Session: 09-03-02: Current and Tidal Energy: Hydrodynamic Analysis

Paper Number: 101076

101076 - Open Water Blade Strain Measurements on a Vertical-Axis Tidal Turbine 

 

Open water testing of marine renewable energy devices represents a significant milestone and hurdle for research teams and companies that seek to reduce the Levelized Cost of Energy (LCOE) to allow these devices to compete in the open electrical generation market.  For open water testing of tidal energy converters (TECs), accurate measurements of loading characteristics on the blades and other structural components correlated with power performance metrics can be invaluable to further refine design principles and models, allowing continued improvement and cost reduction of new turbine designs.  This paper will describe the modifications and additions made to a TEC system to achieve these measurements, along with a discussion the impacts the required modifications had on the measurements and an overview of initial results from the measurement campaign.

A New Energy Corporation Inc. (NECI) vertical-axis turbine (1.7m tall x 3.2m diameter) was retrofitted [Figure 1] to monitor blade strain in real time. A Modular Ocean Data Acquisition (MODAQ) was designed to collect concurrent measurements of blade strain, power output, rotor position, tidal current resource and rotor thrust loading.  The blade measurements are derived from an array of individual strain gauges embedded on each side on one of the four turbine blades. Strain is transmitted wirelessly to MODAQ.  MODAQ was developed by the National Renewable Energy Laboratory (NREL), and the MODAQ system used here was built by UNH in collaboration with NREL and is managed and operated by UNH. The turbine was deployed at the UNH/AMEC Tidal Energy Test Site at Memorial Bridge in Portsmouth, New Hampshire.   

This measurement campaign provides an example of how existing commercially available devices in the marine energy space can be retrofitted to provide additional knowledge about the performance and structural integrity of devices operating in a real flow environment.  This approach allows continued improvement of marine energy technologies and moves marine energy systems closer to cost parity with more established energy industries.

This work aims to complete a measurement campaign on the retrofitted system deployed at the UNH/AMEC Tidal Energy Test Site over a Spring-Neap tidal cycle.   The goal of these measurements is to directly measure and correlate blade loading to inflow and power fluctuations at all points of rotation of the turbine.  The results presented here are compared against previous studies of the turbine’s performance at this site, and a description of any measurable and meaningful impacts the new measurement system has on the operation of the turbine is given. A discussion of the measurements follows, highlighting the strain and moment loads from the blades, along with the inflow and turbine power characteristics.

 

Presenting Author: Aidan Bharath National Renewable Energy Lab

Presenting Author Biography: Aidan Bharath is a Test Engineering Researcher at the National Renewable Energy Lab in Golden, Colorado, USA. His primary area of research is in data acquisition system development for open water testing of both wave energy and tidal energy devices, including novel approaches for DAQ designs or key performance characterization based on IEC testing standards. His background and previous work extends into laboratory scale wave tank testing and ocean energy resource characterization both numerically and experimentally.

Authors:

Aidan Bharath National Renewable Energy Lab
Hannah Ross National Renewable Energy Lab
Casey Nichols National Renewable Energy Lab
Andrew Simms National Renewable Energy Lab
Mark Murphy National Renewable Energy Lab
Robert Raye National Renewable Energy Lab
Patrick O'byrne University of New Hampshire
Michael Monahan University of New Hampshire
Martin Wosnik University of New Hampshire