Geoffrey Chaucer once penned the proverb “Time and tide wait for no man.” This emphasizes how dependable and consistent the tide is. Nothing can change the fact that it comes and leaves twice daily.
We have been harnessing hydropower, or the movement of water in rivers, to run electric generators for more than 140 years. The water currents produced by the tides rolling in and out are used by different types of tidal energy systems to do the same thing.
Similar to wind turbines, tidal turbines are powered by the flow of water rather than air. These turbines power generators, which then send electricity into the system via undersea cables. Aquaculture and ocean research are two examples of ocean enterprises that can be powered by tidal energy.
In places with a wide tidal range—the distance between high tide and low tide—engineers devised methods to harness tidal movement to generate power during the 20th century. Each technique turns tidal energy into electricity using specialized generators.
Production of tidal energy is still in its infancy. So yet, not much power has been generated. There aren’t many commercial-scale tidal power facilities in operation worldwide.
The first was in France’s La Rance. The Sihwa Lake Tidal Power Station in South Korea is the largest facility. Russia, Canada, France, England, and China have the most potential for using this kind of energy.
Table of Contents
Types of Tidal Energy
Anywhere there is a strong enough tidal current, whether it be natural or created, tidal energy systems can function. They may move independently or in groups (arrays), and they can float or rest on the ocean floor. There are now just a few basic categories of systems that are utilized to harvest tidal energy.
- Tidal Stream Generator
- Dynamic Tidal Power
- Tidal Barrage
- Tidal Lagoon
1. Tidal Stream Generator
Turbines are positioned in tidal streams for the majority of tidal energy generators. A swiftly moving body of water produced by tides is known as a tidal stream. A turbine is a device that harnesses the power of fluid flow. This fluid may be liquid (water) or air (wind).
Tidal energy is more potent than wind energy because water is much denser than air. In contrast to wind, tides are steady and predictable. Tidal generators deliver a consistent, dependable stream of electricity wherever they are employed.
Turbine placement is challenging since the enormous machines disturb the tide they are seeking to harness. Depending on the size of the turbine and the location of the tidal stream, the environmental impact could be severe.
The best conditions for turbines are in shallow water. By doing this, more electricity is generated and ships may travel around the turbines. To prevent marine creatures from becoming entangled in the system, tidal generator turbine blades also rotate slowly.
The first tidal power plant in the world was built in Northern Ireland’s Strangford Lough in 2007. Between the Strangford Lough inlet and the Irish Sea, there is a small strait where the wind turbines are situated. The strait’s tide can move at a speed of 4 meters (13 feet) per second.
2. Dynamic Tidal Power
A novel concept for harnessing tidal energy, known as dynamic tidal power (or DTP), is still in the theoretical stages. Utilizing an interplay between kinetic and potential energies in tidal flows is the goal of this technique.
It suggests building extremely long dams (say, 30–50 km long) that extend directly from beaches into the ocean or oceans without confining a neighborhood.
Since the tide would constantly be moving from one side of the dam to the other, these could capture power continuously. But nobody has yet put this concept to the test in the actual world.
3. Tidal Barrage
Tidal barrages are the most effective way to harness tidal energy. An artificial tidal basin is produced by constructing a dam-like structure over an ocean entrance or tidal river. The water flow through the barrage’s turbines is managed by sluice gates.
The potential energy contained in the height (or hydraulic head) differential between high and low tides is utilized by tidal barrages.
The temporary increase in tidal power caused by rising sea levels, which causes the tide to start coming in, is directed into a vast basin behind the dam, which is holding a lot of potential energy. This energy is then transformed back into energy with the retreating tide.
A barrage system’s effects on surroundings may be fairly considerable. The tidal range’s land is destabilized. Plant and animal life in the tidal lagoon could be harmed by the change in water level. The species that may dwell there alter as the salinity inside the tidal lagoon decreases.
Fish are prevented from entering or leaving the tidal lagoon, just like with dams across rivers. Marine animals may become entangled in turbine blades due to their rapid movement. Birds could choose to move to different locations if their food supply is restricted.
When generating tidal energy, a barrage is significantly more expensive than a single turbine. Barrages require greater building and more machinery even when there are no fuel expenditures involved. Barrages need regular supervision to regulate power output, unlike single turbines.
4. Tidal Lagoon
A sizable area of seawater that is surrounded by a retaining wall is called a tidal lagoon. Water flowing into and out of the lagoon generates electricity that is captured by turbines. Although several are being built, there are no tidal lagoons presently.
Building circular retaining walls with turbines installed in them to collect the potential energy of tides is the new tidal energy design option. The artificially formed reservoirs are similar to those created by tidal barrages, but they lack an existing environment.
The blade strikes fish trying to enter the lagoon, turbine noise, and modifications to the sedimentation process are often risks connected with tidal lagoons.
Tidal lagoons don’t have much of an effect on the ecosystem. Rock is a natural building material that can be used to create lagoons. At low tide, they would resemble a low breakwater (sea wall), and at high tide, they would be submerged.
Smaller species may swim inside the structure and larger ones could swim around it. Smaller fish would presumably thrive because the lagoon would be impenetrable to large predators like sharks. Many birds would probably congregate there.
However, the amount of energy produced by generators employing tidal lagoons is probably small. There are currently no working examples. Near its border with North Korea, China is building a tidal lagoon power plant at the Yalu River. In Swansea Bay, Wales, a small tidal lagoon power plant is also being planned by a private enterprise.
Systems that use tidal energy can be quite effective. Tidal turbines, according to engineering firm N-Sci, transform 80% of the energy of the tides into power.
That is significantly more efficient than coal, oil, or natural gas, as well as current wind or solar energy systems. Power plants only release 30% to 45% of the energy contained in these fossil fuels, according to the Energy Information Administration.
The production of tidal energy is still a new technology. Few tidal power plants exist currently, and none exist in the United States. The 254-MW Sihwa Lake power station in South Korea is currently the largest tidal power facility.
Because it is dependable, renewable, and clean, tidal power has a lot of potential. But there are still several significant obstacles to be addressed, particularly in terms of cost.
It is improbable that tidal power will ever be a significant energy source in the United States. There aren’t many places in our country where we might harness tidal energy affordably. Other nations, such as Canada, China, France, Russia, and the United Kingdom, are better placed to benefit from tidal energy’s potential.
In actuality, they’ve already begun. Tidal lagoons on the Yalu River in China, Swansea Bay in Wales, and a 398-MW tidal stream array in Scotland are among the projects now under construction. More initiatives might be undertaken if these plants show to be economical.
What is the most common type of tidal energy?
Tidal stream arrays
One or more turbines are submerged in a tidal stream in the simplest and most typical tidal system. Tidal streams, like straits or ocean inlets, are swiftly flowing bodies of water produced by tidal flow. Unfortunately, there aren’t very many of these places available.
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