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.

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7 Responses to “What Is Ocean Energy?”
  1. filson Glanz says:

    There is great potential in ocean energy using any of the methods suggested above and still others. But getting the units correct is important. the last two paragraphs have several mistakes:
    1) The section “Is ocean energy commercially viable now?” talks of “7 cents a kilowatt/hr.” But that should be a kilowatthour or kwh. The “/” means “per” and makes nonsense. This is not terribly important to understanding for most I suppose. But
    2) in “What does Ocean Energy cost” it says “from 7 cents to 16 cents/kw.” This actually makes logical sense but that is not what is intended. The cost of photovoltaic hardware often is given in cost per Watt (e.g. $6/Watt), but 7 to 16 cents per kW would be very, very cheap! What makes sense here is 7 to 16 cents/kWh (kiloWatthour), a reasonable and competitive value.
    Also Watt is usually in caps since it is a person’s name.
    Sorry to nitpick!

  2. jonathan Stark says:

    Would support any alternative to fossil fuels, as should our goverment, if they weren’t reaping profits from same, sign me up, I would lobby,write letters, whatever, help up become energy independant, you bet!

  3. Roy Johannesen says:

    An intersting form of water power that I did not hear mentioned is an update on clipper-ship technology, and preferably a sailing ship working its way across an ocean current for maximum velocity differential.

    Wind and ocean current velocity differential could then be harvested by simply throwing water turbines overboard.

    The electric energy can be converted into liquid fuel on board, so that when the ship returns to port, it has a cargo of synthetic crude to offload, while it onloads coal as a raw material for a carbon source.

    Water is cracked by the harvested electricity, and the carbon and hydrogen (made from sea water) are then synthesized into hydro-carbon chains of appropriate length to make synthetic oil.

    Thermal energy to convert hydrogen and carbon into liquid fuel come from burning the coal, creating the thermal energy needed for steam reformation of CO2, with the extra hydrogen from electralysis used to make the reformation process cheap and efficienct without the need for expensive catalysts or super-high temperatures or pressures.

    So our sailing ship returns with a valuable fuel in good form, and sells in the port commanding the highest price.

    As an alternative to sails, large conventional windmills can be utilized for both propulsion and electricity production.

    It sounds a little out there, but all the technology pieces to utilize ocean-based renewable resources, wind and current, are already off-the-shelf items.

    Very truly yours,

    Roy Johannesen

  4. Robert Deering says:

    Interesting but complex – why not just make hydrogen from the electricity generated? If you use coal, you still have to mine coal, and the carbon eventually ends up as CO2 in the air, contributing to global warming.

  5. Dr S C Banerjee says:

    Hindu mythology used to consider ocean to be the abode of Goddess of Wealth as well the source of Elixer of life .
    New advancements in technology and global warming vis-a-vis oil crunch , motivating us to tap all sorts of Renewable Energy–perhaps gives us an opportunity to tap a till date un-tapped resource of wealth-The Ocean.

    In fact , energy accounting giving proper weightage to EIA/LCA is likely to prove ocean to have the potential to be cheaper source of Energy than even the conventional fossil fuels , as well .
    Concerted and all out R&D efforts in tapping Ocean Energy is likely to make a country more prosperous –who goes for it first .

  6. P.J.LAKHAPATE says:

    7-16 cents per kwh cost is an operating cost.
    What is the installation cost ?

    Let us see who develop the Ocean Energy first.


  7. Kelcie says:

    Where is ocean energy in the world? Where abouts near the ocean?

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