What Is Ocean Energy?
What is ocean energy?
Ocean energy refers to a range of technologies that utilize the oceans to generate electricity. Many ocean technologies are also adaptable to non-impoundment uses in other water bodies such as lakes or rivers. These technologies are can be separated into three main categories:
Wave Energy Converters: These systems extract the power of ocean waves and convert it into electricity. Typically, these systems use either a water column or some type of surface or just-below-surface buoy to capture the wave power. In addition to oceans, some lakes may offer sufficient wave activity to support wave energy converter technology.
Tidal/Current: These systems capture the energy of ocean currents below the wave surface and convert them into electricity. Typically, these systems rely on underwater turbines, either horizontal or vertical, which rotate in either the ocean current or changing tide (either one way or bi-directionally), almost like an underwater windmill. These technologies can be sized or adapted for ocean or for use in lakes or non-impounded river sites.
Ocean Thermal Energy Technology (OTEC) OTEC generates electricity through the temperature differential in warmer surface water and colder deep water. Of ocean technologies, OTEC has the most limited applicability in the United States because it requires a 40 degree temperature differential that is typically available in locations like Hawaii and other more tropical climates.
Is ocean energy commercially viable now? Yes, but thus far,
on a small scale and not in the United States: The LIMPET project, a
500 kw shore-based wave plant in Scotland has been feeding power to the
grid for 5 years at a cost of 7 cents a kilowatt/hr. Another 600 kw
project similar to LIMPET on Island of Pico in the Azores is
operational. The Pelamis, a Scottish wave energy converter has been
feeding power to the grid in Scotland since August 2004 – and recently
announced plans to construct a 2.25 MW plant off the coast of
Portugal. An Australian company, Energetech, is in the final stages of
anchoring a 500 kw wave energy device in Port Kembla, Australia which
will feed power into the Australian grid.
What does Ocean Energy cost? The cost of power from ocean
technologies ranges from 7 cents to 16 cents/kw in a low case
scenario. But these costs are expected to decline as the industry
matures and as economies of scale make ocean projects less costly. To
compare, back in 1978 wind energy cost 25 cents/kwh to produce – but
now costs between 4.5 and 6 cents/kwh. Wave is already less costly
than wind. Moreover, a recent EPRI Report
found that if wave had obtained the same government subsidies as wind,
it would be a far more advanced technology than at present.