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Vision
Ruth Henning
The vision for Wave Energy Converter (WEC) Crestwing can be seen as a natural continuation of vision from the early seventies about switching from fossil fuels to renewable energy. The vision of Crestwing is in this context that help to ensure that the wave energy gets a place in the palette of renewable energy technologies.
With a background in Mechanical Engineering and ten years experience in marine design, production and development from Odense Steel Ship yard LINDØ it was natural for the inventor Henning Pilgaard(HP) after the energy crisis in seventy-three, to participate in grass root work for a conversion to renewable energy. 
The vision behind the WEC Crestwing was created as a natural development for the inventor Henning Pilgaards (HP) lifelong engagement with the transformation of energy from using fossil fuels to use of renewable energies.(Link to Kerteminde rapporten).
Since 1982, he has worked full time with the transition to renewable energy where he has initiated and conducted a series of complex renewable energy projects, including village projects, two of the first wind farms, regional renewable energy project Bornholm as a green island(Link to extracts from the energy plan of a green island) ,biogas plants, gas engine heat and power plant and the last is the development and realization of the WEC Crestwing.
In the late eighties, Henning and Ruth worked together with Stig Vindeløv, who subsequently formed and created the Danish”Union for wave energy". Discussions with Stig inspired to take wave energy up for serious consideration.
Idea development
The basic idea for Crestwing was developed during the nineties through a creative process where the goal was an efficient, simple and realistic concept, economically and environmentally competitive with the wind sector.
Energy Potential
The Wave energy potential of a coastal location as Hanstholm is only about one third of the potential as in the middle of the North Sea. This is, together with the environmental aspects of a coastal location, the background to focus on a floating concept.
With a background in the marine sector, specializing in mechanical and thermodynamic systems, it was natural to have a hydrodynamic approach. Not at least because only half of the energy in waves is the potential energy where the remaining half is kinetic energy.
Practically all WEC´s of the float type are based on Archimedes' law which states that an object which is wholly or partially immersed in a liquid gets buoyancy, which is equal to the mass of the liquid the object displaces. Maximum potential of wave energy is for these WEC´s half compared to WEC´s which enable use of kinetic energy.
The starting point for reflection, was therefore quite natural a concept where both the potential energy and kinetic energy could be harnessed.
Absorber efficiency
The modern wind turbine, which today dominants the market, is a type of buoyancy wind turbine with aerodynamic wing airfoils. Unlike the old grain mill type that got its power from resistance, where the rotor was pushed by the wind, the wings today create a vacuum which pulls the rotor around. The development of an effective WEC float concept that can compete with the wind energy sector requires an equivalent hydrodynamic design to match the aerodynamic wing airfoils.
Waveenergyfyn's purpose is to contribute to new thinking around wave energy and to promote the development of lightweight and suitable WEC´s documented with the Crestwing concept. In this concept, the work is concentrated around the hydrodynamic forces to utilize the potential of the sea and the potential from the atmospheric pressure in the area between sea and air.
About the Crestwing absorber idea
The philosophy on the overall potential in the limit between air and sea and the hydrodynamic potential, led to the development of the Crestwing concept. The reflections led to a concept whose main parameters are exploiting the atmospheric pressure of approx. 1kp. /cm2 with a simultaneous utilizing of the energy bound in the waves hydrodynamic.
The option in the zone between the air and sea including the hydrodynamic characteristics were part of the development of Crestwing´s concept. By considering these conditions Crestwing is developed into this concept which main parameters are exploiting the atmospheric pressure of approx. 1kp./cm2 and utilization of bonded hydrodynamic energy.
Hereby the path is set for a new effective strategy for floating concepts which so far has operated with forces from buoyancy in the upward movement and the downward movement is ensured by the WEC´s own weight. With Crestwing the downward movement is achieved from the force of the atmospheric pressure, which means that the WEC can be as light as possible which gives a large upward movement. The upward movement is followed by a large and powerful downward movement driven by the atmospheric pressure at 10 ton per m2. The concepts utilization of the atmospheric pressure and at the same time utilization of the bonded hydrodynamic energy gives a significant increase of the WEC´s efficiency.
The Crestwing concept has been documented through comprehensive tests at Aalborg University and DHI. The concept will, with its high efficiency and simple construction, be able to challenge the windmill sector.
It is Waveenergyfyns intension to contribute to innovation and new thinking with in wave energy and participate in promoting the evolution of efficient light weight Wave Energy Converters.
The vision for development and realization of the WEC Crestwing
The development of WEC´s in Denmark typical begins with tests of very small test models in AAU´s wave tank in the scale 1:40 or 1:50. From these small scale models the next step is test offshore (Nissum Bredning) in a scale 1:10. And which now has proved itself; a praxis which is very expensive, time consuming and an inefficient procedure. The testing of WEC´s have been focused around Alborg University’s test facilitates and there capacity where the development is aimed towards offshore tests at Nissum Bredning and Hanstholm.
Waveenergyfyn development strategy is not to go offshore before there is extensive onshore testing as far as possible over the structure, anchoring, efficiency and movement pattern.
Waveenergyfyn's experience from the development work partly from the renewable energy sector and not least the experience from Odense Steel Shipyard has made it natural with a maritime approach for the development of floating concepts.
The maritime sector in Denmark has several hundred years of experience in the development of ships and floating structures. Although steel ship yards more or less have been settled over the past years, we remain among the leaders in marine design and development.
Development, production and launching of floating WECér almost require the involvement of maritime companies with extensive experience in:
· the development of ships and marine structures
· anchoring systems
· equipment, launching and certification
· operation and maintenance in Sea
The opposite of the involvement of marine industries is that inventor and investors form new companies around the individual concepts. Here there will typically sit a few engineers often with a questionable experience from the maritime sector.
Previous development of the Crestwing Concept
Frederikshavn, which historically is a maritime center, had only an insignificant part in the development and construction of the previous wave energy concepts. With knowledge of Frederikshavn status in the maritime field, it was natural for us to contact the Energy City Frederikshavn back in 2009. We have since had an intensive and fruitful cooperation, where there in cooperation with Energy City has been established an interdisciplinary consortium with a number of maritime companies in Northern Jutland.
Waveenergyfyn considers Crestwing in favor of the Danish concept which has the highest onshore documentation and ongoing 1:5 scale tests have so far confirmed the stability. The project is very well documented; the documentation is at level with the documentation normally used for the production of the many different types of boats that have been built over the years on the shipyards in Frederikshavn.
Waveenergyfyn has received grants for the project totaling approx. 3 million.Kr. This has been essential for the realization toward the prototype. Had the Crestwing concept not met the expectations during the extensive onshore testing, the funds invested would have been limited by a shutdown of the project.
Future development potential for Crestwing
We have sufficient knowledge of the strains in anchor, hull and hinge for sizing, design and construction of Crestwing prototype plant. The PTO system requires a continued development work to obtain a PTO efficiency approaching the wind energy sector.
If there isn’t established a better site in the North Sea, the natural development will be building and testing of prototype at Hanstholm site in a size that can subsequently be upgraded and tested on an English site.
If there is established a site in connection with Hornsrev ocean wind park with an appropriate transitional price for electricity production it will be possible for following development of the domestic market.
Provided the development of the PTO system with an efficiency of between 85% and 90% it will be possible with a Crestwing park including 16 units in 2020. The total annual production would then be between 15.2 to 19 GWh (between 3000 and 5000 households' electricity consumption) per. year and employ over 300 people in production. In addition there will be expected production and sale of larger versions of Crestwing for launching in the Atlantic.
under revision
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