The importance of getting your feet wet: Field measurements from the OPERA project
Several fundamental development barriers exist within the wave energy sector associated with uncertainties about technological and economic risk. These factors are symptomatic of the sector; a multitude of device designs that have been proposed to-date and yet performance and reliability data is sparse. This coupled with a general lack of design convergence means that the relevance of published results may not always be applicable. The reluctance to share data is due to perceived or actual risks to commercial competitiveness and intellectual property. The need to prove continued availability, performance efficiency and survivability requires a deep understanding of how the device will operate in a range of expected environmental conditions. At low Technology Readiness Levels (TRL < 4) a mixture of experimental and numerical modelling is typically used to understand the fundamental operational characteristics of the device. Scale prototype testing at sea (TRL 5-6) provides an opportunity not only to ‘shakedown’ the design but also to acquire long-term, device response data, allowing numerical models (i.e. dynamic simulations and fatigue calculations) to be validated in addition to allowing O&M activities to be developed. With the current lack of published field data in mind, the Horizon 2020 funded Open Sea Operating Experience to Reduce Wave Energy Cost (OPERA) project is focused on data collection of offshore and onshore devices. The offshore device; Marmok-A-5 (developed by Oceantec Energias Marinas supported by the Basque government energy agency, EVE), is an oscillating water column comprising a 5m diameter (max) and 41.8m long hollow spar buoy deployed in approximately 85m water depth at the BiMEP test site (Fig. 1). The mooring system features one cell of the shared ‘Karratu’ system proposed in and has been instrumented to record tensions on the two seaward corners of the cell at 20Hz. This, coupled with an onboard IMU and DGPS provides a detailed dataset of device and mooring system response. The dataset along with directional wave buoy measurements recorded nearby and hindcast wind and current fields are currently being used to validate a fully dynamic numerical model of the system . An overview of this process and the challenges associated with offshore data collection will be presented at the PRIMaRE conference.
The work is part of the OPERA (Open Sea Operating Experience to Reduce Wave Energy Cost) project which is funded from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654.444.
Conference presentation: 4th PRIMaRE Conference 2017; Southampton 6th July 2017
4th PRIMaRE conference, University of Southampton, 2017-07-06, 2017-07-07, Southampton, UK