CITRIS sponsored WAVE ENERGY CONVERTER 2013

1. CITRIS sponsoredWAVE ENERGY CONVERTER 2013 UC Davis Mechanical Engineering Alex Beckerman, Kevin Quach, Nick Raymond, Tom Rumble, Teresa Yeh

2. Contents • Introduction • An overview of the CITRIS Renewable Energy Grant proposal, and project’s scope Preliminary Design and Research • Technical Review • Terminology and main features of our WEC design. • Subsystems • Buoy • Spar • PTO • Hydraulics • Electronics • Heave Plate • Construction • A comparison of the two hydraulic motors regarding power performance, efficiency, and cost. • Next Stage • Testing in Bodega Bay • Instruction Manual

3. Project Introduction

4. introduction • CITRIS • 2012 CITRIS Sustainability Competition Winners • $10,000 Renewable Energy Research Grant • (+ $5,400 funding for testing) • Complete project within one year from award

5. introduction Objectives 1. Design and fabricate a Wave Energy Converter (WEC) 2. Use standard parts and components to build the PTO 3. Create a set of instructions and share information over website

6. Preliminary Designs and Research

7. Preliminary design & Research Potential Test Site: Bodega Bay, Ca • Exposed to Pacific ocean waves and wind swell • Local university facility to assist with deployment • Steep ocean floor topography (bathymerty) • Close proximity to UC Davis • Team has personal knowledge of area Image: googlemaps.com

8. Preliminary design & Research Bodega Bay Marine Lab Source: OceanGrafix.com http://www.oceangrafix.com/chart/zoom?chart=18643

9. Preliminary design & Research Significant Wave Height 1981-2008 • NOAA Buoy 46013 • NOAA provides ocean data for last 28 years • Buoy anchored 14 miles off shore • Dominant wave period remains constant • Wave height expected to increase closer to shore Dominant Wave Period 1981-2008 KEY

10. Preliminary design & Research Bond graph Modeling • Transfers system from mechanical translational domain to the electrical domain • Determines hydraulic damping coefficient for given electrical resistance • Damping coefficient used in state space dynamic modeling

11. Preliminary design & Research • State Space Modeling • Model to represent the dynamics of our physical system in ocean • Linear wave model: approximation of ocean waves as sinusoids. [1] • Equations developed within state space using a free body diagram. • The system is modeled as a two body system with individual forces acting on each • body. MatLab Simulation for Different Heave plate sizes used in Iteration Process Free Body Diagram of Buoy- Heave Plate Dynamics

12. Preliminary design and research [ WEC_001] [ WEC_002 ] [ WEC_003 ]

13. Technical Background

14. Technical background PTO Buoy Spar 47.3 ft Have Plate [ WEC_004 ]

15. SUB-SYSTEMS(BUOY)

16. Buoy

17. buoy • Preliminary testing of foam • Fabricated one cubic foot mold out of plywood and wood screws • Filled mold with two part expanding polyurethane foam Results From Initial Foam Test

18. Buoy Lining the mold with plastic to assist with releasing the foam from the mold Positioning the PVC pipes

19. Buoy • Marine grade polyurethane foam • Mixture come in two parts, expands when mixed • Final volume is 15 times the original volume after 20 minutes of curing

20. Buoy Releasing the foam from the mold

21. Buoy The foam was cut with a chainsaw to form the 45°chamfer

22. BUOY The buoy was then sanded down and coated with a pigmented epoxy resin

23. Buoy Steel plates mounted on the upper and lower surfaces of the buoy All thread compresses the plates and secures buoy to the spar

24. SUB-SYSTEMS(SPAR)

25. spar Hydraulic

26. spar

27. spar The bolt holes were drilled on the mill to assist in accurate alignment. Welded components into framework

28. spar Housing for springs and hydraulic shaft Wire rope alignment housing

29. SPAR Addition of strut members

30. SPAR Strut members welded to the spar Secured to the buoy bottom plate

31. Spring alignment

32. Alignment brackets 5 spring alignment brackets to keep the 6 springs inline

33. Alignment brackets Bushing doubles as spring alignment and linear guide for hydraulic rod extension

34. Alignment brackets Cylinder alignment bracket

35. SUB-SYSTEMS(POWER TAKE OFF SYSTEM)

36. Power take-off system

37. Power take-off system • Hydraulic Subsystem elements: • Hydraulic Ram • Bladder Type Accumulator • Piston Type Motor • Standard hydraulic hoses and fittings • System Operation: • Direct drive • Reverses direction with each stroke • Accumulator displaces cylinder rod volume

38. Power take-off system • Hydraulic Motor Drain Port By-pass: • Check valves • Swagelok fittings • Hydraulic subsystem waterproof housing

39. Power take-off system Power take-off systems conveniently contained within water proof boxes

40. Power take-off system • Boxes mount to frame • Frame mounts to top of buoy • Easy to access and maintain

41. Power take-off system • Permanent Magnet DC Motor: • Operated mechanically to function as a generator • Microcontroller: • Logs system data from voltage and current sensors in 16 MB SD card

42. Power take-off system Waterproof microcontroller housing Power dissipates in 1500 Watt 1 ohm resistor

43. Power take-off system

44. SUB-SYSTEMS(HEAVE PLATE)

45. Heave plate

46. Heave plate Steel square tubing arranged into framework . Test fitting before final welding of sheet steel Supported from spar by connections of steel cables

47. Heave plate • Sheet steel limits water flowing around steel frame • Hydrodynamic damping • “Added mass” effect Sheet steel welded to frame using plug and bead welds

48. Heave plate Use of four individual modules advantageous for transportation and storage Plug welds Bead welds

49. Heave plate Steel cable, clips, and thimbles Steel cable threads through eyelets welded on steel frame

50. Heave Plate