Micro-Scale

The 800 kW micro-hydro facility in King Cove, Alaska serves the town's 700 residents Credit: Duane Hippe; Courtesy DOE/NREL

As their name implies, micro-hydroelectric plants are the smallest type of hydroelectric energy systems. They generate between one kilowatt and one megawatt of power. The main application for these hydro systems is in small, isolated villages in developing countries. They are ideal for powering smaller services such as the operation of processing machines.

Small-Scale

Small hydropower systems can supply up to 20 megawatts of energy. These systems are relatively inexpensive and reliable. They have the potential to provide electricity to rural areas in developing countries throughout the world. Small systems are especially important to countries that may not be able to afford the costs of importing fossil fuels such as petroleum from other countries.

"Run-of-the-River"

In some areas of the world, the flow rate and elevation drops of the water are consistent enough that hydroelectric plants can be built directly in the river. The water passes through the plant without greatly changing the flow rate of the river. In many instances a dam is not required, and therefore the hydroelectric plant causes minimal environmental impact on its surroundings. However, one problem with run-of-the-river plants is the obstruction of fish and other aquatic animals. This and other problems are discussed in the next section.

An overhead view of the The Hoover Dam in lower Colorado. Its power plant has a capacity of more than 2,000 megawatts. courtesy US Dept. of the Interior Bureau of Reclamation - Lower Colorado Region More pictures and information of Hoover Dam from The Bureau

Considered a 20th century engineering marvel, The Glen Canyon Dam in Lake Powell, Arizona is also a popular tourist attraction for visitors of the Grand Canyon region. Credit: Larry Gordon; Courtesy DOE/NREL

An overhead shot of ITAIPU courtesy ITAIPU Binacional Visit the ITAIPU official web site for more pictures and information.

By far the largest hydroelectric power plant in the world is ITAIPU, a project jointly developed by Brazil and Paraguay. With a capacity of 12,600 megawatts (MW), it produced a record 89 million MWh of electric power in 1997 - 26.4% of the total demand of Brazil and 79% of Paraguay.