Tidal energy
Our planet has two types of energy - renewable and non-renewable. We have to begin to explore renewable energy sources as we will eventually run out of non-renewable sources such as fossil fuels. In recent years, tidal energy that is powered by ocean tides has emerged as a forerunner of renewable energy.
Tides are the rise and fall of ocean waters. Tides are caused by moon's gravitational pull - as the Earth spins, the ocean water closest to the moon gets pulled towards the moon until it spins away; this action can be used to help generate electricity.
History: People had harnessed tides and used them for many centuries. The oldest excavated tide mill dates to 619; it was found in a monastery in Northern Ireland. This mill was most likely used for grinding grain. Tide mills eventually gained popularity during the Middle Ages. During those times, a tide mill would have a storage pond, which would fill up as the tide came in; and as the tide went out, the water rotated a water wheel. Eventually, tidal power was used to generate electricity, with the first instance being seen in France on the Rance River in 1966.
The Process: Tidal power can be converted into energy in two ways - tidal turbines and tidal barrages. Tidal turbines look like windmills, but their blades are smaller and stronger to deal with the tide. Water currents turn the blades of the turbines, which are attached to a shaft. So when the blades turn, the shaft also turns. This turning motion activates a generator, which in turn generates electricity.
Tidal barrages are similar to dams and are constructed close to a bay or an estuary. As the tide enters the barrage, the tide flows through the dam into an estuary or a bay. When the tide subsides, the barrage's gates close and trap the water. The gates then open and the water hits turbines to produce energy.
Applications: Tidal energy has several applications, some more modern than others. Tidal energy can be used for grain mills. Sometimes countries construct tidal energy stations to help save coastlines from damage as the stations act as barriers to the force of the water current. However, the most critical application is the generation of electricity in a renewable way, without producing greenhouse gases. According to estimates by the Indian government, the country has the potential to produce 8,000 MW of tidal energy. This includes about 7,000 MW in the Gulf of Cambay in Gujarat, 1,200 MW in the Gulf of Kutch and 100 MW in the Gangetic delta in the Sundarbans region of West Bengal.
Advantages: Since tidal energy stations are installed on coastlines, they leave the land area open to be explored for other uses. More importantly, when the process of energy generation takes place, there are no greenhouse gases produced. In addition to this, tidal energy is a renewable resource, which means we will never run out of ocean water. The development of tides is a well understood cycle. This makes it easier to develop tidal energy systems with the correct dimensions. This further means that it is easier to predict how much energy will be generated and when it will be generated.
Disadvantages: Tidal energy stations have high construction costs, making them initially challenging to install. While they do not impact the environment, they affect the area's aquatic life, such as fishes and other small critters, as they die when they come in contact with the blades or when they get trapped in tidal barrages. Tidal power depends on tidal surges, which mainly occur twice a day; the rest of the time, the system is rendered useless.
