Northwest National Marine Renewable Energy Research Articles

Field test study and quasi-static analysis of global characteristics and survivability of a wave energy converter test platform mooring system

This study presents a catenary spread mooring system design of a mobile ocean test berth, named the Ocean Sentinel (OS), and developed by the Northwest National Marine Renewable Energy Center to facilitate the ocean testing of wave energy converters (WECs). The original OS mooring design (which was similar to a conventional WEC point absorber mooring system) was evaluated through a field data analysis using a quasi-static approach. The field data analysis on the measurements of mooring tension and environmental conditions collected during an ocean test of the OS is based on a quasi-static analysis of the analytical catenary equations of mooring chains. Both global and survivability characteristics of the mooring system were evaluated. The global characteristics include the influence of the OS excursion on mooring tension, the directional control of the OS, and the environmental contributions of waves, current, and wind. The relationship between the dynamic mooring tension and the environmental conditions of waves and current was quantified through an empirical equation. It was found that the contribution of current to the mooring tension oscillation increased as the current velocity increased and was significant at high current velocity. The survivability characteristics include the anchor movability and strength capacities of mooring lines. Because anchor movement occurred near the end of the field test, a new systematic procedure of designing a mooring system with adequate anchor resistance was developed and applied to improve the OS mooring system design.

Numerical Analysis and Scaled High Resolution Tank Testing of a Novel Wave Energy Converter

This paper presents a novel point absorber wave energy converter (WEC), developed by Columbia Power Technologies (COLUMBIA POWER), in addition to the related numerical analysis and scaled wave tank testing. Three hydrodynamic modeling tools are employed to evaluate the performance of the WEC, including WAMIT, GL Garrad Hassan's GH WaveDyn, and OrcaFlex. GH WaveDyn is a specialized numerical code being developed specifically for the wave energy industry. Performance and mooring estimates at full scale are evaluated and optimized, followed by the development of a 1:33 scale physical model. The physical tests of the 1:33 scale model WEC were conducted at the multidirectional wave basin of Oregon State University's O.H. Hinsdale Wave Research Laboratory, in conjunction with the Northwest National Marine Renewable Energy Center (NNMREC). This paper concludes with an overview of the next steps for the modeling program and future experimental test plans.

Testing the WET-NZ Wave Energy Converter Using the Ocean Sentinel Instrumentation Buoy

AbstractThis paper describes ocean testing of the half-scale Wave Energy Technology-New Zealand (WET-NZ) prototype wave energy converter (WEC) using the Ocean Sentinel instrumentation buoy during a 6-week deployment period in August‐October 2012. These tests were conducted by the Northwest National Marine Renewable Energy Center (NNMREC) at its Pacific Ocean test site off the coast of Newport, Oregon. The WET-NZ is the product of a research consortium between Callaghan Innovation, a New Zealand Crown Entity, and Power Projects Limited (PPL), a Wellington, New Zealand private company. The Oregon deployment was project managed by Northwest Energy Innovations (NWEI), a Portland, OR firm. NNMREC is a Department of Energy sponsored partnership between Oregon State University (OSU), the University of Washington (UW), and the National Renewable Energy Laboratory (NREL). The Ocean Sentinel instrumentation buoy is a 6-m surface buoy, developed in 2012, that provides a stand-alone electrical load, WEC generator control, and data collection for WECs being tested. The Ocean Sentinel was deployed and operated for the first time during the 2012 WET-NZ tests. During these tests, the operation of the WET-NZ was demonstrated and its performance was characterized, while also proving successful deployment and operation of the Ocean Sentinel.

Scaled Development of a Novel Wave Energy Converter Including Numerical Analysis and High-Resolution Tank Testing

This paper presents the scaled development of a novel point absorber wave energy converter (WEC) developed by Columbia Power Technologies (COLUMBIA POWER, Corvallis, OR, USA), including numerical analysis and scaled wave tank testing. Four hydrodynamic modeling tools are employed to evaluate and optimize the performance of the WEC, including WAMIT, Garrad Hassan's GH WaveDyne, OrcaFlex, and ANSYS AQWA. Performance and mooring estimates at full scale are evaluated and optimized, followed by the development of 1 : 33, 1 : 15, and 1 : 7 scale physical models. The physical tests of the 1 : 33 and 1 : 15 scale WECs were conducted in the wave basins of Oregon State University's O.H. Hinsdale Wave Research Laboratory, in conjunction with the Northwest National Marine Renewable Energy Center (NNMREC). This paper concludes with the development of the 1 : 7 scale WEC and the associated field testing.

A Novel Ocean Sentinel Instrumentation Buoy for Wave Energy Testing

AbstractThis paper presents a novel Ocean Sentinel instrumentation buoy that the Northwest National Marine Renewable Energy Center (NNMREC) has developed with AXYS Technologies for the testing of wave energy converters (WECs). NNMREC is a Department of Energy-sponsored partnership among Oregon State University (OSU), the University of Washington (UW), and the National Renewable Energy Laboratory (NREL). The Ocean Sentinel instrumentation buoy is a surface buoy based on the 6-m NOMAD (Navy Oceanographic Meteorological Automatic Device) design. The Ocean Sentinel provides power analysis, data acquisition, and environmental monitoring, as well as an active converter interface to control power dissipation to an onboard electrical load. The WEC being tested and the instrumentation buoy are moored with approximately 125 meters separation; connected by a power and communication umbilical cable. The Ocean Sentinel was completed in 2012 and was deployed for the testing of a WEC at the NNMREC open-ocean test site, north of Newport, OR, during August and September of 2012.