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Presented by:
SUBHASHIS SARKAR & ABHINAV ANKUR

Tidal Energy

ABSTRACT:-
This work illustrate an aproach to the study of labeling “tidal energy”. paper presents the at most use of the tidal energy as a source of power generation. As we know our fuels are vanishing fastly due to its rapid utilization. It is shown in the paper that how we can produce maximum amount of tidal energy out of the normal tides, and which we can use for our house also. The paper tells about which parts in the world we can use it efficiently and about its advantages and disadvantages. At last but not the least here have proposed one model house for usage of tidal energy directly and utilizing the waste coastal areas.
KEYWORDS:-
Helical turbine, energy production system (EPS)
INTRODUCTION:-
Efforts to create tidal energy date back to the eleventh century where England used tides to turn waterwheels to generate mechanical power. The planetÕs surface is composed of approximately 75% water and there is a lot of potential for energy production. Flowing tidal waters have a vast amount of potential energy; an estimate for potential energy worldwide can be as high as 3000 gigawatts (GW) of energy, which is continuously available from the action of the tides (Baird, 1993). To produce that amount of energy would end the United States dependence on fossil fuels, but do to constraints of the tidal energy process only about 2% or 60 GW can be converted to electricity. The constraints of tidal energy are due to the process in which tidal energy is created. And as we know that the fuels and coals are finishing rapidly we need to have a alternative and the better alternative source for it is TIDAL ENERGY.
Tidal Energy is sustainable, clean, reliable, widely distributed, and can offer significant benefits to many marine nations. Tidal Energy can be captured in an efficient
and cost-effective way. Tidal Energy is not yet recognized by India as an energy resource that should receive support and funding for its development. Tidal Energy is a clean, renewable source of energy--such as solar, wind, biofuels, and low-head hydro-- and deserves official international support and funding for its development.
In this paper it’s shown that where we can use this source of energy efficiently. And some special equipment and turbine has been used for getting the efficient amount of tidal energy. In this paper it will be seen that how the tidal energy is the cheapest sources of energy.
A house has been proposed which can be used in the coastal areas and some river coast also. Which can be run fully by tidal energy and some additional sources of energy has also been including if necessary like wind energy. Is house can be made near the coastal area due to this the tidal energy can be utilized directly near the sea coast and rivers. Each of the houses will be having its own EPS (energy producing system). By this way we can utilize the vast unused area of sea coast in India and the whole world, as we know that the maximum part of the coastal region is empty and is wasted.
The use of tidal energy as a major source of energy is already implemented in many parts of south Asian countries like in Korea Indonesia, and also some south American countries like near the mouth of Amazon.

THE CURRENT SITUATION
Tidal Energy is sustainable, clean, reliable, widely distributed, and can offer significant benefits to many marine nations. Tidal Energy can be captured in an efficient
and cost-effective way. Tidal Energy is not yet recognized by the United Nations as an energy resource that should receive support and funding for its development. Tidal Energy is a clean, renewable source of energy--such as solar, wind, biofuels, and low-head hydro-- and deserves official international support and funding for its development.
Developing Nations that could receive significant benefits from Tidal Energy
Indian Ocean: Comoros, Madagascar, Maldives, Seychelles.
Asia: China, India, Indonesia, Korea, Philippines, Vietnam.
Pacific Ocean: Fiji, Kiribati, Micronesia, Palau, Papua New
Guinea, Samoa, Solomon Islands, Timor, Tuvalu, Vanuatu.
Central and South America: Argentina, Brazil, Ecuador,
Guyana, Panama, and Surinam.
Atlantic Ocean: Cape Verde.
How is tidal energy made?
Tidal energy is made by creating a dam, also called a barrage, across the opening to a tidal basin or estuary (U.S. DOE, 2003). The tides rise and recede due to the gravitational pull that is exerted on the earth by the moon and sun. The high and low tides are created when the sun and moon’s gravitational pull are parallel to each other. When the high and low tides occur there is the greatest potential to turn potential energy into kinetic energy.
Kinetic energy is produced by allowing the gates, or sluice, on both sides of the barrage to open and allow the water to flow through a turbine, which then produces energy for electricity. This event takes place twice daily to allow energy to be generated; this process is very similar to hydroelectric technology used throughout the world.
What are the environmental impacts of using tidal energy?
Many scientists agree that there is a lack of knowledge when dealing with how changing of the tides will affect aquatic and shoreline ecosystems. There is a prediction that the building of tidal barrages in estuaries will affect tidal levels, as well as having an effect on sedimentation and turbidity in the water within the basins. The problem is that it is hard to predict how tidal barrages will there is an estimated decrease of 15 cm to the tidal level if a barrage was built in the Bay of Fundy in Canada (Baird, 1993). On the contrary, if there would be an increase in tidal levels it would lead to flooding in the water basins. Stuard Baird and Dr. Hay hoe for Energy Educators of Ontario feel to increase our knowledge about how tidal barrages affect ecosystems may be the study of the effects after such facilities have been built (Baird, 1993).affect tidal levels (O’Mara, 1999). By building barrages it can either lower or raise the tidal level, for example
Another environmental impact on aquatic ecosystems by building barrages is how tidal stations will affect plants and animals living in the basins. The barrages will restrict these aquatic organisms’ movements and no longer allow them to move with the tides. The only way to leave these areas is through the flow of water through a turbine, which will destroy most organisms.
Open water turbines have environmental impacts as well; figure 3 shows that there is no protection for organisms crossing these turbines. It looks like there will be a lot of organisms harmed by the blades of the turbine if there is no protection from them.
Listed above are the negative environmental impacts that are associated with tidal energy, but there are some very positive environmental impacts dealing with tidal power as well. There are no emissions or pollution associated with tidal energy, unlike the burning of fossil fuels. Tidal energy will help reduce our dependence on fossil fuels for energy and will provide a renewable resource for the future. Tidal energy will help reduce and even prevent many of the environmental problems that we face today.
Future benefits of tidal energy?
The future of tidal energy seems to be leaning towards open water turbines; which by not using a barrage, tidal energy does not have the initial upfront costs of building the damn and avoids some of the environmental impacts that are associated with barrages. Blue Energy Canada, Inc. has started using technology know as a vertical-axis tidal turbine to collect energy from ocean currents. This technology is supposed to get one hundred and ninety times the kWh per unit of fluid value of wind power (Maser, 2004). Also, Dr. Bahaj of the University of Southampton, reports for the Sustainable Energy Research Group that they estimate that tidal turbines have the potential, for the races of the Channel Islands site, to produce the same amount of electricity as three Sizewell B nuclear power stations (equal to 3GW) (Maser, 2004).
Also, a 2002 feasibility report on tidal current energy in British Columbia by Triton Consultants for BC Hydro stated, Future energy costs are expected to reduce considerably as both existing and new technologies are developed over the next few years. Assuming that maximum currents larger than 3.5 m/s can be exploited and present design developments continue, it is estimated that future tidal current energy costs between $.05 and $.07 per kWh are achievable (Maser, 2004).
Tidal energy should be focused on for the next alternative fuel source, it is a renewable energy source with many potential benefits. There are many sites worldwide that can use the barrage and open water turbine processes. There is already a 240 MW barrage style tidal power station located at the mouth of the La Rance river estuary on the northern coast of France. The La Rance tidal power station has been generating electricity since 1966 and has become a very reliable source of electricity for France.
The open water turbines that use tidal currents to move their propellers show a lot of potential, and reduce some of the costs and environmental risks associated with tidal power using barrages. Even though there are some environmental impacts of concern for tidal energy these impacts are much smaller than the impacts and pollution seen from using fossil fuels and nuclear power. Tidal power will not be able to support all of our energy demands, but it will be a valuable source of renewable energy. If developed correctly tidal power can become the primary provider for our future energy requirements.

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Tidal Energy
Energy from the moon
Tides generated by the combination of the moon and sun’s gravitational forces
Greatest affect in spring when moon and sun combine forces
Bays and inlets amplify the height of the tide
In order to be practical for energy production, the height difference needs to be at least 5 meters
Only 40 sites around the world of this magnitude
Overall potential of 3000 gigawatts from movement of tides
How it works
First generation, barrage-style tidal power plants
Works by building Barrage to contain water after high tide, then water has to pass through a turbine to return to low tide
Sites in France (La Rance), Canada (Annapolis), and Russia
Future sites possibly on Severn River in England, San Francisco bay, Passamaquoddy
Second-generation tidal power plants
Barrage not need, limiting total costs
Two types- vertical axis and horizontal axis
Davis Hydro turbine….. Successfully tested in St. Lawrence Seaway
Harness the energy of tidal streams
More efficient because they allow for energy production on both the ebbing and surging tides
One site has potential to equal the generating power of 3 nuclear power plants
disadvantages
Presently costly
Expensive to build and maintain
A 1085MW facility could cost as much as 1.2 billion dollars to construct and run
Connection to the grid
Technology is not fully developed
Barrage style only produces energy for about 10 hours out of the day
Barrage style has environmental affects
Such as fish and plant migration
Silt deposits
Local tides change- affects still under study
Advantages
No pollution
Renewable resource
More efficient than wind because of the density of water
Predictable source of energy vs. wind and solar
Second generation has very few disadvantages
Does not affect wildlife
Does not affect silt deposits
Less costly – both in building and maintenance
Wave Power
Wave Facts:
Waves are caused by a number of forces, i.e. wind, gravitational pull from the sun and moon, changes in atmospheric pressure, earthquakes etc. Waves created by wind are the most common waves. Unequal heating of the Earth’s surface generates wind, and wind blowing over water generates waves.
This energy transfer results in a concentration of the energy involved: the initial solar power level of about 1 kW/m2 is concentrated to an average wave power level of 70kW/m of crest length. This figure rises to an average of 170 kW/m of crest length during the winter, and to more than 1 MW/m during storms.
Wave energy performance measures are characterized by diffuse energy, enormous forces during storms, and variation over wide range in wave size, length, period, and direction.
Wave energy is an irregular and oscillating low-frequency energy source that must be converted to a 60-Hertz frequency before it can be added to the electric utility grid.
World Wave Power Resources
World Energy Council 2001 Survey stated the "potential exploitable wave energy" resources worldwide to be 2 TW. For European waters the resource was estimated to be able to cover more than 50% of the total power consumption.
The wave market is estimated at $32 billion in the United Kingdom and $800 billion worldwide.
The United States has exhibited weak effort compared to overseas projects in Norway, Denmark, Japan and the United Kingdom.
As of 1995, 685 kilowatts (kW) of grid-connected wave generating capacity was operating worldwide. This capacity comes from eight demonstration plants ranging in size from 350 kW to 20 kW.
Until recently the commercial use of wave power has been limited to small systems of tens to hundreds of watts aboard generate power
Wave Power Designs
Oscillating Water Columns (OWC)These devices generate electricity from the wave-driven rise and fall of water in a cylindrical shaft. The rising and falling water column drives air into and out of the top of the shaft, powering an air-driven turbine.
Floats or Pitching DevicesThese devices generate electricity from the bobbing or pitching action of a floating object. The object can be mounted to a floating raft or to a device fixed on the ocean floor.
Wave Surge or Focusing DevicesThese shoreline devices, also called "tapered channel" systems, rely on a shore-mounted structure to channel and concentrate the waves, driving them into an elevated reservoir. These focusing surge devices are sizable barriers that channel large waves to increase wave height for redirection into elevated reservoirs.
Oscillating Water Columns
The Nearshore OWC rests directly on the seabed and is designed to operate in the near-shore environment in a nominal mean water depth of 15m.
Nearshore OWC units also act like artificial reefs, improving environments for fishing while calming the water for a harbor.
OWC designs typically require high maintenance, costly, taut moorings or foundations for operation while only using the extreme upper strata of an ocean site for energy conversion. While focusing devices are less susceptible to storm damage, massive structuring renders them most costly among wave power plant types.
Since 1965, Japan has installed hundreds of OWC-powered navigational buoys and is currently operating two small demonstration OWC power plants. China constructed a 3 kW OWC and India has a 150 kW OWC caisson breakwater device.
A 75 kW shore-based demonstration plant by Queens University, Belfast, using the OWC process described above has operated on the Scottish island of Islay for 10 years
Floating Devices
The Salter Duck, Clam, Archimedes wave swing, and other floating wave energy devices generate electricity through the harmonic motion of the floating part of the device. In these systems, the devices rise and fall according to the motion of the wave and electricity is generated through their motion.
The Salter Duck is able to produce energy very efficiently, however its development was stalled during the 1980s due to a miscalculation in the cost of energy production by a factor of 10 and it has only been in recent years when the technology was reassessed and the error identified.
Tapered Channel Wave Power
These shoreline systems consist of a tapered channel which feeds into a reservoir constructed on a cliff. The narrowing of the channel causes the waves to increase their amplitude (wave height) as they move towards the cliff face which eventually spills over the walls of the channel and into the reservoir which is positioned several meters above mean sea level. The kinetic energy of the moving wave is converted into potential energy as the water is stored in the reservoir. The water then passes through hydroelectric turbines on the way back to sea level thus generating electricity.
This vs. That
Advantages
The energy is free - no fuel needed, no waste produced.
Most designs are inexpensive to operate and maintain.
Waves can produce a great deal of energy.
There are minimal environmental impacts.
Disadvantages
Depends on the waves - sometimes you'll get loads of energy, sometimes nothing.
Needs a suitable site, where waves are consistently strong.
Must be able to withstand very rough weather.
Disturbance or destruction of marine life
Possible threat to navigation from collisions because the wave energy devices rise only a few feet above the water.
Degradation of scenic ocean front views from wave energy devices located near or on the shore, and from onshore overhead electric transmission lines.
Conclusion: Waves harness a lot of the sun’s power, but they are better for surfing than generating electricity.

PRESENTED BY:
CHANDRA PRAKASH

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Introduction
Tide is a periodic rise and fall of the water level of sea. Which are create by the action of the and moon on the water of the earth.
The large scale up and down moment of sea water represents an unlimited source of energy can be converted into electrical energy.
The tidal energy could be converted into electrical energy by means of turbine-generator set.
Energy From The Moon
Tides generated by the combination of the moon and sun’s gravitational forces.
Greatest affect in spring when moon and sun combine forces.
Bays and inlets amplify the height of the tide.
In order to be practical for energy production, the height difference needs to be at least 5 meters.
Only 40 sites around the world of this magnitude.
Overall potential of 3000 gigawatts from movement of tides.
Basic Principle of Tidal Power
Incoming And Outgoing Tides
Types of Turbines
Bulb Turbine
Rim Turbine
Tubular Turbine
Marine Current Turbines
Components of Tidal Power Plant
The power house.
The dam or barrage.
Sluice way from the basins to the sea.
Advantages
Renewable.
Abundant.
Pollution free.
Water is a free resource
Presents no difficulty to migrating aquatic animals.
It is independent of rain and its uncertainty.
Tidal power plants don’t demand large area of land.
Disadvantages
Disturbance to marine life.
Expensive to construct.
No reliability.
Cost of Maintenance is Higher.
Power transmission from offshore facilities harder.
Bed power quality.
Conclusion
By using tidal energy we can produce 16% of world’s energy but the main drawback of it is the cost factor. It is very expensive(estimated about $ 1.2 billion).