From Waves to Watts

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From Waves to Watts
A Sustainable Energy Device for the Charles River
13.017 Design of Ocean Systems I 2003
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From Waves to Watts
Design Challenge

• Determine the power available in the wave action
  of the Charles River, including dependency on
  wind
• Design and construct a device to convert wave
  power into electrical power
• Measure the power output and efficiency of your
  wave energy converter

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From Waves to Watts

• Introduction
• Wave Theory
• Wave Energy Converters
• Overview of our Design
• Tendons
• Turbines and Generators
• Alternative Energy Conversion Methods
• Electronics and Tuning
• Conclusions and Acknowledgements

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From Waves to Watts

• Introduction
• Wave Theory
• Wave Energy Converters
• Overview of our Design
• Tendons
• Turbines and Generators
• Alternative Energy Conversion Methods
• Electronics and Tuning
• Conclusions and Acknowledgements

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From Waves to Watts
European Wave Energy
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From Waves to Watts
Wave Terminology

• Amplitude a
• Wavelength l
• Frequency f
• Period T 1/f
• Angular Frequency w 2pf
• Wave Number k 2p/ l
• Phase Velocity c f l
• Group Velocity cg 1/2 c
• Significant Wave Height HS ( 1/2 a2) 1/2
• Water Density rw

a
l
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From Waves to Watts
Wave Spectra Energy

• Potential Energy PE 1/4 r g a2
• Kinetic Energy KE 1/4 r g a2
• Total Energy from Waves PE KE TE
• TE 1/2 r g a2
• Wave Spectra
• HS2 ?S(w)dw

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From Waves to Watts
Wave Probe Experiment

• Measure wave height and weather data
• 3 Wave Height Probes
• Anemometer
• Wind Vane
• Temperature
• Air Water

Electronics
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From Waves to Watts
Experiment Results

• Hs 0.050 m
• Period 0.83 s
• Wavelength 1.45 m
• Energy 19.19 J
• Peak Frequency 6.76 rad/s

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From Waves to Watts
Experiment Results
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From Waves to Watts

• Introduction
• Wave Theory
• Wave Energy Converters
• Overview of our Design
• Tendons
• Turbines and Generators
• Alternative Energy Conversion Methods
• Electronics and Tuning
• Conclusions and Acknowledgements

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From Waves to Watts
Wave Energy Converters

• Hydroelectric Systems
• Tapered Channel
• Relative Motion Systems
• Cockerell Raft
• Salter Duck
• Pneumatic Systems
• Oscillating Water Column
• Sea Clam

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From Waves to Watts
Tapered Channel
Jenkins, Buck, Norwaves Wave-Energy
Alternative. Alternative Sources of Energy. No.
87, January 1987
http//www.acre.murdoch.edu.au/ago/ocean/wave.html
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From Waves to Watts
Cockerell Raft

• Hinged rafts follow waves
• Power extracted at hinges
• Alternative arrangement Pelamis

McCormick, Michael, Ocean Wave Energy Generation,
1981
Wave Power Delivery Ltd, 2003
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From Waves to Watts
Oscillating Water Column

• Waves enter chamber and push air out through a
  turbine
• Wells turbine rotates in one direction
  regardless of air flow direction
• Fixed (shore-side) and free

http//www.daedalus.gr/DAEI/PRODUCTS/RET/General/O
WC/OWCsimulation2.htm
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From Waves to Watts
Making Our Choice

• Tapered Channel
• Unidirectional
• Requires very low head turbines
• Cockerell Raft
• Subject to high loading
• Power extraction difficult
• Oscillating Water Column
• Completely omnidirectional
• Follows tidal variation of the river

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From Waves to Watts
Making Our Choice

• Tapered Channel
• Unidirectional
• Requires very low head turbines
• Cockerell Raft
• Subject to high loading
• Power extraction difficult
• Oscillating Water Column
• Completely omnidirectional
• Follows tidal variation of the river

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From Waves to Watts

• Introduction
• Wave Theory
• Wave Energy Converters
• Overview of our Design
• Tendons
• Turbines and Generators
• Alternative Energy Conversion Methods
• Electronics and Tuning
• Conclusions and Acknowledgements

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From Waves to Watts
Dynamics of Free OWC

• Base-excited second order system with effective
  mass, stiffness, and damping driven by wave
  action

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From Waves to Watts
Free OWC Model

• Tested in Towing Tank
• Natural Frequency 8.48 rad/sec
• Mass 2.27 kg
• Stiffness 314.1 N/m
• Added Mass 2.10 kg
• Damping 8.2

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From Waves to Watts
Example Dimensions

• Outer Diameter 12
• Inner Diameter 7
• Mass 12 kg
• Tendon Tension 10 N
• Heave Natural Frequency 6.072 rad/sec
• Outer diameter constrained by wave-lengths of
  peak waves

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From Waves to Watts
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From Waves to Watts
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Free Oscillating Water Column Tuned to Resonance
Turbine
Cylindrical Hull
Tendons
Sensors and Electronics
1
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Oscillating Water Column
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Cylindrical Hull
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Turbine
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Turbine
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Sensors and Electronics
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Tendons
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Free Oscillating Water Column Tuned to Resonance
Turbine
Cylindrical Hull
Tendons
Sensors and Electronics
1
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From Waves to Watts

• Introduction
• Wave Theory
• Wave Energy Converters
• Overview of our Design
• Tendons
• Turbines and Generators
• Alternative Energy Conversion Methods
• Electronics and Tuning
• Conclusion and Acknowledgements

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Free Oscillating Water Column Tuned to Resonance
Turbine
Cylindrical Hull
Tendons
Sensors and Electronics
1
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Tendons
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From Waves to Watts
Motions
Surge/Sway
Heave
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Tendons
Top View
Profile View
Tendon Parts
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From Waves to Watts
Differential Element
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From Waves to Watts
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From Waves to Watts
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From Waves to Watts
Vortex Induced Vibration
Reltlt200
Re500
Regtgt500
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From Waves to Watts

• Introduction
• Wave Theory
• Wave Energy Converters
• Overview of our Design
• Tendons
• Turbines and Generators
• Alternative Energy Conversion Methods
• Electronics and Tuning
• Conclusions and Acknowledgements

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Free Oscillating Water Column Tuned to Resonance
Turbine
Cylindrical Hull
Tendons
Sensors and Electronics
1
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Turbine
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From Waves to Watts
Air
Electricity
Turbine
Generator
Waves
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From Waves to Watts
Reaction Turbine
http//www.eng.usouthal.edu/huddleston/eg270/turbi
nes.htm
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From Waves to Watts
Impulse Turbine
http//www.tpub.com/fluid/ch3c.htm
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From Waves to Watts
Wells Turbine
http//www.wave-energy.net/Projects/ProjDescriptio
ns/wert.htm
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From Waves to Watts
Valve Arrangement
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From Waves to Watts
Power Energy Flux
u
A
Flux Rate
Energy/Volume
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r
u
A
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lt .15
lt .6
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From Waves to Watts
Graph radius vs power
Graph velocity vs power
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From Waves to Watts
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From Waves to Watts

• Introduction
• Wave Theory
• Wave Energy Converters
• Overview of our Design
• Tendons
• Turbines and Generators
• Alternative Energy Conversion Methods
• Electronics and Tuning
• Conclusions and Acknowledgements

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From Waves to Watts
Alternative Methods of Energy Extraction

• Piezoelectric Generator
• Magnetic Inductance Linear Generator

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From Waves to Watts
Piezoelectric materials have many desirable
qualities for energy extraction

• Minimize number of conversion steps
• Potential for easy energy extraction
• Multiple possibilities for implementation

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From Waves to Watts
Various Design Possibilities

• Piezoelectric Cable Tendons

• Piezoelectric End Cap

• Piezoelectric Flapping Flags

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Free Oscillating Water Column Tuned to Resonance
Piezoelectric Cable Tendons
1
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Free Oscillating Water Column Tuned to Resonance
Piezoelectric Cap
Oscillating Water Column
1
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Free Oscillating Water Column Tuned to Resonance
Flapping Flags
Turbine
One-way valves
Oscillating Water Column
1
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From Waves to Watts
Piezoelectric Experiment
2W
1.2 k?
Piezo
Vout
10 uF
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From Waves to Watts
Piezoelectric Experiment

• Deformed material at frequency of 1 Hz for three
  minutes
• E3 min 1/2 C V2 1/2 (10uF)(.3V)2
  4.510-7 Joules
• P E3 min / Dt 2.510-9 Watts
• E12 hour PDt 1.0810-4 Joules
• Not even enough to light a low power LED!

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From Waves to Watts
Linear Generator

• Magnet oscillating within coil of wire
• Charge induced from movement of magnetic field
• Vcoil Magnetic Field(B) Lengthwire(l)
  Velocity(v)
• BNturnspDcoilv
• P IV V2 / R

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From Waves to Watts
Linear Generator Experiment
Magnet moving through coil
Vout
2 W
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From Waves to Watts
Linear Generator Experiment

• Magnet passed through coil of wire at velocity
  of approximately 1 m / s
• Oscillatory movement Induced sinusoidal voltage
  of 0.4 volts AC measured with oscilloscope
• P V2 / R 0.42 / 2 .08 watts
• Promising results warrant further research

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From Waves to Watts

• Introduction
• Wave Theory
• Wave Energy Converters
• Overview of our Design
• Tendons
• Turbines and Generators
• Alternative Energy Conversion Methods
• Electronics and Tuning
• Conclusions and Acknowledgements

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Free Oscillating Water Column Tuned to Resonance
Turbine
Cylindrical Hull
Tendons
Sensors and Electronics
1
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Sensors and Electronics
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From Waves to Watts
Electronics and Control System

• Power measurement
• circuitry
• Wave height sensors
• Feedback sensors
• Tattletale Model 8v2
• microcontroller
• Battery to power
• instrumentation
• And maybe actuators and sensors for dynamic
  tuning

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From Waves to Watts
Electronics Needed Measure Power
PV2/R
Turbine
Linear Generator
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From Waves to Watts
Electronics Needed to Determine Efficiency
h Pproduced / Pwaves
Dock-Mounted Wave Probe and Internal Wave Probe
using Conductance
Sensor Electronics Box
8
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From Waves to Watts
Electronics for Feedback

• Tilt sensor for measuring
• pitch and roll

• Accelerometer for
• measuring heave

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From Waves to Watts
Other Electronics

• Weather sensors to
• measuring wind
• conditions
• Paddle wheel for
• measuring current

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From Waves to Watts
Tuning our Oscillating Water Column

• Reasons for tuning
• Interpreting sensor
• data
• Manual tuning

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From Waves to Watts
Automatically Tuning the Device
Feedback Block Diagram
- Complex - Secondary to Challenge
- Utilizes Power
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From Waves to Watts
Automatically Tuning the Device
Pulling up weights to affect the mass
Chain
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From Waves to Watts
Automatically Tuning the Device
Taking on water to affect the mass
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From Waves to Watts
Automatically Tuning the Device
Pivoting fins to affect the added mass
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From Waves to Watts

• Introduction
• Wave Theory
• Wave Energy Converters
• Overview of our Design
• Tendons
• Turbines and Generators
• Alternative Energy Conversion Methods
• Electronics and Tuning
• Conclusions and Acknowledgements

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From Waves to Watts
Plan for Next Term

• Mid September Finalize Design
• Complete analysis of Linear Generator
• Determine power extraction method
• Optimize hull parameters based on experimental
  findings
• Determine how to tune the system

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From Waves to Watts
Plan for Next Term

• October and Early November Fabrication
• Order materials and complete any machining
• Make significant progress on circuitry and
  sensors
• Begin process of developing code for analysis

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From Waves to Watts
Plan for Next Term

• Mid to Late November Implementation
• Test working device in Charles River
• Analyze results of early testing
• Make required improvements to design
• Begin to determine the efficiency of our device

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From Waves to Watts
Plan for Next Term

• Early to Mid December Complete Challenge
• Implement design changes and conduct further
  testing
• Perform detailed analysis of gathered data,
  focusing on efficiency of design
• Complete write up of design process
• Develop presentation and paper

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From Waves to Watts
Conclusions

• Challenge
• Determine the power available in the wave action
  of the Charles River.
• Design and construct a device to convert wave
  power into electrical power.
• Measure the power output and efficiency of the
  wave energy converter.

• Progress to Date
• Completed wave power measurement experiment.
• Designed a Resonant Oscillating Water Column.
  Construction will begin in fall.
• Determined a method to measure the power and
  efficiency of our device.

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From Waves to Watts
Acknowledgements

• Tom Consi, Franz Hover, and Professor Mike
  Triantafyllou
• MIT Ocean Engineering Department
• Towing Tank
• Ian Hutton and the MIT Boat House
• Fran Charles and the MIT Sailing Pavilion
• Professor Steve Leeb
• Professor Alex Techet
• Susan Brown

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Optional Piezoelectrics
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Turbine
One-way valves
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From Waves to Watts
Tapered Channel

• Large concrete channel collects waves wave
  height increases
• Wave crests spill over top of channel into
  reservoir several meters above sea
• Reservoir drains through hydroelectric turbine