fossil fuel will never get exhausted intially there were finding oil onshore then it was shallow waters now just from 199o its been deep water now from 2000 they are finding oil in Ultradeep water reliance gas find was in water depth of 3000m just imagine engineering challenge of having to overcome 3000m of hydrodynamic loading which is variable based on wind, tide and current man will over come many challenges and also remember the earth has more water then land and still we have just not tapped 1% of the ocean, i am subsea engineer so if your keen to know more do mail me we will have a chat rockwater@rediffmail.com