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Wave energy conversion |
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Introduction |
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The coastal waters of the British Isles receive some of the world’s largest wave energy levels with average values of up to 70 kW/m (Fig. 1). As a result, this renewable has the potential to make an important contribution to the UK’s renewable energy mix. Wave energy has seen a sustained revival in the past decade with strong governmental support. At present, approximately 100 wave energy converters (WECs) are under research and development and the first full scale prototypes are under investigation. Dr Valentin Heller worked as a Research Fellow on the physical model tests of the distensible WEC Anaconda, he was involved in the EU funded EquiMar project and he currently addresses some general challenges of distensible structures exposed to waves. |
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Personal research website of Dr Valentin Heller |
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Anaconda WEC |
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Fig. 1. Time averaged wave power world-wide in kW/m wave front based on numerical modelling
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Fig. 2. Left: principle of bulge wave generation with direction of internal oscillatory flow and power take-off (PTO); right: 1:25 scale model tests in a towing tank in Southampton
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The Anaconda consists essentially of a rubber tube, which is closed a both ends and filled with water, and it is moored with its head towards the waves. Pressure variations due to external waves generate bulge waves in this tube as shown in Fig. 2. Bulge waves are also generated in the aortas of mammalian bodies by the pressure pulses of the hearts. Theoretically, the bulges in Anaconda propagate with a +90° phase shift relative to the maximum external pressure and ‘surf’ in front of the wave crests transporting concentrated wave power. This power contained in the bulge is transformed into electrical power with a power take-off (PTO) at the tube stern. The planned full scale prototype will be around 150 m long and 6 m in diameter (Heller et al. 2010). |
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Fig. 3. Set-up at about 1:25 with the 6.8 m long rubber tube, a frame to hold the tube in position up-wave and the model power take-off PTO on the right (Chaplin et al. 2012) |
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Selected publications |
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Journals Chaplin, J.R., Heller, V., Farley, F.J.M., Hearn, G.E., Rainey, R.C.T. (2012). Laboratory testing the Anaconda. Philosophical Transactions of the Royal Society A 370:403-424 (http://dx.doi.org/10.1098/rsta.2011.0256). Others Heller, V. (2012). Development of wave devices from initial conception to commercial demonstration. Sayigh, A. (Ed.) Comprehensive Renewable Energy, Vol. 8, 79-110, Elsevier, Oxford (http://dx.doi.org/10.1016/B978-0-08-087872-0.00804-0). Heller, V., Chaplin, J.R. (2011). Dynamic mechanical analysis of rubber used in Anaconda testing, Proc. 9th European Wave and Tidal Energy Conference, paper 373, 5. - 9. September 2011, Southampton. Chaplin, J.R., Farley, F.J.M., Hearn, G.E., Heller, V., Mendes, A. (2010). Hydrodynamic performance of the Anaconda wavepower device. Proceeding of the HYDRALAB III joint transnational access user meeting, 73-76, J., Grüne, Breteler, M.K., eds. Coastal Research Centre of University Hanover and Technical University Braunschweig, Hanover. Heller, V. (2010). Leading wave power devices. Internal report, Energy and Climate Change Division, University of Southampton, Southampton. Heller, V., Chaplin, J.R., Farley, F.J.M., Hann, M.R., Hearn, G.E. (2010). Physical model tests of the wave energy converter Anaconda. 1st European conference of IAHR, Edinburgh, Paper MREc: 1-6, IAHR, Madrid. McCombes, T., Johnstone, C., Holmes, B., Myers, L.E., Bahaj, A.S., Heller, V., Kofoed, J.P., Finn, J., Bittencourt, C. (2010). Assessment of current practice for tank testing of small marine energy devices. D3.3 of Equitable testing and evaluation of marine energy extraction devices in terms of performance, cost and environmental impact (EquiMar). FP7 of EC, Brussels. Myers, L.E., Bahaj, A.S., Heller, V., Retzler, C., Dhedin, J.-F., Ricci, P., Duperray, O., Mendia, J.L. (2010). Site matching and interaction effects. D5.4 of Equitable testing and evaluation of marine energy extraction devices in terms of performance, cost and environmental impact (EquiMar). FP7 of EC, Brussels.
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Dr Heller was involved in Anaconda experiments carried out in the towing tank at Southampton Solent University and in a wave basin (EPSRC grant). The tank in Southampton was 60 m long, 3.7 m wide, with a water depth of 1.87 m. The set-up is sketched in Fig. 3. The model Anaconda consisted of a 6.815 m long rubber tube of initial diameter 0.215 m, closed at the bow, and connected to a PTO system at the stern. Due to the challenges associated with the down-scaling of full scale PTOs (scale effects), the real PTO was replaced by the model PTO shown on the right hand side in Fig. 3. It allowed the measurement of the generated power as a function of the wave climate. The bulge wave features (size, pressure, velocity, power) were measured with self-made Galinstan strain gauges mounted in circumference direction at ten cross sections along the tube (Chaplin et al. 2012). |
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Last modified: 24.04.2017 |
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