Terry Lettenmaier

A novel ocean sentinel instrumentation buoy for wave energy testing

This 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.

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

This 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.

Advancing the Wave Energy Industry

An extremely abundant and promising source of energy exists in the worlds oceans. Ocean energy exists in the forms of wave, tidal, marine currents, thermal (temperature gradient), and salinity. Among these forms, opportunities and benefits have been identified in the area of ocean wave energy extraction, i.e., using wave energy converters (WECs) to harness the motion of waves and converting that motion into electrical energy. Ocean wave power exhibits several advantageous characteristics including high power density, low variability, and excellent forecastability. The United States is estimated to have 260 TWh of potential wave energy off its coasts, which is approximately 6% of its annual electrical load (comparable to the current traditional hydro power contribution). Ocean waves have well-defined geographical attributes, where the wave power tends to be stronger on the western coasts of land masses and also stronger moving north and south away from the equator. This is due to the global wind cells, primarily the Westerlies, which tend to cause eastwardly moving waves.

Research and ocean testing solutions to advance the wave energy industry

This paper presents the wave energy research thrusts as well as the development of novel scaled and full-scale ocean testing solutions through the Northwest National Marine Renewable Energy Center (NNMREC) headquartered at Oregon State University (OSU). NNMREC performs fundamental technological, social, and environmental research, in addition to providing unique testing facilities. Testing resources include a wave energy linear test bed, 2D and 3D wave tanks, an Ocean Sentinel instrumentation buoy to facilitate open-ocean testing without a cable-to-shore grid connection, as well as developing cable-to-shore grid emulator and grid-connect facilities. All of NNMRECs marine energy converter testing facilities are being branded as the Pacific Marine Energy Center (PMEC), including the scaled lab testing facilities and intermediate and full-scale open water testing facilities. This paper includes an overview of ongoing NNMREC research and advancing ocean testing solutions as well as the 2012 and 2013 Ocean Sentinel deployments, along with the associated testing of materials and technologies for biofouling resistant surfaces.

Power converter and control system developed in the Ocean Sentinel instrumentation buoy for testing wave energy converters

The Ocean Sentinel instrumentation buoy was developed for the non-grid-connected testing of wave energy converters (WECs). This surface buoy provides power analysis and data acquisition, environmental monitoring, as well as an active converter interface to control WEC-generated power dissipation in an onboard electrical load. The first deployment of the Ocean Sentinel was in the summer of 2012 for the testing of a half-scale WEC over a six-week period. This paper presents the Ocean Sentinel instrumentation buoy power converter and control system designed to enable the ocean testing of a wide range of WEC technologies with various power outputs and generator configurations.

Mooring Analysis of a NOMAD Buoy Through Field Testing and Numerical Simulation

This study presents a mooring analysis of the Ocean Sentinel buoy, which is a mobile test platform for Wave Energy Converters (WECs). The Ocean Sentinel is owned and operated by the Northwest National Marine Renewable Energy Center (NNMREC) at Oregon State University (OSU). The study involved a field observation as well as numerical modeling. The Ocean Sentinel was deployed from 7/29/2013 – 10/04/2013 at the NNMREC North Energy Test Site, which is located between 2–3 nautical miles (3.7–5.6 km) offshore of Yaquina Head, north of Newport, OR. It was configured in a three-point mooring with load cells on each mooring line. Prior to deployment, the numerical model was used for design and testing of the Ocean Sentinel mooring system. After deployment, recorded environmental conditions were coupled with the model to simulate deployed conditions, and model predictions of tension in the mooring lines were compared with actual results.Copyright