Wind Energy

Wind Power

Wind map

• Real time wind map

History

• We have been harnessing wind since ancient times

• Sailboats

• Windmills

• American West

• Modern wind turbines

Wind Energy

• Solar energy heats air causing expansion

• This expansion creates kinetic energy in the air movement

• Converts kinetic energy to electrical energy using a turbine and generator

Kinetic Energy

A mass $m$ traveling at a speed $v$ has a kinetic energy

$\frac{1}{2} m v^2$

Note the units $\frac {kg \cdot meter^2}{sec^2} = 1\ Joule$

Fan Law

$Power = \frac{1}{2} \rho A v^3$

• $\rho$ density of air (kg per cubic meter)

• $A$ swept area of wind turbine (square meters)

• $v$ velocity of the air (meters per second)

• Power is in watts

Air density

• How much does the air weigh?

• About 1.2 kg per cubic meter

• Varies with altitude

• Varies with temperature

Vestas Website

Vestas, Turbine Manufacturer

Similarities and differences

• What similarities does wind share with other generation?

• Spinning electromagnetic generators

• No heat engine or fluid

Environmental impacts

• What are the impacts?

• Carbon emissions only during manufacture and installation

• No significant water impact

• Visual impacts?

Wildlife impacts

• Birds and bats can strike the blades and be killed

• How can we reduce deaths?

• Schuster, Bulling, Koppel, Consolidating the State of Knowledge: A Synoptical Review of Wind Energy’s Wildlife Effects

• Sovacool, The Avian and Wildlife Costs of Fossil Fuels and Nuclear Power