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.