Hydroelectric Energy is a clean and sustainable way to cut back on the use of fossil fuels and ultimately better the environment.  But not many people pay attention to hydroelectric energy because we are always at or almost at capacity for making dams seeing as we only have a limited amount of rivers we can dam up.  Hydroelectric energy is nothing used it dates all the way back to the romans; it is also the largest source of emissions-free, renewable electricity in the united states and worldwide.  While hydroelectricity can be great for offsetting the cost of using fossil fuels it can also cause destruction to the environment unless it’s done correctly.

Hydroelectric energy provides about 16% of the worlds electricity which is the second largest provider of electricity right behind fossil fuels.  Worldwide the capacity of electricity is about 950 gigawatts with more than 24% of that in china alone, along with 8% in the united states and 9% in Brazil.  The united states has seen a steady growth of hydroelectric power since 1970 up until 2012 when electricity generation in the U.S. dropped from 12 to 7% due to rapid growth in other fields such as natural  gas, wind and solar technologies.  The world leader in hydroelectric power is Norway who powered more than 64% by just using hydroelectric power Followed by brazil (35.3), and Canada (26.2).

When making hydroelectric power you need to find a way to turn moving water into energy.  you use the kinetic energy in  moving water to produced electricity.  With enough speed and volume this water can spin a turbine which then rotates to generate electricity.  A good rule of thumb would be to say 1 Gal of water per second falling 100 ft can generate 1 KW of electricity .  In order to increase the volume of moving water dams are used to collect water. There is an opening in dams that use gravity to drop water down a pipe, this water causes a turbine to spin, which in turn causes magnets inside a generator to rotate and create electricity.

There are three kind of turbine designs that are used in hydropower facilities and their use various depending on the size of the dam.  The most common of these designs are Kaplan, Francis, and Pelton wheel designs.  The Kaplan turbine is similar to a boat propeller with a runner to change the pitch.  It can have anywhere from 3 to 6 blades, and can provide up to 400 MW of power.  The proformance of the kaplan turbine can be improved by changing the pitch of the blades making it different from any other turbine.  The francis Turbine has a runner too with 9 or more fixed vanes.  This design can be up to 800 MW in size, the runner blades direct water so that it moves in an axial flow.  The last design is the Pelton turbine which consists of a set of specially shaped buckets that are mounted on the outside of a circular disc, making it almost look like a water wheel.  Pelton turbines aren’t typically used but can produced up to 200 MW of power.  Hydroelectric power can also be produced without dams suing a process known as run-of-the-river.  Which uses the speed of the water  to spin turbines and make kinetic enerfy like that.

References:

http://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/how-hydroelectric-energy.html#.VQ3CpZNC_3o

http://education.nationalgeographic.com/education/encyclopedia/hydroelectric-energy/?ar_a=1

http://www.gridovate.com/which-countries-get-the-most-energy-from-hydropower_21763.html