Energy From The Wind - Aaryn Smyth Flashcards
Which wind turbine are you more likely to see in country areas and why?
A horizontal axis wind turbine, as they are able to produce more electricity from any given amount of wind.
Provide the formula to calculate the potential power output of a wind turbine.
P= 1/2 x (rhoe) x A x V3 x C
What does the term “swept area” mean when referring to a wind turbine? Provide the formula to calculate the swept area.
The term swept area simply means the area that the blades cut through as they rotate in the wind. The formula to calculate swept area is simply;
A= ñr2
Which of the wind turbines is most efficient?
HAWT, they are able to produce more electricity in any given amount of wind.
For how long has wind energy been utilised by humans and what was it used for?
Wind energy has been used for thousands of years, it has mainly been used to mill grain, provide mechanical power and to pump water.
Provide the formula for Density.
Density = Mass / Volume
(kg). (m3)
Provide the formula for Velocity.
Velocity = Distance travelled / Time taken
Explain the changes that altitude has on the air density. Explain the changes that the time of year have on density.
As the altitude increases the density of the air decreases as the air is much thinner. In the summer the air will be less dense as the particles will be vibrating more and moving around,therefore less particle per m2, in winter the particles have less kinetic energy and therefore do not move around as much, thus there is more particles per m2
Who was Albert Betz and what did he show?
Albert Betz was a German physicist and in 1928 showed that the maximum amount if energy that can be extracted from the wind is 59.3%. This is due to the fact that some kinetic energy must be left in the air after it leaves the rotor blade.
Explain the term “Cut-in speed”.
The cut in speed of a turbine is the speed at which the turbine first starts to rotate and generate power, this is typically between 3-4m/s
Explain the term “Rated power output”.
Rated output power is the maximum power output at which the electrical generator is capable of operating at.
Explain the term “rated output speed”.
Rated output speed is the speed at which the electrical generator is capable of operating at, typically between 12-17m/s
Explain the term “cut-out speed”.
The term cut-out speed is the speed at which the brakes are applied in a turbine to stop it sustaining damage. This is typically around 25m/s.
Name some factors which affect the maximum energy production in wind turbines.
- Air density
- Hub height
- Terrain of the site
- Size of the turbine itself
Explain what happens if the blades of a turbine turns too slowly through the wind.
If the blades turns too slowly most of the wind will pass through the gaps between the blades and alot of energy is wasted.
