Wave power describes kinetic energy derived from ocean surface waves that is used for pumping water into reservoirs, for water desalination or for electricity generation. Although first experimented with as early as the end of the 18th century, it has not yet been widely employed for commercial purposes. Modern attempts were first initiated in by Yoshio Masuda in the 1940s and 50s, but funding was an issue until the oil crisis in 1973 and became an issue once more when in the 80s the oil prices went back to normal levels again. Prototypes were nonetheless tested at this point, but it was not until the recent interest in climate change and renewable energy that attempts to put the technology to use were seriously resumed.
The wave generators that have been developed since are powered by the kinetic energy that is transferred to the sea from wind passing over its surface, and the subsequent differences between upwind and leeside of the wave crest that causes the resulting waves - and by extension their inherent energ - to grow in size. The larger the waves the more powerful they generally get. However speed, wavelength and water density also factor in towards wave power, meaning bigger is not necessarily always better in terms of the energy it carries.
A wave power device might capture as much as possible of this energy by a buoy, flap or similar surface-following contraption. This is connected to the actual machinery, which is normally situated on the bottom of the ocean. The waves' vertical displacement of the buoy creates pressure in the apparatus that ultimately powers the nearby turbine, generating an electrical current. This is in turn transferred to the power grid by transmission cables. The multiple variations of this process originate in the models of different developers as well as adaptations for shoreline, near shore and offshore use. Although considerable amounts of electricity can be generated in this fashion, it should be noted that it only captures as little as a fifth of the wave total energy of a wave. On the other hand the inefficiency of the process is weighted up by the fact that it does not require fuel, for which the carbon emissions for operating wave power applications are non-existent.
However it is yet uncertain as to what extent wave power truly is environmentally friendly. The main concern in this department is that investments in wave power could be akin to trading reduction of greenhouse gas emissions for a disruption of the marine environment in which the wave power devices are placed. Noise pollution could, for instance, have a considerable impact if it is not properly monitored, not to mention that it could come to change existing patterns of beach sand nourishment. At this point the noise and visibility impact of each design varies, meaning that some types might be more "green" than others. On a more socio-economical note, it could come to force fishermen away from lucrative fishing grounds or even pose a danger to navigating vessels.
At present these risks are largely unconfirmed due to the small scale at which wave farms are currently operational. However since the opening of the first ever one in 2009, in Portugal, the industry has definitely been on the rise. Many different companies in countries all over the globe are currently developing new wave power generators. On top of this funding of future wave power projects have been announced in many parts of the world. It therefore seems likely that wave power will be a notable contributor towards the global power supply in but a matter of years.