**Different form of hydropower projects are as follows:****Run-off river
plant:**This type of hydropower is usually built in the perennial river (flow in
river available throughout the year). Water retaining structure such as dam is
constructed of small heights to increase the head of flow and not for the
storage purposes to be used during the flow slack time. So the power to be
generated is the function of the discharge of the river and maximum during the
excess flow period and decreases during the dry period. Due to the small nature
of the structures to be constructed than that of the storage projects this type
of projects is not much cost and could be built within the relatively short
period of time compared.
In case of wide rivers at the plain area and of perennial type, where gain in
head is difficult to achieve due to the topographical condition but sufficient
discharge is available, power should be generated through the low head plants
embodied with the dam spanning inside the river.
As it is known fact that flow of river during the dry season is the minimum
stage and due to that energy production is also curtailed. As the power demand
is not much varying during the dry period, there will be chances of energy
shortage during the dry season. In order to cope this problem, water is needed
to be stored when there is excess low in the river. In order to store the water,
necessary is to build some storage pond and utilized it during the needy period.
For construction of storage pond retaining structures like dam is required.
Accumulation type: (pumped storage plant)
This type of projects is usually constructed in the countries where there is
storage of water throughout the period or places where there is availability of
two reservoirs naturally. The water stored shall be used again and again in a
cyclic manner during scarcity of flowing water. It could be termed as the plant
for the indirect storage of surplus energy generated by other plants. As the
generated electricity is not possible to be stored, so it has to be instantly
used while being generated. So the electricity generated from any source of
plants (hydroelectric, thermal or nuclear) could be utilized to pump the water
to upstream reservoir and then utilized it when required. Commercially, such
projects are very much suitable when there is much variation of energy demand at
day and the nighttime where the energy rate is different during this period.
During night time cheap energy could be purchased to pump the water to upper
reservoir and at the day time much expensive energy could be produced for
selling. Most of all the best feature of this type project is reversible use of
Tidal hydro project:
Hydropower could also be generated through the tidal rise in the sea and is
termed as the tidal power. The suitable location for such purposes is the bay
where relatively short dam could divide the bay with the sea. Due to action of
the sun and moon, tides get rise at the sea and the rise of potential water
head, thus developed potential head could be utilized for the power generation.
Depending upon the geographical location, depth of water and wind speed, rise in
the water level could be from one meter up to 15 meter. Low head turbines
equipments and sluice holes are embodied inside the dam body. When the tidal
rises the turbines openings are shut and sluice holes are opened to fill the
bay. After the maximum level of the water at eh bay is raised, sluice holes are
shut down and turbines are run for the power generation.