Because energy is produced from the impact of running water on a turbine without consuming the water or creating waste, hydro electric energy is considered a renewable fuel source. Generating trivial amounts of greenhouse gases (GHG) over its life cycle, hydro power is also clean in comparison to utilities fueled by coal, gas or oil. According to Itaipu Binacional, about one-third of the world's potential hydro electric power has been realized, but even this amount has curtailed GHG emissions that would have resulted from ongoing global consumption of 4.4 million barrels of oil a day.
Once the upfront capital costs are recovered from the building of the dam and the hydro electric power plant, the only remaining expenses are operations and maintenance. Because the average lifetime of a hydro electric plant ranges from 50 to 100 years, such plants are capable of providing fuel for a few generations, according to Itaipu Binacional.
In contrast to solar and wind energy, hydro eleectric energy is not encumbered by intermittent periods of down time. If there's no sunlight or wind, solar and wind power plants must resort to stored energy or alternative fuel sources. A hydro electric plant can continually generate power as well as operate with an automated system and a lean staff, according to Bionomicfuel. To accommodate times of peak demand, water can be discharged from storage areas above the dam to produce extra power. Surplus energy can be stored in the grid.
Because water is a domestic and renewable source of energy, hydro electric power plants are not subject to unpredictable spikes in fuel costs, Itaipu Binacional says. Shielded from vacillations in the energy market, hydro electric power plants can therefore offer price stability to consumers.
The size of hydro electric power systems can range from very small, to power a handful of homes, to the Hoover Dam, with a reservoir capacity of 1.4 trillion cubic feet. The advantage of flexible hydro electric technology is that a system can be placed in any number of areas---lake, river, stream---with fast-moving water. According to the Guardian, a study by the Environmental Agency (EA) has identified about 26,000 locations in Welsh and English rivers that are optimal for hydro electric power turbines.