Columbia Power Technologies Research Articles

Statistical Analysis of a 1:7 Scale Field Test Wave Energy Converter Using WEC-Sim

This study uses the open-source wave energy converter simulator (WEC-Sim) code to model the Columbia Power Technologies SeaRay 1:7 scale WEC. WEC-Sim is intended to run quickly on standard desktop equipment and provide a very gentle learning curve for WEC modeling. This paper focuses on the linear implementation of WEC-Sim as that requires the least simulation time and is often the starting point for basic system design. WECSim results are compared against the SeaRay experimental data. Two studies were conducted: A comparison of WEC-Sim predications versus experimental data across 285 trials of varying sea states to determine the overall average power and energy production; and a determination of WEC-Sim's accuracy in predicting the experimental ranges of position, speed, torque, and power. The study of average power production across many sea states shows that the WEC-Sim predicts the average power of the aft float well, within 15%, but the error in the fore float is larger at 34%. The error in total predicted power is 24%. The detailed analysis of range of motion shows WEC-Sim predicted 95th percentile outliers (which dominate the design considerations) in position, speed, and torque by +15%, +14%, and +17%, respectively, for the fore float and -1%, -9%, and -6%, respectively, for the aft float.

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.

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.

LABORATORY OBSERVATIONS AND NUMERICAL MODELING OF THE EFFECTS OF AN ARRAY OF WAVE ENERGY CONVERTERS

This paper investigates the effects of wave energy converters (WECs) on water waves through the analysis of extensive laboratory experiments, as well as subsequent numerical simulations. Data for the analysis was collected during the WEC-Array Experiments performed at the O.H. Hinsdale Wave Research Laboratory at Oregon State University, in collaboration with Columbia Power Technologies, using five 1:33 scale point-absorbing WECs. The observed wave measurement and WEC performance data sets allowed for a direct computation of power removed from the wave field for a large suite of incident wave conditions and WEC array sizes. Using measured power absorption characteristics as a WEC parameterization for SWAN was developed. This parameterization was verified by comparison to the observational data set. Considering the complexity of the problem, the parameterization of WECs by only power absorption is a reasonable predictor of the effect of WECs on the far field.

Comparison of Direct-Drive Power Takeoff Systems for Ocean Wave Energy Applications

This paper presents a comprehensive power takeoff (PTO) analysis program conducted as a collaborative research effort between Columbia Power Technologies, Inc., Oregon State University (OSU), and the U.S. Navy. Eighteen different direct-drive technologies were evaluated analytically and down-selected to five promising designs. Each of the five prototypes was simulated, modeled in SolidWorks, and built at the 200-W peak level and tested on OSU's wave energy linear test bed. The simulations were validated with the 200-W experimental results and then scaled up to 100 kW, with full 100-kW designs including costs, maintenance, operations, etc., to estimate the cost of energy (COE) for each PTO buoy system at utility scale.