the other hand, a small mill set in the rapids of a fast-moving stream is also an example of it in action, on a lesser scale. The truth is that any steady current of flowing water from a river or other waterway can be converted to power.
How is Hydro Electricity Generated?
Power is generated or "manufactured" in large power generating stations using the same basic principle as a small grist mill yet on a much larger and vastly improved scale for better efficiency. These electrical generators are attached to massive turbine devices which spin at great speeds as a result of water rushing through them. These power station turbines are much more efficient at extracting the kinetic energy from the moving water and converting that energy it into power through these generators.
The Hydro Electricity extracted from water depends not only on the volume but on the difference in height between the source and the water's outflow. This height difference is called the head. The amount of potential energy in water is directly proportional to the head. To obtain very high head, water for a hydraulic turbine may be run through a large pipe called a penstock.
For instance, energy is derived to make power by the force of water moving from a higher elevation to a lower elevation through a large tube" otherwise known in technical terms as a "penstock". When the water reaches the end of the penstock, it turns a water wheel or "turbine" at enormous speeds. The turbine rotates, via a connected shaft to an electrical generator, and this generator creates electricity. It is the turbine and generator working in combination that converts "mechanical energy" into "electric energy". The water that makes this possible, is a renewable energy resource, just like the wind that turns the turbine attached to a generator.
Hydro Electricity may be extracted from water but it depends not only on the volume of water but also on the difference in height between the top of the penstock and where the water spins the turbine. This difference in height is often referred to as the "head". From this "head", it can be determined the exact amount of potential energy that can be converted. Therefore, it is advantageous to build power dams as high as possible to convert the maximum energy from mechanical energy.
While many Hydro Electricity generating stations supply world power grids, some projects are created for private business purposes. For example, aluminium manufacturing companies require large amounts of power. And there are many other examples of industries that use hydro electricity in their manufacturing operations.
The animation below demonstrates how a hydro electricity dam works.
Graphic Courtesy: Michigan Technical University
While hydro electricity seems relatively clean and safe in comparison to burning fossil fuels (coal or oil or natural gas), nearly all large hydro electric installations in North America have significant had impacts on nearby environmental habitats once they are brought online. This is because they significantly impede the flow of water in rivers and lakes at the point where the generating dam is installed In turn, this causes significant increases in water levels in corresponding upstream water systems while at the same time creating much lower water levels downstream.