Wave Energy Capturing
Wave energy or wave power is transport and capture of energy by ocean surface waves. This wave energy is using for many purposes such as electricity generation, water desalination, and pumping of water. Wave energy is also a type of non-conventional energy and it is estimate as the largest global resource form of ocean energy.
How waves are forms?
Waves can be either longitudinal or transverse .Water waves are create by wind. They are a combination of transverse and longitudinal motion Transverse waves are always characterize by particle motion being perpendicular to wave motion. A longitudinal wave is a wave in which particles of the medium move in a direction parallel to the direction that that the wave moves. .Air flowing over a large surface of water exerts a tangential stress on water surface, forming waves. Turbulent airflows near surfaces also creates rapid shear stress and pressure fluctuations. If they are in phase with existing water waves, the waves further develop. Winds can also exert stronger force on the upwind face of significantly grown waves, causing further wave growth. In deep water, circular motion of water particles occur and in shallow water, elliptical motion of water particle is occur.
The water movement occurs against the sea bottom, more like causing energy dissipation in deep water. The surface waves sinusoidal have irregular wavelengths, phases and directions. The motion of any particle of water is circular. The wave progresses but the water particles have no net progression. Water on the surface remains on the surface. The amplitudes of the water particle motions decrease exponentially with depth. At a depth of λ/2π below the mean surface position, the amplitude is reduce to 1/e of the surface amplitude. At depths of λ/2 the motion is less than 5% of the surface motion.
A body in water can undergo six types’ movements. Those are sway, roll, yaw, heave, surge and pitch. Heave, Surge and Pitch movements are mainly use in wave energy harnessing.
Energy generation from waves
Types of wave energy converters,
- Point absorbers
- Attenuators
- Terminator
How Point absorbers work
Point absorbers can be anchore to the seabed. So These absorbers are work by creating a relative motion between the floating part and the submerged assembly. Moves up and down from wave motion Once the wave energy is extract the energy can be convert into electricity using electromechanical or hydraulic energy converters.
Uses of Attenuators
A collection of joint, semi-submerged, cylinders (resembling a snake).Attenuaters capture energy by being placed perpendicular to the length of the wave. The principle axis of the cylinders are perpendicular to the wave fronts.Due to passing wave fronts, the each cylinder rise and fall individually resembling the movement of a snake (side movement is also possible). At the joints between cylinders, a hydraulic cylinder (acting as a pumping system) push high-pressure oil through a series of motors to generate electricity .This system is anchored to the seabed.
How to use Terminators
Terminators positioned to intercept and/or terminate incoming waves (by positioning itself perpendicular to the wave direction/ parallel to wave front).
Oscillating water columns (OWC)
OWC structure is like partially submerge enclose structure. So the upper part of the struvture above water is fill with air and incoming waves are funnele in to the bottom part of the structure. Water enters an air-trapped chamber (water inlet is submerged) .Then the wave motion pushes the water up and down like a piston forcing air through a turbine .Turbine is connected to an electrical power generator .This system can be fixed or floating type (Japanese ‘Whale’ is floating type).
Overtopping device (OTD)
OTD deviceses are more like water is collect (by rising waves/ making waves collide on a wall/ funneling through a tapered channel) in a reservoir above the sea level. So then collect water by the overtopping device is release back to the sea through a turbine to generate electricity . OTD can be fix or floating type as OWC.
Wave energy or wave power is transport and capture of energy by ocean surface waves. This wave energy is using for many purposes such as electricity generation, water desalination, and pumping of water. Wave energy is also a type of non-conventional energy and it is estimate as the largest global resource form of ocean energy.…