Things to know about hydropower and hydroelectricity

Hydroelectricity refers to electricity that is generated by hydropower. Hydropower or water power is power that derives from moving or falling water and can be turned into useful form of energy.

At the end of 2010, hydroelectric power plants provided approximately 16% of global electricity generation. China is the country that leads the way in installed hydropower capacity, followed by Canada and United States.

China's Three Gorges Dam is the largest hydroelectric power plant in the world.

Hydroelectric power plants have costs of electricity comparable to fossil fuel fired power plants, in range from 3-5 cents per kilowatt hour.

Hydropower has positive environmental impact when compared with fossil fuels, because fossil fuels, when burn, emit harmful greenhouse gas emissions that cause global warming and climate change.

Hydroelectric power plants aren't totally emission-free but their output level of greenhouse gases is considerably lower in comparison to fossil fuel fired power plants.

Once built, hydroelectric power plants have low maintenance and operational costs (almost everything is automated).

The earliest useful use of water power dates back to the 7th millennium BC (Mesopotamia and ancient Egypt in form of irrigation).

The construction of large hydropower dams can lead to major environmental damage, and can cause flooding, if not done properly.

The first hydroelectric power plant that generated electricity in United States was Schoelkopf Power Station No. 1 near Niagara Falls back in 1881.

The United States currently has over 2000 hydroelectric power plants which account to almost 50% of the nation's total renewable electricity.

The second largest hydroelectric power plant in the world is the Itaipu Dam on the Paraná River. It trails Three Gorges Dam in installed capacity but it leads the world in terms of annual hydroelectricity production. This power plant supplies electricity to two countries, Paraguay and Brazil.

The largest hydropower dam in United States is Grand Coulee Dam on the Columbia River in the state of Washington with the installed capacity of 6809 MW.

Large hydroelectric power plants usually receive all the attention, though the popularity of small, micro and pico hydro systems has been growing in all parts of the world.

It is fairly easy to ramp up and down the production of hydroelectric power plants in order to adapt to changing energy demands.

Hydroelectric power plants have very long lifespan, up to 100 years.

Building large hydropower projects needs to be done with extreme care because eventual failures due to poor construction can lead to catastrophe, such as flooding the downriver settlements and infrastructure.

Paraguay is the only country in the world that produces 100% of its electricity from hydroelectric power plants. In Norway, hydroelectric power plants account for 98-99% of generated electricity.

The third largest hydroelectric power plant is Guri Dam in Venezuela with the capacity of 10200 MW.