Monday, 13 August 2012

Harvesting green tidal energy
5 Aug 2012

Ocean power is an endless source of renewable green energy. It is clean, environmentally acceptable and economically cheap. Electricity generation from ocean energy is based on tidal power, wave energy, ocean thermal energy conversion, ocean winds and salinity gradients. Among these, three well developed technologies are tidal power, wave energy and ocean thermal energy conversion. Tidal energy is a form of hydroelectric that converts the tidal power into electricity. It requires large tidal differences.

This difference between the mean high-water volume and the mean low-water volume of an estuary is called tidal prism. The term 'tidal prism' can be defined as the total amount of water that flows into a harbor or flows out again with movement of the tide in water flow. Tidal energy has been used since the,Roman times and in the middle Ages in Europe to run early tide mills. No doubt, this energy is pollution free and environment friendly. Therefore, world must think to replace fossil fuel based energy by this green energy.

In the present time, a number of countries have already been, using tidal power to generate electricity. World's largest plant for the generation of electricity from tidal power is in La Rancee in France. A number of tidal power based power stations have been established in North America. India has planned to generate electricity from tidal power very soon. Bangladesh has to think about this to overcome its present electricity crisis and the future energy security. The position and shape of Bangladeshi coast and its Islands are favorable for the establishment of tide based power station.

Tides result from the gravitational attraction of the Earth-Moon-Sun system acting on the earth's ocean. Tides are long period waves that result in the cyclical that generate electricity from horizontally flowing tidal currents like wind turbines. Tidal energy is predictable than,wind power and solar power, but cannot be used to generate electricity at consistent level constantly. Twice in every 12.42 hours (24 hours in some locations) the tidal current speed and hence the electricity generation capacity falls to zero. If tidal power is required to produce a sustained based load for local grid, then some form of energy storage or back-up will be needed.

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