Hybrid Offshore Wind and Tidal Systems Andrzej Gruszczynski

Hybrid Offshore Wind and Tidal Systems Andrzej Gruszczynski Duncan Hambrey Emilio Romero Jiménez Iain Sagan Shahzaib Sheaikh Lucia Urra Viana

Introducing HOWa. T The Hybrid Offshore Wind and Tidal System 2 HOWa. T

The HOWa. T Concept + [alternative-energy-news. info] HOWa. T = ? [wind-energy-market. com] 3

Why? Predictable Renewable Energy Generation Increased output from one location Reduced costs through shared transmission infrastructure and foundations Shared maintenance costs Real future potential? HOWa. T 4

Challenges Immature technology Increased structural loads Vibration Costs Future technology? HOWa. T 5

Aims and Objectives Aims Investigate the feasibility of HOWa. T Objectives Possibility of attachment to existing wind turbines Suitable location HOWa. T concept Structural Analysis of foundation Environmental Impact Assessment Estimation of costs and energy output 6 HOWa. T

How to design and implement such a system? 1. Create an attachment for existing offshore windfarms 2. Manufacture the complete hybrid system for new arrays HOWa. T 7

Selected Wind Turbine NREL’s Baseline 5 MW Wind Turbine 8 MW Wind Turbine? Necessary data. HOWa. T [Senu Sirnivas/NREL] 8

Selected Tidal Stream Turbine Atlantis’ Sea. Gen-S 2 MW HOWa. T [Marine Current Turbines] 9

Location Analysis of existing wind farms Combination of Wind and Tidal resources, and appropriate depth Studied with QGIS Isle of Islay Planned tidal and wind farms Better environmental conditions HOWa. T 10

Wind resource Wind data from Port Ellen Steps to obtain wind distribution: Transport data to our location Fit to a statistical distribution Calculate generated power and capacity coefficient HOWa. T [Islayinfo. com] 11

Wind resource Cut-in speed Rated speed Cut-out speed 3 m/s 11. 4 m/s 25 m/s Yearly energy generation Capacity coefficient 23890 MWh 54% HOWa. T 12

HOWa. T 0 12. 75 25. 5 38. 25 51 63. 75 76. 5 89. 25 102 114. 75 127. 5 140. 25 153 165. 75 178. 5 191. 25 204 216. 75 229. 5 242. 25 255 267. 75 280. 5 293. 25 306 318. 75 331. 5 344. 25 357 369. 75 382. 5 395. 25 408 420. 75 433. 5 446. 25 459 471. 75 484. 5 497. 25 510 522. 75 535. 5 548. 25 561 573. 75 586. 5 599. 25 612 624. 75 637. 5 650. 25 663 675. 75 688. 5 701. 25 Current Speed (m/s) Tidal Resource Analysis Peak Spring Current Speed 3. 05 m/s Peak Neap Current Speed 1. 69 m/s Tidal Graph Current Speed Throughout Lunar Cycle 3. 5 3 2. 5 2 1. 5 1 0. 5 0 Hours 13

Tidal Resource Analysis Seagen –S 2 MW chosen to carry out analysis HOWa. T [Marine Current Turbines] 14

Tidal Resource Analysis Turbine Power Output 2500 2000 Power (k. W) 1500 1000 500 0 0 0 25 51 76 101 126 152 177 202 227 253 278 303 328 354 379 404 429 455 480 505 530 556 581 606 631 657 682 707 Power (k. W) Power Output Throughout Lunar Cycle Hours 0 1 3 4 5 6 8 9 1011131415161819202123242526282930313334353638394041434445 Time (hours) Lunar Cycle Energy: 521 MWh Estimated Annual Energy Output: 6. 45 GWh Mean Power Output = 737 k. W Capacity Factor = 36. 8% 15 HOWa. T

Wind Turbine Installation & Retrieval A jack up vessel is used for installation. HOWa. T [Dong Energy, 2017] 16

Support Structure The tidal turbine support structure is welded to the TS This provides the ease of installation. HOWa. T 17

Tidal Turbine Installation & Retrieval • A Dynamic Positioning (DP) vessel is used for installation. HOWa. T 18

HOWa. T 19

Operation 20 HOWa. T

Operation 21 HOWa. T

Maintenance 27 m clearance from the tip of the wind turbine blade to the sea surface A 4 m clearance area from the tip of the tidal turbine to the sea surface. HOWa. T 22

Maintenance 23 HOWa. T

Biofouling Consequences Increase the weight of the structures Increase the drag resistance Loss of efficiency Protection Chemically active antifouling paints Non stick, fouling release coating [Racerocks, 2017] 24 HOWa. T

Supporting Structure Monopile Foundation Offshore wind turbine (OWT) Stress comparison Tidal current turbine Structural Analysis Vibration - Natural Frequency HOWa. T 25

Structural Analysis - Loads Dead Load Wind turbine Tower Tidal current turbine & structure Monopile Aerodynamic load Drag (structure) Thrust (rotor) Hydrodynamic load Drag (structure) + Thrust (rotor) Waves (structure) HOWa. T 26

Structural Analysis – Soil-monopile interaction Offshore Code Comparison Collaboration (OC 3) – Phase II [J. Jonkman and W. Musial , 2010] HOWa. T 27

Structural Analysis – Model Monopile &Tower Soil interaction HOWa. T Beam elements BEAM 188 Non-linear springs COMBIN 39 28

Structural Analysis – Load cases LC 0 – Offshore Wind Turbine Without Current Drag + Current Drag LC 1 – Offshore Wind Turbine +Tidal Drag, thrust, dead load LC 2 – Hybrid Offshore Wind & Tidal HOWa. T 29

Structural Analysis - Von Mises Stress Load case Stress [MPa] LC 0 106 LC 1 114 LC 2 126 HOWa. T 19% 11% 30

Structural Analysis – Modification Thickness modification Load case Stress [MPa] Thickness [mm] LC 0 106 70 LC 1 114 70 LC 2 126 70 LC 2_A 1 112 80 LC 1 LC 2_A 0 106 85 LC 0 LC 2_A 1, A 2– Hybrid Offshore Wind & Tidal - modified HOWa. T 31

Vibration - Natural Frequency Load case Description Natural Frequency [Hz] LC 0 OWT 0. 2167 LC 1 OWT 0. 2167 Beam LC 2 HOWT 0. 2178 LC 2_A 1 HOWT 0. 2246 LC 2_A 0 HOWT 0. 2276 elements BEAM 188 Non-linear springs COMBIN 39 HOWa. T 32

Vibrations Turbin e Lower Rotor Speed [rpm] Higher Rotor Speed [rpm] Wind 6. 9 12. 1 Tidal 6 4 11. 5 Beam elements BEAM 188 Non-linear springs COMBIN 39 HOWa. T 33

Transmission Line [Tennet, 2016] HOWa. T 34

AC vs. DC Losses, line and terminal costs included in cable cost 8 km [Electrical Engineering Portal, 2014] HOWa. T 35

Environmental Impact Assessment + [SSE Islay Ofshore Wind Proposal, 2009] HOWa. T = ? [DP Marine Islay Tidal Project Scoping Report, 2009] 36

Baseline Risk Assessment Project Phases Baseline Risk Assessment - Marine Physical Operation Decommissioning Geology Marine & Coastal Processes Contamination & Water Quality Protected Sites and Species Benthic Ecology & Intertidal Habitats Fish and Shellfish Marine Birds Marine Mammals Biological HOWa. T Construction 37

Marine Birds and Mammals Environmentally Protected Areas [Crown Estate, 2009] HOWa. T 38

Benthic Ecology & Intertidal Habitats Seabed Type HOWa. T [Crown Estate, 2009] 39

Fish and Shellfish Nursery Grounds [Crown Estate, 2009] HOWa. T Spawning Grounds [Crown Estate, 2009] 40

Expected Outcomes HOWa. T 41

Financial Analysis Target Levelised Cost of Energy Comparison with Existing Technology Sensitivity Analysis HOWa. T 42

Contracts For Difference Offshore Wind - 10. 5 p/k. Wh (2015 ~11. 8/k. Wh) Tidal Current – 30 p/k. Wh 15 year Period (Assumed over 20 years) HOWa. T 43

LCOE Energy output: 80% wind, 20% tidal Strike Price = £ 14. 6 p/KWh Lifetime project expenditure must be lower than this HOWa. T [Siemens, 2013] 44

System Cost Estimation Wind Tidal Savings: Structure = 15% Offboard Electrical Equipment = 13% Installation = 8% [NREL, 2014] 36% Saving [Carbon Trust, 2012]

Offshore Wind Vs Hybrid Wind vs Hybrid 160 140 120 £/MWh 100 80 60 40 20 0 Wind Hybrid Strike Price HOWa. T LCOE 46

Sensitivity Analysis – Increasing Array Size LCOE for Increasing Array Size 145 140 LCOE (£/MWh) 135 130 125 120 115 110 105 1 2 3 4 5 6 7 8 9 10 No. of turbines HOWa. T 47

Financial Conclusions Costs Foundation reinforcement Technology development Savings Shared cable and foundation costs HOWa. T Offshore wind currently a better option Government incentives pivotal Tidal cost reductions decisive 48

Project Conclusions Technically feasible thanks to current incentives Limited locations Promising power generation output Unlikely significant environmental impacts Structurally sound, possible vibration issues Significant savings from shared costs HOWa. T 49

Future Potential Tidal technologies more developed Application of energy storage Baseload generation possible HOWa. T 50

Thank You For Listening Any Questions?