Tidal energy

TIDAL ENERGY: A SOURCE GREEN ENERGY

SUBMITTED BY

MANDVI 1302050SUKANYA SAHA 1302060

ABHILASHA MITRA 1302060APAAR 1302086SEMESTER 7TH

SECTION B

FOR GREEN ARCHITECTURE

AR. DEBASREETA MISHRAPILOO MODY COLLEGE OF ARCHITECTURE

TIDAL ENERGY: A GREEN ENERGY SOURCE 2

RENEWABLE & NON CONVENTIONAL ENERGY SOURCES

Renewable energy is generally defined as energy that is collected from resources which are naturally replenished on a human timescale, such as sunlight, wind, rain, tides, waves, and geothermal heat.

Renewable energy often provides energy in four important areas: electricity generation, air and water heating/cooling, transportation, and rural (off-grid) energy services

Non- conventional energy can be defined as the energy sources which are not used as a source of mass production of energy across the world. For eg. Solar, wind, tidal, geothermal, and many others.


WHAT IS TIDAL ENERGY?Tidal energy is a form of hydropower that converts the energy of the tides into electricity or other useful forms of power. The tide is created by the gravitational effect of the sun and the moon on the earth causing cyclical movement of the seas. Tidal energy is therefore an entirely predictable form of renewable energy, which can be harnessed in two forms:• Tidal RangeTidal Range is the vertical difference in height between the high tide and the succeeding low tide.•Tidal StreamTidal Stream is the flow of water as the tide ebbs and floods, and manifests itself as tidal current.


BASIC PHYSICS OF TIDES Tidal forces are periodic variations in

gravitational attraction exerted by celestial bodies. These forces create corresponding motions or currents in the world's oceans.

Due to the strong attraction to the oceans, a bulge in the water level is created, causing a temporary increase in sea level.

When the sea level is raised, water from the middle of the ocean is forced to move toward the shorelines, creating a tide.

This occurrence takes place in an unfailing manner, due to the consistent pattern of the moon’s orbit around the earth. The magnitude and character of this motion reflects the changing positions of the Moon and Sun relative to the Earth, the effects of Earth's rotation, and local geography of the sea floor and coastlines.


TIDAL CURRENTS• SPRING TIDE: A tide just after a new or full moon, when there is the greatest

difference between high and low water.

High spring tides occur when the sun and the moon line up with the earth. This occurs when they are either on the same or opposite sides.

• NEAP TIDE: A tide just after the first or third quarters of the moon when there is least difference between high and low water.

Low neap tides occur when sun and moon line up at 90 to each other. ̊Notes: • FLOOD CURRENTS: Currents moving in the direction of the coast• EBB CURRENTS: Currents receeding from the coast.


TIDAL ENERGY GENERATION METHODS• TIDAL STREAM GENERATOR: Tidal stream generators (or TSGs) make use of

the kinetic energy of moving water to power turbines, in a similar way to wind turbines that use wind to power turbines.

Some tidal generators can be built into the structures of existing bridges or are entirely submersed, thus avoiding concerns over impact on the natural landscape. Land constrictions such as straits or inlets can create high velocities at specific sites, which can be captured with the use of turbines. These turbines can be horizontal, vertical, open, or ducted and are typically placed near the bottom of the water column where tidal velocities are greatest.


TIDAL ENERGY GENERATION METHODS• TIDAL BARRAGE: Tidal barrages make use of the potential energy in the difference in

height (or hydraulic head) between high and low tides. When using tidal barrages to generate power, the potential energy from a tide is seized through strategic placement of specialized dams. When the sea level rises and the tide begins to come in, the temporary increase in tidal power is channelled into a large basin behind the dam, holding a large amount of potential energy. With the receding tide, this energy is then converted into mechanical energy as the water is released through large turbines that create electrical power through the use of generators. Barrages are essentially dams across the full width of a tidal estuary.

RANCE TIDAL POWER STATION, FRANCE


TIDAL ENERGY GENERATION METHODS• DYNAMIC TIDAL POWER: Dynamic tidal power (or DTP) is an untried but promising

technology that would exploit an interaction between potential and kinetic energies in tidal flows. It proposes that very long dams (for example: 30–50 km length) be built from coasts straight out into the sea or ocean, without enclosing an area. Tidal phase differences are introduced across the dam, leading to a significant water-level differential in shallow coastal seas – featuring strong coast-parallel oscillating tidal currents such as found in the UK, China, and Korea.

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TIDAL ENERGY GENERATION METHODS

TIDAL ENERGY: A GREEN ENERGY SOURCE

• TIDAL LAGOON: A newer tidal energy design option is to construct circular retaining walls embedded with turbines that can capture the potential energy of tides

The created reservoirs are similar to those of tidal barrages, except that the location is artificial and does not contain a pre-existing ecosystem. The lagoons can also be in double (or triple) format without pumping or with pumping that will flatten out the power output. The pumping power could be provided by excess to grid demand renewable energy from for example wind turbines or solar photovoltaic arrays. The proposed Tidal Lagoon Swansea Bay in Wales, United Kingdom would be the first tidal power station of this type once built.


TIDAL ENERGY USES

Tidal energy is mainly used for supplying power to the electric power stations using the same principle of production of Hydro Energy

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CURRENT SITUATION OF TIDAL ENERGY

• Tidal Energy is sustainable, clean, reliable, widely distributed, and can offer significant benefits to many marine nations.

• Tidal Energy can be captured in an efficient and cost-effective way.

• Tidal Energy is not yet recognized by the United Nations as an energy resource that should receive support and funding for its development.

• Technological development in this field is not yet developed enough to produce efficient mechanisms to produce tidal energy; hence initial installation cost and maintenance cost is very high.

• Although it is an efficient and green energy source many projects in many countries are on hold due to their rich marine biodiversity.

TIDAL ENERGY: A GREEN ENERGY SOURCE


POTENTIAL AREAS FOR TIDAL RESOURCES


TIDAL ENERGY PRODUCTION SITUATION IN THE WORLD

Tidal energy is a very non conventional source of energy. Although it can be produced by many countries with no carbon footprint; still it is yet to be popularized because of its high production cost and technological shortfalls.


TIDAL ENERGY PRODUCTION STATIONS•OPERATIONAL STATIONS

•UNDER CONSTRUCTION

IMAGE REFERENCE: WIKIPEDIA


TIDAL ENERGY PRODUCTION STATIONS

•PROPOSED TIDAL POWER STATIONS

IMAGE REFERENCE: WIKIPEDIA

A tidal power plant has been proposed in Durgaduani of Sundarban, West Bengal,India but is withheld due to many controversies; of which environmental impact being the prime concern.


ADVANTAGES OF TIDAL ENERGY

Advantages of Tidal Energy (General)1) It is an inexhaustible source of energy.2) Tidal energy is environment friendly energy and doesn't produce greenhouse gases.3) As 71% of Earth’s surface is covered by water, there is scope to generate this energy on large scale.4) We can predict the rise and fall of tides as they follow cyclic fashion.5) Efficiency of tidal power is far greater as compared to coal, solar or wind energy. Its efficiency is around 80%.6) Although cost of construction of tidal power is high but maintenance costs are relatively low.7) Tidal Energy doesn’t require any kind of fuel to run.8) The life of tidal energy power plant is very long.9) The energy density of tidal energy is relatively higher than other renewable energy sources.


DISADVANTAGES OF TIDAL ENERGY

Disadvantages of Tidal Barrages•They change the movement of water into and out of estuaries, which can disrupt the life cycles of certain marine life.•They can prevent the movement of fish and other wildlife into and out of estuaries, which can disrupt spawning.•Turbines can kill wildlife that tries to swim through them.•They can increase silt deposits, which can block out sunlight and prevent plants from growing•They can change the structure of the coast and lead to erosion of dunes and other critical habitat•They prevent access to rivers and cut off shipping•Costly to build•Locations are highly limited



Disadvantages of Tidal Stream Generators•Spinning blades can kill marine wildlife•Acoustic disturbances can affect migration and other aspects of marine life•They can change the movement and rise of tides•They can interfere with shipping channels•They are more prone to damage by high waves and rough water than other systems

Disadvantages of Dynamic Tidal Power Schemes•They are very costly•They are untested and therefore their usefulness and environmental impacts are unknown•They can disrupt migration of marine life•They can change coastal structures in unpredictable ways



GENERAL1) Cost of construction of tidal power plant is high.2) There are very few ideal locations for construction of plant and they too are localized to coastal regions only.3) Intensity of sea waves is unpredictable and there can be damage to power generation units.4) Influences aquatic life adversely and can disrupt migration of fish.5) The actual generation is for a short period of time. The tides only happen twice a day so electricity can be produced only for that time.6) Frozen sea, low or weak tides, straight shorelines, low tidal rise or fall are some of the obstructions.7) This technology is still not cost effective and more technological advancements are required to make it commercially viable.8) Usually the places where tidal energy is produced are far away from the places where it is consumed. This transmission is expensive and difficult.


REFERENCES•Wikipedia.org•Study.com•Tidal energy ltd.

Environment

Tidal energy