May 10th, 2009 
Tushar Mathur Hydro-power has been used for a variety of functions over the years. It was used in flour mills, where water-wheels turn a shaft, that ground the flour, and even in irrigation system thousands of years ago. These days, it has a more prominent role as a renewable source of energy.
There are three methods to producing hydro-power: hydro-electric energy, tidal energy. and through ocean waves.
Hydroelectric dams:
This is the most common form of hydro-power, making up the majority of all renewable energy produced. Electricity is produced in hydroelectric dams where the force of falling water drives massive turbines.
What makes hydro-electric dams so popular is that they have two very important roles – to store and distribute water to various cities, and generate thousands of megawatts of electricity at the same time.
The disadvantage is the devastating effect dams can have on plants, animals and even humans. When dams are built they flood large tracts of land that were once occupied by various species and communities of people. Furthermore, the water-borne animals, such as fish can also be affected. An example would be salmon that are blocked from swimming upstream to spawn by the newly erected dam.
Tidal Power:
Using the tides is the second most common form of hydro-power. Here, electricity is generated by using the low and high tides.
France and Russia have successfully used tidal power since 1966. One system is used in large bays and estuaries where water from the high tide is dammed up and diverted through turbines at low tide.
Because it works with the tides, the system is very predicable. However this is also its pitfall, since it only works every 6 hours when the tides changes.
A second, more recent, tidal system looks very much like an underwater wind turbine. Large windmill like turbines are sunk in shallow water, where they are slowly spun by shifting tidal water.
Since this system is an underwater version of a wind turbine, the technology is up to date and refined. Also, water has a high density than air, so the turbines can spin in the lightest of currents.
The drawback is that the current systems can only be built in shallow water, where tidal activity is greatest. This is very limiting since many other economic activities – like oyster farming – occur in the shallows. Furthermore, these structures can damage marine life on the seafloor.
Wave Power:
This is the latest in hydro-power technology. Here oceans surface waves displace and compress air that is then fed through turbines, that generate power. These systems are either attached on floating platforms in the open ocean, or built along the shore where waves break.
Although this technology is relatively new, it has been estimated that there is enough energy in ocean waves to produce up to 2000 Megawatts of power.
But, like any renewable energy system, there are environmental implications. These systems can damage the various corals and other ocean species along our coastlines. And the hydraulic fluid used could cause major water pollution if it ever leaked out into the sea.
Conclusion:
Over the years we have come up with advanced methods of using water to produce power. Though there are a variety of benefits to using this kind of renewable energy, there are still a number of social and environmental concerns.
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