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“Tidal Energy and its prospects in Bangladesh”

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Supervised By

Dr.Farseem Mannan MohammedyDept. of Electrical & Electronic Engineering(EEE)Bangladesh University of Engineering & Technology(BUET).

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Group Members

Md. Mahbubuzzaman (ID: ET063502) Mohd. Shahidul Islam (ID: ET063508) Md. Mahfuzar Rahman (ID: ET061259)

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Outline

Objective

Energy situation in Bangladesh

Tidal energy: an alternative

Production methods of Tidal Power

Prospects in Bangladesh

Output power & cost estimated

Future possibility

Conclusion

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Objective

We collect Tidal data & theoretical analysis for help of production and estimation of generation capacity of Bangladesh.

We tried to establish the fact that tidal energy can be a useful

alternative to fossil fuel and reduce power crisis.

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Energy situation in Bangladesh

Rapid growth in the demand of energy with accompanying shortages.

We are facing a severe power crisis.

Bangladesh at present generates 4538 MW power daily against its pick hour demand of 5500 MW (as of 30-08-2010) every day.

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A major portion of the generated power comes from natural

gas, coal, oil, hydroelectricity etc.

Natural gas alone is responsible for almost 83% of total energy production.

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Unfortunately, Bangladesh is facing a serious gas crisis also.

In this crisis period, power generation based on alternative resources has become a crying need for Bangladesh.

Renewable energy, a viable solution in this case.

Solar, tidal, wind, wave and geothermal energy are considered as renewable energy.

Tidal energy technology and future prospects of all selected technologies for power generation.

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Tidal energy: an alternative

Tidal power is generated by capturing the energy of tides caused by the gravitational pull of the moon and sun on the world’s oceans.

The effect of the moon is about twice the of the sun due to its much closer position to the earth.

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As a result, the tide closely follows the moon during its rotation around the earth, causing the movement of a huge amount of water twice daily.

Tides are predictable in nature as well as vast in amount.

There is no doubt that it can play a vital role in power generation.

The rise and fall of the tide is regular, which makes it very predictable and reliable.

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Production Methods

Production Methods of tidal power:

Tidal Barrages Tidal Fence Tidal Turbine

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Tidal Barrages These work quite like a hydro-electric system.

A huge dam (called a "barrage") is built across a river estuary.

The ebb and flow of the tides can be used to turn a turbine.

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Tidal Barrages( animated image)

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Category of generation

Ebb Generation The return of the tide to the sea (falling tide) The largest existing projects are:

Flood generation The rise of the tide toward land (rising tide)

• La Rance, France, 240 MW• Annapolis Royal, Canada, 18 MW• Murmansk, Russia, 0.4 MW

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Two-way generation Requires reversible pitch turbines, or pumps as turbines,

which are usually more complex and expensive. Multiple basin systems

Multiple-basin schemes involve two or three basins formed nearby to each other, equipped with sluice gates in between them.

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Location Bristol Channel (Severn Estuary), England

Tidal Range 14m

Length 16093.44m

Output Power 8640 MW

Duration time for Construction 8 years

Construction Cost £15 billion

No. of Turbine Uses 216

Life Time 120 years

Severn Barrage Tidal Power Plant

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Severn Barrage Tidal Power Plant

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Advantages of Tidal Barrages

High predictability. No fuel cost. Protection against floods. Low maintenance cost. Benefits for transportation (bridge). Some environmental benefits.

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Disadvantages of Tidal Barrages

The barrages sometimes interfere with shipping.

A barrage across an estuary is very expensive to build.

Barrages affect fish migration and other wildlife.

Expensive to construct.

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Tidal Fence Tidal fences look like huge turnstiles. They can reach across

channels between small islands or across straits between the mainland and an island.

Generate as much energy as winds of much higher velocity. Because seawater has a much higher density than air.

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Location Dalupiri (Samar), Philippines

No. of Turbine uses 274

Turbine generates power 7-14 MW

Length of the plant 4000 m

Depth of the plant 41m

Total output 2200 MW

Cost $2.8 Billion

There are no large-scale commercial tidal fences currently in operation anywhere in the world.

There are plans to construct a fence across the Dalupiri.

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Advantages of Tidal Fence

All the electrical equipment (Generators & Transformers) can be kept high above the water.

Produces electricity 24 hours a day.

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Disadvantages of Tidal Fence

It is very costly.

Maintenances is very difficult.

Required large area.

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Tidal Turbine Tidal turbines look like wind turbines. They are arrayed

underwater in rows, as in some wind farms. Ideal locations for tidal turbine farms are close to shore in

water depths of 20 to 30 meters (65.5 to 98.5 feet).

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Tidal Turbine (video clip)

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There are no operational tidal turbine farms.

European Union officials had identified 106 sites in Europe as suitable locations for such farms.

The Philippines, Indonesia, China, and Japan also have underwater turbine farm sites that could be developed in the

future.

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Advantages of Tidal Turbines

Low Visual Impact. Mainly, if not totally underwater.

Low Noise Pollution. Sound levels transmitted are very low. High Predictability.

Tides predicted years in advance, unlike wind. High Power Density.

Much smaller turbines than wind turbines for the same power.

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Disadvantages of Tidal Turbines

High power distribution costs.

High maintenance costs.

Fairly limited upside capacity.

Irregular power generation.

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Upcoming Tidal Power Project:

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Electromechanical works – general aspects

Turbine Type.

Gates.

Transmission Line and Connections.

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Turbine Types

Most common are

The Bulb type The Rim type The Tubular type Vertical-axis tidal turbine Horizontal-axis tidal turbine

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The Bulb type :

A bulb turbine is one in which water flows around the turbine.

If maintenance is required then the water must be stopped which causes a problem and is time consuming with possible loss of generation.

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The Rim type :

The generator is mounted at right angles to the to the turbine blades, making access easier.

This type of turbine is not suitable for pumping and it is difficult to regulate its performance.

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The Tubular type :

The blades of this turbine are connected to a long shaft.

They are orientated at an angle so that the generator is sitting on top of the barrage.

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Vertical-axis tidal turbine :

Vertical-axis turbines, in which the axis of rotation is vertical with respect to the ground (and roughly perpendicular to the water stream).

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Horizontal-axis tidal turbine :

Horizontal-axis turbines, in which the axis of rotation is horizontal with respect to the ground (and roughly parallel to the water stream).

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Gates

Gated structures are commonly used in salt water applications, for example tidal barrages and lock gates.

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Transmission Line and Connections

The transmission of generated power from the tidal power station will require the installation of considerable lengths of overhead high voltage transmission line.

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Tidal Power Prospects in Bangladesh

Bangladesh has a long coastal area with 2~6 m tidal head/height rise and fall. Bangladesh may harness energy from coastal tidal resources by applying two

technologies:

Low head tidal movements (2~5 m head).

Station River HighWater (m)

LowWater (m)

Range (m)

Hiron point Pussur 3.02 0.12 2.90

Golachipa Lohalia 2.87 0.32 2.55

Patuakhali Lowkate 2.50 0.32 2.18

Barisal Kirton Khola 1.76 0.20 1.56

Chandpur Dakatia 1.68 0.31 1.37

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Medium head tidal movements (> 5 m head).

Station River High Water (m)

Low Water (m)

Range(m)

Sandwip Meghna 5.73 0.20 5.53

Mongla Pussur 4.30 0.03 4.27

Sadarghat(Ctg.) Karnaphuli 4.26 0.32 3.94

Cox’s bazar Baghkhali 3.97 0.43 3.54

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Tidal Level in Coastal Bangladesh (BIWTA, February-March, 2010)

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The Sandwip Project

The 5 m tides experienced at Sandwip results in poor accessibility, with the island constantly surrounded by mud flats, except during high tides.

A flood control barrage exists around the entire island and this contains 28 sluice gates.

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The tides in Sandwip show roughly a 5 hour 'in' and 7 hour 'out' cycle. Traditional tidal technology would generate large quantities of energy during approximately 6 hours of this cycle.

Low tide High tide

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Sandwip, River: MeghnaFrom the previous table,Tidal Range = 5.53m

Let, Basin area, A= 4 × 106 m2

Density of sea water ,d= 1025.18 kg/m3

Potential energy( high tide)= ½ × A × d ×g ×h2

= ½ × 4 × 106 × 1025 × 9.81 × (5.53)2

= 6.14 × 1011 J (approx)

Now we have 2 high tides and 2 low tides every day. At low tide the potential energy is zero. Therefore,

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The total energy potential per day = Energy for a single high tide × 2 = 6.14 × 1011 × 2 = 1.23 × 1012 J

Therefore, the mean power generation potential = Energy generation potential / per day

= 1.23 × 1012 J / 86400 s = 14.23 MW

Assuming the power conversion efficiency to be 30%: The daily-average power generated

= 14.23 MW × 30%

= 4.27 MW (approx) (for 1 turbine).

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*Here , we use only 1 turbine each of above prospects sites .

Output power of tidal energy in some prospects sites of Bangladesh.

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Cost Estimated for Sandwip Sites:

Contingencies Amount (Taka)

1) Feasibility study (Preliminary civil design ,E/M design, System modeling, Project management)

68,700

2) Development (Detail design, Tendering , Project management, Construction supervision)

1,52,76,000

3) Construction-Civil works (Basin ,Access Road, Site Establishment, Powerhouse Construction)

76,38,21,000

4) Construction-E/M Works (Turbine/Generator/Control, Circuit Breaker and Protection, Transmission Line, Communications, Fire and Intruder Alarms, Monitoring and Control, Installations)

1,78,71,000

5) Operation and Maintenance 25,05,000

6) Total Cost 79,95,41,400

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Overview of Sandwip Project

Tidal Range 5.53 m

Basin area 4 × 106 m2

No. of Sluice gates 28

No. of turbine uses 05

Type of turbine Tubular turbine

Minimum construction time 03 years

Total cost 79,95,41,400 taka

Total output 21.35 MW

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Sandwip, as is seen with a tidal range of 5.53 meters and an estimated power of 21.35 MW is undoubtedly the place to continue further research.

If we use more turbine then output power will be increases.

so, we can easily say that , Sandwip is the most promising sites in all coastal area of Bangladesh.

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The accumulated data show that the coastal area of Bangladesh can be a suitable place for such a power plant installation.

Although more research and analysis is necessary before going to actual generation process.

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Advantages of Tidal energy

Tidal Energy is sustainable, clean, and reliable.

It reduces the dependence upon fossil fuels. It produces clean electricity, with no production of greenhouse

gas or pollution. It produces energy for free, once the initial costs are

recovered. Produces electricity 24 hours a day and 365 days a year.

It is highly efficient.

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Disadvantages of Tidal energy

Technology isn't fully developed.

The mud flats and destroys the living animals and birds on it.

A lot of maintenance is required for barrage systems for their salt resistance parts.

The people who rely on fishing are affected by it.

Like other renewable energy and conventional power generation it’s so much expensive.

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Future Possibility We can see a bright future of the tidal power and when we fix

several problems.

First we have to make the cost lower, so that it can be built in a large scale.

Secondly, the turbine has to be more effective, technology of its working process should be fully developed.

In Bangladesh ,tidal energy can be a useful alternative to reduce power crisis.

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Conclusion

Comparing with wind energy and solar energy, tidal power seems not a big sustainable resource, but it is doing a fast-rate progress in recent decades.

Tides are a substantial source of clean renewable energy. Tides play a very important role in global climate formation. The accumulated data show that the coastal area of

Bangladesh can be a suitable place for such a power plant installation.

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THANKS TO ALL