An Introduction to wind power

By Jack Bradley, University of Bradford

Introduction to Wind Power • History of wind power • Wind resource • How wind turbines work • Some basic characteristics • Relative efficiencies • Environmental Impacts

Where we use our energy

In the home

Where Our Energy Comes From?

World Primary Energy Consumption 2001

Excluding Biomass (Approx 445EJ).

Oil 33% Natural Gas 21% Biomass 12% Hydro electric 6% Nuclear Energy 6% Coal 22%

Future Energy Sources

UK Wind Resource • 990 TWh Onshore of which 60+ will be recoverable.

• 2869 TWh Offshore of which 100+ will be recoverable.

World Wind Resource • 1200 TW World Resource •10TW Theoretically recoverable •Worlds Energy Consumption 1.3TW

Source Twidell And Weir

Persian (2000 b.c) Direction of Prevailing Wind

Windmills

1970’s and 80’s

2000+

Wind Pumps

Early Electricity Source www.windpower.dk

World Wind Markets

A

l

v

Power Law

KE

 1 2

mv

2

Power

(

P

) 

KE t

 1 2 .

mv

2

t



P

(

watts

)

m



mass

.

flowrate t



A

.

l

.



t



A

.

v

.

  1 2

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3

Turbine Size Source Renewable Energy World Mar 02

Simple Wind Loggers

Wind Speed Distribution Curves 700 600

Normalised Wind Speed Distibution

k=2 Annual Mean =1 500 400 300 200 100 0 0.0002

0.9

Mean 1.8

2.7

3.6

4.5

Energy Distribution

Normalised Speed and Energy Frequency

k=2 v,mean=5 0.08 0.06 0.04 0.02 0 0 5 10 15 Wind speed (m/s) 20 25

European Wind Atlas

NOABL

Basic Principles Drag Machines

Basic Components of HAWT Direction of Blade Rotation Low Speed Shaft Direction Free wind Swept Area Hub Rotor made up hub and blades Tower Nacelle Yaw Bearing

Lift Machines Horizontal Axis Lift Drag True Wind Direction

Lift Machines Horizontal Axis Driving Force Lift Apparent wind direction True Wind Direction Direction of Blade Movement Drag

Lift Machines Horizontal Axis Driving Force Apparent wind direction v R

Direction of Blade Movement V b

Lift Drag True Wind Direction v

Tip Speed Ratio (TSR)

Tip Speed Ratio

(  ) 

Blade Tip Speed Windspeed

C p

TSR

Solidity

Solidity



Total Blade Area Swept Area

 High Solidity machines have low TSR and High Torque  Low Solidity machines have high TSR and low torques

Different Types of WEC Source Boyle

Anemometers • Spot measurements of little use.

• Average wind speeds required • Simple Anemometer gives Run of Wind measurement

UK Wind Speeds

Impacts (Noise) Source Boyle

Impacts (Visual)

Impacts (Birds) • It is estimated for 1000MW in Holland • 21,000 bird deaths • 1,000,000 due to power lines • 1,500,000 due to wild fowlers • 9,000,000 due to road traffic Source Winkleman 1995

Conclusions • Huge world resource • Power in the wind is proportional to the cube of the speed • Assessment of site wind speed is critical • Like all generation wind power has environmental impacts • Careful siting can minimise these problems