Power Conversion Unit Bench Testing of DUO-DS Wave-powered Desalination System

This upload includes the data collected between September 9 and September 26, 2025, at the National Renewable Energy Laboratory in Arvada Colorado. Sea Potential built a single power conversion unit (PCU) along with the pipework for a reverse osmosis system, which was actuated using NREL's large amplitude motion platform. The full scale wave energy converter (WEC) would feature three of these PCUs, which would sit in a buoyant "float". Suspended from the PCUs 3m below the float is a submerged "tank" which acts as a reaction mass. Waves interacting with the WEC impart greater forces on the float than the tank, resulting in differential motion between the two bodies. The PCUs extract energy from this differential motion, pumping pressurized seawater through a reverse osmosis system to produce clean drinking water.

Using NREL's Large Amplitude Motion Platform (LAMP) the connection between the PCU and the tank could be simulated. The goal of these tests was to characterize the performance of the PCU and pipework and identify which components could be improved. The results also aimed to inform control over different components of the system to optimize the power captured in different sea states. The number of tests was limited by time constraints and technical challenges, so the results here do not include any realistic sea state tests and rather focus on quasi-static and sinusoidal tests which produce enough forces, displacements and fluid flow to evaluate the efficiency of various components in the system.

The data was recorded at 100Hz by NREL's EDAS system, including readings of all of Sea Potential's sensors (pressure, force, stroke and flowrate), as well as the position of LAMP in 6 degrees of freedom. All data was downsampled to 10Hz to focus on the timescales of interest and reduce the size of files produced.

Software requirements for viewing the data are as follows:
MATLAB: Required to load .mat files (all processed data) and run "DUO_BenchTest_Viewer" and other supplementary scripts
Excel: Required to load test log and .csv files containing 6dof commanded motion profiles
Word: Required to open "SP-DUO MHKDR Read Me"

A PDF containing static figures of the results of each test is also contained, as well as a PDF of the test report which provides detailed background and methodology and relates the test data to the intended outcomes of the project. These illustrate the majority of the data and conclusions without needing to load the data files.

For a detailed look at the data, each .mat file contains a struct with all processed data read by LAMP and EDAS, as well as calculated data. A field titled "units" contains the engineering units of each channel in the file (the units of each channel are also contained in the read me file). An additional field also contains the file names of the raw data and LAMP control files associated with that test. The "DUO_BenchTest_Viewer" provides a UI window from which data can be loaded, and simple plots and windowed statistics can be generated.

Please start by reading the "SP-DUO MHKDR Read Me" document for details on the files contained in this upload, as well as descriptions and figures of the test article and methods used.