Introduction hydroelectric Power what is it?

Low-head Hydropower 
A low-head dam is one with a water drop of less than 65 feet and a generating capacity less than 
15,000 kW. Large, high-head dams can produce more power at lower costs than low-head dams, 
but construction of large dams may be limited by lack of suitable sites, by environmental 
considerations, or by economic conditions. In contrast, there are many existing small dams and 
drops in elevation along canals where small generating plants could be installed. New low-head 
dams could be built to increase output as well. The key to the usefulness of such units is their 
ability to generate power near where it is needed, reducing the power inevitably lost during 
transmission. 

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Peaking with Hydropower 
Demands for power vary greatly during the day and night. These demands vary considerably 
from season to season, as well. For example, the highest peaks are usually found during summer 
daylight hours when air conditioners are running. 
Nuclear and fossil fuel plants are not efficient for producing power for the short periods of 
increased demand during peak periods. Their operational requirements and their long startup 
times make them more efficient for meeting baseload needs. 
Since hydroelectric generators can be started or stopped almost instantly, hydropower is more 
responsive than most other energy sources for meeting peak demands. Water can be stored 
overnight in a reservoir until needed during the day, and then released through turbines to 
generate power to help supply the peakload demand. This mixing of power sources offers a 
utility company the flexibility to operate steam plants most efficiently as base plants while 
meeting peak needs with the help of hydropower. This technique can help ensure reliable 
supplies and may help eliminate brownouts and blackouts caused by partial or total power 
failures. 
Today, many of 
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powerplants are used to meet 
peak electrical energy 
demands, rather than 
operating around the clock to 
meet the total daily demand. 
Increasing use of other 
energy-producing 
powerplants in the future 
will not make hydroelectric 
powerplants obsolete or 
unnecessary. On the 
contrary, hydropower can be 
even more important. While 
nuclear or fossil-fuel 
powerplants can provide 
baseloads, hydroelectric 
powerplants can deal more 
economically with varying 
peakload demands. This is a 
job they are well suited for. 

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