A 'friend' of mine has proposed an idea on how to achieve energy, to me it kinda sounds like perpetual motion but not too sure. Anyways here it goes; Instead of damming up a river to create a resevoir we would use a recirculating system of water. There would be a resevoir of water but it would be a closed system. The only problem I encountered was being able to pump the water to the top after falling and turning the turbine generators. The solution is to use bouyancy. Air is lighter than water. Using this principle we could build a series of water pumps. These would use air pumps to inflate or fill rising and falling balloons or ballasts to generate power needed to bring the water back to the top. There would need to be quite a few of these in the resevoir to pump the correct amount back to the top. The other thing that is good is that these ballasts would be attached to columns. During the rise and fall the ballast systems would also create energy as well as turn turbines for the pump system. They would use magnetic cogs instead of mechanical ones. As it rises magnetic teeth would turn cogs within a casing as the ballast system rises. When it reaches the surface there will be an interlocking of the top sort like a soket plug for the exchange of electricty. With these principles there many ways to build it. That in conjuction with solar power, lunar power(The use of tidal forces and ocean waves to turn turbines) The energy would be virtually free. Meaning that the only cost would be regular maintanence.