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Hydro Energy

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Hydropower is the conversion of energy embodied in moving water into useful power. People have been harnessing the power of water for thousands of years for irrigation and operation of mechanical equipment and more recently for electricity generation. In fact, hydroelectric power now supplies about 19 percent of the world’s electricity. In the United States, hydropower accounts for only 7 percent of the total electricity production, but over 70 percent of the total installed renewable energy capacity.

Most industrialized nations have developed their hydropower potential, but undeveloped resources remain in countries such as China, India, Brazil, and regions of Africa and Latin America. In some countries with access to large untapped hydro resources, the resources are located far from electric load centers, posing a problem for transmission of electricity over long distan\ces. Solving this technological problem and providing efficient transmission of electric power from off-grid hydropower plants is a major opportunity for investment and leadership in many countries around the world.

Hydropower plants are a clean, emission-free source of electricity. The natural hydrological cycle replenishes the resource, but also making it vulnerable to droughts. Competition for scarce water resources for agriculture, recreation, and fishing can affect the availability of water for power production. However, the potential for small hydro project development for rural electrification remains high in countries with concentrations of rural populations living near rivers and streams.

Large hydropower plants with capacities in the tens of megawatts are typically impoundment systems and require a dam that stops or reduces a river’s flow to store water in a reservoir. Penstocks carry water from the reservoir to water turbines, which in turn drive electric generators. Impoundment systems offer the advantage of controlled power output and other benefits such as water recreation associated with reservoirs, irrigation, and flood control. However, dams negatively impact fish populations by interfering with migration patterns. Water quality both in the reservoir and downstream of the dam can be affected by changes in water flow and dissolved oxygen levels.

Large new hydropower projects often require planning to remove communities from areas that will be flooded after a dam is built and other measures to manage environmental impact. Recent research has also raised concern about the possible effect of large reservoirs on atmospheric concentrations of greenhouse.

Small hydropower plants with capacities ranging from a few kilowatts to several megawatts, are typically diversion systems, which divert some water from a river through a canal or penstock to a turbine. Small hydropower plants can provide electricity for isolated rural populations. These systems range in size from household-sized systems to ones that can supply power to entire villages and commercial or industrial loads. Diversion systems, also called run-of-river systems, do not require dams or reservoirs, are suitable for small hydropower projects, and have less impact on the environment.

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