EN ER G Y FR O M TID E S A N D W A V E S -- Dr. P. S. Kulkarni Electrical Engineering Department, Visvesvaraya National Institute of Technology [Deemed University], Nagpur 440 010, INDIA (e-mail :
[email protected]). Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 1 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 ?. . . ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 2 Dec. 18, 2004 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. ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 3 Dec. 18, 2004 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. Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 4 Global Estimated Energy Consumption (in 10 ^ 15 kWh) Country United States Germany Canada France Japan India U.K. Others Dec. 18, 2004 1990 A.D. 40 10 10 8 7 5 5 50 2000 A.D. 80 20 20 20 15 15 10 150 2010 A.D. 160 40 40 40 35 40 25 300 5 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 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. ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 6 Dec. 18, 2004 INDIAN POWER SCENARIO Installed 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 -------------------------------------------------- Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 7 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 -------------------------------------------------------- Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 8 SOLAR ENERGY UTILIZATION Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 9 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. ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 10 Dec. 18, 2004 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. Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 11 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. ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 12 Dec. 18, 2004 Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 13 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 . Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 14 Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 15 Tidal Power Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 16 Relative high and low tides showing variation in range during lunar month 12h, 25m New moon First quarter Full moon Third quarter New moon 29.5 d Spring tide Neap tide Spring tide Neap tide Spring tide Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 17 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. ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 18 Dec. 18, 2004 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. ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 19 Dec. 18, 2004 Gravitational effect of the Sun and the Moon on tidal range Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 20 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 Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 21 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 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 22 Dec. 18, 2004 FOUR POSSIBLE SITES IN INDIA Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 23 The estimated potential of important Renewable Sources of Energy in West Bengal Sl. No. 1. 2. 3. 4. 5. 6. 7. 8. Sources/Systems Biogas Plants (Nos.) Improved Chulhas (Nos) Biomass Based Power Solar Energy Wind Energy Small Hydro Power Tidal Power Urban & Industrial Wastes Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati Potential 0.7 Million 6.6 Million 200 MW 20 MW per sq. K.M. 115 MW 250 MW 100 MW 250 MW 24 Renewable Energy Power Projects in the pipeline In West Bengal 1. 2. 3. 4. 5. Tidel Power Plants Biomass Based Power Plants Wind Power Generation Small Hydel Power Generation Solar PV Power Generation 3 MW 1 MW 2 MW 12 MW 400 MW Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 25 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 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati Dec. 18, 2004 26 Gravitational Attraction Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 27 Tidal Energy The gravitational force F between two bodies (say between sun and a water molecule on the earth) is given by KMm where F! 2 (1) r M = mass of sun m = mass of water molecule r = distance betn. sun and water molecule, m K = gravitational constant. Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 28 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). ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 29 Dec. 18, 2004 Tides Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 30 Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 31 Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 32 Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 33 SINGLE BASIN TIDAL SCHEME Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 34 SINGLE BASIN TIDAL SCHEME SINGLE BASIN TIDAL SCHEME SINGLE EBB CYCLE SYSTEM SINGLE TIDE CYCLE SYSTEM Disadvantages: Needs Small Size Plant Operation over a longer period Energy Generated = 1.5 * Energy (Tide Cycle System) ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati Dec. 18, 2004 35 Ebb generating system with a bulb turbine Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 36 Bulb Turbine Rim Turbine (Straflo turbine used at Annapolis Royal TPP) Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 37 Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 38 OCEAN AND POOL LEVELS AND POWER GENERATED IN A SIMPLE SINGLE-POOL TIDAL SYSTEM. Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 39 Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 40 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 dW ! but g dm h gc dm ! V dW ! g V gc dh h dh (1) (2) (3) so that where Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 41 AVERAGE POWER Pav W ! work done by the water , J g ! gravitational acceleration , 9.81 m s 2 g c ! conversion actor , 1.0 kg N.s 2 h ! head, m m ! mass lowing through turbine, kg V ! water density, kg m 3 ! sur ace area o pool, considered cons tan t , sq.m ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati Dec. 18, 2004 42 AVERAGE POWER Pav The total theoretical work during a full emptying (or filling) period is obtained by integrating Eq. (3) as g W ! ´ dW ! V A´ h dh gc R R 1g V A R2 W! 2 gc (4) 0 0 Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 43 AVERAGE POWER Pav Thus the work is proportional to the range to the power 2. the power generated during each of the above periods is equal to W divided by the time duration of that period. Zero power is generated during the rest of the time. The average theoretical power delivered by the water is W divided by the total time it takes each period to repeat itself, or 6h, 12.5m, or 22,350 s. Thus Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 44 AVERAGE POWER Pav Pav ! 1 1 g V A R2 x 22350 2 g c ! 1 g V A R2 44700 g c (5) where Pav ! average theoretical power , W Assuming an average seawater density of 1025 kg/m3, the average theoretical power per unit pool area would be given by Pav ! 0.225 R 2 A W / m2 (6 ) 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. Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 45 POWER GENERATED AT BAY OF FUNDY A ! 13000 km2 R !8 m Assuming Efficiency! 27.5% av av ! 0.225 x 2 x A x eff. ! 0.225 x 82 x 13000x 0.275! 51480 MW Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 46 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: A ! 20 x 10 6 m 2 R !8 m Pav ! 0.225 x R 2 x A ! 0.225 x 8 2 x 20 x 10 6 ! 288 x 10 6 W E ! Pav x 3600 E ! 10.368 x 10 8 kWh Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 47 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 r R where, R is the range =12 m. r is the head below which turbine stops operating = 3 m. W ! ´ dW Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 48 Problems r r W ! ´ g V A h dh ! g V A R R ´ h dh ! 1 g V A R2 r2 2 g V A R2 r2 W Thus the average power Pav ! ! time 44700 1 x 9.81 x 1025 x 30 x 10 6 x 12 2 3 2 ! 44700 ! 911.04 x 10 6 W 911.04 x 10 6 Energy generated ! x 3600 ! 3279.7 x 10 6 kWh 1000 Considering turbine generator e iciency, Energy generated ! 3279.7 x 10 6 x 0.73 kWh ! 2394.18 x 10 6 kWh Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 49 SINGLE POOL SINGLE EFFECT TIDAL SCHEME Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 50 SINGLE POOL DOUBLE EFFECT TIDAL SCHEME Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 51 DOUBLE BASIN PAIRED BASIN SCHEME Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 52 DOUBLE BASIN LINKED BASIN SCHEME Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 53 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. Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 54 Tidal Energy Storage Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 55 Environmental Impacts Tidal energy systems can have environmental impacts on tidal basins because of reduced tidal flow and silt buildup. Dec. 18, 2004 ISTE STTP at Electrical Engg. Deptt, GCOE, Amravati 56