Wave Energy

  1. What is wave energy?
  2. What are the different potential harnessing technologies?
  3. What are the latest developments both in Ireland and within the industry?
  4. How much of a contribution could Wave energy make to Irelands' future energy needs?
  5. Are there any commercial wave energy projects in operation?
  6. What are the potential environmental impacts that need to be considered?

  1. What is wave energy?

    In terms of power generation, wave energy involves the harnessing and converting of the kinetic or moving energy present in the motion of ocean waves into a more usable form of energy i.e. electricity.

  2. What are the different potential harnessing technologies?

    Many different prototypes for wave energy harnessing devices have been developed. While there is huge variety in terms of design and harnessing method, many designs could be described as being a variation of one of the following types:

    • Attenuators are long multi-segment floating structures placed in parallel to the direction of the waves. As the device is lifted and dropped simultaneously at different points on the structure, this causes expansions and contraction where the segments are connected. This flexing motion can then power hydraulic pumps or other converters which may then power a generator.
    • Point absorbers operate on the basis of using the bobbing motion of the wave at a fixed point to cause a difference in relative motion of components within, or attached to a floating structure, such as a floating buoy within a fixed cylinder. This stretching and compressing motion can then be used to drive electromechanical or hydraulic energy converters.
    • Termination wave devices involve the physical capturing or reflection of the power of the wave. The oscillating water column is a form of terminator device in which water enters through a subsurface opening into a chamber with air trapped above it. The wave action causes the captured water to move up and down a column like a piston, forcing air though an opening connected to a turbine which then generates electricity.

  3. What are the latest developments both in Ireland and within the industry?

    In December 2007, it was announced that Pacific Gas and Electrical, CA, USA had entered into a 2 MW power purchase agreement with Finavera Renewables, a Canadian company. However, the plan is not due for completion until 2012.

    The latest developments for wave energy in Ireland involved the Irish company “Wavebob” announcing that it had secured the backing of one of Europe's leading electricity providers, Vättenfall AB of Sweden, to and develop a commercial wave farm on the western seaboard, with a target date of 2010.

  4. How much of a contribution could Wave energy make to Irelands' future energy needs?

    The 2005 Ocean Energy strategy from the DCMNR, cites Ireland as having huge Ocean Energy potential most particularly with regard to its wave resources.

    Drawing from Pontes, M.T. et al, (1998), "The European Wave Energy Resource" , the strategy states that the calculated theoretical wave resource for Europe is of the order of 320,000 MW with the highest resources available near the west coast of Ireland.

     It estimates that the practical wave energy resource offshore is greater than 6,000 MW or 59 TWh per annum as per the public consultation document options for the development of wave energy in Ireland. The potential is there for wave energy to be a crucial contributor towards Ireland's future energy requirements.

    However in order for wave energy to be successful, the proper infrastructural preparations need to be carried out to incorporate another intermittent and site-specific energy source on the national grid.

  5. Are there any commercial wave energy projects in operation?

    While recent developments have been extremely encouraging as yet there is no commercial wave energy array in operation.

    Currently* the world's first array, a system of attenuators, is due to come into operation shortly in Aguçadoura, 5 KM off the coast of Portugal. The 2.25 MW project is currently waiting to start commercial production subject to final commissioning.

    *As of 07/07/08

  6. What are the potential environmental impacts that need to be considered?

    Wave energy technology has yet to have a comprehensive body of environmental impact research behind it, therefore we cannot say for certain that we are fully aware of every potential environmental impact in the future.

    Possible impacts which have been identified include:

    • construction impacts from the initial installation process
    • effects on the usage of recreational sites
    • coastal erosion,
    • sedimentary flow patterns,
    • navigation hazards and the disturbance of fish and marine biology.