# Wind Energy

## Wind Power

## Wind map

* [Real time wind map](http://hint.fm/wind/)

## 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](http://www.vestas.com)

## 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](https://link.springer.com/article/10.1007%2Fs00267-015-0501-5)
* [Sovacool, The Avian and Wildlife Costs of Fossil Fuels and Nuclear Power](https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2198024)