Page 283 - Handbook of Energy Engineering Calculations
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are  parties  of  interest  in  the  harnessing  of  hydro  sites,  and  stringent
               government  regulations  prevail,  including  those  of  the  U.S.  Corps  of
               Engineers, Federal Power Commission, Bureau of Reclamation, Geological
               Survey, and Securities and Exchange Commission.


               5. Assess ways that the selected capacity can be used to serve customers

               Prime capacity is that which is continuously available. Firm capacity is much
               larger and is dependent upon interconnection with other power plants and the
               extent  to  which  load  curves  permit  variable-capacity  operation.  The
               incremental  cost  for  additional  turbine-generator  capacity  is  small,  so  that

               many  alternatives  for  economic  development  of  a  site  must  be  considered.
               The alternatives include a wide variety of base load, peak load, run-of-river,
               and pumped-storage plants. All are concerned with fitting installed capacity,
               runoff,  and  storage  to  the  load  curve  of  the  power  system  and  to  give

               minimum cost over the life of the installation. In this evaluation it is essential
               clearly  to  distinguish  capacity  (kW)  from  energy  (kWh)  as  they  are  not
               interchangeable. In any practical evaluation of water power in this electrical
               era, it should be recognized that the most favorable economics will be found

               with  an  interconnected  electric  system  where  the  different  methods  of
               generating power are complementary as well as competitive.
                  As noted above, there is an increasing tendency in many areas to allocate
               hydro capacity to peaking service and to foster pumped-water storage for the

               same  objective.  Pumped  storage,  to  be  practical,  requires  the  use  of  two
               reservoirs for the storage of water—one at considerably higher elevation, say,
               500  to  1000  ft  (150  to  300  m).  A  reversible  pump-turbine  operates
               alternatively (1) to raise water from the lower to the upper reservoir during

               off-peak  periods,  and  (2)  to  generate  power  during  peak-load  periods  by
               letting the water flow in the opposite direction through the turbine. Proximity
               of favorable sites on an interconnected electrical transmission system reduces
               the investment burden. Under such circumstances the return of 2 kWh on-

               peak for 3 kWh pumping off-peak has been demonstrated to be an attractive
               method of economically utilizing interconnected fossil-fuel, nuclear-fuel, and
               hydro-power plants.


               Related Calculations. The procedures and considerations given here apply to

               hydroelectric  installations  anywhere  in  the  world.  Since  each  hydro  site  is
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