"gravity is going to be the same for the rest of time, it's a simple technology" mick ireland
Every hydroelectric project is different from the other. The geographic location, economics, political involvement and many other factors determine the size, type and overall energy production of each project. Hydropower is an extremely site specific technology; however, “The idea behind hydroelectric power is quite straightforward; it harnesses the kinetic energy of falling water.” (Carless, 57) The technology has evolved to improve efficiencies; however, the basics have remained the same and they will for the rest of time. Hydropower is the cheapest and most reliable renewable energy source.
WHY HYDROPOWER IS CONSIDERED REWEWABLE
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TWO IMPORTANT WORDS: HEAD AND FLOW
"Head and flow are two variables which determine the hydro system most suitable for a site. The head refers to the height of the falling water from the headwater (above the drop) to the tailwater (below the drop). Head is usually measured in feet. This falling action exerts pressure which is converted into useful energy. The flow rate refers to the water's rate of flow and is measured in unites of cfs (cubic feet per second). Most turbines have specifications which limit their use to certain head and flow rates. A system with a high head and low flow os more economical than a system which a high flow and low head, which has the same capacity. High flows depend upon large volumes of water, and therefore require larger equipment to utilize the resource." (Energy Efficiency and Renewable Energy Clearinghouse) |
THE DIFFERENT TYPES OF HYDROPOWER
IMPOUNDMENT/CONVENTIONAL This is the most common type of hydropower and can be built on a large or small scale. A dam is built which creates a reservoir, allowing the water to be released under controlled circumstances. The water flows through a penstock, and then into a turbine which spins and generates electricity. The water then flows back into the river. PUMPED-STORAGE "Pumped storage is an essential solution for grid reliability, providing one of the few large-scale, affordable means of storing and deploying electricity. Pumped storage projects store and generate energy by moving water between two reservoirs at different elevations. At times of low electricity demand, like at night or on weekends, excess energy is used to pump water to an upper reservoir. During periods of high electricity demand, the stored water is released through turbines in the same manner as a conventional hydro station, flowing downhill from the upper reservoir into the lower and generating electricity. The turbine is then able to also act as a pump, moving water back uphill." Source-National Hydropower Association |
RUN OF THE RIVER/DIVERSION This type of hydropower does not require a dam to be built; rather, it uses the natural flow of the river to generate electricity. A certain amount of water will be diverted from the river, travel through a penstock that ranges from fifty feet to several miles. Arriving at the powerhouse, the water will pass through a generator and then return to the river. The ecological damage is less severe; however, there is no way to guarantee electricity at a certain times because there is no reservoir. |