1)When planning exploitation of the natural energy west of a country.
2)Progress takes time and needs a lot of capital investment Advance decisions must be taken for profitable investment in various projects to make them electrical and economical.
3)For this purpose, the anticipated electrical energy demand should be known.
4)The resources available in the country for electrical power production, e.g. for steam stations , hydro atom and nuclear power stations, can then be developed considering the electrical power and energy requirements, and the locations regions where demand is expected
5)Forecasts may be long-term forecast, medium-term forecasts or short-term forecasts.
6) Long term forecasts covering a 20 years period provide a basis for examining the energy supply problems of the country in a broader perspective in relation to various other modes of development, including conversion and substitution of different forms of primary and secondary energy
7)It takes 4 to 6 years for construction and installation of equipment in power stations, Medium-term forecasts of S or 6 years are, therefore, very important for planning the size of the stations.
8) Forecasts of demand and energy are required to estimate the additional installed capacity required to facilitate the plant maintenance programme and to estimate the firm capacity of the restricted hydro-plants.
9) Short term forecast of one or two years are mainly of value for deciding operating procedures, and for preparation of budget estimates.
