As science looks forward to explore and identify new sources of alternate energy, there is an increased focus on harnessing the inherent power of nature to create more energy sources. Tidal energy is one form of energy which uses the energy of tides to power turbines to generate electricity. A tide is caused by a periodic variation in the gravitational forces of primarily Earth and moon, and also the sun. This variation causes the water level to fluctuate – a rise is called a high tide and a decrease is called a low tide. This phenomenon occurs daily or sometimes more than once, and is prominent in large water bodies such as seas and oceans.
Tides have been used to power grain mills since ancient times. They were believed to be used during the Roman times- with evidence of usage in 6’ century being found in Ireland. This was done by using a tide mill which is a structure build to store water at the time of a high tide, and then release it during the low tide. The accumulated water is used to move giant wheels which were used to crush grains. The town of Rupelmonde near Antwerp Belgium has one of the historic tide mils which is still working.
This natural phenomenon is now being used to generate electricity by driving turbines. They make use of the energy accumulated by the tide by its motion, and also by its height to drive turbines which generate electricity. An example of tidal generator is the Sihwa Lake Tidal Power Station in South Korea that was commissioned in the year 2011. This plant produces a peak of 254 MW of electricity, and is the world’s biggest tidal power station. The second largest plant is the Rance tidal power station, which can generate up to a peak of 240 MW of electricity during both high and low tides.
The cost of setting-up a tidal power generator is expensive, and the quantity of power generated by it would not make it very quickly recover the manufacturing costs. However, over a period of time, such generating units can actively contribute to the total power generation. Also, it’s a renewable form of energy which does not involve polluting the environment, and can be harnessed as an energy alternative. The biggest challenge of tidal power generation is the less number of places where the tidal energy is strong enough to drive turbines to produce substantial current. Also, the high costs involved in setting-up the plants do not make it an economically viable option. There is an ongoing research in optimizing the generation by designing new turbine systems, and it remains to be seen as to how they are incorporated.