hydroelectric schemes? any help is very helpful?

Hydroelectric power operates on the principle of using flowing or falling water or the weight of water to turn turbines/generators to generate power.

In some designs, water is impounded in a lake or reservoir ...like Hoover Dam..and released through tunnels or shafts into turbines which can then turn to provide electrical power from generators...turned by the turbines.

Some designs use flowing or falling water in large rivers like Niagara Falls...the first large hydroelectric plant in the US. (The first smaller design was built in Appleton , Wisconsin in 1882)

Other designs use the height difference in tides...at high tide which can be several feet or more higher than low tide, water is trapped behind locks which allow the water to be released through turbines at low tide. A gallon of water weighs around 8.35 pounds so if you trap enough water, you have a tremendous amount of stored energy which can be used to turn turbines and create power. Flowing water in rivers, water stored in reservoirs or water stored behind locks during high tides can all be used to create power.

Pumped storage designs incorporate reusing some of the water again.

"In contrast to conventional hydropower plants, pumped storage plants reuse water. After water initially produces electricity, it flows from the turbines into a lower reservoir located below the dam. During off-peak hours (periods of low energy demand), some of the water is pumped into an upper reservoir and reused during periods of peak-demand"

http://www.green-trust.org/hydro.htm

Some hydroelectric designs also use the flow of water in ocean currents to generate power....if the current is flowing fast or strong enough, the water rushing by turbine blades can generate power although there are issues with harming aquatic life forms like fish. Some designs have paddles instead of turbine blades and can be more efficient and safer. By some estimates, micro-hydroelectric plants in the rivers of the US could provide all the electrical needs we have....they use turbines which are more efficent and safer for wildlife. Only 2 percent of the 75,000 dams in the US are used to create power.

http://wiki.uiowa.edu/display/greenergy/Hydroelect...

http://oregon.gov/ENERGY/RENEW/Hydro/Hydro_index.s...

Water for the hydro electric plant at Niagara Falls is stored in all but one of the great lakes. That is lake Ontario.

tidal storage: I don't think there is even a pilot plant. but I picture 4 one square kilometer impounds separated by dams in shallow water, so they form a square 2 kilometers on an edge. as the tide comes in electricity is generated filling two of these impounds. Just before the tide peaks these two are filled a full as possible, without generating electricity. If there is an empty impound, electricity can be generated, if needed, by moving water from the ocean or a full impound (or almost full) to the empty impound. As the tide goes out a full impound can generate electricity by returning water to the ocean. Just before low tide one or two impounds should be emptied as completely as possible, without generating electricity. In typical locations there is several hours per day when the flow of the tide is negligible. At these times we need a full impound and/or an empty impound to generate electricity if it is needed. Any significant periods when no 60 hertz electricity can be generated, will reduce the value of the project. Small amounts of low frequency ac can be used to charge batteries when the height difference is less than 1/2 meter = 19 inches, but battery storage is not yet economically viable, but perhaps close. The 6 turbines and 4 alternators (perhaps more are needed) will each only get about 25% utilization, so this reduces the economic viability of the project. The salty water will create corrosion problems and at least a rare creature, including trespassing humans will be killed by the equipment. A bad storm may mean that no electricity can be produced as protecting the costly infrastructure is a high priority. The facility may produce less than $1000 per day worth of electricity at typical wholesale prices, so pay back is likely forever considering repairs and at least one staff member is needed 24/7 Larger scale may result in diminishing returns instead of economy of scale.

pump storage is economically difficult without a tall steep hill, as the tank needs to mounted on a tall tower. Neil