SURFTEC: Survivability and Reliability of Floating Tidal Energy Converters

SuperGen UK Centre for Marine Energy Research Annual Assembly 2018 SURFTEC: Survivability and Reliability of Floating Tidal Energy Converters Thomas Lake, Alison Williams, Michael Togneri, Ian Masters, Jack Hughes Marine Energy Research Group, Swansea University

Overview Project focuses on Floating Tidal Energy Converters (FTECs) Devices that move in relation to changes in sea level One or more turbines suspended from a floating structure Issues associated with costs and operation Identifying and understanding extreme loads Environmental extremes Determining accessibility, serviceability, fault intervals and device life cycles Aim is to produce a design optimisation tool Reliability and Survivability of FTECs

Objectives Develop numerical model that couples Swansea University s BEMT code with a floating platform model Carry out a measurement campaign with FTEC developer Produce a generic FTEC design and operational strategy document Photo of PLAT-I at Connel, taken by John Howe from SAMS

Measurement Campaign Undertaken with Sustainable Marine Energy Ltd (SME) PLAT-I device Three-hulled platform hosting four SCHOTTEL Hydro Instream Turbines Initial deployment at Connel, Oban Late 2017 to Spring 2018 Second deployment at Grand Passage, Canada Autumn 2018 to Spring 2019 Aim to obtain synchronous data measurements for Flow conditions Position of device Loads on device Data required for model validation

Data logging equipment Motion sensors and logging equipment designed and built in house Needed to be robust, waterproof and as close to plug and play as possible Some failures, but plenty of good data System redesigned to be (slightly) more user friendly for 2 nd deployment Industry benefit: Relatively low cost, easy to integrate. Plug and play

Site work Initial ~3 month measurement campaign at Connel Bridge last winter on the SME PLAT-I device Data collected for range of operating conditions ADV mounted to the platform recording at 64Hz Motion data captured at 20Hz (low) or 84Hz (high) High rate data recorded on SD card, low rate data streamed live When SD card full, only low rate data could be saved Raw motion data (Low rate) Raw motion data (High rate) Raw ADV data Total raw data 22GB 43GB 8GB 73GB Industry benefit: Provided additional data, allowing for more confidence in results

Motion tracking Accelerometer, compass and gyro data combined with GPS to give position and heading information Pitch and roll to follow, but some challenges to work around Scope to examine different influences on platform motion Industry benefit: Some lessons learned regarding sensor choice and placement Will allow validation of software models Shows stabilising effect of rotors on floating platform Proven low cost system for motion tracking See also Jeffcoate, Cresswell, Field Performance Testing of a Floating Tidal Energy Platform Part 2: Load Performance, AWTEC 2018.

Turbulence

New BEMT implementation Rewrite of existing MATLAB code as C++ Implemented as a library with different frontends MATLAB and Python bindings possible Allow researchers to use whichever they prefer ~30 times faster than MATLAB implementation Some features still missing or in need of testing [WIP] Industry benefit: Faster, easier to integrate with other tools than previous versions

Floating body motion Work by Jack Hughes associated PhD Student Studying induced motions and loading of moored and unmoored floating bodies using WEC-sim Comparing WEC-sim to existing results from testing at COAST and simulations in OpenFOAM* Using OpenFOAM to generate viscous drag coefficient for specified geometries Due to start evaluating OpenFAST with the same test cases before integrating either WEC-sim or OpenFAST with the BEMT model Moored Unmoored Industry benefit: Increased confidence in free/oss tools Will feed into other aspects of the project *Ransley, E.J., 2015. Survivability of wave energy converter and mooring coupled system using CFD

Ongoing Work Further data collection ongoing at Grand Passage (SME) Expanded data collection system includes wave data Couple BEMT with WEC-Sim or OpenFAST and validate Validated model to calculate FTEC loads Range of environmental data (supplied by EMEC) Fatigue model (Guidance from Black & Veatch) A strategy guide for FTEC device reliability and survivability