NCES Wave Plant

WAVE ENERGY CONVERSION(OCEAN ENERGY)

Learning Outcomes

2

After completion of this topic, students will able to

General objective• discuss the various ocean energy sources• interpret the energy transformation in wave energy

conversion• discuss the working of various type wave energy plant

Specific objectives• define the wave energy• write benefits and application of wave energy system• explain the types of wave energy plant

FUNDAMENTALS OF OCEAN

• 75% of the Earth Covered by water• Ocean water stores much more heat than the

atmosphere• World’s total estimated ocean energy are about

130 × 106 . • Five Principal ocean: Indian ocean, Pacific

ocean, Arctic ocean, Antarctic ocean, Atlantic ocean

OCEAN ENERGY

Ocean Energy

Ocean Thermal Energy

Ocean Wave Energy

Ocean Tidal Energy

Ocean Geothermal

Energy

Ocean Salinity Gradient Energy

Ocean Chemical Energy

Ocean Nuclear Energy

Ocean Biogas energy

OCEAN ENERGY CONVERSION TECHOLOGY

• Ocean Thermal Energy: Energy aquired into ocean by solar radiation. Temperature differences between the upper level and deep level of water in sea (Difference in thermal energy) are utilized.

• Ocean Biomass Energy: Ocean covered with aquatic biomass like algae, kelp , water hyacinths, animals etc. The ocen biomass may be converted into methane (bio-gas) by wet anaerobic digestion process.


• Ocean Tidal Energy: hydro energy available in tides. Ocean tides occur due to gravitational attractive forces from sun and moon. The level of ocean water rises periodically during high tides and drops during low tide. Head difference during this high and low tide is utilized for power production.

• Ocean Geothermal Energy: Geothermal field are available in off shore of sea.


• Ocean Chemical Energy: Chemical energy in ocean water. Ocean water contains the Sodium, Hydrogen, Oxygen, Chlorine, iodine, etc.

• Ocean Salinity Gradient Energy: Difference in salinity between ocean and river water can be utilized for electricity generation

Ocean Chemical Energy

Photochemical Process Or Photo Biological Conversion Process

Useful Secondary Energy (hydrogen and nitrogen)


• Ocean Salinity Gradient Energy: When saline water is separated from fresh water by a charged semi permeable membrane, electric potential developed between the electrode. One cell produced 1W.

• Ocean Current Energy: Ocean current has high kinetic energy which can be converted into electrical energy by turbo generator.


• Ocean Nuclear Energy: Nuclear resources available from ocean water and ocean bed.

• Ocean Wave Energy: Ocean wave occurs due to rotation of earth wind flow over the ocean. Wave have interval of 4 to 12 sec with crest height of 3 m and above. Ocean wave machine is rotated by wave energy. Wave machine drives the generator rotor, pump to store the water at high level, compressor to store the air in compressed air storage plant.

WAWE ENERGY• Energy of interchanging between potential and

kinetic energy in the wave• Cycloid motion of wave particles carries energy

forward without much current• Typical periodicities are one to thirty seconds, thus

there are low-energy periods between high-energy points

• In 1799, Girard & son of Paris proposed using wave power for powering pumps and saws

• California coast could generate 7 to 17 MW per mile

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TYPES OF WAVE AND ENERGY

WAWE ENERGY

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• Kinetic energy (movement) exists in the moving waves of the ocean. That energy can be used to power a turbine. See in Fig. This is only one type of wave-energy system.

• Others actually use the up and down motion of the wave to power a piston that moves up and down inside a cylinder. That piston can also turn a generator.

ADVANTAGES• 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.

DIS-ADVANTAGES• 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.

WORLD WAVE POWERR RESOURCES

• “Potential exploitable wave energy" resources worldwide to be 2 TW. • For European countries 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.

Figures in kW/m

WAVE POWER HARNESS METHOD

1. Wave energy is to bend or focus the waves into a narrow channel of concentration, to increase their power and size. Then waves can be channelled into a catch basin or used directly to spin turbines. The energy of the waves is converted into electricity by means of surge devices and oscillating column devices. Wave energy conversion (WEC) is one of the most feasible future technologies. These energy systems are not developed and maturated commercially due to the complexities, sea conditions, and difficulty of interconnection and transmission of electricity through turbulent water bodies. In addition, they may require higher operation and maintenance costs in comparison to the land power systems due to their location at sea.


2. A typical ocean wave energy harvesting system consists of a wave power absorber, a turbine, a generator, and power electronic interfaces. The absorber captures the kinetic energy of the ocean waves. The absorbed mechanical kinetic energy of the waves is either conveyed to turbines or the absorber directly drives the generator. Turbines are generally used with systems that feature rotational generators.

In other methods, a linear motion generator is used, and this can be directly driven by the power absorber or movement of the device. Both linear and rotational generators produce variable frequency and variable amplitude AC voltage.


Both linear and rotational generators produce variable frequency and variable amplitude AC voltage. This AC voltage is rectified to DC voltage in order to take advantage of the DC energy transmission capabilities of salty ocean water.

OSCILLATING WATER COLUMN (OWC)

An oscillating water column is a partially submerged, hollow structure. It is open to the sea below the water line, enclosing a column of air on top of a column of water. Waves cause the water column to rise and fall, which in turn compresses and decompresses the air column.

OSCILLATING WATER COLUMN (OWC)

Waves cause the water column to rise and fall, which in turn compresses and decompresses the air column. This trapped air is allowed to flow to and from the atmosphere via a turbine, which usually has the ability to rotate regardless of the direction of the airflow. The rotation of the turbine is used to generate electricity.

OSCILLATING WATER COLUMN

OSCILLATING WAVE SURGE CONVETER

Oscillating wave surge converters extract energy from wave surges and the movement of water particles within them. The arm oscillates as a pendulum mounted on a pivoted joint in response to the movement of water in the waves.

OVERTOPPING/TERMINATOR DEVICE

Overtopping devices capture water as waves break into a storage reservoir. The water is then returned to the sea passing through a conventional low-head turbine which generates power. An overtopping device may use ‘collectors’ to concentrate the wave energy.

FLOATING DEVICE - ATTENUATOR

An attenuator is a floating device which operates parallel to the wave direction and effectively rides the waves. These devices capture energy from the relative motion of the two arms as the wave passes them.

ATTENUATOR –PELAMIS

One of the most well-known examples of this is the Pelamis, a series of long cylindrical floating devices connected to each other with hinges and anchored to the seabed. The cylindrical parts drive hydraulic rams in the connecting sections and those in turn drive an electric generator. The devices send the electricity through cables to the sea floor where it then travels through a cable to shore.

FLOATING DEVICE- POINT ABSORBER

A point absorber is a floating structure which absorbs energy from all directions through its movements at/near the water surface. In a vertical tube below the water, waves rush in and drive a piston, a buoyant disk connected to hose pumps, up and down topressurize seawater inside. The pressurized water then drives a built-in turbine connected to an electrical generator

SUBMERGED PRESSURE DIFFRENTIAL

Submerged pressure differential devices are typically located near shore and attached to the seabed. The motion of the waves causes the sea level to rise and fall above the device, inducing a pressure differential in the device. The alternating pressure pumps fluid through a system to generate electricity.

BULGE WAVE DEVICE

Bulge wave technology consists of a rubber tube filled with water, moored to the seabed heading into the waves. The water enters through the stern and the passing wave causes pressure variations along the length of the tube, creating a ‘bulge’. As the bulge travels through the tube it grows, gathering energy which can be used to drive a standard low-head turbine located at the bow, where the water then returns to the sea.

ROTATING MASS DEVICE

Two forms of rotation are used to capture energy by the movement of the device heaving and swaying in the waves. This motion drives either an eccentric weight or a gyroscope causes precession.

In both cases the movement is attached to an electric generator inside the device.

TAPPERED CHANEEL 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.

WAVE AIR TURBINE

SALTER “DUCKS”• Scottish physicist Prof. Stephen Salter invented “Nodding Duck”

energy converter in 1970• Salter “ducks” rock up and down as the wave passes beneath it.

This oscillating mechanical energy is converted to electrical energy

• Destroyed by storm• The “duck” device bobs back and forth as waves pass, this

motion moves a pendulum that is connected to a generator that produces electricity

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SALTER “DUCKS”

NCES Wave Plant

Engineering

Transcript of NCES Wave Plant