Explain how the tidal energy is harnessed and write one limitation of the use of tidal energy.
Answers
ANSWER :
▶️Tidal energy is harnessed by constructing a dam near the shores. ▶️During the high tides water flows into the dam and during the low tides, water flows out. This flowing water rotates the turbine, present at the opening of the dam and produces electricity.
How Tidal Energy is Converted into Electricity?
Tidal energy is converted into electricity using three main tidal technologies:
- Tidal Turbines
- Tidal Barrages
- Tidal lagoons
Tidal Turbines
Tidal turbines utilize the same technology to wind turbines. The only difference is that the blades of tidal turbines are way stronger and shorter. So, the best way to compare tidal turbines is underwater windmills. Ideally, the water currents turn the turbine. The turbine is connected to a generator through a shaft. So, when the turbine turns, the shaft also turns. The turning shaft activates a generator, which generates electricity. The initial cost of setting up this tidal stream system is quite on the higher side, not to mention the difficulty in maintenance. However, it remains a cheaper alternative and doesn’t cause environmental degradation compare to other tidal technologies.
Tidal Barrages
Tidal Barrages are the most efficient tidal energy technologies. They resemble dams used in hydropower plants. The difference is they are a lot bigger since they are constructed across a Bay or an Estuary. For the barrage to be able to produce power, the tidal range, which is the difference between low and high tide, has to be more than 5 meters. As the tide enters the system, ocean or sea water flows via the dam into the basin. When the tides subside, the system’s gates close, trapping the water in the estuary or basin. When the tides start to move out, the gates in the dam that consist of turbines, open up, and water begins to flow out hitting the turbines, which eventually turn to produce energy. Construction of tidal barrages involves high upfront capital costs, plus they have devastating effects on the local environment.
Tidal lagoons
This technology has a lot in common with tidal barrages. It’s just that it doesn’t involve a lot of initial capital outlay and it’s friendly to the environment. Tidal lagoon is a power station separated from the rest of the ocean or sea. Its functionality is similar to tidal barrage since when the tide goes up, the lagoon completely fills up. When the tide subsides, the water is allowed to drain out through an opening consisting of turbines. The outward flow of water turns the turbine, which generates energy.
Advantages of Tidal Energy
By taking the time to critically analyze the advantages and disadvantages of tidal energy, you can get a clear picture of whether it’s a sustainable energy resource or not. Below is an outline of the upsides and downsides to tidal energy
It’s environmentally friendly
The fact that tidal energy technologies are installed on the coastlines and offshore makes them good for the environment since land will not be interfered with. Also, tidal energy is a clean source of energy, meaning it doesn’t release any greenhouses gasses to the atmosphere.
It’s renewable energy source
Tides harnessed to produce tidal energy result from the combined gravitational pull of the sun, moon, and earth in conjunction with the rotation of the planet around its axis. This is a natural process that occurs every single day. This means that tides will continue to occur and production of tidal energy will continue until the end of time.
It’s highly predictable
Development of tides is a well-understood cycle. This makes it a lot easier to develop tidal energy systems with the right dimensions. Why? Because the level of power the system will be exposed to is already determined. Which explains why the capacity of the installed equipment and the entire physical size has completely no energy generation limitations, even though stream generators and tidal turbines used resemble those of wind turbines.
Cost-competitive
Tidal energy technologies once constructed have the potential to generate electricity for many years, which means they are long lasting. Although the upfront costs of setting up a tidal power plant are relatively high, the return on investment will be realized in the long run. A typical example is the La Rance tidal barrage, which is still producing electricity since 1966.
Minimizes over-dependence on fossil fuels
Fossil-based sources of energy such as oil, coal and natural gas emit greenhouse gasses that lead to climate change and global warming. Tidal energy offers a green and renewable alternative to cut back on greenhouse gas emissions.
Offers a sense of protection
Barrages and dams that are utilized to tap tidal energy for the generation of electricity could insulate coastal areas and ship ports from high impact and dangerous tides in the course of bad weather and storms.
It’s quite effective than wind even at low speeds
Oceans currents have the capacity to produce more energy than air currents because ocean water is 832 times denser than air. This means ocean currents applies greater force on the turbines to generate more energy.
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