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close this book Local Experience With Micro-Hydro Technology
close this folder B. Development of hydropower resources
View the document 1. THE UNUSED HYDROPOWER POTENTIAL
View the document 2. DISTRIBUTION OF RESOURCE AVAILABILITY OVER TIME AND GEOGRAPHICAL AREA
View the document 3. CHARACTERISTICS OF HYDROPOWER RESOURCES
View the document 4. BIG OR SMALL HYDRO?

3. CHARACTERISTICS OF HYDROPOWER RESOURCES

Perhaps the most particular characteristic is that no two potential sites are alike. Topography, flow regime and volume of the river concerned, together with the geological condition of the site are variables that make each installation unique. It is also true that hydro resources must be harnessed where the potential exists. In situations where likely consumers are far away from the generating site, transmission costs are considerable. Before electricity generation came into use, all activities relying on hydropower were situated adjacent to or near the generating site, because only mechanical power transmission was possible. Therefore it is obvious that the economic value of hydro potential varies considerably in different environments.

The lack of accurate long-term hydrological data and to some extent topographical maps of insufficient detail place a severe constraint on hydropower development, mainly in developing countries. It is a specific characteristic that reliable predictability of possible firm power capability is only possible with accurate runoff data over a very long period (>30 years).

Unlike the technologies associated with many new and other renewable energy sources, equipment associated with hydropower is well developed, relatively simple, and very reliable. Because no heat (as e.g. in combustion) is involved, equipment has a long life and malfunctioning is rare. Experience is considerable with the operation of hydropower plants in output ranges from less than one kW upto hundreds of MW for a single unit.

Hydro plants are non-consuming generators of power. Once water has passed through the turbine, it is available again (although at a lower elevation) for other uses. It is a non-polluting technology which, however, may have some negative environmental impacts. From the energy conversion point of view, it is a technology with very high efficiencies, in most cases more than double that of conventional thermal power plants. This is due to the fact that a volume of water that can be made to fall a vertical distance, represents kinetic energy which can more easily be converted into the mechanical rotary power needed to generate electricity, than caloric energies.

The fact of high capital intensity in hydropower development has not favoured this resource during the time of cheap oil. Now this disadvantage is relatively smaller and outweighs in many instances variable (and probably rising) fuel costs of thermal plants, due to relatively low and stable operating costs, which are largely insensitive to outside inflation and other factors.