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What is Tidal energy - How Does Tidal enery work



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What is Tidal Energy ?

Tidal energy comes into existence due to rise and fall of tides when ocean surges. It is also a form of renewable energy and currently used to generate electricity in La Rance, France and Annapolis Royal, Nova Scotia, Canada. To generate electricity from tides a significant range of power is required between high and low tide. Researchers are still exploring about this form of energy as it is a new subject of study for them yet. Currently just two commercial size tidal power plants are operating worldwide; therefore limited amount of electricity is being generated with help of tidal energy. Tidal power has potential future as it more reliable than solar energy and wind power. Process of research is slow on tides because this area needs high investment and there are limited sites to work on this area.

 



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How tidal power works?

To utilize tidal power, tidal turbines are developed. These turbines look like underwater windmill and have blades on it like wind turbine. Blades on this turbine rotate at a consistent speed with fast moving current of waves. The rotor attached with the turbine use power of moving blades to drive generators that produce electricity. We all know that density of water is 832 times more than density of air; therefore blades of water turbine are smaller in size as compared to a normal wind turbine. Designing, installation and maintenance of water turbine was a big challenge for engineers but they solved all these issue with some set of engineering techniques.


Note: This image show water turbine installed inside barrage and wings rotatoes with flow of water to producing electricity.
tidal energy


Note: This video show water turbine installed inside barrage
and wings rotatoes with flow of water to producing electricity.

Ways to use tidal power:

Tides produce by ocean can be used in three different ways to get energy and generate electric power. First is its wave energy or kinetic energy that water gets due to movement of waves. This energy can power the turbine if waves rise to a chamber and force the air out from there. In this ways moving air can spin the turbine. Second is energy of tides that come into the shore. These tides can be trapped in a dam and electricity can be generated by operating dam as regular hydroelectric power plant. Third form is ocean’s thermal energy. We all know temperature is different in different depths of ocean; this idea can be used with power plants. This difference in temperature can help in generating electricity; similar projects are introduced in Japan and Hawaii to generate electricity.

Types of Tidal Generators:

There are three ways to get tidal energy and converting it into electric current, tidal streams, barrages, and tidal lagoons. Tidal turbines about which we have talked earlier use tidal stream to rotate blades of turbine. In other kind of generator large dam which is known as barrage is used. Barrage can be constructed across rivers or bays so that water can spill over the top. Turbines places inside the barrage use tidal power same like tidal stream and generate electricity. In third type tidal lagoons are constructed in which ocean water is stored. These lagoons can be near natural coastline and they work almost same like barrages.

On going Tidal energy projects:

There are many on going tidal power projects world wide, out of which the largest tidal energy station is in Europe ,it is in Rance estuary in north France, and it was developed in 1966. This tidal station is only one in entire Europe.

Tidal station, Rance estuary France

 

Proposed Tidal energy projects world wide

There is a proposed project with name Severn Barrage, in Wales. This project has been proposed in past but it never got initiated. This project estimated cost is about  £15 million. It is also stated that it will produce energy which is massive 8000 MW, which is more than 12 nuclear worth of power station. Some proposals have mentioned that it will provide 2500 MG worth of power, there is huge difference between power generation estimation and it is not appropriate to risk £15 millions worth of money. This is the main reason why this project is not yet start.

Other projects which are yet to be completed:

Tidal Power Projects ( Click the link for details) Capacity in MegaWatts

Expected years for completion

In Canada, CORE Project 15MW 2011 - Completed
In South Korea, Wando Hoenggan Waterway, 300MW 2015
In New Zealand, Kaipara Harbour 200MW 2018
In Scotland, Pentland Firth Tidal Energy Project 10MW  
In Scotland, Islay Project 2MW  

 

Cost estimation for tidal energy station:

The cost associated for developing tidal power station can vary from project to project. if capacity of generating electricity of the project is in megawatts that is obviously going to cost a lot more than if capacity is limited in kilowatts. We generally do not see tidal power plants capacity worth in Kilowatts. It is more suitable and economical when developed for large scale electricity generation.

For instance, project Severn Estuary in UK  cost US $15 billion which produces 8000 MW. 2200 MW worth of tidal power station project in San Berandino which spent US $ billion.

Advantages and Disadvantages:

Tidal energy is helping this world in reduced emission of carbon with some other significant economic benefits. This kind of renewable source has power to lighten 15 million homes by saving 70 million tones of carbon. Tidal power is still at its initial stage but growth of this sector will bring more then 16,000 jobs in UK alone.


Besides benefits, there are also some drawbacks of adopting this technology like cost of installing tidal turbine, environmental impact etc. although using tidal power does not release carbon to the environment but still some studies show that it has negative impact on aquatic and shoreline ecosystems.

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