Tidal renewable energy, also known as simply tidal energy or wave energy, is power generated from ocean tides. As ocean tides are created by the moon's gravitational pull, they generate energy. People may harvest this energy, and even create more, through the use of sizable underwater turbines, or tide generators, in oceanic areas known for high tidal movements. These turbines are very similar to wind turbines, though they are much stronger, as water is much denser than air.
During high tide, ocean water can be collected behind a barrage, and then released as the tide ebbs. As the water is dispensed, it passes through the turbine. By harnessing the kinetic energy of both high and low tides in the turbine, electricity can be produced. By eliminating the need for other sources of electricity that may produce a heavy environmental impact, tidal renewable energy is considered an effective form of alternative energy.
In addition to barrages, tidal fences may be used to collect wave energy. Composed of vertical axis turbines mounted onto a fence, they allow water to pass through, and direct it into turbines for use. The use of tidal fences is generally ideal in areas where the fence may connect two separate landmasses.
Since the rise and fall of ocean tides are constant, tidal renewable energy is considered as reliable as solar power, and other forms of green energy. Green energy sources include wind energy, geothermal power, and even nuclear power. All of these forms of energy are considered to have less impact on the environment than those that rely on fossil fuels. Utilizing tidal renewable energy is considered to be a potentially viable solution to environmental concerns such as global warming.
There are also certain disadvantages involved with using tidal renewable energy. The designs developed by the scientific community have yet to produce a fraction of the amount of electricity that people use on a daily basis. While the oceans are vast, with unlimited wave supply, few locations exist with both enough tidal range and feasible inlets for use, making producing energy on a massive scale difficult.
It has also been suggested that efforts to harvest tidal renewable energy could actually damage the environment. The barrages used in river estuaries to collect tidal energy may have the capability of changing water flow over time, which could cause an averse effect for the habitat of marine animals, plants, and birds. Tidal barrages can also affect recreation and ocean navigation. While tidal fences are considered to be more environmentally friendly as well as less costly than barrages, they too can create disturbances for marine life.