tidal energy2students

Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati

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-- Dr. P. S. KulkarniElectrical Engineering Department, Visvesvaraya National Institute of

Technology [Deemed University],

Nagpur 440 010, INDIA (e-mail : [email protected]).

ENERGY FROM TIDES AND WAVES


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FAQs What is Tidal / Wave Energy? How Tidal / Wave Energy is generated? What are the current developments in the

Tidal / Wave Energy technology? What are the difficulties in Energy

Conversion process? How is the Energy stored? What is the Impact on the Environment ?. .

.


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I. INTRODUCTION

Renewable Resources: Sources of Energy that are virtually Inexhaustible and Pollution-free.

Role of Renewable Energy (RE) Meeting energy demand, Enhancing

energy security, Reducing greenhouse gas (GHG) emissions and, as a result, contributing to Sustainable Development.


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Energy for Sustainable Development Sustainable development demands a sustainable supply of energy resources that in the long term, is readily and sustainably available at reasonable cost in the country.

Sustainable development could only be achieved by provision of high quality and environmentally responsible energy on time, at a reasonable price.


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Global Estimated Energy Consumption (in 10 ^ 15 kWh)Country 1990 A.D. 2000 A.D. 2010 A.D.United States

40 80 160

Germany 10 20 40Canada 10 20 40France 8 20 40Japan 7 15 35India 5 15 40U.K. 5 10 25

Others 50 150 300


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INDIAN POWER SCENARIO Second highest global population Ranked as the sixth largest energy consumer in

the world Need $170 billion for generation and transmission

projects to meet power demand by 2012. Natural Gas - Preferred fuel Wind Power to make a contribution of as much as

20,000 MW to the fuel mix. Nuclear Power is also a critical element of the

government’s strategy to avoid dependence on energy imports in the future.


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INDIAN POWER SCENARIOInstalled Gen. Capacity : As on (31.3.04)

Steam (72 %) 79,838 MW Hydro (26 %) 29,500 MW Nuclear (02 %) 2,720 MW---------------------------------------------------Total : 1,12,058 MW---------------------------------------------------


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Modewise Gen. of Electricity in India (As on 31.3.04)

Thermal (84 %) 4,66,618 GWh Hydro (13 %) 73,796 GWh Nuclear (03 %) 17,720 GWh---------------------------------------------------------Total : 5,58,134 GWh ---------------------------------------------------------


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SOLAR ENERGY UTILIZATION


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Ocean Energy Systems Energy conversion technologies that

harness the energy in tides, waves, and thermal gradients in the oceans.

OTEC : Ocean Thermal Energy Conversion: The process or technologies for producing energy by harnessing the temperature differences (thermal gradients) between ocean surface waters and that of ocean depths. OTEC plants are used in both Japan, and in Hawaii, Atlantic coast in some demonstration projects.


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Suitability of site for Tidal Power Plant The tidal range R should be large. The storage area should be large. The site should allow the

development of the necessary plant for reasonable cost.

It should be environmentally acceptable.


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Tidal Energy The tides offer a source of energy because of

the potential energy of the raised tide water or the kinetic energy of tidal stream.

Tidal Energy is a Renewable Energy. Tidal Energy is a form of Hydro Energy

recurring with every tide. Tide is a periodic rise and fall of the water level of sea which is carried by the gravitational attraction between the earth, the sun and the moon.


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Principle of Tidal Power A tidal power plant works on the

principle of a dam or barrage that captures water in a basin at the peak of a tidal flow, then directs the water through a hydroelectric turbine as the tide ebbs.

Tidal Power is proportional to square of Tidal Range ‘R’.


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Tidal Power


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29.5 d

New moon First quarter Full moon Third quarter New moon

Spring tide Neap tide Neap tideSpring tide Spring tide

Relative high and low tides showing variation in range during lunar month

12h, 25m


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Important Terms Spring Tide: Tide when the tidal range is

maximum on full moon and new moon. Neap Tide: Tide when the tidal range is minimum

on first quarter and third quarter moon. Diurnal Tide : Tide occurring during the daytime

than at night; Daily. Tidal Range (m): Diff. betn consecutive high tide

and low tide water levels. Dam — A structure for impeding and controlling

the flow of water in a water course, and which increases the water elevation to create the hydraulic head. The reservoir creates, in effect, stored energy.


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Important Terms Barrage: A Dam. Barrages are usually of

smaller heights than the dams. Barrage is designed for lesser head of water.

Ebb Tide: Tide associated with decreasing level of water.

Estuary: 1) A part of river or stream which is influenced by tide in the main sea. 2) Mouth of river where river current meets the tidal current.

Sluice Way: Passage-way (gated) or artificial channel to let water through.


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Gravitational effect of the Sun and the Moon on tidal range


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Tidal Power Plants in World 1966 – At La Rance Estuary (France*) (240 MW, 24 units of Bulb Turbine, Mean ‘R’ = 8.4 m;

Max. ‘R’ =13.5 m; Effective ‘A’ = 20 sq. km; Basin vol.=1.84x108 sq.m., Turbine Dia. = 7.6 m) Bay of Fundy Betn. USA and Canada (16 MW)* Kislaya inlet on the Barents sea in the USSR

(< 500 kW)*

The English Channel * :Power plants in operation


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Bulb type Turbine Plants Axial-flow tur. –Propeller / Kaplan

with Hor. Shaft. High Hyd. Eff. Low Inertia Stable operation Low Average Temp. High Generator Losses


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FOUR POSSIBLE SITES IN INDIA


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The estimated potential of important Renewable Sources of Energy in West Bengal

Sl. No. Sources/Systems Potential 1. Biogas Plants (Nos.) 0.7 Million 2. Improved Chulhas (Nos) 6.6 Million 3. Biomass Based Power 200 MW 4. Solar Energy 20 MW per sq. K.M. 5. Wind Energy 115 MW 6. Small Hydro Power 250 MW 7. Tidal Power 100 MW 8. Urban & Industrial Wastes 250 MW


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Renewable Energy Power Projects in the pipelineIn West Bengal

1. Tidel Power Plants 3 MW 2. Biomass Based Power Plants 1 MW 3. Wind Power Generation 2 MW 4. Small Hydel Power Generation 12 MW 5. Solar PV Power Generation 400 MW


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Tidal Energy Conversion Schemes Single Basin Schemes:1 or 2 effect

scheme Modified Single Effect Scheme Two Basin Scheme Multiple Basin Scheme Pumped Water Storage Scheme


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Gravitational Attraction


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Tidal Energy The gravitational force F between two bodies

(say between sun and a water molecule on the earth) is given by

whereM = mass of sunm = mass of water moleculer = distance betn. sun and water molecule, mK = gravitational constant.

)1(r

KMmF 2


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Tidal Energy The tides arise twice a day. The difference in Potential Energy during High

tide and Low Tide is Tidal Energy. The tides are rhythmic but not constant, nor do

they occur on a regular daily schedule. Their occurrence is due to a balance of forces, mainly the gravitational force of the moon but also that of the sun, both acting together with that of the earth to balance the centrifugal force on the water due to the earth’s rotation. The result is the rhythmic rise and fall of water.

The tides are characterized by their schedule and range ‘R’ (m).


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Tides


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http://www.enn.com/news/wire-stories/2002/11/11072002/reu_48896.asp


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SINGLE BASIN TIDAL SCHEME


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Disadvantages: Needs Small Size Plant Operation over a longer period Energy Generated = 1.5 * Energy (Tide Cycle System)

SINGLE EBB CYCLE SYSTEM

SINGLE TIDE CYCLE SYSTEM


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Ebb generating system with a bulb turbine


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Bulb Turbine

Rim Turbine(Straflo turbine used at Annapolis Royal TPP)


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OCEAN AND POOL LEVELS AND POWER GENERATED IN A SIMPLE SINGLE-POOL TIDAL SYSTEM.


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AVERAGE POWER Pav

For a tidal range ‘R’, and an intermediate head ‘h’ at a given time

during the emptying process, the differential work done by the

water is equal to its potential energy at the time, or

where

)3(dhhAggdWthatso

)2(dhAdmbut

)1(hdmggdW

c

c


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AVERAGE POWER Pav

m.sq,ttanconsconsidered,poolofareasurfaceAmkg,densitywater

m,headhkg,turbinethroughflowingmassm

s.Nkg0.1,factorconversiong

sm81.9,onacceleratinalgravitatiog

J,waterthebydoneworkW

3

2c

2


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AVERAGE POWER Pav

The total theoretical work during a full

emptying (or filling) period is obtained by

integrating Eq. (3) as)4(RA

gg

21W

dhhAggdWW

2

c

0

Rc

0

R


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AVERAGE POWER Pav

Thus the work is proportional to the range tothe power 2. the power generated during eachof the above periods is equal to W divided bythe time duration of that period. Zero power isgenerated during the rest of the time. Theaverage theoretical power delivered by thewater is W divided by the total time it takes each period to repeat itself, or 6h, 12.5m, or22,350 s. Thus


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AVERAGE POWER Pav

W,powerltheoreticaaveragePwhere

)5(RAgg

447001RA

gg

21x

223501P

av

2

c

2

cav

Assuming an average seawater density of 1025 kg/m3, the average theoretical power per unit pool area would be given by

)6(m/WR225.0AP 22av

The actual power generated by a real tidal system would be less than the above because of frictional losses and inefficiencies in the turbines and electric generators and might only be 25-30 % of the above.


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POWER GENERATED AT BAY OF FUNDY

MW51480275.0x13000x8x225.0P

.effxAxRx225.0P

%5.27EfficiencygminAssum8R

km13000A

2av

2av

2


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Problems Prob. 1: The basin area of a tidal

power plant is 20 x106 m2. The tidal range is 8 m. Calculate the energy generated in kwh.

Soln:

kWh10x368.10E

3600xPEW10x28810x20x8x225.0AxRx225.0P

m8Rm10x20A

8

av

6622av

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Problems Prob. 2: A tidal power plant of the simple single

basin type, has a basin area of 30 x 106 m2. The tide has a range of 12 m. The turbine, however, stops operating when the head on it falls below 3 m. Calculate the energy generated in one filling (or emptying) process, in kWh if the turbine-gen. efficiency is 0.73.

Soln :The total theoretical work W is given by

where,R is the range =12 m.r is the head below which turbine stops operating = 3 m.

r

R

dWW


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Problems

kWh10x18.2394kWh73.0x10x7.3279generatedEnergy

,efficiencygeneratorturbinegConsiderin

kWh10x7.32793600x1000

10x04.911generatedEnergy

W10x04.911

312x10x30x1025x81.9x44700

144700

rRAgtimeWPpoweraveragetheThus

rRAg21dhhAgdhhAgW

66

66

6

226

22

av

22r

R

r

R


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SINGLE POOL SINGLE EFFECT TIDAL SCHEME


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SINGLE POOL DOUBLE EFFECT TIDAL SCHEME


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DOUBLE BASIN PAIRED BASIN SCHEME


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DOUBLE BASIN LINKED BASIN SCHEME


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TWO BASIN SCHEME It involves additional investment into civil

structures and equipment. In addition, the power generating efficiency of the plant which is directly prop. to the basin area decreases by one half when the basin area is halved.

Although uninterrupted power generation would be possible, the natural capacity varies by 2 or 3 times, a phenomenon which cannot be obviated.


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Tidal Energy Storage


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Environmental Impacts Tidal energy systems can have

environmental impacts on tidal basins because of reduced tidal flow and silt buildup.

tidal energy2students

Documents

average theoretical

tidal power

tidal power

basin area

renewable

tidal energy

power generated

important