The fall and movement of water is part of a continuous natural cycle called the water cycle. Energy from the sun evaporates water in the earth’s oceans and rivers and draws it upward as water vapor. When the water vapor reaches the cooler air in the atmosphere, it condenses and forms clouds. The moisture eventually falls to the earth as rain or snow, replenishing the water in the oceans and rivers. Gravity drives the water, moving it from high ground to low ground. The force of moving water can be extremely powerful. Hydropower is called a renewable energy source because the water on the earth is continuously replenished by precipitation. As long as the water cycle continues, we won’t run out of this energy source.
It has become "the leading source of renewable energy". It provides more than 97% of all electricity generated by renewable sources worldwide. Other sources including solar, geothermal, wind, and biomass account for less than 3% of renewable electricity production." In the US , 81% of the electricity produced by renewable sources comes from hydropower. "Worldwide, about 20% of all electricity is generated by hydropower." Some regions depend on it more than others. For example, 75% of the electricity produced in New Zealand and over 99% of the electricity produced in Norway come from hydropower.
The use of hydropower "prevents the burning of 22 billion gallons of oil or 120 million tons of coal each year." In other words, "the carbon emissions avoided by the nation's hydroelectric industry are the equivalent of an additional 67 million passenger cars on the road 50 percent more than there are currently." The advantages of hydropower are therefore convincing, but there are some serious drawbacks that are causing people to reconsider its overall benefit.
Source: http://www.altenergy.org
http://www.need.org
Next article, we talk about the history of Hydropower.
