1. 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% (1.2x) greater at one site compared to another, the power will be about_____ greater at that site. 3) Show equation to calculate:_______________ Reference wind.ppt on lecture page

2. 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 2x greater on one wind machine compared to another, the power will be about____ greater on that machine. 6) Show equation:_____________________

3. Finding Available Wind Energy  Increasing tower height increases power exponentially.  7 ) Why?________________________________ …equation for relationship between power and height also, just remember cubed… V/V o =(H/H o ) a, where: V o is wind speed at original height V is wind speed at new height H o 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

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

5. 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 Gipe (1999)

6. 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?______________ _____________________________

7. 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?

8. Wind Energy (Reference Skystream 3.7 data sheet) ENERGY 15) If your daily average watt-hrs is 16.67kwh/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?