Tide power is a ecology efficient means of capaturing energy created as waters moves in the oceans currents and tides. Currently there are two methods to capture tide energy: (1) Kinetic energy, is energy created when water is moving in waters and oceans. In order to capture this energy one needs the use of turbines that produces energy when they spin. So for example, if you place turbines at areas where you have high speeds of water that move into rivers or bays, you can generate free energy. People have used this kind of energy for a long time. If you recall in Europe during the castle ages, and you have water wheels in the rivers that rotate to produce grain. China is another country that has harraness this power back in the Ming Dynasty. So the technology is not new. Its how efficient and cost effective we can produce the energy today that is causing us to take another peek at the opportunity.