Brian KlimmPeter OzolsTapan PatelJeffrey WalshDaniel West

Capstone DesignNortheastern UniversityDecember 4, 2007

Problem Statement

• Design a wind powered system that will provide an energy source to an off the grid location

• Design an innovative system that incorporates power storage through a battery backup system providing 3 days of continuous use without recharging

Background: Product Niche & Economics

• Economics– Pros

• Eliminates utility bills• Majority of cost is upfront in

materials and construction• Aboveground electric cables

can be as much as $10 per ft– Cons

• Financial and land costs limit the market

• NIMBY, aesthetics play a factor

• Reason for Design– Desire to reduce one’s carbon

footprint– 1kWh produced by wind

turbine = 3.41 ft3 of natural gas or 0.0034 gal of oil

– Reduce or eliminate reliance on the power grid

Background:Market Options

• Small Wind Turbines range from 20 W to 100 kW

• Southwest Windpower– SkyStream 3.7– Air Breeze– Air-X– Whisper 100 & 200

• Bergey

50 kW

400 W

3 kW

10 kW10 kW

Selecting a Feasible Site

• Key Factors– Average wind speeds– Local regulations– Proximity to Northeastern

• Narrowed to Nantucket, Cape Cod and NUHOC Lodge– Nantucket was the only site

that fit the 3 criterion

• Laws & Regulations– Zoning laws must be analyzed

on a case-to-case basis– Nantucket, MA

• 60 ft tower height limit• Guy wires may be no closer

than 15 ft from property line• Noise limitations• Fence around tower• Drawing package must be

submitted to Town Council

Wind Power & Energy:Small Cabin Layout

Wind Power & Energy:Power Estimates for Cabin Layout

Appliances Specifications How Often Used Number of

AppliancesAverage kWh per

month Total (kWh)

Energy Star Compact Fluorescent Lights (100 Watt incandescent) 28 Watts 4 hrs./day 7 3.36 23.52

Ceiling Fan, high speed 12 hrs./day 1 23.4 23.4

Energy Star Refrigerator/freezer 17.5 cubic feet 8 hr./day 1 60 60

Microwave Oven 30 min./day 1 12 12

Television, 32" LCD 6 hrs./day 1 27 27

Coffee Maker 15 min./day 1 11.25 11.25

Outlets 6 0

Washing Machine 8 loads/wk. 1 80 80

Water Pump 0.5 hrs/day 1 16.5 16.5

Total Monthly Power 253.67

Total Yearly Power 3044.04

V = Velocity in mphEPF = Energy Pattern Factor of 1.91 for a Rayleigh Distribution of wind speedsPower Density Based on Sea Level Conditions

V = Velocity in mphEPF = Energy Pattern Factor of 1.91 for a Rayleigh Distribution of wind speedsPower Density Based on Sea Level Conditions

AEO = Annual Energy OutputP/A = Power DensityP = Power in WindA = Swept Area% Efficiency = Betz Limit and Turbine Components = 30%

2rA

Swept Area

r = length of a single blade

Wind Power & Energy:Estimated Output

W

kW

yr

hEfficiencyA

A

PAEO

1000

1760,8%

EPFVDensityPower 305472.0

Wind Power & Energy:Estimated Wind Energy Output

Assumptions:– Temperature 15 C (59 F)– Air density 1.225 kg/m3

– Sea level pressure 29.92 in Hg– Energy Pattern Factor 1.91– Swept Area 3.58 (m2)– Blade Length 1.0668 (m)

Design Site

Annual Average

Wind Speed

mph

Power

Density

W/m

Annual

Energy

Density

kWh/m2

Overall

Conversion

Effciency

%

Annual

Energy

Output

kWh/m2

Nantucket, MA 15.00 352.73 2213.59 0.30 3314.02

2

Wind Power & Energy:Energy Output With Varied Blade Length

Blade Length (m) Swept Area (m2)

Annual Energy

Output (kWh/m2)0.25 0.196 182.0100.50 0.785 728.0420.75 1.767 1638.0931.00 3.142 2912.1661.25 4.909 4550.2601.50 7.069 6552.3741.75 9.621 8918.5092.00 12.566 11648.6652.25 15.904 14742.8412.50 19.635 18201.0392.75 23.758 22023.2573.00 28.274 26209.4963.25 33.183 30759.7553.50 38.485 35674.0363.75 44.179 40952.3374.00 50.265 46594.659

Blade Length (m) Swept Area (m2)

Annual Energy

Output (kWh/m2)0.25 0.196 182.0100.50 0.785 728.0420.75 1.767 1638.0931.00 3.142 2912.1661.25 4.909 4550.2601.50 7.069 6552.3741.75 9.621 8918.5092.00 12.566 11648.6652.25 15.904 14742.8412.50 19.635 18201.0392.75 23.758 22023.2573.00 28.274 26209.4963.25 33.183 30759.7553.50 38.485 35674.0363.75 44.179 40952.3374.00 50.265 46594.659

Wind System Components:Alternator

• Two commonly used options for wind powered generation – Induction Motor– Permanent Magnet Alternator

• Induction Motors need to be connected to the grid and require energy to start

• PMA requires no connection or power to start

Wind System Components:Rotor Blades

• More blades, more torque, slower speed• Less blades, higher speeds, but reduced

torque requiring higher winds• Three blade design is most commonly

used• Offers best balance between start up

speed and rotational speed.

Wind System Components:Rotor Blades

• Airfoil Design– Better performance – Higher price

• Drag Design– Easy to manufacture – Low price

Wind System Components:Rotor Blades

• Utilizes 3 blade design• 7ft rotor diameter

– TLG Wind Power

• 6061 T6 Aluminum rolled sheet metal

Wind System Components:Power Output

• At Nantucket’s average wind speed of 15 mph, the blades spin at 500 RPM

• At 500 RPM, the PMA produces 41 Volts at 9 Amps

• The resulting power is 369 Watts and 265 kWh per month

Off-the-Grid System

GENERATOR

BATTERIES

INVERTER

3 phase AC

AC LOADS

(120 VAC 60Hz)

WIND

VARIABLE SPEED

RECTIFIER

CHARGE CONTROLLER

DIVERSION LOAD

DC

Wind System Components:Electrical System Diagram

• Electrical Power conversion and management components:– Southwest Windpower Charge Controller– Outback FX3048T Inverter

Wind System Components:Power Storage Configuration

• 48V 516Ah system– 8x 12V 258Ah Concorde PVX-2580L AGM lead acid batteries

Wind System Components:Proof of Concept Electrical Configuration

Wind System Components:Support Tower

• Height• Strength• Cost• Footprint

Monopole Tower

Lattice Tower

Guyed Tower

Wind System Components:Support Tower

• Southwest Windpower Air-X 45 Foot Tower– Includes all hardware excluding

tubing and anchors– $210 for the kit, $2000 for the

tubing and anchors– Instruction manual included

Conceptual Design Model

Proof of Concept Model

Proof of Concept Model

Questions?

Actual Cost

Prototype Cost

Background:Patent Search

• One of the first patents filed for a wind powered generator was in 1891

• The system utilized a tail vane to direct the rotor into the wind and also a secondary battery to store the generated electricity

Nantucket Satellite Image

Structural Analysis

Structural Analysis