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1) POWER in the wind: (P, watts) Is proportional to the cube( 3 ) of: p = air density

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.

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1) POWER in the wind: (P, watts) Is proportional to the cube( 3 ) of: p = air density

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  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:_______________

  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?________________________________ V/Vo=(H/Ho)a, where: Vo is wind speed at original height V is wind speed at new height Hois 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…

  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?

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