wind power for the rock - mickpeterson.org

Wind Power for the Rock

University of Maine Mechanical Engineering

Fall 07-Spring 08

Written by: Brendan Owen Justin Letteney

Stephen McGann

Supervised by Professor “Mick” Peterson

Executive Summary The group’s task was to design a wind energy system for College of the Atlantic (COA) while

also supplying Maine Maritime Academy (MMA) with at least a 100 foot tower for their

Anemometer array. The group was successful in meeting the requirements of the two institutions

and designed a system configuration that has the ability to replace the current diesel generator,

hold an Anemometer array, and allows for future expansion.

A complete site evaluation of Mount Desert Rock (MDR) was performed and showed it is a

perfect candidate for wind power production and wind research. After analyzing 2006

continuous wind speed data supplied by the National Oceanic and Atmospheric Administration

(NOAA) and reviewing available literature the group can say the following:

1) The average wind speed for 2006, 2002 and 2000 was steadily at ~8.4 m/s

2) The monthly average for 2006 never was less than 6 m/s

3) The daily average for 2006 was between 5.4 and 10.5 m/s for 208 days out of the year

4) Based on available data the maximum wind speed does not exceed 45 m/s

The selected tower is the American Tower Company 100 ft heavy duty triangular lattice tower. It

is a free standing tower that has a minimal foot print of ~27 square feet and a survival wind

speed rating of 53 m/s (120 mph). The tower is designed to allow for the addition of standing

platforms and a ladder that stretches the entire height. This will allow COA and MMA students

to mount, dismount and service any equipment they choose to add to the tower. The tower is

intended to be either mounted directly to the island surface or to a cement foundation that is

anchored to the island surface. The anchoring system that is to be used is Hilti’s HIT RE 500

chemical adhesive epoxy. The group conducted a pullout test with this system and concluded

that a minimum embedment depth of eight inches is required to support a load of ca. 54000 lb.

This is more than twice the calculated load on a single anchor bolt of the tower.

The wind turbine selected is the Southwest Windpower Air-X Marine 400 watt turbine. The

turbine weighs ca. 13 lb allowing easy installation and dismounting by COA staff. With the

suggested total of six turbines, the system will provide the research station with a total of 1140

kWh per 5 month season. The current battery bank, with a rating of 3600 Ah, can be completely

recharged in roughly 3 days should it be drained completely. This is the worst case scenario

without considering the diesel generator as a backup. The system, including the cost of

installation, will require a total investment in the range of $40000 to $50000.

Index

1. Introduction _________________________________________________________ 1

1.1 Project Background ______________________________________________________ 1

1.2 Problem Statements ______________________________________________________ 1 1.2.1 College of the Atlantic’s Need for an Alternate Energy Source _________________________ 1 1.2.2 Why Wind __________________________________________________________________ 1 1.2.3 Maine Maritime ______________________________________________________________ 2

1.3 Design Objectives ________________________________________________________ 2 1.3.1 College of the Atlantic Design Objectives __________________________________________ 2 1.3.2 Maine Maritime Design Objectives _______________________________________________ 3

1.4 Team Objectives _________________________________________________________ 3

2. Hardware Selection ___________________________________________________ 4

2.1 Site Evaluation ___________________________________________________________ 5 2.1.1 Digital Data Processing and Statistical Analysis _____________________________________ 6 2.1.2 Results of Continuous Wind Data Analysis _________________________________________ 7

2.2 Worst Case Conditions on Mount Desert Rock ________________________________ 9

2.3 Hardware Options _______________________________________________________ 12 2.3.1 The Tower _________________________________________________________________ 12 2.3.2 The Turbine ________________________________________________________________ 14 2.3.3 Desalination ________________________________________________________________ 15

3. Final Design Description ______________________________________________ 19

4. Design Evaluation ___________________________________________________ 22

4.1 Design Analysis of American Tower Company 100 Foot Triangular Lattice Tower _ 22 4.1.1 Applied Loads and Reactions __________________________________________________ 22 4.1.2 Simple FEA Model as Hand Calculation Verification ________________________________ 24 4.1.3 Tower Loads and Anchoring System _____________________________________________ 25

4.2 Air-X Marine Performance _______________________________________________ 26

4.3 Desalination Unit Analysis ________________________________________________ 27

4.4 Installation _____________________________________________________________ 27

4.5 Projected Costs _________________________________________________________ 28

4.6 Miscelaneous Design Considerations ________________________________________ 29 4.6.1 Grounding _________________________________________________________________ 29 4.6.2 Potential Interference with Cost Guard Helipad ____________________________________ 29 4.6.3 Migratory Bird ______________________________________________________________ 30

5. Conclusions and Recomenndations _____________________________________ 31

References ___________________________________________________________ 33

Appendix A ____________________________________________________________ #

Appendix B ____________________________________________________________ #

Appendix C ___________________________________________________________ #

Appendix D ____________________________________________________________ #

List of Figures

Figure Number Figure Title Page Number 1 Maine Coastal Wind Energy Densities 2

2 NOAA Stations and Buoy Locations in Maine

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3 3 Hourly Average Wind Speed for 2006 MDR

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4 Wind Speed and Energy Distribution Graph 8

5 Wind Rose Plot of wind direction on MDR for 2006

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6 American Tower Company 100ft Heavy Duity Tower Dimensions

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7 Air-X Marine Dimensions 16

8 American Tower Company, 100ft Heavy Duty Tower Dimensions

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9 Air-X Marine Turbine Dimensions 19

10 Instantaneous Power Output for Air-X Marine and Monthly Energy Output for Air-X Marine

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11 Aquifer 150M Desalination Unit Manufactured by Spectra Watermakers Inc. Shown with optional solar cell

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12 Tower Loads for Hand Calculations 23 13 Nodal Displacement contour plot 25 14 Southwest Windpower Air-X Marine 26 15 Air-x Marine Performance Curve 26 16 Aquifer 150M 27

17 Imaginary surfaces for Military Helicopter Landing Surfaces

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18 Steel Beach Barrier 32 19 Example for Freestanding Drilling Rig 33

List of Tables

Table Number Title Page Number

1 Equation Symbols used in this Section (section 2)

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2 MDRMI station description 5

3 Values of Importance, based on 2006 MDRMI data

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4 Maine wind speed data during tropical storms (TS) and hurricanes (H (rating))

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5 Maximum wind speeds during storms and the year of the storm measured on MDR

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6 Tower options 13 7 Current energy use on MDR 14 8 Southwest Windpower Turbine Specifications 15 9 Desalination Unit Selection Criteria 16 10 Aquifier 150M Specifications 17 11 Calculated Wind Load Values 23 12 Results of Tower Finite Element Analysis 24 13 Projected Cost Per Unit 28 14 Total Projected Cost for Design 28

Contributions

Section 1: Introduction .......................................................................... Stephen McGann

Section 2: Hardware Selection Process .................................................... Brendan Owen

Section 3: Final Design Description......................................................... Justin Letteney

Section 4: Design Evaluation ........................................................ S. McGann / B. Owen

Section 5: Conclusions and Recommendations ..................................... Justin Letteney

Senior Design Project: “Wind for the Rock”

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1. Introduction

1.1 Project Background

“Mount Desert Rock is a remote, treeless island situated approximately 25 nautical miles south

of Bar Harbor, Maine and is now owned by the College of the Atlantic. Since the early 19th

century the island has had a light tower, and various buildings to house light-keeper families. In

the 1950s the island was occupied by the United States Coastguard. Now it is the home of the

Edward McBlair Marine Research Station. Mount Desert Rock has 4 buildings perched

precariously on its rocky ledges; the boathouse, light tower, generator shed and light-keeper's

house. The boathouse has space for 4 research inflatable boats, and is rigged with a hydraulic

hauling system and chain hoist. The light tower reaches over 70ft in height above sea level, and

has two exterior platforms provide excellent views 360° around the island. The generator shed is

currently used as an equipment room; the college plans to convert this space into a wet-lab.

Finally, the house itself has accommodations for 20 researchers/students, two classrooms, a

recreation room, kitchen and dining room, and radio room. Power is currently provided by a

small gas generator supplying a bank of deep-cycle batteries that distribute 110V via an inverter”

[1].

1.2 Problem Statements

1.2.1 College of the Atlantic’s Need for an Alternate Energy Source

College of the Atlantic has expressed a desire to replace their existing method for generating

power, a small gas generator, with an alternate renewable source. Currently they are required to

bring the generator’s fuel 25 miles by boat, and offload it by hand onto the island. This work

intensive process has led the facility’s administrators to forgo power consuming devices such as

a desalination unit or water cultivation tanks.

1.2.2 Why Wind

It was decided that the most effective energy generation method for Mount Desert Rock would

be a wind power system. Wind density maps for the state of Maine show Mount Desert Rock is

an ideal site for wind generation with an energy density of 600 – 800 watts per square meter at

an altitude of 50 meters. Figure 1 on the following page shows the energy densities along the

Maine coast.


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Figure 1 Maine coastal wind energy densities, taken from www.eere.energy.gov

1.2.3 Maine Maritime

Maine Maritime has expressed an interest in developing a wind data acquisition site on Mount

Desert Rock. At the moment most of costal New England lacks sufficient wind profile data

necessary for the development of offshore wind generation. Maine Maritime would like to

assemble an anemometer array on Mount Desert Rock. In addition to providing onsite data, it

would serve as a calibration point for portable SODAR devices, which could be used to develop

wind profiles along the coast of Maine.

1.3 Design Objectives

1.3.1 College of the Atlantic Design Objectives

An off the grid wind power system must be designed to replace College of the Atlantic’s current

diesel generator. It must be able to support all of the island’s current power needs, estimated at

415 kWh per season, and be able to meet the needs of any additions in the foreseeable future

including a portable desalination unit which will also be examined by the University of Maine

group.


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1.3.2 Maine Maritime Design Objectives

In order for Maine Maritime to develop an adequate wind profile, a tower of at least one hundred

feet must be erected on the island. This tower must be able to withstand the extreme winter

conditions and allow for equipment on it to be serviced as necessary.

1.4 Team Objectives

The University of Maine group objective was to design a functioning wind power system for

College of the Atlantic’s Mount Desert Rock research facility. The system will also provide the

necessary hardware to allow for installation of an anemometer array which will be operated by

the Maine Maritime Academy for the development of wind profile data on Mount Desert Rock.


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2. Hardware Selection Process

Table 1 Equation symbols used in this section

Actual measured wind speed

Adjusted wind speed for chosen tower

hight

Actual altitude of Anemometer at MDRM1

Station (ca. 22 meters above ground)

Arithmetic average wind speed for the year

2006.

Root mean cubed wind speed

Design wind speed

Root mean cubed power per squared meter

Air density, assumed constant at 1.225

kg/m^3

Wind distribution function

Weibull distribution from factor

Weibull distribution scale factor

Power density function

Air turbine power coefficient

Rotor swept area


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2.1 Site Evaluation

The first step in any wind power project is to evaluate the candidate site if data is available. The

best source for wind speed data along Maine’s coast is the National Oceanic and Atmospheric

Administration (NOAA) network of buoys and stations [2]. Figure 2 shows the stations and

buoys that have readily available meteorological data for Maine’s coast that can be accessed via

NOAA’s website. Fortunately, the station MDRM1 is situated on the Mount Desert Rock (MDR)

lighthouse.

Figure 2 NOAA stations and buoy locations in Maine, Image reproduced from www.noaa.gov

According to NOAA’s website the station on MDR has the following properties:

Table 2 MDRM1 station description, data taken from www.noaa.gov

Owned and maintained by National Data Buoy Center

Station Type C-MAN Station

Location 43.97 N 68.13 W (43°58'06" N 68°07'42" W)

Site elevation 9.1 m above mean sea level

Air temp height 15.2 m above site elevation

Anemometer height 22.6 m above site elevation

Barometer elevation 16.5 m above mean sea level


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Gabriel Blanco et al conducted a study on the feasibility of wind/hybrid power systems for New

England islands in 2002 in which they established MDR has a high annual average wind speed of

8.4 m/s [3]. This study was based on MDRM1 data from the year 2000 and for this work data

from 2006 was used to verify earlier findings and find suitable turbine solutions for MDR.

2.1.1 Digital Data Processing and Statistical Analysis

As stated in the previous section, the wind data on MDR is taken at roughly the proposed tower height

which makes an adjustment to the measured speeds unnecessary. The arithmetic average wind speed for

the year 2006 is given by,

where n is the total number of valid data points from NOAA.

Since the wind speed can vary by 30-35% over the mean throughout the year, the root mean

cubed wind speed is a more qualitative measure of the candidate sites mean wind speed and is

given by,

this is the wind speed that one could expect to see at any given point throughout the year.

The root mean cubed Power per squared meter then is given by,

where ρ is the density of the air (1.225 kg/m^3), taken to be constant for this analysis.

Most wind speed distributions are best described by a Weibull distribution. The Weibull

probability distribution h as a function of wind speed is given by the following,

where the form and scale factors, k and c, are dependent on location. k and c are generated by

fitting a Weibull distribution curve to the actual wind data distribution. The Mode Wind Speed,

the speed of the wind most of the time, is the wind speed associated with the maximum of the

distribution function. The power density is given by,


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The design wind speed will be given by the location of the power density maximum and should

correspond with the wind turbine wind speed rating for maximum output. and are the

power coefficient and rotor swept area of the selected turbine [4]. At this stage the turbine model

is unknown so the power coefficient was dropped from the equation and the area was divided out

to give a power density per unit area. This will not alter the location of the maximum on the

density vs. wind speed graph in terms of wind speed. The MATLAB code that was used to

analyze the data set can be found in Appendix A.

2.1.2 Results of Continuous Wind Data Analysis

Figure 3 shows the variation in hourly average wind speed for the year 2006 on MDR. The

dashed line shows the annual average for 2006 which is 8.405 m/s.

Figure 3 Hourly average wind speeds for 2006 on MDR

The wind speed distribution and energy density curves are shown in Figure 4 on the following

page along with markers for the most important wind speed values.


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Figure 4 Wind speed and energy distribution graph for 2006

Other valuable pieces of information that were gathered from the 2006 wind data were the

primary directions in which the wind blows across MDR. The following figure shows a wind

rose plot of the analyzed data.

Figure 5 Wind Rose Plot of wind direction on MDR for 2006, 0˚ = North

As Figure 5 shows the prevailing wind directions are north-east and south-east.

The following table lists the most important values that were calculated from the 2006

continuous wind speed data supplied by MDRM1.


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Table 3 Values of importance, based on 2006 MDRM1 data

Value m/s mph

Root Mean Cubed Wind Speed 2006 10.2 22.8

Mean wind Speed 2006 8.405 18.8

Mode wind Speed 2006 7.4 16.6

Design Wind Speed 2006 12.2 27.3

Maximum Wind Speed 2006 26.9 60.25

Root Mean Cubed Power per Squared Meter 644 W/m^2

Based on the calculated values, specifically the design wind speed, the turbine that is selected for

MDR should have a rated wind speed for maximum output around 12.2 m/s. The expected power

per square meter is what is actually available but does not consider the power coefficient of the

turbine. In reality the maximum a turbine can deliver is governed by the Betz limit which has a

value of 0.59. Modern turbines have power coefficients of ca. 0.50 [4]. The analyzed data further

showed that the monthly average wind speed is always greater than 6 m/s and the daily average

was between 5.4 and 10.5 m/s on 208 days out of the year 2006.

2.2 Worst Case Conditions on Mount Desert Rock

The unique location of Mount Desert Rock results in some of the most extreme weather

condition on Maine's cost. This alone is reason enough to demand the most reliable tower and

turbine combination for this project. Also, consideration must be given to the fact that the Coast

Guard retains a right of way on the island and frequently lands on MDR with a helicopter to

service the lighthouse. Any structure that is erected on MDR cannot in any way present a risk to

existing installation and visitors. To ensure that the turbine and tower selected will not be subject

to overloading, available historical wind speed data during storms and hurricanes was analyzed.

The following table lists the maximum wind speeds measured in Maine during major storms

between 1869 and 1996 [5].


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Table 4 Maine wind speed data during tropical storms (TS) and hurricanes ( H (rating)), table reproduced from [5]

Year Name

Type in

Maine

Max Recorded

Winds in Maine (mph)

Location of Reported

Winds

1869 Gale N/A 54 ¬

1869 Saxby’s Gale N/A 45 ¬

1888 no name TS 50 ¬

1889 no name TS

no record (max. winds

during storm 120mph) ¬

1894 no name TS








1938

New England

Hurricane H (1) 70 ¬

1944

Great Antlantic

Hurricane TS 60 Portland


1952 Able TS N/A ¬

1953 Carol H(1) N/A ¬

1954 Carol H(1) 78 ¬

1954 Edna H(1) 74 ¬

1960 Brenda TS est. 45 ¬

1960 Donna H(1) 77 Portland

1961 Esther TS N/A ¬


1962 Daisy H(1) 60 ¬

1963 Ginny TS 100 Rockland

1971 Doria TS 61 ¬

1971 Heidi TS 50 ¬

1972 Carrie TS



1976 Belle N/A 61 ¬


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1979 David TS 69 Lewiston

1985 Gloria H(1) 86

Goat Island, 80 @ Old-

Orchard

1988 Chris&Alberto TD est.20 ¬

1991 Bob TS 61 ¬

1996 Bertha TS 22 Portland

1996 Edouard TS 28 Portland

Since the wind speeds listed above were presumably all measure on land they, where possible,

were compared to wind speed data taken on MDR during the storm periods. Table 5 lists the

maximum wind and gust speeds measured on MDR during the storms Bertha (1996), Edouard

(1996), Bob (1991), Chris&Alberto (1988) and Gloria (1985). 1985 is the earliest available data

set from MDRM1. Also listed in Table 5 are the maximum wind and gust speeds for the years

between 2000 and 2006.

Table 5 Maximum wind speeds during storms and the year of storm measured on MDR

Year Max Wind Speed

in Year (m/s)

Max Gust Speed

in Year (m/s)

Max Wind Speed During

Hurrican/Tropical Storm

Max Gust Wind Speed

During Hurrican/Tropical Storm

1985 25.3 30.9 22.2 25.8

1988 26.8 30.9 15.5 17

1991 30 33 26.8 31.4

1996 24.8 28.7 16.8 18.8

2000 30 33 ¬ ¬

2001 26.8 30.4 ¬ ¬

2002 27.1 31 ¬ ¬

2003 30.2 34.2 ¬ ¬

2004 26 29.5 ¬ ¬

2005 27.8 30.7 ¬ ¬

2006 26.9 31.4 ¬ ¬

The preceding two tables show there are no recorded wind speeds in excess of 100 mph (45 m/s)

in Maine or on MDR. Since most towers and small scale wind turbines have a maximum

survivable wind speed rating around 120 mph, it can be confidently said that the selected system

will survive the conditions on MDR.


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2.3 Hardware Options

Based on the wind speed analysis for Mount Desert Rock (MDR) there are several hardware

options in terms of towers and turbines to choose from. The guideline for the tower height was

set by Maine Maritime Academy (MMA). In order to generate a sufficiently accurate wind shear

profile that can be used to calibrate there SODAR equipment they suggested that a tower height

of 100 ft should be the minimum if possible.

The College of the Atlantic (COA) on the other hand required that their current fuel consumption

be completely covered by a wind turbine system. COA estimated that they use on the order of

40-50 gallons of diesel fuel every season. Assuming that the COA facilities are in operation

between May and September, their monthly fuel consumption would be between 8-10 gallons

and their generator can distribute roughly 8.3 kWh per gallon of fuel. This means that the wind

system has to generate between 66.4 and 83 kWh per month to match the generator. In addition

to the current level of consumption, COA would also like to have a system that can

accommodate future additions to the electrical load. Notably, they would like to add a

desalination unit and cultivation tanks in the near future.

The power requirements clearly are in the small scale wind power system range which for the

sake of this report will mean that the turbine will not exceed a 3kW generating capacity. The

following sections will cover the available tower and turbine options and compare them in order

to find the best suited combination for this application.

2.3.1 The Tower

The two main types of small scale wind turbine towers that are readily available in a range of

heights up to 100 ft are free standing and guyed wire supported towers. Both types can have

tubular or lattice structure designs and can come with gin poles or without. From the beginning

the guyed wired towers were neglected because the Coast Guard frequently uses the helicopter

landing area on MDR. Not only would the guyed wires add an obstruction for the Coast Guard,

they would also pose a serious risk to visitors should one or more ever fail. A second reason for

not considering a guyed wire type tower was that even the smallest one had a footprint that was

many times larger than any free standing version.

Among the free standing towers there is one other difference aside from the mast design. They

can either have the ability to be tilted up into place once they are assembled (or they have a


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telescope type design) or they have to be stacked one segment at a time with a crane or other

lifting device. Due to the location of MDR it would be advantageous if the selected tower had a

gin pole or other tilting/telescoping mechanism because all assembly work could be done on site

and the tower would finally be tilted up into position. While researching available freestanding

towers, it was quickly found that the tubular freestanding tower designs could be more than twice

as expensive as lattice towers. This led to the decision that the final choice would be a

freestanding lattice tower. The following table lists the towers that were taken into final

consideration.

Table 6 Tower options, data taken from www.glenmartin.com and www.amertower.com

Manufacturer/Supplier Design Gin Pole or Telescope

Footprint (sqr ft)

Max Load (in terms of turbine kW range)

Height (ft)

Glen Martin Inc. Solid Legged Triangular Lattice

Gin Pole Optional (adds to the price)

~57 10 100

Glen Martin Inc. Pipe Legged Triangular Lattice


~57 10 100

American Tower Company

Pipe Legged Triangular Lattice


~27 3 100

All three towers listed can withstand winds of up to 120 mph depending on the turbine size. The

American tower company version was chosen as the final candidate mainly because it has the

smaller footprint, is lighter and because the representative was readily available and willing to

meet with the group in person to discuss the project. Figure 6 on the following page shows the

general dimensions of the American Tower Company’s heavy duty triangular lattice tower.


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Figure 6 American Tower Company, 100ft Heavy Duty Tower Dimensions, reproduced from www.amertower.com

2.3.2 The Turbine

College of the Atlantic did not supply a detailed list of all appliances and other electrical units

that are on MDR so the turbine had to be chosen based on the information listed in the following

table.

Table 7 Current energy use on MDR

Monthly Generator Output (estimate) 66.4-83 kWh

Battery Bank Size 3600 Ah

Inverter Size 2000 W

Immediate Additions to Existing Equipment Portable Desalination Unit

Aside from the requirements listed above, it had to be considered that the turbines are intended to

be removed at the end of every season and that COA staff would have to perform this task.

Raising the tower down and back up again is a task for a trained crew and would cost COA large


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sums of money each year which means that the turbine has to be dismounted and lowered to the

ground instead. This would be easiest if the turbine were small and light enough to be carried by

one person which would make routine maintenance easier as well.

Since there are multiple manufacturers of small scale wind turbines, it was decided to choose a

manufacturer that offers the widest range in terms of generator output. Southwest Windpower

based in Flagstaff, Arizona offers wind turbines with ratings of 400, 900, 1000 and 3000W. The

following table lists the specifications of these four models.

Table 8 Southwest Windpower turbine specifications, data taken from www.windenergy.com

Model Weight (kg)

Rotor Diameter (m)

Start-Up Wind Speed (m/s)

Voltage (V)

Rated Power

Kilowatt Hours Per Month (kWh/mo)

Survival Wind speed (m/s)

Over-speed Protection

Number of Blades

Air-X marine

5.85 1.15 3.58 12, 24, 48 DC

400W @ 12.5 m/s

38 kWh/mo @ 5.4 m/s

49.2 Electronic torque control

3

Whisper 100

21 2.1 3.4 12,24,36, 48 DC

900W @ 12.5 m/s

100 kWh/mo @ 5.4 m/s

55 Side-furling

3

Whisper 200

30 2.7 3.1 24,36,48 DC

1000W @ 11.6 m/s

200 kWh/mo @ 5.4 m/s

55 Side-furling

3

Whisper 500

70 4.5 3.4 24,36,48 DC

3000W @ 10.5 m/s

538 kWh/mo @ 5.4 m/s

55 Side-furling

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Looking at the monthly average energy requirements of MDR and keeping in mind that COA

plans to add equipment to their current system, it at first seemed logical to opt for one of the

three Whisper models. We consulted John Rush from Evolo Energy Solutions, they install wind

energy systems throughout Maine, and we were strongly advised not to choose a Whisper turbine

model for our application. Mr. Rush told the group that the over speed protection system of the

three Whisper models was not designed to handle high wind speeds and gusts. The side furling

mechanism protects the turbine by turning it out of the wind and tilting the head back, thus

bringing the blades out of the wind and stalling them. In wind speeds of as little as 18 m/s this

can cause the turbine head to bounce up and down causing considerable vibrations and damage

to the furling damper. Mr. Rush advised the group to instead opt for a series of Air-X turbines

because they use an electronic torque over speed protection. If this turbine is subjected to higher

than rated wind speeds, the controller shorts out the turbine thus slowing the blades down until

safe conditions resume. Other attractive features of the Air-X are that they are available in a


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marine grade version and light enough to be carried by a single. The following figure shows the

main dimensions of the Air-X Marine wind turbine.

Figure 7 Air-X Marine Dimensions, drawing taken from www.windenergy.com

The selected tower is more than capable of accommodating an array of six or more of the Air-X

type turbines so the monthly energy requirement can be met and the system can be expanded

beyond what is currently required.

2.3.3 Desalination

Currently COA supplies the research station with potable water by transporting 5 gallon plastic

water containers with a zodiac. In total they estimate that they use 500 gallons of drinking water

a week. This means multiple trips have to be made every month to deliver supplies. A

desalination unit would eliminate the need for these trips. The group decided on a set of criteria

listed in the following table that a desalination unit must fulfill to be considered adequate.

Table 9 Desalination unit selection criteria

1 Portable 2 As light as possible 3 Low power usage 4 Be able to supply one weeks

worth of water in less than a week 5 Preferably 12 VDC

After doing some research on available units that are on the market, the group finally decided on

the Spectra Watermakers Aquifer 150 desalination unit. This unit fulfills all of the requirements

that the group agreed upon. It is a mobile desalination unit that can supply 150 gallons of potable


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water per day if run continuously. The Aquifer 150 is also equipped with a 12V battery supply

that can be charged from any adequate source so it can be charged directly from the wind power

system. The following table lists the technical specifications for the selected unit.

Table 10 Aquifer 150 specifications, data taken from www.spectrawatermakers.com

Manufacturer and Model Spectra Watermakers Aquifer 150 Output 150 gal/day, 6.3 gal/hr @

25˚C seawater temperature Pump HP 1/8 HP (93.2 W) Ah/gal 1.4 Wh/gal 17 Current 9A Total Weight 48kg


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3. Final Design Description For the final design we chose the 100 foot heavy duty tower from American Tower Company

and the Air-X Marine turbine. Figure 8 shows the general dimensions of the American Tower

Company’s heavy duty triangular lattice tower. The 100 foot heavy duty tower is designed to

withstand winds up to 120 mph and a total turbine load of 3 kW. Full tower specifications are

also included in Appendix B.

Figure 8: American Tower Company, 100 ft Heavy Duty Tower Dimensions, Figure adapted from http://www.amertower.com/pdf's/100heavy.pdf

The Air-X Marine wind turbine was chosen for its small size, making it easy for one man to

carry down from the top of the tower. The Air-X Marine turbine also uses an electronic torque

over-speed protection system which is stable when subjected to wind speeds higher than its rated

speed. Figure 9 shows the general dimensions for Air-X Marine turbine. Figure 10 shows the

power output of the Air-X Marine turbine for a given instantaneous wind speed and the average


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monthly energy output of the turbine for a given average annual wind speed. Detailed

specifications for the Air-X Marine wind turbine are included in Appendix C.

Figure 9: Air-X Marine Turbine Dimensions, taken from www.windenergy.com

Figure 10: Instantaneous Power Output for Air-X Marine and Monthly Energy Output for Air-X Marine, adapted from http://www.windenergy.com/documents/spec_sheets/3-CMLT-1339-01_Air_X_Spec.pdf

The installation of the wind turbine will make it possible to use a desalination unit which will

eliminate the need to deliver potable water to the island from the mainland. We chose the

Aquifer 150 desalination unit manufactured by Spectra Watermakers Inc. The Aquifer 150 is a

self contained portable unit which makes it convenient to transport to and from the island. The

Aquifer 150 can desalinate sea water at a rate of 6.25 gallons per hour taking the unit


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approximately 80 hours to produce a week’s worth of potable water based on the current use by

COA. Figure 11 shows the desalination unit setup (with optional solar cell). Detailed

specifications for the Aquifer 150 are included in Appendix D.

Figure 11: Aquifer 150 Desalination Unit Manufactured by Spectra Watermakers Inc. Shown with optional solar cell

, Figure adapted from http://www.spectrawatermakers.com/documents/Aquifer150.pdf

When installed, the tower will be anchored directly to the rock or to a concrete foundation

poured on the rock. Hilti HIT RE 500 epoxy adhesive anchor system was chosen to anchor the

tower and/or foundation. The RE 500 epoxy adhesive anchor system can be used with threaded

rod to anchor the tower directly to the rock. The chosen anchor system can also be used with

rebar to anchor a poured concrete foundation to the rock. The RE 500 epoxy adhesive anchor

system was tested in Mosquito Mountain granite quarry located in Prospect, Maine. The test

results showed that an eight inch embedment withstands a load of roughly 27 tons. The required

anchor embedment length will need to be determined after testing the anchor system on Mount

Desert Rock.

Several options to deliver and install the system are still being considered. The tower can be

assembled on the mainland, delivered by barge in five sections and then moved from the barge to

the island by helicopter. The helicopter would be able to stack each section of the tower. Another


21

option is to bring the tower out to the island unassembled in a large boat and assemble it on the

island. The tower would be assembled horizontally and then erected in one piece by helicopter.


22

4. Design Evaluation 4.1 Design Analysis of American Tower Company 100 Foot Triangular Lattice Tower 4.1.1 Applied Loads and Reactions The maximum thrust load of the chosen wind turbine, the Air-X Marine by Southwest

Windpower, is 150lb per turbine and the group’s design calls for six such turbines. The turbine

loads were assumed to act equally distributed at the top of the main legs of the tower in a

horizontal direction. See Figure 12 on the following page for details.

Also considered is the drag force acting on the tower due to the wind. The turbine model and the

tower are both rated for a maximum wind speed of 120mph (176 ft/s). If 120 mph is assumed to

be the wind speed at 100 ft then the wind speed distribution along the height of the tower is

given by,

( )6.)( 0 Eqv

hvhv

α

∗=

where and are the reference wind speed and reference height, and α is the “friction”

coefficient of the ground. In our case the reference wind speed and height are 120 mph and 100

ft respectively and alpha is 0.1 for rock and water surfaces. Evaluating Equation 1 showed that

within the first 20 ft of tower the wind speed reaches roughly 85% of its maximum value.

Therefore, the group assumed that it was reasonable to model the wind load as a constant wind

speed of 120 mph along the height of the tower. Based on fluid mechanics the drag force acting

on an object immersed in a moving fluid is given by,

( )7.2

1 2 EqAreavCF fluidfluidDDrag ∗∗∗∗= ρ

where ρ and v are the fluid density and velocity, Area is the projected area of the obstruction and

is the drag coefficient of the lattice tower. According to ASCE-7 the drag coefficient for a

triangular lattice tower with flat-sided members can be estimated by,

( )8.4.37.4*4.3 2 EqCD +∗−= δδ

where δ is the solidity of one face and is given by,


23

The drag coefficient for lattice towers with circular members is dependant on Reynolds number

and can be as little as one half that of flat-sided member towers [6]. Since the chosen tower is a

combination of the two the group assumed that it is reasonable to calculate with the flat-sided

member drag coefficient estimate without underestimating the actual load. Table 11 lists the

calculated values for the wind load.

Table 11 Calculated Wind Loading Values

Enclosed Area Of One Face 468.4 ft^2 Member Area Of One Face 87.5 ft^2 Solidity Of One Face 0.2 Drag Coefficient For Triangular Lattice Tower accounting for shielding and interference between members

2.6

Drag Force Due To Wind Loading 7971 lb, acting at 50 ft above the ground

This load was modeled as equally distributed among the three main legs at 50 ft as shown in

Figure 12. Based on the loads derived above and the model shown in Figure 12 the group

calculated that the worst case reaction for one anchor group is roughly 75000 lb. This means that

each anchor bolt will be subjected to a static load of roughly 18512 lb in addition to the

pretension load applied at installation.

Figure 12 Tower loads for hand calculations


24

4.1.2 Simple FEA Model as Hand Calculation Verification

A simple finite element model of the tower was constructed using Link8 elements in ANSYS to

verify the hand calculations made. The results of the computer analysis were exactly the same as

the hand calculations. The predicted anchor reactions are listed in Table 12 under Node numbers

1-3.

Table 12 Results of Tower Finite Element Analysis

Node Load FX (lbs)

Load FY (lbs)

Load FZ (Lbs)

1 -1180.5 -840.34 -37020.

2 2558.6 -3231.3 -37029.

3 -1378.1 -4799.3 74048

40 --- 2657.0 ---

41 --- 2657.0 ---

42 --- 2657.0 ---

76 --- 300.00 ---

77 --- 300.00 ---

78 --- 300.00 ---

Figure 13 on the following page shows a contour plot of the predicted nodal displacement do to

the applied loads. The group is not sure about the accuracy of the displacements calculated due

to the simplicity of the elements used. The model can be used in the future to calculate mode

shapes and natural frequencies though.


25

Figure 13 Nodal displacement contour plot, generated using ANSYS vs. 10

4.1.3 Tower Loads and Anchoring System Based on the calculated reactions we estimate the force acting on the anchor bolts will be 18512

pounds at 120 mph wind speed. Hilti HIT RE 500 epoxy was chosen to chemically anchor the

tower or a cement foundation into granite. Due to the inability to predict granite’s mechanical

properties Hilti does not offer any experimental data with regards to the ultimate strength of the

epoxy when it is being used in this function. The University of Maine group completed a failure

test or RE 500 in granite. The test went well in the sense that the group is confidant that HIT RE

500 is a suitable chemical anchoring system for our application. The group cannot make a

reliable statement on the ultimate bonding strength since we were limited to a 20 ton hole jack,

but we think, given the suggested anchoring depths for the selected tower of over 3 ft for the

tower anchors, this system should work. The group is confident that the anchor depth of 8” can

support a static load of roughly 54000 lb. A complete report on the anchor test performed can be

found on the group’s web page.

(http://www.umaine.edu/mecheng/Peterson/Classes/Design/2007_8/Project_webs/Wind_for_roc

k/Reports/20T_Rock_Anchor_Pullout.pdf )


26

4.2 Air-X Marine Performance

The Air-X Marine wind turbine shown in Figure 14 was chosen for the island primarily because

of its low weight and its portability. Weighting only13 lbs it was the turbine that could be most

easily serviced and maintained by COA staff.

Using Southwest Windpower’s projections for the Air-X, shown

in Figure 15, we can predict that the generator will produce

approximately 38 kWh a month at an average monthly wind

speed of 12 mph.

College of the Atlantic currently has a 3600 Ah, 12 volt lead

acid battery bank located on the island. This battery bank is

assumed to have a total capacity of 43.2 kilowatt hours given by,

CurrentVoltagePower ×= .

By this estimate it will require one Air-X generator 818.5 hours to fully charge the bank. Over

the course of a five month season one

Air-X turbine will generate

approximately 190 kWh at an average

monthly wind speed of 12 mph. The

wind turbine’s output over the course of

a season can be calculated by

multiplying its monthly output by the

number of operating months, as shown

in Equation 10.

tPutSeasonalOuMonthsMonth

Output =∗ (Eq. 10)

The island’s staff estimates that between 40 and 50 gallons of diesel fuel are used seasonally on

the island. Assuming that the diesel generator can produce 8.3 kWh of energy per gallon of fuel

used, College of the Atlantic requires between 66.4 and 83 kWh monthly, as shown in Equations

11 and 12.

onlConsumptiMonthlyFueonthsOperationM

elUseSeasonalFu = (Eq. 11)

Figure 14 Southwest Windpower Air-X Marine, taken from www.windenergy.com

Figure 15 Air-X Marine performance curve, taken form www.windenergy.com


27

tionrgyConsumpMonthlyEneGallon

kWhonlConsumptiMonthlyFue =* (Eq. 12)

With the addition of a desalination unit, this brings the island’s total monthly energy

consumption to 100.4 – 117 kWh. This is the amount of energy that will have to be generated by

the wind turbines on a monthly basis. To ensure continuous power is provided to the island we

recommended the installation of six units which will provide approximately 228 kWh a month,

or 1140 kWh a season, more then twice the island’s current seasonal usage of 332 - 415kWh.

4.3 Desalination Unit Analysis

The Aquifer 150, shown in Figure 16, was chosen for its light weight and compact nature. It has

a total weight 106 lb and is fully contained in a water tight carrying case which can be easily

unloaded onto the island by College of the Atlantic

staff.

The Aquifer 150 has an energy consumption rate of

0.017 kWh per gallon of water desalinated. The

current estimate for water usage on the island is 500

gallons weekly. The Aquifer 150 would use 34 kWh

of energy to provide one month of water, or about

170 kWh per season. The Aquifer generates 6.25

gallons of freshwater an hour operating at maximum

capacity, at that rate it will take approximately 80

hours to provide Mount Desert Rock with 500

gallons of potable water.

4.4 Installation

The American Tower Company 100 Foot Triangular Lattice Tower that was selected for the

project can be assembled into five 20 ft modules that are then bolted together. The assembly of

these sections can be done on the mainland, and brought over by barge, or the individual pieces

can be brought to the island and assembled there. In either case, a sky crane will then be used to

erect the tower out of the 20 ft sections, which will avoid the hazards of trying to tilt the

assembled tower up through use of a gin pole apparatus.

Figure 16 Aquifer 150, taken from www.spectrawatermakers.com


28

4.5 Projected Costs

The estimated costs of each component of the project are listed in Table 13.

Table 13 Projected cost per unit

Item Model Manufacturer/Lender Cost ($)

Turbine Air-X, Marine Southwest Windpower 700/per Unit

Tower 100ft Heavy Duty Communications Tower

American Tower Company

Ca. 16,000 (depends on accessories)

Desalination Unit Auqifier 150 Spectra 6995

Rock Drill and Compressor

Chicago 55lb drill Kennebec Rental 541/Week

Drill Bits 2” diameter ---- 57/per drill bit

Impact Hammer (electr.)

Hilti or equivalent Sunbelt Rentals 175/ Week

Helicopter Transport ----- Maine Helicopter 1100/hr, will have better

quote by Feb. 11

Deep Cycle Lead Acid Battery

12 Volt 225 Ah Gel Cell Sealed Lead Acid

Battery

Marathon 349.95/unit

The total cost of installation of the tower is show in Table 14.

Table 14 Total projected cost for the design

Items Cost ($)

Turbines 4200

Tower (American Tower version) 16,000

Desalination 6995


29

Tool Rental (assuming 1 full week rental) 716

Drill Bits (assuming a minimum of 3 will be needed) 171

Helicopter Rental (based on a total of 10hr) 11,000

Total of known costs 39,082

It should be noted that the costs of additional batteries are not included in this total, we are not

certain as to how much College of the Atlantic would like to expand its bank.

4.6 Miscellaneous Design Considerations

Several non hardware related considerations arose over the course of the project. The analysis of

each is detailed here.

4.6.1 Grounding

Due to Mount Desert Rocks location it suffers a significant number of lightening strikes

annually. This problem will only be exacerbated with the installation of a one hundred foot steel

tower. Due to the island’s small area and granite composition there has never been an effective

grounding system installed. The Cost Guard has improvised by employing an automated system

to replace lighthouse’s bulb in the event of a lightening strike. In order to protect the sensitive

equipment that will be installed on the tower, an effective grounding method must be developed.

The first effective method would be to drill a series of holes across the island, embed copper rods

into them using Betonite clay and ground the tower to those [7]. The second would be to ground

the tower directly to the surrounding ocean, and allow the low resistance saline water to dissipate

the charge.

4.6.2 Potential Interference with Cost Guard Helipad

The Cost Guard maintains a helipad on the island which it uses to service the lighthouse.

Research indicates that the island is far too small for the installation of a 100ft tower within the

confines of FAA guidelines shown in Figure 17.


30

Figure 17 Imaginary surfaces for military helicopter landing surfaces, taken from www. faa.gov/regulations_policies/

In order for the tower to be installed, it would have to be specially approved by the Coast Guard,

as stated in FAA regulations [8].

4.6.3 Migratory Bird

The University of Maine group was unable to find site specific data with regards to migratory

birds on Mount Desert Rock. However Paul Kerlinger states, “little evidence was found

implicating towers less than about 300-450 feet in tower kills that involved anything greater than

a few birds.”[9]


31

5. Conclusions and Recommendations The design goals of this project changed over the course of the school year. First, our only goal

was to provide COA with an off-grid power system for their summer program on Mount Desert

Rock. By the end of the fall semester the design goals expanded to include a required tower

height of 100 feet and expanded power requirements including a desalination unit and a

cultivation tank. Our overall design meets the revised goals. The chosen tower meets the height

requirements for the MMA students and will have a service ladder allowing them access all the

way to the top of the tower. The turbines are small enough to be carried down easily by one

person for winter storage. By choosing a free standing tower in place of a tilting tower makes

turbine removal and installation more complicated by requiring a person to climb the

freestanding tower. A tilting tower would eliminate the need for climbing the tower to install and

remove the turbines but would add the cost of a professional crew to operate the tilting tower.

The designed system includes six Southwest Windpower Air-X Marine wind turbines which will

provide approximately 228 kWh a month, or 1140 kWh a season, more than twice the island’s

current seasonal usage of 332 - 415kWh. It will take the six turbines approximately 136.4 hours

to fully charge the existing battery bank. The system also includes a Spectra Watermakers

Aquifer 150 desalination unit which will desalinate 500 gallons of potable water in

approximately 80 hours. Currently the estimated weekly use of potable water is 500 gallons.

Mount Desert Rock is located in the path of migratory song birds making it a place where many

stop to rest. Due to the height of the designed system it is possible for it to harm the endangered

birds of prey which hunt the song birds on the island. The University of Maine group was unable

to find site specific data with regards to migratory birds on Mount Desert Rock. However Paul

Kerlinger states, “little evidence was found implicating towers less than about 300-450 feet in

tower kills that involved anything greater than a few birds.” [9]

Many steps are required to finalize the actual installation of the designed system. A specific

installation site on MDR needs to be selected and receive approval from the Coast Guard. A

system needs to be designed to protect the tower’s base from winter storm damage. While

visiting the island, we were shown two large rocks resting on a high point, later estimated to be

approximately 50 tons each, that are moved around every winter by storm swells that cover the

entire island. Our group considered using a triangularly shaped steel beach barrier, like the


32

military used in World War II, to protect the tower base. Figure 18 illustrates the general shape

of the barrier.

Figure 18 Steel Beach Barrier, adapted from http://www.juniorgeneral.org/donated/xaxk/ddaybarriers.gif

Steps for delivery and installation of the designed system need to be refined further. One major

step is testing rock anchors to failure in Mount Desert Rock granite. Another major step would

be to further investigate electrical grounding of the turbine and tower to protect against lightning

strikes. Currently two options for grounding are available. One option is to run a copper ground

wire from the tower to a naval brass wire grounded in the sea. Another option is to connect the

grounding wire from the tower to metal rods cemented in a series of holes drilled in the granite

using highly conductive Betonite clay. The number and depth of the holes to ensure good

grounding still need to be determined. Several options to assemble, deliver, and install the tower

are available. The tower can be assembled on the mainland, delivered by barge in five sections

and then moved from the barge to the island by helicopter. The helicopter would then be able to

stack each section of the tower. Another option is to bring the tower out to the island

unassembled in a large boat and assemble the tower on the island. The tower would be

assembled horizontally and then erected in one piece by helicopter. When installing the anchors

for the tower or the cement foundation, we recommend using a freestanding drill rig similar to

the one shown in Figure 19. According the foreman from the quarry where the anchor testing

was performed, the pictured drill rig is capable of drilling through approximately ten feet of solid

granite in four minutes.


33

Figure 19 Example for Freestanding Drilling Rig (circled in yellow), picture taken during rock anchor testing

References

[1]. College of the Atlantic. Mount Desert Rock. [cited 4 May 2008].Available from http://www.coa.edu/html/mountdesertrock.html

[2]National Oceanic and Atmospheric Administration. [cited on 4 May 2008].Available from

http://www.ndbc.noaa.gov/maps/northeest.html [3]Blanco, Gabriel, James F. Manwell, and Jon G. McGowan. “ A Feasibility Study for

Wind/Hybrid Power System Applications for New England Islands”. Renewable Energy Research Laboratory, University of Massachusetts. Amherst, MA. 2002

[4] Shenck, Nate. “Wind Power System, Wind Energy I”. Massachusetts Department of

Technology. Available from www.alumni.media.mit.edu/~nate/AES/Wind_Theory_1.pdf [5] Cotterly, Wayne. “Hurricanes & tropical Storms, Their Impact on Maine and Androscoggin

County”. 1996. [cited 4 May 2008].Available from http://www.pivot.net/~cotterly/hurricane.pdf


34

[6] Holmes, John D. . “Wind Loading of Structures”. Spon Press. New York: 2003. ISBN 0-419-24610-X (Print Edition)s

[7]Copper.org. “Copper Grounding System Protects Mt. Washinghton Towers”. [cited 4 may2008] Available from http://www.copperinyourhome.com/applications/electrical/pq/casestudy/mtwashington.html

[8] FAA. Section 3. IDENTIFYING/EVALUATING AERONAUTICAL EFFECT [cited on 4 May 2008]Available from http://www.faa.gov/regulations_policies/

[9]Kerlinger, Paul. “AVIAN MORTALITY AT COMMUNICATION TOWERS: A REVIEW OF RECENT LITERATURE, RESEARCH, AND METHODOLOGY”.[cited on 4 May 2008]. Available from http://library.fws.gov/Pubs9/avian_mortality00.pdf

Data and Picture Sources

Southwest Windpower. Air-X Marine Owners Manuel .[cited 4 May 2008]. Available from http://www.windenergy.com/documents/manuals/0057_REV_D_AIR-X_Marine_Manual.pdf

Spectra Watermakers. Aquifer 150. [cited on 4 May 2008].Available at

http://www.spectrawatermakers.com/aquifer/index.html NOAA. [cited on 4 May 2008]. Available from www.noaaa.gov American Tower Company, 100ft Heavy Duty Tower Dimensions. [cited 4 May 2008].

http://www.amertower.com/pdf’s/100heavy.pdf Federal Aviation Administration, Imaginary surfaces for Military Helicopter Landing

Surfaces.[cited 4 May 2008]. Available from www.faa.gov/regulations_policies/ Steel Beach Barrier.[cited 4 May 2008]. Available from

http://www.juniorgeneral.org/donated/xaxk/ddaybarriers.gif

APPENDIX A

Appendix A: Wind Data Analysis Code for MatLab (by Brendan Owen) Maine code: %% MDRM1 Availability and Energy Density clear all clc data1; %%Emediate Conclusions from MDRM1 data % All values are based on the bouy hight above sea level Vmean = mean(MDRM1(:,7)); Vrmc = ((1/length(MDRM1(:,7)))* sum(MDRM1(:,7).^3)) ^(1/3) ; rho = 1.225; A = 1/(2*length(MDRM1(:,7))); for i=1:1:length(MDRM1(:,7)) B(i,1) = rho * MDRM1(i,7)^3; end B = sum(B); Prmc = A*B; % figure(1) % plot(hour,hour_avgs,'g'); Windrose %%Determin Weibull coefficients for Wind speed dist ribution bins = linspace(0,38,150); data = hour_avgs; % % Optimisation run to fit Weibull coefficients A = eye(2); b = [4 20]'; x0 = [2 3]; % initial guess options = optimset; options.TolCon = 1e-16; options.TolFun = 1e-16; options.TolX = 1e-16; options.Display = 'off' ; options.MaxFunEvals = 1e6; [x,fval] = fmincon(@(x)w_minconfun(bins,x(1),x(2),data),x0,A,b ,[],[],[],[],[],options); x %% Weibull vs. Histogram w_dist = weibull_dist(bins,x(1),x(2)); wind_hist = hist(data,bins); wind_int = sum(0.5*(wind_hist(2:end)+wind_hist(1:en d-1))*(bins(2)-bins(1))); wind_hist = wind_hist./wind_int; figure(3) plot(bins,wind_hist*8760); hold on plot(bins,w_dist*8760, 'r' ); %% Energy distribution (per square meter) P_msq = .25 * rho .* ((day_avgs).^3); Edist = bins.^3 .* w_dist; Pow_msq_month = .25*rho.*month_avgs.^3; plot(bins,Edist, 'k' ); hold off figure(4)

APPENDIX A

plot(hour,hour_avgs, 'g' ); %figure(4) % plot(month,Pow_msq_month);

Load wind speed data from NOAA and break it down, MDRM1 is the data set being read in: %% MDRM1 load MDRM1 %% Generate hour, day and month averages % Arithmic hour average based on measurements taken every 10 min form bouy % MDRM1 % hour hour_breaks = find( diff(MDRM1(:,4)) ~= 0 ); hour_avgs = zeros(size(hour_breaks)); for idx = 2:length(hour_breaks) hour_avgs(idx-1) = mean(MDRM1(hour_breaks(idx-1 ):hour_breaks(idx),7)); end hour = 1:1:length(hour_breaks); %day day_breaks = find( diff(MDRM1(:,3)) ~= 0 ); day_avgs = zeros(size(day_breaks)); for idx = 2:length(day_breaks) day_avgs(idx-1)= mean(MDRM1(day_breaks(idx-1):d ay_breaks(idx),7)); end day = 1:1:length(day_breaks); %month month_breaks = find(diff(MDRM1(:,2))~=0); month_avgs = zeros(size(month_breaks)); for idx = 2:length(month_breaks) month_avgs(idx-1) = mean(MDRM1(month_breaks(idx -1):month_breaks(idx),7)); end month = 1:1:length(month_avgs); Functions:

1) Weibull Distribution: function [w_dist] = weibull_dist(bins,k,c) w_dist = zeros(size(bins)); w_dist = (k/c) * (bins/c).^(k-1).* exp(-(bins/c).^k );

Special Plots: Wind Rose : %%Generating Wind Rose wdir = zeros(size(MDRM1(:,6))); wdir = MDRM1(:,6); wdir = wdir * pi/180; figure(2) rose(wdir,36); hline = findobj(gca, 'Type' , 'line' ); set(hline, 'LineWidth' ,1.5)

APPENDIX B

Appendix B : American Tower Company 100ft Heavy Duty Lattice Tower

APPENDIX B

APPENDIX C

Appendix C: Soutwest Windpower Air-X Marine

APPENDIX D

Appendix D: Spectra Watersystems Aquifer 150

wind power for the rock - mickpeterson.org

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