By taking advantage of gravity and the water cycle, we have tapped into one of nature's engines to create a useful form of energy. In fact, humans have been capturing the energy of moving water for thousands of years. Today, harnessing the power of moving water to generate electricity, known as hydroelectric power, is the largest source of emissions-free, renewable electricity worldwide.
The process involved in electricity generation via hydroelectric process is quite simple. Dam construction over a moving water body leads to the proper channeling of water and an explosive resultant force behind its movement. This water, in with all it force and kinetic energy pushes turbines. The kinetic energy of the moving water is then converted to a rotational energy of the moving turbines, and these turbines by extension spins a generator which achieves the final step of electricity production.
The benefits and drawbacks of any proposed hydropower development must be weighed before moving forward with any project. Still, if it's done right, hydropower can be a sustainable and nonpolluting source of electricity that can help decrease our dependence on fossil fuels.
According to a survey conducted in the year 2011, hydropower provided 16% of the world’s electricity, second only to fossil fuels. Worldwide capacity in 2011 was 950 gigawatts (GW), with 24% in China, 8% in the United States, and 9% in Brazil. Globally, hydroelectric capacity has more than doubled since 1970.