The basic idea behind the development of Crestwing has been to develop a wave energy converter which:
From the beginning of the development of Crestwing the focus has been on gaining as much knowledge and information through onshore tests as possible, because tests offshore are expensive and risky. Crestwing has undergone ongoing development and testing since 2005.
The initial tests were conducted in The Great Belt under the brand name Waveenergy Fyn, where inventor and founder Henning Pilgaard himself tested the seaworthiness of the device and, more importantly, whether his theory of the atmospheric pressure could be proven. After the idea was proved for him and those close to the project, the task was to convince others.
Test in wavetank at Aalborg university, scale: 1:30
Aalborg University, AAU, is the most experienced university in Denmark regarding testing of maritime structures. AAU participated in 2008-09 with tests of Crestwing for one year.
Tests with various weights on the device were carried out at AAU to understand how or if the weight of the device would influence the system.
Weights in different sizes (up to 40 kg) was placed on the plant. It turned out to have no relevance to the efficiency and function of the plant.
The goal was to demonstrate that the system did not only work through Archimedes´ principle of displacement. If the efficiency rose when the pontoons were heavier, it would mean that the atmospheric pressure only had a minor influence on the system. These tests showed that the weight had little to none influence on the efficiency of the device.
The tests showed that Crestwing can achieve an annual efficiency of 40-50 % with potential for advancement. For individual waves it was possible to utilize more than 80 % of energy.
Compared to the original design, the concept has been developed during the test runs, among other things it went from four to two pontons, but the principle of the atmospheric pressure remains central to the functionality of Crestwing.
Danish Hydraulic Institute (DHI) participated in 2010-11 for more than a year with tests of Crestwing.
Load cells and force transducers were mounted in order to measure forces in the hinge, structure, anchoring and push rod, as a basis for development and construction of full-scale device. Throughout the test run, the movements of the plant in the six degrees of freedom were measured. The conditions underneath the pontoons were measured to document the vacuum below the device.
Throughout the trial, forces in the anchoring system were measured. It became clear, that keeping forces low in the anchoring system by the use of flexible anchor line is crucial to the efficiency. These tests gave us the data for building a full scale device for the North Sea.
Fladstrandsanlægget in Kattegat scale 1:5, is now on a shipyard.
Frederikshavn is historically a maritime center; they have many shipyards and engine manufacturers, a well-equipped harbor and one of the largest ports in Denmark.
Crestwing and Energy City Frederikshavn have since 2009 had an intensive and successful cooperation.
Test in bigger wavetank at DHI, scale 1:15
In 2011, carpenter students (and their teacher) of the technical school EUC Nord built a wooden model in size 10 x 2.5 m called the Fladstrand model. This model was in autumn 2011 tested in the ocean close to Frederikshavn for behavior and survival, the model was exposed to several storms and performed well through the two to three months the tests lasted.
During 2012-13 there was built a new PTO (Power Take Off) system and three students from “MARTEC engineer school” have completed their bachelor through building a test bench and doing tests on the PTO. It turned out that the little model has an efficiency about 80 %. Since there is bigger resistance in a small model, there was completed calculations of a full-scale PTO and it showed efficiency about 90 %.
In August 2015, Crestwing establishes itself in a warehouse at the harbor in Sæby, south of Frederikshavn. For the next couple of years, the prototype Tordenskiold was built. Tordenskiold measures 30 x 7.5 m and is built in steel with a weight of 65 tonnes.
Alongside the construction of the prototype itself, there was further development on PTO, hinges, anchoring and design in general.
In September 2018, Tordenskiold was tugged to the harbor in Frederikshavn and officially baptized and inaugurated.
Tordenskiold was tugged to the harbor in Frederikshavn and officially baptized and inaugurated.
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