From the Moon via the Tides

"If you take a square meter on the ground, with solar, you have around 100 watts of energy. A square meter in the air, with wind you may have a thousand watts. But off the coasts of Europe and North-America, you have energy densities of 20,000 to 70,000 watts per square meter of ocean" - Max Carcas of Ocean Power Delivery

Ocean power or tidal power is essentially a form of lunar-cum-solar power. The potential is not really as great as that claimed for wind or solar. The total usable tidal power of the world's oceans is equal to that of all the nuclear or hydroelectric power plants in the world, whereas, "Wind power could generate enough electricity to support the world's energy needs several times over" according to the famous Stanford University study. Solar power? As the Russians showed back in 1992, a 25 yard wide reflector in space could light up a 2 mile wide stretch on earth. Also according to a more detailed study of the tidal power potential world-wide released by the Wind Energy Council, the annual plant load factor rarely approaches 30% (wind does better than that sometimes.)

However ocean power continues to reflect an important interim step towards global power nirvana. Solar and wind power farms are sprawling structures, but in certain regions ocean power generating structures can be much more compact and face a bright economic future. There have been some studies in this direction in India with potential sites identified in Gujarat and West Bengal:

"The identified economic tidal power potential in India is of the order of 8000-9000 MW with about 7000 MW in the Gulf of Cambay about 1200 MW in the Gulf of Kachchh and less than 100 MW in Sundarbans. The Kachchh Tidal Power Project with an installed capacity of about 900 MW is estimated to cost about Rs. 1460/- crore generating lectricity at about 90 paise per unit. The techno-economic feasibility report is now being examined."