|
Hydroelectric power is the technology of generating electric power from the movement of water through rivers, streams, and tides thanks to the potential energy of the elevation of waters. Water is fed via a channel to a turbine where it strikes the turbine blades and causes the shaft to rotate. To generate electricity the rotating shaft is connected to a generator which converts the motion of the shaft into electrical energy.
Hydroelectric power now supplies about 715,000 MW or 19% of world electricity and large dams are still being designed. Apart from a few countries with an abundance of it, hydro power is normally applied to peak-load demand, because it is so readily stopped and started. Nevertheless, hydroelectric power is probably not a major option for the future of energy production in the developed nations because most major sites within these nations with the potential for harnessing gravity in this way are either already being exploited or are unavailable for other reasons such as environmental considerations.
Hydroelectric power can be far less expensive than electricity generated from fossil fuel or nuclear energy. Areas with abundant hydroelectric power attract industry with low cost electricity. Recently, increased environmental concerns surrounding hydroelectric power, have begun to outweigh cheap electricity in some countries.
The chief advantage of hydroelectric dams is their ability to handle seasonal (as well as daily) high peak loads. When the electricity demands drop, the dam simply stores more water. Some electricity generators use water dams to store excess energy (often during the night), by using the electricity to pump water up into a basin. The electricity can be re-generated when demand increases. In practice the utilization of stored water in river dams is sometimes complicated by demands for irrigation which may occur out of phase with peak electrical demands.
Small hydro:
Small hydro is the application of hydroelectric power on a commercial scale serving a small community or medium sized industry. A generating capacity of up to 10 MW is becoming generally accepted as the upper limit of what can be termed small hydro. Small hydro can be further subdivided into mini hydro, usually defined as less than 1,000 kW, and micro hydro which is less than 100 kW. Micro hydro is usually the application of hydroelectric power sized for small communities, single families or small enterprise.
Small scale hydro or micro-hydro power has been increasingly used as an alternative energy source, especially in remote areas other power sources are not viable. Small scale hydro power systems can be installed in small rivers or streams with little environmental effect on things such as fish migration.
There are some major factors to consider when installing a micro-hydro system. First, the amount of water flow available on a consistant basis. Periods of little or no rain can greatly affect power output. Second is what is known as head, this is the amount of drop the water has between the intake and the exit of the system. The more head, the larger amount of power can be generated. Third, there can be legal and regulatory issues that must be researched. Most counties, cities, and states have their own regulations about water rights and easements. | 
