7.2 Plants As Solar Energy Converters

Wave power is the transport of energy by wind waves, and the capture of that energy to do useful work for example, electricity generation, water desalination, or. Wave power Wikipedia. This article is about transport and the capture of energy in ocean waves. For other aspects of waves in the ocean, see Wind wave. For other uses of wave or waves, see Wave disambiguation. Plants As Solar Energy Converters' title='7.2 Plants As Solar Energy Converters' />Wave power is the transport of energy by wind waves, and the capture of that energy to do useful work for example, electricity generation, water desalination, or the pumping of water into reservoirs. A machine able to exploit wave power is generally known as a wave energy converter WEC. Wave power is distinct from the diurnal flux of tidal power and the steady gyre of ocean currents. Nora Epub Nl. Wave power generation is not currently a widely employed commercial technology, although there have been attempts to use it since at least 1. In 2. 00. 8, the first experimental wave farm was opened in Portugal, at the Aguadoura Wave Park. Physical conceptsedit. When an object bobs up and down on a ripple in a pond, it follows approximately an elliptical trajectory. Motion of a particle in an ocean wave. A At deep water. The elliptical motion of fluid particles decreases rapidly with increasing depth below the surface. B At shallow water ocean floor is now at B. The elliptical movement of a fluid particle flattens with decreasing depth. Propagation direction. Wave crest. 3 Wave trough. Photograph of the elliptical trajectories of water particles under a progressive and periodic surface gravity wave in a wave flume. The wave conditions are mean water depth d  2. H  0. 3. 39 ft 0. T  1. 1. 2 s. 3Waves are generated by wind passing over the surface of the sea. As long as the waves propagate slower than the wind speed just above the waves, there is an energy transfer from the wind to the waves. Both air pressure differences between the upwind and the lee side of a wave crest, as well as friction on the water surface by the wind, making the water to go into the shear stress causes the growth of the waves. Wave height is determined by wind speed, the duration of time the wind has been blowing, fetch the distance over which the wind excites the waves and by the depth and topography of the seafloor which can focus or disperse the energy of the waves. A given wind speed has a matching practical limit over which time or distance will not produce larger waves. When this limit has been reached the sea is said to be fully developed. In general, larger waves are more powerful but wave power is also determined by wave speed, wavelength, and water density. Oscillatory motion is highest at the surface and diminishes exponentially with depth. My comment The Department of Energy high wind penetration plans require a lot of offshore wind. But is it possible, affordable, or wise to do this7.2 Plants As Solar Energy ConvertersHowever, for standing waves clapotis near a reflecting coast, wave energy is also present as pressure oscillations at great depth, producing microseisms. These pressure fluctuations at greater depth are too small to be interesting from the point of view of wave power. The waves propagate on the ocean surface, and the wave energy is also transported horizontally with the group velocity. The mean transport rate of the wave energy through a vertical plane of unit width, parallel to a wave crest, is called the wave energy flux or wave power, which must not be confused with the actual power generated by a wave power device. Wave power formulaeditIn deep water where the water depth is larger than half the wavelength, the wave energy flux isaPg. Hm. 02. Te0. 5k. Wm. Hm. 02. Te,displaystyle Pfrac rho g26. Hm. 02Teapprox left0. Plants As Solar Energy Converters' title='7.2 Plants As Solar Energy Converters' />Wtextm3cdot textsrightHm. Te,with P the wave energy flux per unit of wave crest length, Hm. Te the wave energy period, the water density and g the acceleration by gravity. The above formula states that wave power is proportional to the wave energy period and to the square of the wave height. When the significant wave height is given in metres, and the wave period in seconds, the result is the wave power in kilowatts k. W per metre of wavefront length. Example Consider moderate ocean swells, in deep water, a few km off a coastline, with a wave height of 3 m and a wave energy period of 8 seconds. Using the formula to solve for power, we get. Change Serial Battle For Middle Earth. P0. 5k. Wm. 3s3m28s3. Wm,displaystyle Papprox 0. Wtextm3cdot texts3cdot textm28cdot textsapprox 3. Wtextm,meaning there are 3. In major storms, the largest waves offshore are about 1. According to the above formula, such waves carry about 1. MW of power across each metre of wavefront. An effective wave power device captures as much as possible of the wave energy flux. As a result, the waves will be of lower height in the region behind the wave power device. Wave energy and wave energy fluxeditIn a sea state, the averagemean energy density per unit area of gravity waves on the water surface is proportional to the wave height squared, according to linear wave theory 49E1. Hm. 02,displaystyle Efrac 18rho g. Hm. 02,b1. E is the mean wave energy density per unit horizontal area Jm. The potential energy density is equal to the kinetic energy,4 both contributing half to the wave energy density E, as can be expected from the equipartition theorem. In ocean waves, surface tension effects are negligible for wavelengths above a few decimetres. As the waves propagate, their energy is transported. The energy transport velocity is the group velocity. As a result, the wave energy flux, through a vertical plane of unit width perpendicular to the wave propagation direction, is equal to 1. PEcg, displaystyle PE,cg, with cg the group velocity ms. Due to the dispersion relation for water waves under the action of gravity, the group velocity depends on the wavelength, or equivalently, on the wave period. T. Further, the dispersion relation is a function of the water depth h. As a result, the group velocity behaves differently in the limits of deep and shallow water, and at intermediate depths 49Deep water characteristics and opportunitieseditDeep water corresponds with a water depth larger than half the wavelength, which is the common situation in the sea and ocean. In deep water, longer period waves propagate faster and transport their energy faster. The deep water group velocity is half the phase velocity. In shallow water, for wavelengths larger than about twenty times the water depth, as found quite often near the coast, the group velocity is equal to the phase velocity. HistoryeditThe first known patent to use energy from ocean waves dates back to 1. Paris by Girard and his son. An early application of wave power was a device constructed around 1. Bochaux Praceique to light and power his house at Royan, near Bordeaux in France. It appears that this was the first oscillating water column type of wave energy device. From 1. 85. 5 to 1. UK alone. 1. 3Modern scientific pursuit of wave energy was pioneered by Yoshio Masudas experiments in the 1. He tested various concepts of wave energy devices at sea, with several hundred units used to power navigation lights. Among these was the concept of extracting power from the angular motion at the joints of an articulated raft, which was proposed in the 1. Masuda. 1. 7A renewed interest in wave energy was motivated by the oil crisis in 1.