Marine Renewables Infrastructure Network

Infrastructure Access Report

Infrastructure: QUB Portaferry Tidal Test Centre

User-Project: OSTReTiC Operating SCHOTTEL Turbine in Real Tidal Currents

SCHOTTEL – Josef Becker Forschungszentrum GmbH

Status: Final Version: <<01>> Date: 26-Nov-2014

EC FP7 “Capacities” Specific Programme Research Infrastructure Action

Infrastructure Access Report: OSTReTiC

ABOUT MARINET MARINET (Marine Renewables Infrastructure Network for emerging Energy Technologies) is an EC-funded network of research centres and organisations that are working together to accelerate the development of marine renewable energy - wave, tidal & offshore-wind. The initiative is funded through the EC's Seventh Framework Programme (FP7) and runs for four years until 2015. The network of 29 partners with 42 specialist marine research facilities is spread across 11 EU countries and 1 International Cooperation Partner Country (Brazil).

MARINET offers periods of free-of-charge access to test facilities at a range of world-class research centres. Companies and research groups can avail of this Transnational Access (TA) to test devices at any scale in areas such as wave energy, tidal energy, offshore-wind energy and environmental data or to conduct tests on cross-cutting areas such as power take-off systems, grid integration, materials or moorings. In total, over 700 weeks of access is available to an estimated 300 projects and 800 external users, with at least four calls for access applications over the 4-year initiative.

MARINET partners are also working to implement common standards for testing in order to streamline the development process, conducting research to improve testing capabilities across the network, providing training at various facilities in the network in order to enhance personnel expertise and organising industry networking events in order to facilitate partnerships and knowledge exchange.

The aim of the initiative is to streamline the capabilities of test infrastructures in order to enhance their impact and accelerate the commercialisation of marine renewable energy. See www.fp7-marinet.eu for more details.

Partners

Ireland Netherlands University College Cork, HMRC (UCC_HMRC) Stichting Tidal Testing Centre (TTC) Coordinator Stichting Energieonderzoek Centrum Nederland Sustainable Energy Authority of Ireland (SEAI_OEDU) (ECNeth)

Denmark Germany Aalborg Universitet (AAU) Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V (Fh_IWES) Danmarks Tekniske Universitet (RISOE)

Gottfried Wilhelm Leibniz Universität Hannover (LUH)

France Universitaet Stuttgart (USTUTT) Ecole Centrale de Nantes (ECN)

Institut Français de Recherche Pour l'Exploitation de Portugal la Mer (IFREMER) Wave Energy Centre – Centro de Energia das Ondas

(WavEC)

United Kingdom

National Renewable Energy Centre Ltd. (NAREC) Italy Università degli Studi di Firenze (UNIFI-CRIACIV) The University of Exeter (UNEXE) Università degli Studi di Firenze (UNIFI-PIN) European Marine Energy Centre Ltd. (EMEC) Università degli Studi della Tuscia (UNI_TUS)

University of Strathclyde (UNI_STRATH) Consiglio Nazionale delle Ricerche (CNR-INSEAN)

The University of Edinburgh (UEDIN) Brazil Queen’s University Belfast (QUB) Instituto de Pesquisas Tecnológicas do Estado de São

Paulo S.A. (IPT) Plymouth University(PU)

Spain Norway Sintef Energi AS (SINTEF) Ente Vasco de la Energía (EVE)

Tecnalia Research & Innovation Foundation Norges Teknisk-Naturvitenskapelige Universitet (NTNU) (TECNALIA)

Belgium 1-Tech (1_TECH)

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DOCUMENT INFORMATION Title Operating SCHOTTEL Turbine in Real Tidal Currents Distribution Public Document Reference MARINET-TA1-OSTReTiC

User-Group Leader, Lead Ralf Starzmann SCHOTTEL Author Mainzer Straße 99 D - 56322 Spay, Germany

User-Group Members, Stefan Scholl SCHOTTEL Contributing Authors Infrastructure Accessed: QUB Portaferry Tidal Test Centre Infrastructure Manager Bjoern Elsaesser (or Main Contact)

REVISION HISTORY Rev. Date Description Prepared by Approved By Status (Name) Infrastructure (Draft/Final) Manager 01 First Draft Ralf Starzmann 02 Second Draft Penny Jeffcoate 03 Final Ralf Starzmann Bjoern Elsaesser Final

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ABOUT THIS REPORT One of the requirements of the EC in enabling a user group to benefit from free-of-charge access to an infrastructure is that the user group must be entitled to disseminate the foreground (information and results) that they have generated under the project in order to progress the state-of-the-art of the sector. Notwithstanding this, the EC also state that dissemination activities shall be compatible with the protection of intellectual property rights, confidentiality obligations and the legitimate interests of the owner(s) of the foreground.

The aim of this report is therefore to meet the first requirement of publicly disseminating the knowledge generated through this MARINET infrastructure access project in an accessible format in order to: • progress the state-of-the-art • publicise resulting progress made for the technology/industry • provide evidence of progress made along the Structured Development Plan • provide due diligence material for potential future investment and financing • share lessons learned • avoid potential future replication by others • provide opportunities for future collaboration • etc. In some cases, the user group may wish to protect some of this information which they deem commercially sensitive, and so may choose to present results in a normalised (non-dimensional) format or withhold certain design data – this is acceptable and allowed for in the second requirement outlined above.

ACKNOWLEDGEMENT The work described in this publication has received support from MARINET, a European Community - Research Infrastructure Action under the FP7 “Capacities” Specific Programme.

LEGAL DISCLAIMER The views expressed, and responsibility for the content of this publication, lie solely with the authors. The European Commission is not liable for any use that may be made of the information contained herein. This work may rely on data from sources external to the MARINET project Consortium. Members of the Consortium do not accept liability for loss or damage suffered by any third party as a result of errors or inaccuracies in such data. The information in this document is provided “as is” and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information at its sole risk and neither the European Commission nor any member of the MARINET Consortium is liable for any use that may be made of the information.

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EXECUTIVE SUMMARY

Within this MARINET project SCHOTTEL successfully tested its Hydrokinetic Turbines at the QUB tidal test centre in Strangford Lough, Northern Ireland. It offers an ideal testing environment for “small” tidal turbines using a vessel- mounted setup. The full-scale tests included 288 operating hours under realistic and highly turbulent conditions, resulting in an expansive and highly valuable data set.

For the trial SCHOTTEL attached the turbine with a rotor diameter of four (and three) meters to a moored barge. It was mounted on a lifting frame at the stern and lowered down into the operating position for testing. Additionally, the barge was equipped with a large range of measurement devices and sensors to monitor the test results. The turbine shaft rotations, torque and power output were recorded for use in the performance assessment. Load cells measured the resulting thrust force, while detailed measurements of flow conditions were also taken.

The testing method and characterisation of turbine performance have been developed according to the latest standards of the International Electrotechnical Commission (IEC). The result: the turbine with a rotor diameter of four meters proved both its reliability, as well it´s performance, in the field.

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CONTENTS

1 INTRODUCTION & BACKGROUND ...... 7

1.1 INTRODUCTION ...... 7 1.2 DEVELOPMENT SO FAR ...... 7 1.2.1 Stage Gate Progress ...... 7 1.2.2 Plan For This Access ...... 9 2 OUTLINE OF WORK CARRIED OUT ...... 9

2.1 SETUP ...... 9 2.2 TESTS ...... 11 2.2.1 Test Plan ...... 11 2.3 RESULTS ...... 12 2.4 ANALYSIS & CONCLUSIONS...... 13 3 MAIN LEARNING OUTCOMES ...... 13

3.1 PROGRESS MADE ...... 13 3.1.1 Progress Made: For This User-Group or Technology ...... 13 3.1.2 Progress Made: For Marine Renewable Energy Industry ...... 14 3.2 KEY LESSONS LEARNED ...... 14 4 FURTHER INFORMATION ...... 14

4.1 SCIENTIFIC PUBLICATIONS ...... 14 4.2 WEBSITE & SOCIAL MEDIA ...... 14 5 APPENDICES ...... 14

5.1 STAGE DEVELOPMENT SUMMARY TABLE ...... 14

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1 INTRODUCTION & BACKGROUND

1.1 INTRODUCTION Based on extensive experience of marine propulsion systems, SCHOTTEL has developed the STG50, a turbine that generates electricity from tidal currents. Model testing and RANS-CFD simulations were used to optimize the rotor blade shape. A complete drive train system was developed and extensive laboratory tests were used to develop an initial power control configuration as well as to test the drive train under nominal and overload conditions. Firstly sea trials were performed using a harbor tug with the full-scale STG unit mounted on a rig at the bow. The turbine was tested under a wide range of conditions, achieved by varying the speed of the tug. The development work to date is in line with the completion of “Stage 2” of the structured development plan and the main outcomes of testing campaign have been:

• Entire system works as expected • Rated power is delivered as predicted • No cavitation erosion at overspeed

The next stage is focused on building up operational experience in a range of flow conditions that are representative of turbulent tidal currents that the turbine will be operating in on commercial projects. Furthermore, a performance assessment according to IEC is envisaged.

1.2 DEVELOPMENT SO FAR 1.2.1 Stage Gate Progress Previously completed:  Planned for this project: 

STAGE GATE CRITERIA Status Stage 1 – Concept Validation • Linear monochromatic waves to validate or calibrate numerical models of the system (25 – 100 waves) • Finite monochromatic waves to include higher order effects (25 –100 waves) • Hull(s) sea worthiness in real seas (scaled duration at 3 hours) • Restricted degrees of freedom (DofF) if required by the early mathematical models • Provide the empirical hydrodynamic co-efficient associated with the device (for mathematical modelling tuning) • Investigate physical process governing device response. May not be well defined theoretically or numerically solvable • Real seaway productivity (scaled duration at 20-30 minutes) • Initially 2-D (flume) test programme • Short crested seas need only be run at this early stage if the devices anticipated performance would be significantly affected by them • Evidence of the device seaworthiness  • Initial indication of the full system load regimes 

Stage 2 – Design Validation • Accurately simulated PTO characteristics  • Performance in real seaways (long and short crested)  • Survival loading and extreme motion behaviour.  • Active damping control (may be deferred to Stage 3)

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STAGE GATE CRITERIA Status • Device design changes and modifications • Mooring arrangements and effects on motion • Data for proposed PTO design and bench testing (Stage 3) • Engineering Design (Prototype), feasibility and costing  • Site Review for Stage 3 and Stage 4 deployments • Over topping rates

Stage 3 – Sub-Systems Validation • To investigate physical properties not well scaled & validate performance figures • To employ a realistic/actual PTO and generating system & develop control strategies  • To qualify environmental factors (i.e. the device on the environment and vice versa) e.g. marine growth,  corrosion, windage and current drag • To validate electrical supply quality and power electronic requirements. • To quantify survival conditions, mooring behaviour and hull seaworthiness • Manufacturing, deployment, recovery and O&M (component reliability) • Project planning and management, including licensing, certification, insurance etc.

Stage 4 – Solo Device Validation • Hull seaworthiness and survival strategies • Mooring and cable connection issues, including failure modes • PTO performance and reliability  • Component and assembly longevity • Electricity supply quality (absorbed/pneumatic power-converted/electrical power) • Application in local wave climate conditions • Project management, manufacturing, deployment, recovery, etc • Service, maintenance and operational experience [O&M] • Accepted EIA

Stage 5 – Multi-Device Demonstration • Economic Feasibility/Profitability • Multiple units performance • Device array interactions • Power supply interaction & quality • Environmental impact issues • Full technical and economic due diligence • Compliance of all operations with existing legal requirements

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1.2.2 Plan For This Access SCHOTTEL has developed the STG, aiming to make tidal current energy economically competitive with well- established energy sources. The next stage in the development and demonstration of the STG unit for commercial deployment on tidal energy sites is focused on gaining more operating hours on the STG machine and operating in more realistic “turbulent” conditions with the turbine fixed within a flowing current. The aim of the operational testing is:

• Test the overall performance of rotor, drive train and generator system • Record the overall performance of the STG at a range of speeds according to IEC • Generate operating hours under realistic conditions in the field • Test the original 4m rotor as well as a recently developed 3m blade • Investigate different control strategies on the performance • Investigate the downstream wake of the turbine • Characterize the acoustic signature of the turbine • Characterize the inflow turbulence (using different sensors) • Environmental monitoring of the device 2 OUTLINE OF WORK CARRIED OUT

2.1 SETUP The STG turbine was mounted on a support frame suspended below a testing barge. The barge was 10m long by 4m wide by 1m high. The barge was 0.35m submerged, giving a total displacement of approximately 14ton. The turbine support was mounted on the stern of the barge and attached to a lifting A-frame. Figure 1.1 shows the turbine and frame in the testing position and Figure 1.2 shows the turbine and frame in the lifted position. The turbine could be lifted clear of the water (between tests and for checks) and lowered for operation. When lowered the turbine hub was 3.4m below the surface so the blade tips swept an area from 1.4m to 5.4m below the surface. The layout of the equipment on the barge deck is shown in Figure 1.3. A number of sensors were used to measure the performance of the turbine itself, as well as the surrounding environment. This included ADPs, ADVs, hydrophones, downscan sonar and load cells, as well as torque and rotational speed measurement.

Figure 1.1: Barge with turbine in testing position

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Figure 1.2: Barge with turbine in lifted position

Figure 1.3: Barge equipment layout

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2.2 TESTS 2.2.1 Test Plan The tests were focused on continuous operation, during which the turbine was generating power. Gathering operating hours was the main aim of carrying out the tests in Northern Island to demonstrate the reliability of the turbine. Furthermore, modified control strategies were tested as well as a 3m diameter rotor blade. Table 2.1 shows an overview of the test plan, including access period time for Fraunhofer IWES, which was run in collaboration with this project.

Week

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Commissioning

4m Rotor

Control Strategy

Turbulence Measurements

Acoustic Measurements

Wake Measurements

3m Rotor

Decommissioning

Table 2.1 Test plan

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2.3 RESULTS

The variations in the inflow velocity, electrical power, thrust, rotational speed and barge pitch during one flood cycle, on the 12th July 2014, are shown below in 2.1.

4

2 [m/s] n

i

u 0 0 1 2 3 4 5 6 40

[kW] 20 l

e P

0 0 1 2 3 4 5 6

40

20

T [kN]

0 0 1 2 3 4 5 6

50

n [rpm] 0 0 1 2 3 4 5 6

5

0

pitch [deg] pitch -5

0 1 2 3 4 5 6 t [h]

Figure 2.1 Exemplary measured time series

The raw data was processed according to IEC/TS 62600-200 to produce a scatter diagram, as shown in Figure 2.2. The results show that as the velocity increases the power increases exponentially, according to the power curve. This curve follows the same trend as experienced in field pushing tests, with cut-in power at approximately 0.8m/s and approximately 18kW at 2m/s. The variation in the results, i.e. between max and min, increases with velocity, potentially due to the variation shown in Figure 2.1. The mean results are, however, consistent with those predicted from previous tests.

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50 Minimum Maximum 40 Mean Standard Deviation [kW] n i 30

20

10

0 Mean Recorded TEC Active Power P Power Active TEC Recorded Mean

-10

0 0.5 1 1.5 2 2.5 Mean Power Weighted Tidal Current Velocity U [m/s] in

Figure 2.2 Power Performance Curve

2.4 ANALYSIS & CONCLUSIONS Full-scale testing of the SCHOTTEL STG turbine has been undertaken at QUB’s tidal test facility over a 14 week period, 4 weeks of which were access time for Fraunhofer IWES, in 2014. The key objective of the testing program was to test the full-scale turbine in turbulent flows. The tests were conducted in the QUB site, during flood tide and daylight hours for 48 days of testing, to collect 288 hours of data. The SCHOTTEL STG turbine was tested in flows between 0 and 2.5m/s, to achieve time-averaged electrical power output up to 19kW. The testing method was therefore appropriate for testing a full-scale device at these flow speeds. During the testing the turbine RPM, torque, mechanical power, electrical power and thrust were recorded. Simultaneously, the inflow velocity, turbulence (measured with 3 different instruments) and wake velocities were also recorded. The location, depth and mammal activity were also tracked and an acoustic analysis of the turbine was carried out. All the performance data was recorded and processed according to the IEC standards. The velocity, power, thrust and pitch curves produced were as expected, both time-varying and time-averaged. 3 MAIN LEARNING OUTCOMES

3.1 PROGRESS MADE 3.1.1 Progress Made: For This User-Group or Technology The testing resulted in significant operational experience in a real tidal environment. An expansive data set with all relevant performance variables has been collected and will be analysed in more detail in the future. The data analysed so far enables the user-group to validate previous pushing-tests, as well as numerical models used to predict the performance. Furthermore, an improved control strategy as well as field data of the turbine wake has been collected.

3.1.1.1 Next Steps for Research or Staged Development Plan – Exit/Change & Retest/Proceed? SCHOTTEL is working on a second generation turbine to further improve the power train performance based on the recent testing carried out. As a next step, it is anticipated to test the turbine at higher flow speeds in a turbulent tidal environment, to go up to rated speed, and measure the entire power curve according to IEC/TS 62600-200. Based on

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the wake study (which so far only covered the near-wake region) another aim would be to cover the far wake, up to 10 diameters downstream of the device.

3.1.2 Progress Made: For Marine Renewable Energy Industry The testing showed that a moored barge setup can be used for field studies of medium- and full-scale tidal devices. The testing method also allows simultaneous data collection to investigate the performance of a full-scale device in tidal flows applying the recently published IEC technical specification. The tested device proved that a robust and simple system is essential to provide reliable energy conversion for future commercial projects.

3.2 KEY LESSONS LEARNED • Operational experience in a tidal race • Measurement equipment testing under real sea conditions • An accessible test platform is very valuable • It is possible to apply the IEC specification to post-process the herein measured data set • The STG turbine has proven it´s functionality and performance in the field

4 FURTHER INFORMATION

4.1 SCIENTIFIC PUBLICATIONS List of any scientific publications planned as a result of this work: • Journal: International Journal of Marine Energy Corresponding Author: Penelope Jeffcoate Co-Authors: Ralf Starzmann; Bjoern Elsaesser; Stefan Scholl Title: Field Measurements of a Full Scale Tidal Turbine Paper submitted - Currently under review • EWTEC 2014 – Currently preparing abstracts • Wake measurements of full-scale turbine – Currently preparing

4.2 WEBSITE & SOCIAL MEDIA Website: www.schottel.de Twitter: https://twitter.com/schottel_hydro 5 APPENDICES

5.1 STAGE DEVELOPMENT SUMMARY TABLE The table following offers an overview of the test programmes recommended by IEA-OES for each Technology Readiness Level. This is only offered as a guide and is in no way extensive of the full test programme that should be committed to at each TRL.

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