Tidal energy - Used, benefits and Advantages & Disadvantages

                     TIDAL ENERGY

 

Tidal energy is a renewable source of, mainly, electrical power which uses tidal currents for a generation. Tides are created by the gravitational effect of the moon and sun on the earth causing the cyclical movement of the seas. Nowadays, this energy source is not widely exploited, however, is receiving increased interest and investment due to the predictability of tides and stability which this would be offered in an electrical network.

 

The gravitational pull of the moon and sun along with the rotation of the earth cause the tides. In some places, tides cause water levels near the shore to vary up to 50 feet. Producing tidal energy economically requires a tidal range of at least 10-12 feet.

 

As with all marine technologies, tidal energy installations are typically much more expensive than others onshore renewable energy options such as solar and wind energy. So far in Canada, it is only in Nova Scotia but it is in the process of being built-in many other countries.

 

There currently exist two explicit methods of tidal energy capture; the first and best known are tidal range devise or tidal range technologies which operate using the potential the energy difference between two bodies of water either side of a man-made.

 

The 2^nd technology is advanced and newer and just beginning to be tested out on a commercial scale around the world. They fast-flowing currents to spin turbines.

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What are the benefits of tidal energy projects?

There are many benefits to the projects –

 

Technological:-   Improvement of turbine efficiency should provide a significant increase in energy yield. There are a number of additional technological aspects that determine the performance and costs of tidal current technologies:1) support structures, 2) array formation and 3) electrical connections to shore.

For tidal current technology to become a challenging alternative to conventional energy sources, increased alternation needs to be paid to technical risks in design, construction, installation and operation. Then importing knowledge and experience from other industry sectors, such as offshore oil and gas installations and offshore wind farms, environmental impact assessments and of course engineering standards, is of great importance.

Ecological:-  The potential for traditional tidal technology, which closes streams or river arms with a dam or in impoundments, is limited due to ecological constraints. A more innovative type of tidal range technology, which does not close impoundments completely, is currently in the developmental phase and will also be of interest. The ecological impacts for tidal stream technologies are deemed to be less than tidal range technologies, but environmental regulators lack the appropriate expertise or tools to assess the environmental risks such as the impact on biodiversity in sea waters.

 

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Societal:- The installation of tidal range technology leads to several important societal benefits besides renewable energy. These include flood defense, improve environmental and ecological water quality, and fisheries and tourism functions.

Industrial:- The development of tidal stream technologies has been linked to small and micro-enterprises. Consequently, there is a lack of cohesion within the industry, with many different designs and a number of small scale producers. However, large turbine manufacturers have entered this emerging sector by becoming involved in the start-up phase. The involvement of large and multi-disciplinary industries can be expected to promote synergies, which will generate economies of scale and reduce costs.

Financial:- The greatest barriers to tidal range technology advances are the relatively high upfront costs related to the developments of the dikes or embankments and the ecological implications of encloses or impoundments. According to reports, costs need to be brought down to at least 50%. Most project costs for tidal stream technologies are provided through government funds or technology developers themselves.

Infrastructural:- In Europe, the European Commission together with industry and the Member States is supporting the development of an integrated offshore grid structure to deliver offshore wind to consumers.

Planning and licensing procedures:- Planning and licensing processes for ocean energy therefore need to be open comprehensive enough to take these concerns into account. This is particularly true for sensitive areas in relation to environmental protection and nature conservation.

Leading countries are regions with good tidal resources, such as South Korea with tidal range differences of 9 to 14m, and Canada at various locations along the Lawrance River. Similarly, tidal range projects are explored in Western Australia. New test sites are planned in Chile, China, New Zealand, Portugal, Spain, and the USA.

There are many potential sites for tidal barrages worldwide, nut the upfront construction costs of the tidal barrage and associated environmental impacts are a major obstacle to further development.

Most of these initiatives are typically multi-stakeholder projects, seeking finance from the public as well as private partners. Furthermore, range projects appear to have great benefits in cases where existing dams or compounds are used, and where the objective of energy production is combined with water quality improvement.

 

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How do we use tidal energy?

 

Tidal is the result of the interaction of the gravity of the sun, earth, and moon. The rise and fall of the tides – in some cases by more than 12m — creates potential energy, and the ebb and flow currents create kinetic energy. Both forms of energy can be harvested by tidal energy technologies like renewable energy.

The tidal mill has been used in Europe around the year 700. Since the 1960s, five projects have been developed commercially.

Tidal range technologies harvested the potential energy by the difference between low and high tides.

Most conventional tidal range schemes use bulb turbines, which are comparable to hydropower turbines that are installed in a dam( run of rivers hydropower plant). Technology developments are comparable to the development of wind turbines. There are a number of other designs that are in the research and development stage. This category includes rotating screw-like devices and tidal kites that carry turbines below their wings.

What are the advantages and disadvantages of tidal energy?

Advantages –

1. Tidal current and the tidal range is that they are relatively predictable with daily, bi-weekly,    biannual and even annual cycles over a longer time span of a number of years.

2. Tidal energy can be generated both day and night.

3. Tidal energy is endless renewable.

4. Tidal energy plants have very low running costs.

5. Tidal energy creates no emissions due to the way it works.

 

Disadvantages –

1. Actually, the prime problem of tidal energy is an environmental issue because we have unknown its effect in environmental.

2. The initial cost of setting up The tidal energy operator plant is too high.

3. It may impact on sea fish, marine mammals, and birds.

4. Tidal energy is one of the most location-specific renewable energy sources.

5. Tidal turbines can be difficult to maintain.

6. Both tidal turbines and tidal barrages can restrict access to open waters.

 

Some other details:-

Worldwide, the tidal resources are considerable and also largely unmapped. However, global resources are estimated at 3 TW. The technically harvestable part of this resource, in areas close to the coast, is estimated by several sources at 1 TW, which is equivalent to the current installed capacity in hydropower. Total tidal range deployment in 2012 was around 514 MW, and around 6MW for tidal current.

The first tidal barrage was complete in the Rance River in north-western France (Brittany) in 1966, but due to plans for greater use of nuclear energy, the further pursuit of tidal energy was abandoned. Between 1966 and 2011, a number of small tidal plants were built in other countries where tidal energy resource is abundant.

Extensive plans exist for tidal barrage projects in India, Korea, the Philippines, and Russia adding up to around 115 gigawatts. Deployment projections for tidal current up to 2020 are in the range of 200MW.