Desai Harshad Suresh B050254EE

Tidal power is a form of hydropower.Tidal power is a form of hydropower.

Exploits the rise and fall in sea levels due Exploits the rise and fall in sea levels due to the tides, or the movement of water to the tides, or the movement of water caused by tidal currents.caused by tidal currents.

Although not widely used, tidal power has Although not widely used, tidal power has potential for energy generation and is potential for energy generation and is more predictable than wind power. more predictable than wind power.

Tidal energy is not a new concept.Tidal energy is not a new concept.

Energy in this form was used to grind Energy in this form was used to grind grains since 11grains since 11thth century in France and century in France and England.England.

Tidal Stream SystemsTidal Stream Systems::These make use of the kinetic energy These make use of the kinetic energy

of moving water to power turbines. of moving water to power turbines.

Barrage tidal powerBarrage tidal power::This type uses the potential energy This type uses the potential energy

from the difference in height between from the difference in height between high and low tides.high and low tides.

A relatively new technology.A relatively new technology.

Tidal stream generators draw energy from Tidal stream generators draw energy from currents in the same way as wind turbines.currents in the same way as wind turbines.

Water, being 832 times denser than air, Water, being 832 times denser than air, provides significant power from one generator.provides significant power from one generator.

As in wind power, location of the plant is As in wind power, location of the plant is important.important.

Location:Location:Tidal Stream Systems need to be Tidal Stream Systems need to be

located in areas with fast currents where located in areas with fast currents where natural flows are concentrated between natural flows are concentrated between obstructions.obstructions.Examples of such sites include entrance to Examples of such sites include entrance to bays and rivers, around rocky points, bays and rivers, around rocky points, headlands, or between islands.headlands, or between islands.

Potential sites suggested include Potential sites suggested include Channel Islands in UK, Strait of Gibraltar, Channel Islands in UK, Strait of Gibraltar, East River in NYC, Cook Strait in NZ, East River in NYC, Cook Strait in NZ, Vancouver island in Canada. Vancouver island in Canada.

The picture shows rotors in The picture shows rotors in Harland and Harland and WolffWolff, Belfast, before installation in , Belfast, before installation in StrangfordStrangford LoughLough

An artist s impression of the 40 MW Pentland Firth design at adepth of 60m and a 20m rotor for power generation

Alongside is a hybrid image of Marine Current Turbines existing SeaFlow 300kW proto type turbine which was the world s first offshore tidal turbine and was installed off Lynmouth, Devon in May 2003.

Turbines:Turbines:An emerging tidal stream An emerging tidal stream

technology is the shrouded tidal turbine technology is the shrouded tidal turbine enclosed in a enclosed in a VenturiVenturi shaped shroud or shaped shroud or duct producing a sub atmosphere of low duct producing a sub atmosphere of low pressure behind the turbine, allowing the pressure behind the turbine, allowing the turbine to operate at higher efficiency and turbine to operate at higher efficiency and typically 3typically 3 4 times higher power output 4 times higher power output than a turbine of the same size in free than a turbine of the same size in free stream.stream.

Economics:Economics:Tidal stream systems are low cost Tidal stream systems are low cost

compared to barrage and fence types.compared to barrage and fence types.

The setThe set--up cost for such systems is not up cost for such systems is not as high as that for barrage types.as high as that for barrage types.

Also the efficiency of the turbines can Also the efficiency of the turbines can be increased using shrouded turbines. be increased using shrouded turbines.

This method involves building a barrage over a This method involves building a barrage over a river.river.

The barrage turbines generate as water flows The barrage turbines generate as water flows in and out of the estuary.in and out of the estuary.

These systems are similar to a hydro dam that These systems are similar to a hydro dam that produces Static Head or produces Static Head or pressure headpressure head. When . When the water level outside of the basin or lagoon the water level outside of the basin or lagoon changes relative to the water level inside, the changes relative to the water level inside, the turbines are able to produce power. turbines are able to produce power.

La Rance- a Barrage type Tidal Power Plant in France

The power can be generated using either The power can be generated using either of Ebb Generation (Outflow generation), of Ebb Generation (Outflow generation), Flood Generation, Pumping, TwoFlood Generation, Pumping, Two-- basin basin Schemes.Schemes.

Environmental ImpactsEnvironmental Impacts::

The placement of a barrage into an The placement of a barrage into an estuary has a considerable effect on the estuary has a considerable effect on the water inside the basin and on the water inside the basin and on the ecosystem. Many governments have ecosystem. Many governments have been reluctant in recent times to grant been reluctant in recent times to grant approval for tidal barrages.approval for tidal barrages.

The impacts can be listed as The impacts can be listed as

Changes in Turbidity, Salinity, Changes in Turbidity, Salinity, accumulation of sediments at the estuary accumulation of sediments at the estuary and increase in fish mortality. and increase in fish mortality.

Economics:Economics:These type of tidal plants have high These type of tidal plants have high

capital cost and a very low running cost.capital cost and a very low running cost.

As a result a tidal power scheme may not As a result a tidal power scheme may not produce returns for many years.produce returns for many years.

A tidal power scheme is a longA tidal power scheme is a long--term term source of electricity. It is important to source of electricity. It is important to realize its full potential so that realize its full potential so that

Many countries have initiated tidal power Many countries have initiated tidal power schemes in bay areas and in seas.schemes in bay areas and in seas.

In India tidal power projects are being In India tidal power projects are being developed in Gulf of developed in Gulf of KutchKutch and the Gulf of and the Gulf of KhambatKhambat. .

CONLUSIONS:

It is the conversion of wind energy into It is the conversion of wind energy into useful form of energy, like electricity useful form of energy, like electricity using wind turbines.using wind turbines.

Wind power is used in large scale Wind power is used in large scale wind wind farmsfarms for national electrical grids as well for national electrical grids as well as in small individual turbines for as in small individual turbines for providing electricity to rural residences or providing electricity to rural residences or gridgrid--isolated locations. isolated locations.

It is estimated that there is 50It is estimated that there is 50--100 times 100 times more wind energy than plant biomass more wind energy than plant biomass energy available on Earth.energy available on Earth.

The power in the wind can be extracted The power in the wind can be extracted by allowing it to blow past moving wings by allowing it to blow past moving wings that exert that exert torquetorque on a rotor. The amount on a rotor. The amount of of powerpower transferred is directly transferred is directly proportional to proportional to the the density of the air, the density of the air, the area swept out by the rotor, and the cube area swept out by the rotor, and the cube of the wind speed. of the wind speed.

As a general rule, wind generators are As a general rule, wind generators are practical where the average wind speed practical where the average wind speed is 10 mph (16 km/h or 4.5 is 10 mph (16 km/h or 4.5 m/sm/s) or ) or greater. Usually sites are pregreater. Usually sites are pre--selected on selected on basis of a basis of a wind atlaswind atlas, and validated with , and validated with wind measurements.wind measurements.

Thus, Metrology plays an important role Thus, Metrology plays an important role in turbine placement. in turbine placement.

Onshore Installations:Onshore Installations:

Onshore turbine installations in hilly or Onshore turbine installations in hilly or mountainous regions tend to be on mountainous regions tend to be on ridgelines generally three kilometers or ridgelines generally three kilometers or more inland from the nearest shoreline. more inland from the nearest shoreline.

This is done to exploit the soThis is done to exploit the so--called called topographic acceleration.topographic acceleration.

An on shore installation in Tamil Nadu, India.

Offshore Installations:Offshore Installations:

Offshore wind development zones are Offshore wind development zones are generally considered to be ten kilometers generally considered to be ten kilometers or more from land. or more from land.

Offshore wind turbines are less obtrusive Offshore wind turbines are less obtrusive than turbines on land, as their apparent than turbines on land, as their apparent size and noise can be mitigated by size and noise can be mitigated by distance distance

An Offshore installation near Copenhagen

Near Shore Installations:Near Shore Installations:NearNear--Shore turbine installations are Shore turbine installations are

generally considered to be inside a zone generally considered to be inside a zone that is on land within three kilometers of a that is on land within three kilometers of a shoreline or on water within ten shoreline or on water within ten kilometers of land. kilometers of land.

These areas tend to be windy and are These areas tend to be windy and are good sites for turbine installation, good sites for turbine installation, because a primary source of wind is because a primary source of wind is convection caused by the differential convection caused by the differential heating and cooling of land and sea over heating and cooling of land and sea over the cycle of day and night.the cycle of day and night.

A near shore installation in Denmark

Airborne Installations:Airborne Installations:

Wind turbines might also be flown in Wind turbines might also be flown in high speed winds at altitude, although no high speed winds at altitude, although no such systems currently exist in the such systems currently exist in the marketplace.marketplace.

Asia s largest wind park in Satara district of Maharashtra with 201 MW on installation, commissioned by Suzlon Energy in 2001

Wind power can be generated for a grid Wind power can be generated for a grid as well for single customers.as well for single customers.

Small Wind is defined as wind generation Small Wind is defined as wind generation systems with capacities of 100 kW or systems with capacities of 100 kW or less and are usually used to power less and are usually used to power homes, farms, and small businesses. homes, farms, and small businesses. These systems help to reduce or These systems help to reduce or eliminate electricity bills, to avoid the eliminate electricity bills, to avoid the unpredictability of natural gas prices, or unpredictability of natural gas prices, or simply to generate clean power.simply to generate clean power.

Growth and Cost trendsGrowth and Cost trends::

Due to the exponential rise in usage of wind energy worldwide the wind energy costs are reduced. However installation costs have risen significantly.

Scalability:Scalability:A key issue debated about wind A key issue debated about wind

power is its ability to scale to meet a power is its ability to scale to meet a substantial portion of the world's energy substantial portion of the world's energy demand. demand.

There are significant economic, technical, There are significant economic, technical, and ecological issues about the largeand ecological issues about the large--scale use of wind power that may limit its scale use of wind power that may limit its ability to replace other forms of energy ability to replace other forms of energy production. production.

Economics and feasibilityEconomics and feasibility::

Without the tax incentives (also know Without the tax incentives (also know as subsidies) almost no wind power as subsidies) almost no wind power installation is economically feasible at installation is economically feasible at present.present.

Intermittency and VariabilityIntermittency and Variability::

Electricity generated from wind power Electricity generated from wind power can be highly variable at several different can be highly variable at several different timescales: from hour to hour, daily, and timescales: from hour to hour, daily, and seasonally seasonally

This variability can present substantial This variability can present substantial challenges to incorporating large amounts of challenges to incorporating large amounts of wind power into a grid system, since to wind power into a grid system, since to maintain grid stability, energy supply and maintain grid stability, energy supply and demand must remain in balance. demand must remain in balance.

There is an inverse relationship with wind There is an inverse relationship with wind speed and peak demand of electricity.speed and peak demand of electricity.

The The intermittencyintermittency of wind seldom creates of wind seldom creates problems when using wind power at low to problems when using wind power at low to moderate penetration levels (though such moderate penetration levels (though such intermittency has caused problems for grid intermittency has caused problems for grid stability in Denmark and Germany, where stability in Denmark and Germany, where penetration is greatest penetration is greatest

Grid ManagementGrid Management::Variability of wind output creates a Variability of wind output creates a

challenge to integrating high levels of challenge to integrating high levels of wind into energy grids based on existing wind into energy grids based on existing operating procedures.operating procedures.PredictabilityPredictability::

It is related to It is related to variabilityvariability but but essentially different.essentially different.

It is the short term (hourly or daily) It is the short term (hourly or daily) predictability.predictability.

Because of its variable nature, wind Because of its variable nature, wind energy forecasting presents a challenge.energy forecasting presents a challenge.

Wind energy is the best option available Wind energy is the best option available in alternate energy sources.in alternate energy sources.India ranks 4India ranks 4thth in world in terms of wind in world in terms of wind energy generation.energy generation.According to 2006 data India has an According to 2006 data India has an installed wind power capacity ofinstalled wind power capacity of6270 MW. (Global Wind Energy Council 6270 MW. (Global Wind Energy Council Statistics)Statistics)

Wind Energy, as estimated is more than Wind Energy, as estimated is more than surplus for present day human needs.surplus for present day human needs.

However the problems in areas of However the problems in areas of intermittency, grid management, intermittency, grid management, predictability, energy storage, safety of predictability, energy storage, safety of wildlife and others must be addressed to wildlife and others must be addressed to realize its full potential. realize its full potential.

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