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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!