Preston Montford, Shrewsbury

Advanced Wind Weekend

April 2008

Introductions…

V3 Power: Aran Eales, Tom Dixon,

Richard BridleRES:

Who are you?

Energy Usage UK

Fuel Used in Electricity Generation

in the UK: 1999

Renewable Sources Used to Generate Electricity: UK

2000

Benefits of Wind:• Available away from the power grid • Pollution free, • Sustainable• Doesn’t require fuel• Doesn’t create green house gases• Small land use required (2% on

farmlands)• Community Ownership, people

empowered

Drawbacks of wind

• Capital intensive• Wind is unreliable• Carbon Impact of build materials (Danish

wind energy association say energy payback less than a year on good site)

• Geographical/Location constraints• Danger to wildlife- siting needs to be

considered in relation to flight patterns

WIND - Air in a hurry…Solar energy creates pressure differences Air moves from high to low pressure causing wind

World Wind PatternsBoundary Layer Effect

World Wind Resource

• 1200 TW World Resource•10TW Theoretically recoverable•Worlds Energy Consumption 1.3TW•Huge potential resource

Wind Speed Map of UK

Persian (2000 b.c)

Direction of Prevailing Wind

Drag machine - used for grinding corn

History of Wind Power

Cretean Turbine

Wind Pumps

•Developed in 19th Century•Enabled colonisation of Australian outback•Still used widely in Africa

Early Electricity

Source www.windpower.dk

• End of 19th Century

• Used to charge batteries

• 12kW

• 12m blade diameter

• Development abandoned due to cheap fossil fuels

1970s and 80s

• 75kW Vestas• 1983• grid-connect

70s oil crisis renewed interest in wind power - especially in California, Denmark and Holland.

• 15kW Polenko• 1983• stand-alone

1990s• In late 80s

renewable generation subsidised through NFFO

• Cemmaes wind farm - first in UK

• In 2003 300kW machines replaced with 850kW

Small Scale 2000+

Source Proven Engineering

• Suited for remote power supplies

• 600W Proven

• 2.4m rotor diameter

The Biggest Turbine Ever Built

• 5MW

• 126m rotor diameter

• Installed off the coast of Scotland

POWER AVAILABLE IN THE WIND

Equations you should know:

K.E. = 1/2 mv2

Mass = density x volume

Distance = speed x time

K.E. = 1/2 mv2

K.E. = ½.(.V).v2

K.E. = ½.(.A.D).v2

K.E. = ½.(.A).(v.t).v2

K.E. = ½..A.v3.t

Power = Energy = 1/2 A v3

Time

Power = 1/2 A v3

Increase diameter of blades:

Squared increase in power

Swept area A = r2

= /4 d2

(doubling size of blades gives 4 times as much power)

Cubic increase in power

(If windspeed doubles, you get 8 times as much power)

Increase wind speed:

Tip Speed Ratio (TSR)

Windspeed

SpeedTipBladeRatioSpeedTip )(

Cp

TSR

TSR for our turbine is about 4 – depending on how well the blades are carved…

Solidity

AreaSwept

AreaBladeTotalSolidity

High Solidity machines have low TSR and High Torque

Low Solidity machines have high TSR and low torques

Turbine Characteristics - Efficiency

The turbine we will build...

•Hugh Piggot’s Design:

www.scoraigwind.com

•500W Rated output

•2.4m blade diameter

•Materials available locally in most areas of the world

•Low Embodied Energy

•Man Power

•Recycled Materials

Blades

Stages• Width• Twist• Thickness• Aerofoil• Wedges and Disks

Tools• Planes, chisels, mallets, ruler, pencils

Skills• Patience, accuracy

Twist - DRAG

Wind

Blade Movement

Reflected Wind

DRAG

Aerofoil - LIFT

Head Wind

Apparent Wind

Resultant Wind

Lift

Blade Motion

Conservation of Energy

Same for an Aerofoil

Bernoulli Effect

Higher speed over the airofoil causes low pressure

Lower speed under the aerofoil causes high pressure

Pressure difference causes upwards force

This is LIFT

Alternator

Components• 2 magnet disks• 1 Stator• Bridge Rectifiers

Jobs• Mould prep• Magnet positioning• Casting

Faradays Law of induction

Passing a magnet over a wire causes a current to flow along the wire

Alternator Theory

Alternator Theory

Alternator Theory

Alternator Theory

One end of each coilis connected to the“ring neutral”

Alternator Theory

One end of each coilis connected to the“ring neutral”

The other end is sent to a bridge rectifier

Rectifier theory

Coil connections

Coil outputs

Mounting and Tail

Materials• Bearing• Angle Iron• Steel Pipe• Nuts and Bolts

Skills• Welding• Grinding• Filing

FURLING

GOOD LUCK!