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Tidal Energy: A Review


Abstract and Figures

The phenomenon of rise and fall in the ocean waters, called tides, is due to the attractive forces between the celestial bodies; Sun, Earth and the Moon. When the ocean water rises to a maximum extent, it is called spring tide and when they fall off to the lowest possible extent, it is called neap tide. With progress in technology, the usage of electric and electronic devices is exponentially increasing and there is a need to produce extra power other than the existing, in order to meet the future demands. Tidal energy can be considered as one of the best existing source of renewable energies. Unlike the wind, solar, thermal energy etc., tidal energy is something that has a long term perspective and it can be forecasted more accurately. Tidal energy is clean and not depleting. Because of these features it is unique and suitable to use it as a power generating source in the future. There are various types of tidal power plants across the world with varying tidal elevation. Also, the method of conversion of tidal energy into electrical energy is site specific. But generally, the method followed for extracting energy from tides is similar to the conventional hydroelectric power plants. In this paper, the tides at some locations across the world and along the Indian coast, tidal power plants across the world, resource allocation of tidal power plants, advantages and disadvantages of tidal power will be reviewed from the literature. Keywords: Tidal energy, tidal barrage, tidal stream, electrical energy.
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Proceedings of International Conference on Hydraulics, Water Resources
and Coastal Engineering (Hydro2016), CWPRS Pune, India
8th 10th December 2016
Vikas M1Subba Rao2Jaya Kumar Seelam3
1Research scholar,NITK, Surathkal,575025, India and Assistant Professor, RVCE, Bengalugu-560059,India
2Professor, Dept. of Applied Mechanics, NITK, Surathkal,575025, India,
3Principal Scientist, Ocean Engineering Division, CSIR-NIO,Goa,403 00
The phenomenon of rise and fall in the ocean waters, called tides, is due to the attractive forces
between the celestial bodies; Sun, Earth and the Moon. When the ocean water rises to a maximum
extent, it is called spring tide and when they fall off to the lowest possible extent, it is called neap tide.
With progress in technology, the usage of electric and electronic devices is exponentially increasing
and there is a need to produce extra power other than the existing, in order to meet the future
demands. Tidal energy can be considered as one of the best existing source of renewable energies.
Unlike the wind, solar, thermal energy etc., tidal energy is something that has a long term perspective
and it can be forecasted more accurately. Tidal energy is clean and not depleting. Because of these
features it is unique and suitable to use it as a power generating source in the future. There are various
types of tidal power plants across the world with varying tidal elevation. Also, the method of
conversion of tidal energy into electrical energy is site specific. But generally, the method followed
for extracting energy from tides is similar to the conventional hydroelectric power plants. In this
paper, the tides at some locations across the world and along the Indian coast, tidal power plants
across the world, resource allocation of tidal power plants, advantages and disadvantages of tidal
power will be reviewed from the literature.
Keywords: Tidal energy, tidal barrage, tidal stream, electrical energy.
There are numerous diverse forms of ocean energy that are being explored as potential sources for
energy extraction. Some of them are ocean current energy, tidalenergy, wave energy, offshore wind
energyand thermal energy (Nicholls and Turnock, 2008). Even though the tidal power is still an
immature concept, it is definitely a major contributor for electricity generation from renewable
sources in the near future(Shaikh and Shaikh, 2011).
The occurrence of tides was witnessed from Roman times and this energy was used on rivers such as
the joint estuary of the Tigris, the Tibet River in Rome and Euphrates Rivers even much earlier
(Charlier and Finkl, 2009). The flow of water in the form of tides, induced due to the relative
positions of the planets Sun-Earth-Mooncan surely be considered as one of the reliable sources of
energy if suitable systems are designed with an economic plan (Nicholls and Turnock, 2008). In the
recent past, use of renewable energy resources for the extraction of energy has been the point of
discussion (Cave and Evans, 1984; Bryden et al., 1995; Sodin, 2001).
Researchers working on renewable energy are mainly interested to extract the energy from tides
because of its advantages over other forms of renewable energies as the forecasting of tides is easier
and accurate from time and magnitude point of view, the density of sea water is much denser than
wind, lack of extreme flow speeds and negligible asthetic damage. (Shaikh and Shaikh, 2011).
1.1 Tides
Tides are the periodic motion of the waters of the sea due to the inter-attractive forces between the
celestial bodies. Tides are very long-period waves that move through the oceans in response to the
Proceedings of Hydro2016, CWPRS Pune, India Dec 8th 10th, 2016
Tidal energy : a review
forces exerted by the moon and sun. Tide and current are not the same. Tide is the vertical rise and
fall of the water and tidal current is the horizontal flow. In simple words, the tide rises and falls, the
tidal current floods and ebbs. The principal of tidal forces are generated by the Moon and Sun. The
Moon is the main tide-generating body. Due to its greater distance, the Sun’s effect is only 46 per cent
of the Moon’s.
1.2 Energy from the tides
There are three types of tides: diurnal, semidiurnal and mixed. (Hagerman G., Polagye B, 2006).Tidal
Energy is one of the new and evolving technologies, which is commercially not viable and still in
Research & Development (R&D) stage. Tidal energy is inexhaustible and can be considered as a
renewable energy source (Shaikh and Shaikh, 2011). Itis an advantage because it is less vulnerable to
climate change; while the other sources are all vulnerable to the random changes in climate(Nicholls
and Turnock, 2008). The review given by the Energy Technology Support Unit (ETSU) on the Tidal
Stream Energy was the initial attempt to estimate the energy from tidal stream resources in the UK
(ETSU, 1993). The points marked by the ESTU were later studied and modified in 2001 in a
document submitted to the UK Department of Trade and Industry (DTI) by Binnie, Black and Veatch.
Most of the existing technology used for tidal energy conversionis from the wind power industry
(Bahaj et al., 2007; Batten et al, 2007; Fraenkel, 2002). Researchers have predctited that UK has is
capable to produce over 20% of its electrical needs from its tidal resources (Callaghan, 2006). It is
also a fact that the studies carried out so far in predcting the energy that can be extracted from tides,
has only focused on the past and present availability of the energy. But it is also important to consider
and address the effects of exploiting the renewable energy sources for energy extraction. There has to
be an understanding among the developers as to when and where to stop the energy extraction so that
there is minimum or no disturbance caused to the regular natural phenomenon.
1.3 Tidal energy in India
The tides that are generated along some parts of the Indian coastline have the potential to extract
energy from the turbines. The tidal elevation in India is as high as 8.5 m at Bhavnagar, Gujaratand as
low as 0.5 m at the Southern part of India. Survey of India predicts tide levels at somelocations along
the Indian coastline and Tide Tables are published for every year (Sanil Kumar V. et al, 2006).
As per the studies carried out by Central Water and Power Commission (CWPC) in 1975, the Gulf of
Kutch and Gulf of khambhatin Gujarat and Sunderbans area in West Bengal are the only suitable sites
in India for the production of Tidal Energy. In 1980s, Central Electricity Authority (CEA) took up a
study for the assessment of tidal energy potential in India. CEA listed few places of Potential Tidal
Energy extraction in India shown in Table 1.
No tidal power generation plant has been installed in India due to its high cost of generation of
electricity and lack of techno-economic viability. However, there are proposals for setting up of tidal
power stations at Gujarat.
Table 1.Tidal Energy Potential in India
Tidal potential (MW)
Gulf of Khambhat
Gulf of Kutch
Gangatic Delta, Sunderbans
West Bengal
1.3.1 Demonstration Project at Sunderbans
A report was submitted by West Bengal Renewable Energy Development Agency (WBREDA) in
2001 for setting up a 3.65 megawatt capacity tidal power station at Durgaduani Creek in Sundarbans
Island of West Bengal. These details were submitted to the Ministryon June 2006. Also, WBREDA
Proceedings of Hydro2016, CWPRS Pune, India Dec 8th 10th, 2016
Tidal energy : a review
entered into a MoU with the National Hydroelectric Power Corporation Limited (NHPC), Faridabad
for updating of the Project Report and its execution. The updated Report prepared by NHPC was
received by the Ministry in November, 2007. The NHPC Limited was given responsibility to
complete the project. However, the project has been discontinued due to very high tender cost.
1.3.2 Tidal Power Projects in Gulf of Kutch, Gujarat
A committee was established under the Central Electricity Authority (CEA) on the 900MW Kutch
Tidal Power Project for estimating the cost of the project. The project was not found to be
commercially viable due to high capital cost as well as high cost of generation of electricity.
In January 2011, Gujarat signed a MoUwith Gujarat Power Corporation Ltd. (GPCL) for establishing
a 250 MW tidal power project at Mandavi district in Gulf of Kutch. GPCL has initially started a
50MW tidal power project in Kutch. GPCL has made a request for grant for the tidal power plant to
Ministry of New and Renewable Energy (MNRE).
The experience gained in the above project will decide the future course of action for the
advancement of tidal energy in India.
1.4 Tidal energy around the world
The necessity to reduce CO2emissions and gradual increase in cost of fossil fuel has resulted in a
significantly increased use of tidal energy (Nicholls and Turnock, 2008). Today, tidal energy around
the world is increasingly being considered as a potential source of renewable energy (Bryden and
Scott, 2007). Extreme tides are found in many locations across the globe. Some of them are: the
Pentland Firth, Scotland; the Severn estuary; the Aleutians; the fjords of Norway; the Philippines; the
Straits of Messina, Italy; the Bosporus, Turkey; the English Channel; Indonesia, and the straits of
Alaska and British Columbia.
The first major hydroelectric plant was put to operation in 1967 that used the energy of the tides to
generate electricity. It producedabout 540,000 kW of electricity (Charlier and Finkl, 2009). Studies
have shown that the European territorial waters have 106 locations for extracting tidal energy that
would provide electricity of 48 TW per year. It is estimated around 50,000 MW of installed capacity
being achievable along the coasts of British Columbia alone. There are greater predictions of
extracting energy of about 90,000 MW off the North West coast of Russia and about 20,000 MW at
the inlet or Mezen river and White Sea. There are also estimations along the West coast of India
having potential to generate 8,000MW.
Table 2 gives the highest available tidal levels in some of the regions that have the potential to
establish tidal power stations. Tidal power plants have already been set up at some of these places and
some are still in the planning phase.The main characteristics of four large-scale tidal power plants that
were constructed after World War II and currently exist are given in Table 3.
Table 2. Highest tides of the global ocean (Gorlov A. M., 2001)
Bay of Fundy
Severn Estuary
Port of Ganville
La Rance
Puerto Rio Gallegos
Bay of Mezen (White Sea)
Penzhinskaya Guba
(Sea of Okhotsk)
Proceedings of Hydro2016, CWPRS Pune, India Dec 8th 10th, 2016
Tidal energy : a review
Table 3.Existing large tidal power plants (Gorlov A. M., 2001)
Bay area
Avg. tide
Installed Power
La Rance
Kislaya Guba
Different methods have been suggested by authors for the extraction of tidal energy. However the
basic principle behind the methods remains same. However, there are two primary methods to extract
energy from the tides.
a. Estuaries into which large amounts of ocean water flows in due to high tidal range,
are captured behind barrages and the turbines are rotated by utilizing the potential
energy of the stored water.
b. The kinetic energy of moving water can be used to extract energy similar to the
principle of extraction of wind energy.
Both methods that are mentioned above have been suggested and followed and each has its own
advantages and disadvantages (Bryden and Melville, 2004). It may also be possible to employ
pumping strategies for barrages to obtain better efficiency and to match electricity demand better
(MacKay, 2007).
The devices that are used in the energy generation vary in size, shape and specifications. ISSC (2006)
has classified the devices into three types:
a. Tidal barrages that store tidal flow and generate power through discharge.
b. Tidal fences which block a passage and extract energy in either or both directions of
tidal flow.
c. Tidal current devices which are fixed or moored within a tidal stream.
2.1 Tidal barrage
Tidal barriage is a structure generally built across the mouth of the estuary through which the water
flows in and out of the basin. The tidal barriage has sluice gates that allows the flow of water in and
out of the basin. The water flows into the bay during high tide and the water is retained by closing the
sluice gates at the beginning of low tide. The barrage gates are controlled by knowing the tidal range
of the location and operating it at right times of the tidal cycle. There are turbines located at the sluice
gates which produce electricity when the gates are opened during the low tide. Using this principle,
authors have mentioned different ways of extraction of energy like ebb generation, flood generation,
ebb and flood generation, pumping, two basin schemes etc. Figure 1 shows the Plan view of a
hypothetical tidal barrage. Even though the barrage method has high theoretical efficiency, only one
large scale tidal barriage has been constructed at La Rance, France (Blunden and Bahaj, 2006).
The advantage of using barrage to method to generate electricity in comparision with fossil fuels is
that it reduces the greenhouse effects, to provide a better environment. La Rance tidal power plant,
France is an example for barrage method.On the top of the barrage there is a four-lane highway that
cuts 35 km of distance between the towns of Saint Malo and Dinard representing.
Proceedings of Hydro2016, CWPRS Pune, India Dec 8th 10th, 2016
Tidal energy : a review
Figure 1.Top view of La Rance tidal power plant barrage (750m in length)
2.2 Tidal stream energy
In the early 1990s, tidal power was mainly focused on harnessing the tidal flow and generating the
energy by means of potential storage rather than through tidal stream. Tidal stream technologies have
made massive progress towards commercialisation in the last decade. Extensive research is being
carried out in UK waters related to tidal stream energy. UK has a target at achieve 20% of its
electricity requirement through ocean resources by 2020. About 40 energy converting machines are
being developed and prorotypes are being tested in the labs and in waters of UK (Irena, 2014). Since
the tidal stream energy is still a emerging technology, it has no standardizations, but variety of devices
are being developed to make use of the water flow to extract electricity. However, the efficiency of
each of the devices has to be flawlessly examined by extensive testing to choose the appropriate
device for a particular location.
2.3 Calculation of tidal energy
The total tidal energy is the energy due to the tidal stream (kinetic energy) and the energy due
to release of the stored water in the basin (potential energy). It is also a fact that the increase
in tidal variation or the tidal stream energy results in increase of energy extraction to a large
extent (Shaikh and Shaikh, 2011).
2.3.1 Kinetic energy
The kinetic energy of the stream flow flowing across the cross section with a velocity is given by
(Bryden et al., 2004).
is the density of sea water (kg/m3)
Cpis the power coefficient
A is the area of cross section of the channel (m2)
V is current velocity (m/s)
The power output or the efficiency of the turbine " " depends on the design of the turbine. The power
output for a turbine from these kinetic systems can be obtained by the following equation (Shaikh and
Shaikh, 2011).
Proceedings of Hydro2016, CWPRS Pune, India Dec 8th 10th, 2016
Tidal energy : a review
is turbine efficiency
P is power generated (in watts)
isdensity of the water (seawater is 1025 kg/m³)
A is sweep area of the turbine (in m²)
V is velocity of the flow
2.3.2 Potential energy
The potential energy is mainly dependent on the tidal prism of the basin. Potential energy
obtained due to the stored water can be calculated as (Gorlov, 2001; Shaikh and Shaikh,
= ℎ (3)
h is the vertical tidal range,
A is the horizontal area of the barrage basin,
is the density of water = 1025 kg per cubic meter (seawater varies between 1021 and 1030 kg/m3)
g is the acceleration due to the Earth's gravity = 9.81 m/s2
From equation 3, it can be seen that the potential energy varies with square of tidal range. So, a
barriage should be placed in such a location where it is possible to achieve maximum storage
head.Black and Veatch (2003) suggest that the ideal water depths to achieve the best possible power
output at few potential sites around the UK range between 25 and 40 m and the recommend diameter
of the rotor to range between 10 m and 20 m. (Frost et. al, 2015). The inlets that are between islands
having large basin area are considered to have a greater amplification effect because of the reduction
in the throat area and the water depth relative to the surroundings, producing a venturi effect. This
accelerates the water as it is forced through a channel with a smaller cross-sectional area (Bryden I G
and Melville G T, 2004).
2.4 Tidal energy devices
There are wide range of tidal energy devices used for energy extraction based on site
conditions. The details of some of them is given in Table 4.
Table 4.Tidal energy extraction devices
Seagen, Marine Current
Turbines Ltd. UK
1 MW
Twin two bladed rotor, sheath
mounted, horizontal axis tidal turbine
The Blue
Concept,Hammerfest Strom,
1 MW
Three bladed pile mounted horizontal
axis tidal turbine
Proceedings of Hydro2016, CWPRS Pune, India Dec 8th 10th, 2016
Tidal energy : a review
THG, Tidal Hydraulic
3 MW
Array of four bladed horizontal axis
turbines attached to a gravity mounted
TidEL SMD Hydrovision, UK
1 MW
Twin two bladed tethered rotor, able
to yaw into the current
Stingray, Engineering
Business Ltd., UK
500 kW
Oscillating Hydroplane
Blue energy, Blue energy Inc.,
500 kW
Four bladed, moored, surface
piercing, vertical axis turbine
Some preliminary standards are given by Couch and Bryden to identify sites that are suitable for the
development of a tidal energy extraction. The most important variables generally considered are:
1. The local water depth: Existing device technology concepts are generally limited to operational
water depths of 2545 metres.
2. The location of the nearest exploitable grid connection: For an immature industry, the economics of
tidal energy extraction require easy access to a nearby grid connection with spare capacity; otherwise
the capital cost cannot be viably recouped across the life of the project.
3. An energetic and persistent resource: Large mean spring and neap tide velocities are highly
desirable. Some sites have the added advantage of minimizing the low velocity periods of the tidal
cycle as the local dynamics ensure that the tidal flow reverses through the slack period at an
accelerated rate. The sites that the developers are interested to extract energy tend to have peak spring
tidal velocities of 3+ m/s.
If these three primary criteria are met, a site is considered to have solid potential for future
development. The majority of coastal locations can be rejected out of hand by consideration of just
these three variables (Couch and Bryden, 2006).
The English Channel, theArctic Ocean, The Gulf of Mexico, The Amazon, The Straits of Magellan
and Taiwan are some of the possible locations for locationg tidal devices. Table 6 shows some
potential sites for tidal power installations.There are estimates that the energy that can be globally
extracted is around 1800 TWh/year (Nicholls and Turnock, 2008). But, it has to be taken care that the
effect on environment, economic and social constraints have to ve addressed (Sun X et al., 2008). It is
suggested that 10% of the extraction of energy can be considered as guideline for harnessing
renewable energy resources (Bryden I.G. et al., 2004). The estimated construction costs for existing
and proposed tidal barrages are given in Table 5.
Proceedings of Hydro2016, CWPRS Pune, India Dec 8th 10th, 2016
Tidal energy : a review
Table 5.Estimated construction costs for existing and proposed tidal barrages
Power Generation
costs (Million
n costs per
La Rance
Sihwa Lake
Gulf of Kutch
Wyre barrage
Garorim Bay
Mersey barrage
Dalupiri Blue
Severn barrage
Penzhina Bay
Note: Cost equivalent for 2012
Based on Wyre Energy Ltd., 2013.
Table 6. Some potential sites for tidal power installations (Gorlov A. M., 2001)
Bay area (Km2)
Avg. Tide
Potential Power (MW)
Cook Inlet
Up to 18000
San Jose
Carolim Bay
Technology and economics, however, dictate that only those areas where currents can exceed 2m/s
might be suitable for exploitation (Bryden I G and Melville G T, 2004).
Tidal power is a renewable and sustainable energy resource.It reduces dependence
upon fossil fuels.
It produces no liquid or solid pollution.It has little visual impact.
Tidal power exists on a worldwide scale from deep ocean waters.
Tidally driven coastal currents provide an energy density four times greater than air,
which means that a 15m diameter turbine will generate as much energy generated by a
60mdiameter windmill.
Tidal currents are both predictable and reliable, a feature which gives them an
advantage over both wind and solar systems. Power outputs can be accurately
calculated far in advance, allowing for easy integration with existing electricity grids.
Proceedings of Hydro2016, CWPRS Pune, India Dec 8th 10th, 2016
Tidal energy : a review
High cost of construction, installation and generation.
Barrages can disrupt natural migratory routes for marine animals and normal boating
Turbines can kill up to 15% of fish in area, although technology has advanced, the
turbines have to move slow enough not to kill many.
Flooding and ecological changes.
Research is still in initial stages.
The tidal energy industry has to develop a new generation of efficient, low cost and
environmentally friendly apparatus for power extraction from free or ultra-low head
water flow.
The negative environmental impacts of tidal barrages are probably much smaller than
those of other sources of electricity, but are not well understood at this time. It is
important to consider the influence of energy extraction while estimating the available
energy from a potential tidal energy site.
The future costs of other sources of electricity, and concern over their environmental
impacts, will ultimately determine whether humankind extensively harnesses the
gravitational power of the moon.
As yet the majority of this tidal energy resource is under-utilised; however, if
effectively captured using suitably engineered systems, it could be capable of making
a major contribution to our future energy needs.
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Ocean Renewable Energy (ORE), particularly the tidal energy, has seen increasing interests in the development of renewable energy in the Philippines. Currently, the proposed and operational tidal stream turbine blade designs are intended for areas of higher tidal flow velocities (> 4 m/s). However, the Philippines is situated in the tropical region where tidal stream flows are characterized by low flow velocities (< 2 m/s). Using the existing blade designs on tropical site conditions may result in lower efficiency and uneconomical results. This study tackles the design and simulation of Horizontal-Axis Tidal Turbine (HATT) blades for the tropical site conditions such as those found in the Philippines. A coupled Reynolds Average Navier-Stokes (RANS) and Blade Element Momentum Theory (BEMT) is used to design a notional HATT blade and evaluate its performance. RANS-BEMT approach allows the study of the tidal turbine blades’ interaction with the surrounding fluid as it considers the turbulence through RANS simulation and surface pressure distribution along the blades to check the design for cavitation in the hydrodynamic analysis.This study starts with the characterization of the potential sites for tidal energy extraction. The Davao Gulf in Davao del Sur, Philippines is one of the potential areas for tidal in-stream technology that remains unexplored. Conducting a numerical hydrodynamic modeling and resource assessment of tidal stream potential in Davao Gulf will quantify the amount of resource available in the region and pinpoints the areas that are most suitable for tidal in-stream turbine deployment. To demonstrate this process, the Davao Gulf’s hydrodynamic model is simulated using TELEMAC-2D to determine the Probability Distribution Function (PDF) of the tidal stream velocities from a potential installation site. The simulated site’s hydrodynamic model is then validated by comparing its predicted values with the in-situ data available. The free surface of the hydrodynamic model obtained in this study has RMSE and Pearson’s R values of 0.119 m and 0.989, respectively, which indicates a very high accuracy and correlation against the in-situ measured data. As for the site’s selection criteria, the potential site must have depths ranging from 30 to 50 m that can accommodate a 10 m diameter HATT and where the mean spring tide velocity is the highest. From these given criteria, the coordinate (6.958, 125.715) is chosen as the potential site for a HATT installation. The selected location shows a maximum flow velocity of 1.6 m/s and the most frequent velocity of 0.65 m/s.In designing the HATT blade, the NACA 63815 hydrofoil is used for blade profile due to its high lift to drag ratio compared to other candidate hydrofoils. An open-source BEMT code is utilized in calculating the turbine blade geometry, such as chord and twist distributions of the chosen hydrofoil across the blade span. Then, its 3D model is simulated in ANSYS Fluent to calculate its performance curves and hydrodynamic loads at different flow velocities. The simulation shows that the HATT has a maximum power coefficient of 0.36 at a Tip Speed Ratio (TSR) of 6.2, as well as a very low likelihood of cavitating. The turbine’s power performance curve and the selected site’s PDF are then used to calculate the estimated Annual Energy Production (AEP) of the notional HATT for the chosen location, estimated at 32,000 kWh/yr.
... The magnitude depends on changing positions of the Sun and Moon in relation to the Earth, Earth's rotation effects and the shape of the coastlines and sea floor. Potentiality of tidal energy production directly depends on the velocities of tidal current or the height of water level (Rashid et al. 2012;Vikas et al. 2016). ...
... As the tidal currents or tides are both reliable and predictable, tidal power has an advantage over both solar and wind power systems. Tidal power generation can be precisely calculated in advance, letting for easy incorporation with prevailing electricity grids (Vikas et al. 2016). ...
Energy sources may be broadly categorized as renewable and non‐renewable energy sources. With unprecedented population growth and economic development, the global energy demand is also increasing exponentially, which eventually leads to depletion of non‐renewable sources. Renewable energy sources are inexhaustible as they replenish naturally and over relatively short periods of time. The main renewable energy resources include solar energy, hydropower, wind energy, biomass, geothermal energy and tidal energy. The utilization of these renewable energy sources offers a wide variety of remarkable benefits as these are reliable, cost‐effective, environment‐friendly, produce minimum secondary wastes and ultimately lead to sustainable development. These sources can cover two‐thirds of the entire energy demand at worldwide level and thus, can contribute significantly to mitigate the emission of greenhouse gases and ultimately global warming. Thus the significance of renewable sources cannot be undervalued. This chapter aims to discuss the various types of renewable energy sources, their importance and role in sustainable development. The limitations and future prospects of renewable energy are also discussed.
... Earlier research activities comprise several test campaigns on a first prototype. The system is designed to exploit the kinetic energy available in natural stream flows, according to a widely diffused and studied concept [3] [4]. ...
... The overall conversion efficiency from water current kinetic energy to electrical output has to account also for other sources of loss, due to the mechanical and electrical efficiencies. A further electromechanical efficiency, , has to be applied to the hydrodynamic power coefficient in order to determine the effective power output: (3) where and respectively represent the mechanical and electrical losses. Another important non-dimensional parameter is represented by the thrust coefficient, defined as (4) where is the thrust acting on the rotor. ...
... Due to the turbines being placed under water, it has little visual impact as some claimed that renewable energy technologies are too big and destroys the natural scenery. Some places take advantage of Tidal barrages to connect two islands together by placing roads on the tidal barrages [17]. The tides in Brunei are caused by the ocean current from the South China Sea. ...
Conference Paper
The average tidal range in Brunei’s Coastal waters is calculated to be 0.6m with a maximum tidal range of 2.28m. the analysis was based upon data set obtained by BSP from 1st May 1985 up to 4th June 1986. Tidal Harmonic Analysis was used to breakdown the harmonic components of the tide data into its corresponding tidal constituents to evaluate and make future prediction of the tides. The method of tidal analysis used is called Harmonic Analysis by Least Squares. To calculate the solution, MATLAB was used with World Tides and World Currents extension being integrated. From the data set it can be seen that Brunei experiences a diurnal tide. From the analysis done, the dominant tidal constituents for Brunei coastal waters are the K1, O1 and M2 tidal constituents with an amplitude of 0.360m, 0.318m and 0.210m. By comparing the predicted data generated by the analysis and data from Survey Department, the results show promising results which ensures that the analysis is reliable in making future predictions for the tides at the coastal waters of Brunei Darussalam.
... Many tidal energy extraction devices have been reported such as Seagen, The Blue Concept, THG, TidEL SMD Hydrovision, and Blue Energy, etc. (Vikas et al., 2016). The Kuroshio ( Fig. 1) crosses in the east coast of Taiwan. ...
In response to the increasing renewable energy demand, harvesting the energy from Kuroshio become an important task in Taiwan. In this study, the ANSYS-FLUENT and ANSYS-AQWA were used to design a Spar platform for carrying multiple current energy harvesters. The platform follows the design code of ABS rules (ABS, 2014). The designed spar model was established in OrcaFlex, and so as the mooring line system, including the anchor chain and duct chain was built. The simulated results show the spar is stable under normal and storm wave conditions. The pre-designed nozzle-diffuser-duct (NDD) can capture 15 kW of current energy, however, as a megawatt power plant, 60 ducts are needed to be deployed. The proposed SPAR platform could be used as a carrier to overcome the difficulties of deploying 60 NDDs to seabed and it may also reduce the construction costs. The simulated results show the spar and associated NDDs are stable under normal and storm wave conditions. This study suggests the platform may be expected to carry more than 60 NDDs and the megawatt Kuroshio energy harvester is feasible to be deployed at the east coast of Taiwan in the future.
... For the above of unsatisfactory situations, a search has been going on all over the world for alternative energy sources. There are many alternative energy sources [4][5][6][7][8][9] in our society. Wind power [4] depends strongly on climate and location, but it can be used almost anywhere globally. ...
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Sea wave power may help to solve the problem of energy crisis of the world with pollution free environment. Low cost and efficient electric power generation is main challenge in this sector. In this research work a linear generator has been characterized to find optimum condition in the laboratory environment. A machine named simple harmonic oscillator has been used in our laboratory as alternate of the sea wave. The electric power of the linear generator has been increased with turn's number of the induction coil and frequency of the coil oscillation. In a series of magnets the arrangement of 2 cm gap between the magnets gives the maximum output for the bobbin length 3 cm that was interested. Repulsion arrangement of the magnets is relatively better. The ferromagnetic core increases the electric power. Considering all above arrangement it is expected that an efficient and low cost power plant may be developed by the linear generator.
Offshore oil and gas (O&G) production represents 25% of the “blue economy” market and is an important source of income for many coastal nations. This chapter discusses how the O&G offshore industry can lead a sustainable transition from a “brown economy” to a “blue economy”, especially with research funding and government commitment, as well as broader partnerships and diverse investment strategies. An overview of the world’s current and future energy situation, the challenges and environmental risks of offshore O&G production, as well as different types of offshore renewable energy options are also presented. The role of science and technology is crucial in this transition process (as demonstrated by two cases studies: Brazil and Norway) to overcome the O&G industry challenges and ensure economic profitability, while reducing environmental impacts in the ocean and coastal areas.KeywordsFossil fuelsEnergy transitionEnhanced oil recovery (EOR)Carbon capture utilization and storage (CCUS)
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Wind charge is produced naturally in space. Knowing the nature of space charge is important for various purposes. If the charge is received for the whole year long by the antenna then, in this process, the charge can be used as electric power.In the present work, the nature of wind-charge of space in Dhaka and Narayanganj cities has been observed. A net-type antenna is used to receive the wind charge. The results show that the power is decreased with the antenna gap. The output power is increased with the antenna’s gross area and the speed of air. Overall output power was increased with humidity. The wind of a higher distance from the ground carries more electric charge. The research works reveal that the electric charge is inhomogeneous in the wind and it is collect-able as the electric power. The nature of the results is similar for both cities but output power is larger for Dhaka than Narayanganj. This alternative power source is environmentally friendly because of reducing thunder and lighting due to taking charge from wind. Thus,we will get a more danger-free environment.
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The results from an experimental study of a model diffuser augmented tidal stream turbine are presented with a particular focus on the impact of the diffuser upon the turbine's performance in yawed flows. This study is the first to examine yaw effects with quantification of blockage corrections and is the first study of the wake recovery characteristics of such devices. The device was designed using an innovative optimisation procedure resulting in a diffuser that was able to maintain the turbine's performance to yaw angles of up to ±30°. It is shown that the diffuser's performance is strongly influenced by its length to diameter ratio and by the jet flow that develops through the turbine's tip gap. Although the performance characteristics of an individual turbine can be significantly improved by diffuser augmentation under yawed flow, a wake recovery rate that is less than half that of a bare rotor raises doubts about their suitability for array deployment.
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With many Tidal Energy Conversion (TEC) devices at full scale prototype stage there are two distinct design groups for Horizontal Axis Tidal Turbines (HATTs). Devices with a yaw mechanism allowing the turbine to always face into the flow, and devices with blades that can rotate through 180° to harness a strongly bi-directional flow. As marine turbine technology verges on the realm of economic viability this paper reveals the performance of Cardiff University's concept tidal turbine with its support structure either upstream or downstream and with various proximities between the rotating plane of the turbine and its support stanchion. Through the use of validated Computational Fluid Dynamics (CFD) modelling this work shows the optimal proximity between rotor plane and stanchion as well as establishing, in the given context, the use of a yaw mechanism to be superior to a bi-directional system from a performance perspective.
The various technological developments for converting the power of tides, waves, or any water in motion to electricity is discussed. A sampling of technologies identified includes wave generators and free-floating power buoys that use waves for energy and turbines of various sizes to take advantages of the potential energy in tides, rivers and other water in motion. Scottish company, Ocean Power Delivery Ltd., has developed Pelamis, a snakeline floating device, for producing electricity. The Australian company Energetech is installing a pilot wave energy project, with a top system output of 750 kW, off the Australian coast.
Reviews the technologies available for harnessing energy from the oceans, the projects dedicated to research on the subject and the controversies and debates inherent in such use of the ocean system. The authors conclude that despite opposition, the use of the oceans for power generation is becoming increasingly more attractive and realistic. After detailing the state of the art in chapter one, chapters then deal with: offshore wind power stations; ocean current energy conversion; solar ponds; wave energy; ocean thermal energy; tidal power; salinity energy; geothermal energy; and marine biomass energy. A glossary, references with notes, and a bibliography are included. (S.J.Stone)
Engineers' dreams and fossil energy replacement schemes can come true. Man has been tapping the energy of the sea to provide power for his industries for centuries. Tidal energy combined with that of waves and marine winds rank among those most successfully put the work. Large scale plants are capital intensive but smaller ones, particularly built in China, have proven profitable. Since the initiation of the St Malo project in France, similar projects have gone into active service where methods have been devised to cut down on costs, new types of turbines developed and cost competitiveness considerably improved. Tidal power has enormous potential. The book reviews recent progress in extracting power from the ocean, surveys the history of tidal power harnessing and updates a prior publication by the author. © Springer-Verlag Berlin Heidelberg 2009. All rights are reserved.
The characteristics of tidal constituents along the nearshore waters of Karnataka, west coast of India, are described. These are based on the sea level data measured at three locations by the Valeport wave and tide gauge during the presummer monsoon period. The objective of the study is to identify the tidal and nontidal variations along the coast. Analysis shows that astronomical tides are responsible for most of the observed sea level variability along the Karnataka coast. Ninety-seven percent of the variation in measured sea level at Honnavar and Malpe and 96% of the sea level variation at Kundapur was due to tide. The observed nontidal sea levels were related to local wind forcing. The study shows that when the wind from the south was strong, a rise in sea level was observed, and when the wind from the north was strong, a fall in sea level was observed. Correlation between the alongshore component of wind and nontidal sea level was 0.54 at Malpe and 0.48 at Honnavar. The nontidal sea level variation was found to vary according to the significant wave height. High residuals of sea level were found during high waves. Amplification of shallow-water constituents were relatively high compared with other constituents from south to north along the study area.
There is an apparent lack of understanding of the tidal resource and its response to harvesting of energy among the principal proponents of the fledgling UK tidal energy industry: the device developers, principally supported by government funding. The authors' intent is to widen understanding of the different hydrodynamic conditions and controls that generate favourable conditions for tidal energy extraction. This paper outlines the generic hydrodynamic conditions that typically provide the most important fundamental requirement for harvesting tidal energy, namely, a large tidal current resource. Five generic tidal regimes are presented, and the suitability of each regime for harvesting of energy is considered. Of the five regimes, two cases are identified as being most prevalent, but are generally unsuitable for economic exploitation. Understanding the significant differences between the driving mechanisms of each of the flow regimes is therefore key to effective site selection for large-scale development. Furthermore, the response of the different regimes to energy extraction from the system is not consistent, further impacting on site selection. Numerical simulations of idealized examples highlighting the different hydrodynamic conditions in operation will be used to support descriptions of the relevant tidal flow regimes.
This paper briefly outlines the principles of energy extraction from tidal currents and develops a simple model, based upon open channel flow, for the assessment of the influence of such extraction upon the underlying hydraulics. It is shown that energy extraction does alter the flow within a simple channel. Extraction of 10% of the energy flux in a natural, undisturbed channel would produce a flow speed reduction of under 3% rising to 6% for the extraction of 20% of the natural flux. The authors suggest that 10% extraction could be considered as a guideline for developers wishing to make a conservative estimate of the extractable resource in a simple channel.