Reference wind ppt on lecture page 1

Reference wind. ppt on lecture page • 1) POWER in the wind: (P, watts) • Is proportional to the cube(3) of: • p = air density • A = area intercepting wind; • v = instantaneous wind velocity • r = blade length 2) ex. If wind speed is 20% (1. 2 x) greater at one site compared to another, the power will be about_____ greater at that site. 3) Show equation to calculate: ________

r • 4) POWER in the wind: (P, watts) • Is proportional to the square(2) of: • p = air density • A = area intercepting wind; • v = instantaneous wind velocity • r = blade length 5) ex. If blade length (r) is 2 x greater on one wind machine compared to another, the power will be about____ greater on that machine. 6) Show equation: ___________

Finding Available Wind Energy ØIncreasing tower height increases power exponentially. Ø 7) Why? ________________ V/Vo=(H/Ho)a, where: Vo is wind speed at original height V is wind speed at new height Ho is original height H is new height 8) a (alpha): What is Alpha? ___________ Over rough terrain, alpha = 0. 25. Over smooth terrain (water/ice), alpha = 0. 1 …equation for relationship between power and height also, just remember cubed…

Gipe (1999) 9) At an average annual wind speed of 10 mph, what % of the time does the wind blow 8 mph? ______

Gipe (1999) • Batteries and inverters are critical to the success of a hybrid system – Energy storage – Conversion of DC to AC • 10) What is a hybrid system? ___________ • Improvements of inverter technology have made it easier to live off the grid with AC appliances

Grip-hoists • Tractel’s Super Pull-All is a great model • If you are going to buy anything for wind turbine, buy a griphoist • Better than hoists: – Readily portable – Easier to control 11) Used for what? ______________________

Wind Energy (Reference Skystream 3. 7 data sheet) POWER • 12) What is the Cut-in wind speed in mph and meters/sec? • 13) What is the rated wind speed in mph and meters/sec? • 14) What is the shut-down speed in mph and meters/sec?

Wind Energy (Reference Skystream 3. 7 data sheet) ENERGY 15) If your daily average watt-hrs is 16. 67 kwh/day What average annual wind speed do you need to provide this much power? 16) If your average annual wind speed is 8. 5 m/s, how many kwhs/day are produced?