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Waves are generated by winds blowing over the ocean surface.  Wave energy is effectively a stored and concentrated form of solar energy since the winds that produce them are caused by pressure differences in the atmosphere caused by the sun's differential heating of the earth's surface. Waves can efficiently transport energy for thousands of miles and retain their energy long after the winds that first created them have died down, which makes waves one of the most concentrated and consistent sources of renewable energy. 

Globally, the potential use of wave power is, unsurprisingly, limited to areas of the world where there are waves. On a global scale, this is dictated by global wind patterns, with the result that waves are more prevalent in the mid-latitudes (40-60(N/S), than nearer the equator where the lack of ocean wind is referred to as the 'doldrums'.  Interestingly, this potential for wave power contrasts with that of solar power, which is more effective in lower latitudes

Harnessing wave energy comes without the emission of harmful green house gases. This is the main motivation factor behind further development of this way of power generation.

Like with most green energy sources, wave power is also renewable. Since this energy source ultimately comes from the heat energy that is emitted from the sun, it will not disappear for some time – in fact, several billion years or as long time it takes for the sun to burn out.

The energy density is typically around 30-40 kW for every meter (2.2 feet) of wave along the shore. As we go further into the ocean 100kW for every meter is not uncommon.

Solar energy, radiant light and heat from the sun

radiant light and heat from the sun,

Waves are a powerful source of energy.

The problem is that it's not easy to harness this energy and convert it into electricity in large amounts.

wave power stations are rare

What are photovoltaics? The word comes from “photo” (light) and “voltaic” (energy produced by a chemical reaction). Photovoltaic technology refers to the conversion of light into energy at the atomic level. Certain materials, such as silicon, cadmium, and selenium, have the ability to absorb light photons and release electrons. Solar photovoltaic technology harnesses these freed electrons and uses their electric current as DC electricity (NASA 2002). Fully powered by the sun, solar photovoltaics are a free, clean, and renewable source of energy that can be used independently of or in conjunction with conventional grid energy. Unlike solar thermal systems, solar energy panels require little maintenance, necessitate no moving parts, and last for 30-40 years.

Wind power is safe, clean and increasingly affordable – with the potential for production on a much larger scale.Government support is crucial in ensuring the expansion of wind power. We believe such support should be transitional and limited. In the US, there is continuing uncertainty over the renewal of the production tax credit, which provides incentives to invest in wind energy. We are working with other wind energy suppliers to make an effective case for wind energy generation and the renewal of the production tax credit.Wind farms can provide large volumes of electricity (sometimes at a lower cost than conventional power generation)

Wind power is safe, clean and increasingly affordable – with the potential for production on a much larger scale.Government support is crucial in ensuring the expansion of wind power. We believe such support should be transitional and limited. In the US, there is continuing uncertainty over the renewal of the production tax credit, which provides incentives to invest in wind energy. We are working with other wind energy suppliers to make an effective case for wind energy generation and the renewal of the production tax credit.Wind farms can provide large volumes of electricity (sometimes at a lower cost than conventional power generation) Wind energy and the environment While wind farms can be an attractive alternative energy offering, they can also stir debate. During the planning stage for each new wind farm we assess the potential social and environmental impacts.The impact on wildlife and habitat The impact of wind farms on local residentsNoise from wind turbinesShadow flicker Interference with communications signalsWe then take steps to manage any negative impacts through engineering design changes, technology and other elements.

Wind power is safe, clean and increasingly affordable – with the potential for production on a much larger scale.Government support is crucial in ensuring the expansion of wind power. We believe such support should be transitional and limited. In the US, there is continuing uncertainty over the renewal of the production tax credit, which provides incentives to invest in wind energy. We are working with other wind energy suppliers to make an effective case for wind energy generation and the renewal of the production tax credit.

Wind power is produced by using wind generators to harness the kinetic energy of wind. It is gaining worldwide popularity as a large scale energy source, although it still only provides less than one percent of global energy consumption. The articles listed below explore wind power and its usage around the world.

Because waves are erratic, the amount of energy a wave generator can produce is unpredictable and, therefore, cannot be used as a sole reliable energy source.

accidental hydraulic fluid leaks can cause a major environmental problem.

A collision could cause a hydraulic spill or leak and become an environmental hazard.

The major challenge to using wind as a source of power is that it is intermittent and does not always blow when electricity is needed. Wind cannot be stored (although wind-generated electricity can be stored, if batteries are used), and not all winds can be harnessed to meet the timing of electricity demands. Further, good wind sites are often located in remote locations far from areas of electric power demand (such as cities).

Although wind power plants have relatively little impact on the environment compared to fossil fuel power plants, there is some concern over the noise produced by the rotor blades, aesthetic (visual) impacts, and birds and bats having been killed (avian/bat mortality) by flying into the rotors. Most of these problems have been resolved or greatly reduced through technological development or by properly siting wind plants.

A Renewable Non-Polluting Resource Wind energy is a free, renewable resource, so no matter how much is used today, there will still be the same supply in the future. Wind energy is also a source of clean, non-polluting, electricity. Unlike conventional power plants, wind plants emit no air pollutants or greenhouse gases. According to the U.S. Department of energy, in 1990, California's wind power plants offset the emission of more than 2.5 billion pounds of carbon dioxide, and 15 million pounds of other pollutants that would have otherwise been produced. It would take a forest of 90 million to 175 million trees to provide the same air quality.

Tidal energy is one of the oldest forms of energy used by humans. Indeed, tide mills, in use on the Spanish, French and British coasts, date back to 787 A.D.. Tide mills consisted of a storage pond, filled by the incoming (flood) tide through a sluice and emptied during the outgoing (ebb) tide through a water wheel. The tides turned waterwheels, producing mechanical power to mill grain. We even have one remaining in New York- which worked well into the 20th century.

Tidal power is non-polluting, reliable and predictable.Tidal barrages, undersea tidal turbines - like wind turbines but driven by the sea - and a variety of machines harnessing undersea currents are under development. Unlike wind and waves, tidal currents are entirely predictable.

A tidal range of at least 7 m is required for economical operation and for sufficient head of water for the turbines

Tidal energy use harnesses the water flow created primarily by the moon orbiting the Earth. As water is pulled toward the gravity of the moon, currents are created that can turn generator turbines.

Tidal energy use involving dams creates many of the same environmental concerns as damming rivers. Tidal dams restrict fish migration and cause silt build up which affects tidal basin ecosystems in negative ways. Systems that take advantage of natural narrow channels with high tidal flow rates have less negative environmental impact than dammed systems. But they are not without environmental problems. Both systems use turbines that can cause fish kills. But these are being replaced by new, more fish friendly turbines. The art and science of environmentally friendly hydro engineering is well advanced and will certainly be applied to any tidal energy project.

Because of intermittency and variable flow problems of tidal energy, it is a very limited resource. The DOE Tidal energy link, above, states that there are only about 40 really good sites on Earth with high enough flows to be considered economically practical

It was used in the watermills along the shores of England during the Roman age and also used along the shores of France and Spain. This period was around 900 AD. The water rising from the tides was impounded in barrages and it was allowed to flow through waterwheels and other energy capturing devices thus capturing the energy and converting it into useful work used to grind grains and produce flour. The first tidal mill in the US was built in Salem, MA in 1635.

Tidal turbines look like wind turbines. They are arrayed underwater in rows, as in some wind farms. The turbines function best where coastal currents run between 3.6 and 4.9 knots (4 and 5.5 mph). In currents of that speed, a 49.2-foot (15-meter) diameter tidal turbine can generate as much energy as a 197-foot (60-meter) diameter wind turbine. Ideal locations for tidal turbine farms are close to shore in water 65.5–98.5 feet (20–30 meters) deep

Wave energy is produced when electricity generators are placed on the surface of the ocean

Energy output is determined by wave height, wave speed, wavelength, and water density.

The energy provided is most often used in desalination plants, power plants and water pumps.

According to the American Wind Energy Association, the total U.S. production of wind power is around 25 gigawatts