Ocean EnergyKelley Fletcher
Dustin EseltineRyan Sargent
Group 5
Ocean Energy• The Need:
– With the constant rise in cost of non-renewable energy sources, alternative sources of renewable energy are becoming more important
– Energy produced by ocean waves is constant.– Constant energy = infinite supply– Infinite supply = Lower Cost
• Objective:– Design a device that converts ocean waves into
useable electrical energy
Current Solutions• Heaving
Floats– Rise and fall of
waves causes float to rise and fall creating energy.
• Pitching Device– Rise and fall or waves
causes the float to pitch– Pitching motion is then
converted to energy.
Wave Direction
Current Solutions• Oscillating Water
Column– Waves cause a pressure
change inside a chamber.– Oscillating air or water
drives energy device (eg. turbine)
• Surge Device-Ocean Waves flow into narrowing
chamber-Water forced into reservoir-Energy flows through turbine
back into ocean.
Current Solutions Cont.
Archimedes Wave Swing•Passing Waves causes the top chamber to rise and fall
•Rise and fall of top chamber cause pressure difference inside device
•Pressure difference runs hydraulic motor
Current Solutions Cont.
Oscillating Water Column•Waves coming into coast cause rise and fall inside chamber
•Rise and fall of water in chamber pushes air through turbine.
•Dual cycle, needs bi-directional turbine
Design Goals
• After researching current designs the following design goals were created:– Not a coastal based system.– Not a hydraulic based system.– Make the system scalable.– Design system to be relatively safe from natural
occurrences such as storms
Anchor System
•D-Rings attach buoy to anchoring cables.•The three cables from the buoy are attached to the single cable using a turnbuckle.•This system allows for minor height adjustments after installation.•Single cable attaches to buried concrete anchor.
How It Works• Passing waves cause a
differential pressure change in a submerged chamber.
• The pressure change causes an airflow through a nozzle.
• The airflow is used to run a Pelton Turbine.
• ½-wave = 1stroke• 2 strokes in a cycle:
– Compression– Suction
Compression Suction
Ocean Hydrodynamics
L= Wave LengthH= Wave HeightD= Water Depth
Note:•One wave = Crest to Crest –or- Trough to Trough•Particle depth is considered a negative value•Design calculations based upon ½wave
Ocean Hydrodynamics Cont.
22
2sin)/2cosh(]/)(2sinh[
2
2cos)/2cosh(]/)(2cosh[
2
uwV
Tt
LLdz
LgTHw
Tt
LLdz
LgTHu
Underwater particle velocities are related to:• Wave Height(H)• Wave Length(L)• Water Depth(d)• Particle depth(z)• Wave Period(T)
Deep Water•Circular velocity profile
Shallow-Transitional•Elliptical velocity profile
Particle Velocity Equations
Calculating Volumetric Airflow
SiteSiteSiteSite
SiteSite
PCCP
stantConPPP
00
00
siteSiteSite
atmsiteSiteSite
ZVVP
ZVPZVP
220
020
2
21
21
21
21
hPZT
tY
Tt
XT
tB
Tt
AP
ZT
tY
Tt
XT
tB
Tt
AP
atmsiteabssite
sitesite
2cos
2sin
212
cos2
sin21
2cos
2sin
212
cos2
sin21
_
Equation of State – P1V1 = P2V2
Bernoulli’s Equation
Substituting for Velocity
-Bernoulli’s Eq. Allowed Psite to be solved.
-Once Psite was known the particle velocity equations were substituted for surface and site velocities.
Volumetric Airflow Cont.
tP
PC
tQ Site
Site
Site
2
Volumetric Airflow-Once Psite was known, volumetric airflow could be derived.
Volumetric Airflow – Q-Bar
hPT
tYT
tXZT
tBT
tA
CQ
tt
PPCt
ttQQ
atmSite
T TSite
Site
SiteT
2cos2sin2
2cos2sin2
22222222
2/
0
2/
02
2/
0
-Integrating Q gave us Q-bar. Allowing t to be replaced by T/2 (one cycle time.)
Q-Bar = Volumetric air flow for one cycle
Water Data •Using the National Oceanic and Atmospheric Administration’s website buoy #46212 was chosen.•Data was downloaded from the NOAA website for Wave Height, Wave Period, and Atmospheric Pressure.
Ocean Wave Data •Water data was compiled using excel, equations, and buoy data.•Average values were tabulated for each day and then for each month.
Volumetric Airflow Data •Volumetric airflow data compiled from buoy data•Average values were compiled daily, monthly, and then yearly.•Yearly values were used for turbine calculations.•Daily values allowed the group to calculate the turbines power output for any day of the year.
Power ConversionDouble Acting Turbine•Bi-direction turbine•Possibly self starting
Wells Turbine•Bi-directional Turbine•Not self starting•Blades symmetric to rotation axis
Paddle Wheel Design•Simplistic in operation and construction•Self starting
Pelton Turbine•Advanced paddle wheel design•”Buckets” increase amount of energy extracted from jet stream•Scalable design•Self Starting•Turbine is up to 91% efficient
Turbine CalculationsVolumetric air flow was used to calculate the following:• Pitch Circle Diameter (PCD)• Jet Diameter• Jet Area• Jet Velocity 3
0121.4
Q
PCD
Pitch Circle Diameter- PCD determines turbine size
PCDD jet 11.0
Jet Velocity-Jet diameter = Nozzle Diameter
4
2Jetjet
jetDQ
AQ
V
Jet area = cross sectional area of nozzle-Jet velocity is determined from average flow rate and jet diameter.
Jet Diameter
Power Output
•At 100% efficiency and Flow the Turbine Produces 56.85 Watts•Normal overall system efficiency for Pelton Turbines is 60%•About 40 Watts would be produced at 60% efficiency•Generator is only capable of handling 18 Watts of Continuous power. 12 volts x 1.5 amps
cos14
2
JetShaft
VQW
Turbine Power Output
-Shaft work = Theoretical power Output
Turbine AnalysisUsing COSMOSWorks, material data, and calculated values a brief analysis was completed.
TurbineMax. Deflection – 0.003 in.Max. Stress - 485 PSI
Turbine BladesMax. Deflection – 4.2e-04 in.Max. Stress – 56.69PSI
Safety Factor - 111Infinite Life – SLA Model
The Prototype Design•Fully scalable turbine system•Submerged design protects device•Power output of one “buoy” = 18 Watts
Prototype Design Cont.
Project Future
1) Build a prototype model2) Prototype would be tested for:• Turbine efficiency, Air vs. Water• Stability• Actual power output• Actual volumetric flow rate
3) Safety mechanisms may need to be designed to prevent water entering system.
The prototype design concept is complete. The next steps in the project are:
Questions? Thank you for your time.
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