Page 282 - Handbook of Energy Engineering Calculations

the total investment than is the cost for the basic structures, real estate, and
transmission facilities. Long life is characteristic of hydroelectric
installations, and the annual carrying charges of 6 to 12 percent on the
investment are a minimum for the power field. Operating and maintenance
costs are lower than for other types of generating stations.

3. Assess the site and its runoff and static head
The fundamental elements of potential power, as given in the equation above,
are runoff Q and head H. Despite the apparent basic simplicities of the
relation, the technical and economic development of a hydro site is a complex

problem. No two sites are alike, so the opportunity for standardization of
structures and equipment is nearly nonexistent. The head would appear to be
a simple surveying problem based largely on topography. However, geologic
conditions, as revealed by core drillings, can eliminate an otherwise

economically desirable site. Runoff is complicated, especially when records
of flow are inadequate. Hydrology is basic to an understanding of water flow
and its variations. Runoff must be related to precipitation and to the disposal
of precipitation. It is vitally influenced by climatic conditions, seasonal

changes, temperature and humidity of the atmosphere, meteorological
phenomena, character of the watershed, infiltration, seepage, evaporation,
percolation, and transpiration. Hydrographic data are essential to show the
variations of runoff over a period of many years. Reservoirs, by providing

storage, reduce the extremes of flow variation, which are often as high as 100
to 1 or occasionally 1000 to 1.

4. Evaluate the economic factors affecting the generating capacity installed
The economic factors affecting the capacity to be installed, which must be

evaluated on any project, include load requirements, runoff, head,
development cost, operating cost, value of output, alternative methods of
generation, flood control, navigation, rights of other industries on the stream
(such as fishing and lumbering), and national defense. Some of these factors
are components of multipurpose developments with their attendant problems

in the proper allocation of costs to the several purposes. The prevalence of
government construction, ownership, and operation, with its subsidized
financial formulas which are so different from those for investor-owned

projects, further complicates economic evaluation. Many people and groups