Tidal Energy with Davidson Hill Venturi turbine.

A great source of energy largely untapped is is the energy from the ocean currents it is also called Tidal Energy. The tides in oceans are caused by the gravitational effects of the sun and moon. Tides follow a pattern and can be predicted years in advance unlike wind. Water is 832 times denser than air so a relatively small turbine can produce large amounts of electricity as compared to Wind Turbines. 

This is the diagram of the davidson hill venturi turbine , it makes use of the Venturi effect the flow of ocean current is in the smaller side of the turbine so at the other end where the area of the crossection is larger there  velocity of flow of water is reduced thus creating a low pressure area which leads to more current rushing towards that side via the turbine thus making the turbine rotate a very high amount of efficiency is achievable through the Davidson Hill Venturi turbine ,This video of Davidson Hill Turbine will explain more .

Tidal energy is a largely untapped but a very promising source of energy , and it would have very low maintenance costs. This link would shows that a DHV turbine with a 10 meter rotor will produce a few megwatts of electricity at moderate water speeds. 

      Fossil fuel and coal are  getting scarse and of course their combusiton leads to realese of green house gases which are resulting in global warming tapping into renewable sources of energy like tidal energy can produce many terawatts of energy without producing any pollution no loss of limited natural resource. 

We can do away with coal and gas based power plants at least in areas of earth that are within a distance of 1000 kms from the ocean.

       Talking in context of India we have one of the longest coastlines in the world, the power of the sea currents across Arabian Sea, Indian ocean and Bay of Bengal can be tapped into and power can be generated for entire south, east and western parts of India.