Wave energy, also called wave power, is harnessed by placing wave energy converters in or near the water to convert wave energy into electricity. The wave energy converters come in two forms: one that captures the energy of waves in deep water and one that harnesses the more shallow-water waves found near shorelines. There are two different categories of wave power technology — those based on buoyancy and those based on adhesion. Buoyancy-based systems use floating technologies, while adhesion-based systems use submerged technology to capture energy from waves and tides.
What are waves?
Waves are vibrations that travel through a medium, like air or water. The medium can be solid (like a drumhead) or fluid (like water). Waves are characterized by amplitude, frequency, wavelength, period, the direction of motion (travelling away from its source), and speed. Since waves travel away from their source at a given speed, they have energy associated with them. A single wave has an amount of mechanical energy proportional to its height multiplied by its velocity.
However, there are other types of wave energy and ocean surface waves: radio and microwave frequencies, for example, all involve electromagnetic radiation travelling as waves in free space. This section focuses on ocean surface waves (those generated on Earth’sEarth’s oceans due to wind patterns such as storms). But understanding how these relate to more significant scientific concepts is essential when it comes time to analyze wave power systems more closely in Chapter 4.
The typical ocean wave pattern has five characteristics:
Frequency is how many waves pass a given point in a given amount of time, measured in hertz (Hz). The period is how long it takes for one wave to pass a fixed point (such as one second or 30 seconds). The higher your frequency or shorter your period, the waves begin to sound more like a buzz than breakers. Wavelength determines how far apart crests are from troughs; if two ranges are 100 feet apart, that’s a crest-to-crest distance of 200 feet and a wavelength of 100 feet.
Direction determines if waves are converging or diverging; you can tell where they join by listening for an increasing volume, while divergent waves diminish in importance with distance. Converging waves tend to be more extensive—and they won’t roll up on shore when they hit land. Divergence means energy dissipates before reaching shore, reducing energy transfer into the swell.
How wave energy works
Wave energy is harnessed by converting wave motion into electricity. Wave energy devices capture ocean waves, river waves, wind waves (turbine) or surface waves on lakes and rivers. They do not convert gravitational potential energy at the Earth’s. Earth’s surface to other forms of energy such as kinetic or mechanical. Wave power is an exciting type of renewable technology that can generate electricity.
This can be done by using different techniques. One technique uses buoys that float on top of the water with attached electrical generators. The water current rotates a rotor, which then activates a generator. Another method uses boats that move up and down at high speed, capturing their movement with hydraulics to turn hydraulic turbines inside a container where hydraulic pumps are fixed. These two methods have advantages as well as limitations.
Wave power principles
The ocean has enormous amounts of energy in it. That’sThat’s just a fact, said Louis-Philippe Simoneau, head of Canada’sCanada’s National Renewable Energy Laboratory (NREL). Some 2.5 quintillions (2.5 x 10) joules of potential energy move around our planet every day in waves alone—enough to power 100 million homes for an entire year.
As demonstrated by Olympic snowboarder Ross Rebagliati and Paralympic snowboarder Miquel Lopez, who won gold medals for Canada at last month’s Winter Games in Pyeongchang after a pair of Canadian startups designed their equipment: all that power can be converted into electricity. Here’sHere’s how wave energy works. An offshore wave passing over devices called Pelamis P-750 undulates onshore as generators generate electricity.
The difference between wave power and wind power
Wave power comes from energy in ocean waves. This energy is sometimes trapped by coastal structures, such as breakwaters, to create standing waves that can be used for electricity generation. Wind power is available everywhere on Earth and uses wind turbines to generate mechanical power. Both are renewable sources of energy and are an excellent alternative to fossil fuels. Wave generators harness ocean waves to produce electrical power through motion or pressure difference mechanisms.
These devices convert wave energy into shaft rotational power using some mechanical system, which may use pumps (to raise water), paddles (to move water) or both. Turbines pump water directly into a generator to turn it with hydraulic pressure; less water fills these reservoirs when more electricity is needed.
The benefits of using wave power
Wave power can be converted into electrical energy in a variety of ways. The simplest is to attach a generator to buoys that bob up and down with ocean waves. Ocean buoys are anchored to the seafloor like a floating object would be. Depending on what kind of generator they’re attached to, they’re stuck using wires, ropes or chains (heavyweights) that can either be taught or slack. Such devices tap only a tiny fraction of wave energy, but they generate electricity continuously.
Other systems use oscillating water columns to extract energy from moving water in more locations at once and more efficiently harvest wave power overall. Oscillating Water Columns: In these systems, pairs of hollow vertical tubes act as buoys—and generators—in deep water or between islands where there’s no shallow shoreline for anchoring surface buoys directly to an ocean floor.
also, read: wave power https://www.eia.gov/energyexplained/hydropower/wave-power.php