Electricity can be generated from tidal and wave energy sources through the use of specialized technologies designed to capture the kinetic and potential energy of moving water. Both tidal and wave energy are forms of marine renewable energy that harness the power of ocean currents and waves to produce electricity.
Tidal Energy Generation:
Tidal energy is generated by harnessing the gravitational forces between the Earth, Moon, and Sun that create ocean tides. There are two main methods of harnessing tidal energy: tidal stream systems and tidal range systems.
Tidal Stream Systems: These systems use underwater turbines similar to underwater wind turbines. As tidal currents flow, the turbines are placed in their path, and the movement of water causes the turbines to rotate, generating electricity. Tidal stream systems are typically located in areas with strong tidal currents, such as narrow channels and straits.
Tidal Range Systems: Tidal range systems make use of the difference in water levels between high and low tides. They often involve building barrages or tidal lagoons across estuaries or bays. The rising tide fills the area behind the barrage, and as the tide recedes, the stored water is released through turbines to generate electricity.
Wave Energy Generation:
Wave energy is generated by capturing the motion of ocean waves and converting it into electricity. Various devices have been developed to achieve this:
Point Absorbers: These are floating devices that move up and down with the motion of the waves. The vertical motion drives a hydraulic system that generates electricity.
Oscillating Water Columns: These are partially submerged chambers with a column of air above the water level. As waves enter the chamber, the air column rises and falls, driving a turbine to generate electricity.
Attenuators: Attenuators are long, multi-segmented structures oriented parallel to the direction of the wave. The segments move relative to each other with the motion of the waves, driving hydraulic systems or generators.
Overtopping Devices: These devices capture the energy of waves by allowing them to flow into a reservoir or over a ramp. The potential energy of the water is then used to drive turbines and generate electricity as the water flows back into the sea.
These technologies harness the natural movements of water to generate mechanical energy, which is then converted into electrical energy through generators or other power-conversion systems. Tidal and wave energy sources have the advantage of being predictable and consistent, as ocean currents and wave patterns are influenced by gravitational forces and weather conditions. However, these technologies also face challenges such as the harsh marine environment, maintenance, and the need for appropriate locations with suitable resource availability.