Wave power

About: Wave power is a research topic. Over the lifetime, 2671 publications have been published within this topic receiving 41439 citations. The topic is also known as: wind wave energy & sea wave energy.

An Experience of Wave Power Generator through Tests and Improvement

Abstract: A wave power generator was a good target for an inventor. I began to invent a wave power generator in 1945, but has taken a long time to get a feasible device, and large scale application is still at the development stage.

Ultra‐relativistic radiation belt extinction and ULF wave radial diffusion: Modeling the September 2014 extended dropout event

Abstract: In September 2014 an unusually long lasting (≳10 days) ultra-relativistic electron flux depletion occurred in the outer radiation belt despite ongoing solar wind forcing. We simulate this period using a ULF wave radial diffusion model, driven by observed ULF wave power coupled to flux variations at the outer boundary at L* = 5, including empirical electron loss models due to chorus and hiss wave scattering. Our results show that unexplained rapid main phase loss, that depletes the belt within hours, is essential to explain the observations. Such ultra-relativistic electron extinction decouples the pre- and post-storm flux, revealing the subsequent belt dynamics to be surprisingly independent of pre-storm flux. However, once this extinction is included ULF wave transport and coupling to the outer boundary explain the extended depletion event, and also the eventual flux recovery. Neither local acceleration nor ongoing losses from hiss or chorus wave scattering to the atmosphere are required.

Ocean energy systems

Abstract: Energy is stored by nature in the tides, waves, and thermal and salinity gradients of the world`s oceans. Although the total energy flux of each of these renewable resources is large, only a small fraction of their potential is likely to be exploited in the foreseeable future. There are two reasons for this. First, ocean energy is spread diffusely over a wide area, requiring large and expensive plants for its collection; and second, the energy is often available in areas remote from centers of consumption. Tidal energy, which entails the use of estuarine barrages at sites having high tidal ranges, offers the best prospects in the short to medium term. Not only are its components commercially available, but many of the best sites for implementation have been identified. Indeed, on the basis of current field experience, tidal power may be regarded as a technically proven, dependable and long-lived source of electric power. The exploitation of wave energy, by comparison, is still in its infancy. Small shoreline and nearshore devices are likely to be developed first, but their applicability and potential is limited. More powerful, large-wave offshore energy plants are unlikely to be deployed for a few decades, although the bulkmore » of ocean-energy potential is located offshore. Ocean thermal energy conversion (OTEC), which is currently in the prototype stage, is costly and largely restricted to tropical locations. Its applications are likely to be limited. Salt-gradient energy, once a focus of interest, is not expected to be exploited in the foreseeable future. Overall, the pace and extent of commercial exploitation of ocean energy is likely to be affected by the rising environmental costs of fossil fuels and by the availability of construction capital at modes real interest rates. If the largest projects are to succeed, however, government support at the national level may be necessary. 42 refs., 13 figs., 4 tabs.« less

Seismic Halos Around Active Regions: An MHD Theory

Abstract: Comprehending the manner in which magnetic fields affect propagating waves is a first step toward constructing accurate helioseismic models of active region sub-surface structure and dynamics. Here, we present a numerical method to compute the linear interaction of waves with magnetic fields embedded in a solar-like stratified background. The ideal Magneto-Hydrodynamic (MHD) equations are solved in a 3-dimensional box that straddles the solar photosphere, extending from 35 Mm within to 1.2 Mm into the atmosphere. One of the challenges in performing these simulations involves generating a Magneto-Hydro-Static (MHS) state wherein the stratification assumes horizontal inhomogeneity in addition to the strong vertical stratification associated with the near-surface layers. Keeping in mind that the aim of this effort is to understand and characterize linear MHD interactions, we discuss a means of computing statically consistent background states. Power maps computed from simulations of waves interacting with thick flux tubes of peak photospheric field strengths 600 G and 3000 G are presented. Strong modal power reduction in the `umbral' regions of the flux tube enveloped by a halo of increased wave power are seen in the simulations with the thick flux tubes. These enhancements are also seen in Doppler velocity power maps of active regions observed in the Sun, leading us to propose that the halo has MHD underpinnings.

Resonant wave acceleration of minor ions in the solar wind

Abstract: This paper extends some previous work on the acceleration of minor ions in the solar wind to include the effects of wave acceleration and heating arising from minor ions interacting via the gyroresonance with ion cyclotron waves. Resonant wave acceleration is made up of two contributions, the first, and generally the more important, is a ‘local’ acceleration which is proportional to the wave power and the number of resonant particles and is also sensitive to the details of the distribution function; while the other contribution is basically ‘fluid dynamic’ in character, arises from the inhomogeneity of the medium and is proportional to the radial gradient of the resonant wave power. Under suitable cir-cumstances both contributions exhibit the feature that heavier ions receive greater acceleration than lighter ones. Also the kinematics of the resonance shows that the resonance wave acceleration switches off above a maximum differential speed, between ions and protons, which increases with increasing ratio of mass to charge. We also examine briefly possible beam instabilities driven by the streaming of minor ions relative to protons.