Development and Validation of Technical and Economic Feasibility of a Multi MW Wave Dragon Offshore Wave Energy Converter


Title: Development and Validation of Technical and Economic Feasibility of a Multi MW Wave Dragon Offshore Wave Energy Converter
Authors: Wave Dragon
Publication Date:
April 17, 2009
Document Number: 019883
Pages: 49
Sponsoring Organization:
Technology Type:

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Wave Dragon (2009). Development and Validation of Technical and Economic Feasibility of a Multi MW Wave Dragon Offshore Wave Energy Converter. Report by Wave Dragon ApS. pp 49.

The Wave Dragon is an offshore Wave Energy Converter of the overtopping type. The develop-ment work is, to a large extent, built on proven technologies and Wave Dragon is by far the larg-est wave energy converter known today. Each unit will have a rated power of 1.5-12 MW or more depending on how energetic the wave climate is at the deployment site. In addition to this Wave Dragon - due to its large size - can act as a floating foundation for MW wind turbines, thus adding a very significant contribution to annual power production at a marginal cost.


Towards commercialisation


Wave Dragon marks a sig¬nificant breakthrough towards commercial exploitation of the abundant energy concentrated in ocean waves. Seagoing trials of the Wave Dragon prototype has proven its off¬shore sur¬vivability since March 2003 and more than verified the potential for commercial feasibility of large scale power gene¬ration below the costs of off¬shore wind power. Wave Dragon is unique among wave energy converters as it harnesses the energy of waves directly via water turbines in a one-step conversion system, housed in a very simple construction in which, im-portantly; the turbines are the only moving parts.


Big is beautiful…


By using the overtopping principles for energy absorption there is no upper limit on device size and rated power for Wave Dragon.


Wave Dragon’s competitive advantage lies in its scale and hence capital cost; only 9 units are required to make a 100 MW power station compared to 100-1000 units required by most tech-nologies and the few moving parts improve reliability and reduce maintenance costs. The design simply reapplies a well proven existing technology that has been around for 80 years. Wave Dragon is essentially a floating hydro-electric dam.


Major challenges


Developers of wave energy converters face a series of major challenges: First they have to devel-op machinery that can operate and survive in this very rough environment and secondly they have to optimise operation and maintenance systems to make wave power plants a viable solution. Wave energy converters have to compete with other renewable energy technologies: it has become obvious that wave power can be much cheaper than, for instance, photovoltaic power and there are good reasons to believe that wave power in a few years will be a serious competitor to offshore wind power.


System availability


During the long term testing in a real sea environment the Wave Dragon prototype has progressed to the point where it is now producing electricity 80% of the time. This real sea testing has also proven Wave Dragon’s seaworthiness, floating stability and power production potential. Operation of the device in the harsh offshore environment has led to a number of smaller compo-nent failures. All of these have been investigated and technical solutions have been found, thus preventing costly (in both time and money) problems from occurring in the future. The work done up to now has confirmed that the performance predicted on the basis of wave tank testing and turbine model tests will be achieved in a full scale prototype.


This project will develop the technological basis for a commercially viable solution to the bulk generation of renewable power and thus add to Europe’s ability to tackle the problems of security of supply and green house gas emissions.


Expected results


The quantitative objectives are referring to a 24 kW/m wave climate:


  • Higher energy production of each unit to a total of 10 GWh/y resulting in a total improve-ment of 12%; 5% from improvement by better control system and 7% from the new power take off system
  • A reduction in the overall installation capacity cost of 5% compared with the state of the art
  • A reduction of operation and maintenance cost of 5%


The test program will demonstrate the availability, power production predictability, power pro-duction capability and medium to long term electricity generation costs at €0.052/kWh in a wave climate of 24kW/m, which could be found relatively close to the coast at the major part of the EC Atlantic coast. In a 36kW/m wave climate the corresponding cost of energy will be €0.04/kWh

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