Presentation is loading. Please wait.

Presentation is loading. Please wait.

Wind Energy: The Myths and the Math SWC 2014, Stevens Point- June 18, 2014 Dr. David J. Laino Principal Engineer Endurance Wind Power

Similar presentations


Presentation on theme: "Wind Energy: The Myths and the Math SWC 2014, Stevens Point- June 18, 2014 Dr. David J. Laino Principal Engineer Endurance Wind Power"— Presentation transcript:

1 Wind Energy: The Myths and the Math SWC 2014, Stevens Point- June 18, 2014 Dr. David J. Laino Principal Engineer Endurance Wind Power ©2014 David Laino (used by permission)

2 Myths “Low wind speed design” “No cut-out wind speed” “Revolutionary Advancement” “Beats Betz” “Funnels the wind” “More blades is better” “No blades is best” ©2014 David Laino

3 Outline Wind energy What is it? How do we extract it? Low and high wind myths Short tower myth Wind Turbine Design Betz Limit Efficiency myths Turbine Types Revolutionary technology myths Rotor solidity myths Areas for Innovation ©2014 David Laino

4 “Science Schmience. It spins!” Wind is an ethereal entity, that can neither be smelled nor seen. In this way it is not unlike the ch’i, prana, or the Jedi Force. It is a mystery that we know is there but cannot fully define. Hence, we do not truly understand wind, so harnessing its mysterious power is fertile ground for discovery and experiment. No experience required. “All you need in this life is ignorance and confidence; then success is sure. ” ― Mark Twain ©2014 David Laino

5 Math: Energy in the wind Wind is movement of an air mass Moving mass has kinetic energy Newtonian Physics: E k = ½ mv 2 Mass of air = density (  ) x Volume Volume = Area ( A ) x Velocity ( v ) x Time ( t ) Kinetic Energy of the Wind: E wind = ½  v 3 A t A t v ©2014 David Laino

6 The Power in the Wind Power = Energy / time ∴ 26% increase in wind speed = 2x Power 2x wind speed = 8x Power P wind = ½  v 3 AE wind = ½  v 3 AtP wind  v 3 ©2014 David Laino

7 Myth: The Power in Low Wind MATH: (tiny wind speed) 3 = tiny number Real world: Typical cut-in: 4 m/s = 39 W/m 2 Claim: Low wind cut-in: 2 m/s = 4.9 W/m 2 Reality: Not enough power to overcome real-world inefficiencies ©2014 David Laino

8 Myth: The High Wind Speed Turbine Claim: No need to shut down, it operates in hurricane winds! Check: Time at any given wind speed is defined by a distribution Typical cut-out = 25 m/s ©2014 David Laino

9 Math: The High Wind Speed Turbine Energy = Power x time X Lots of Power! Hmmm… Wind energy exposure gain = % Reality: No Time = No Energy ©2014 David Laino

10 Lesson: What a wind turbine does Convert the kinetic energy of the moving air into electrical energy Input: Wind Output: Electricity Less Wind Wind turbine slows the wind as it passes through, reducing the kinetic energy, converting it to mechanical energy. ©2014 David Laino

11 MYTH: No need for tall towers FACT: Obstructions block the wind FACT: Friction with the ground slows the wind FACT: More height = more wind. REALITY: All wind turbines require tall towers to be effective. No, you are not special Wind Shear ©2014 David Laino

12 MYTH: Betz Limit Applies ONLY to Propeller Turbines NO Um… ©2014 David Laino

13 MATH: Betz Limit Proof P wind = ½  v 3 A P out = ½  {½  A (v in + v out )/2}  (v in 2 - v out 2 ) C p = P out /P avail = ½ [1-(v out /v in ) 2 ] [1 + v out /v in ] C p-max = v out /v in = 0.33 Note: Purely mathematical No assumption on turbine type Applies to ANY wind energy machine mass flow rate through A drop in speed squared A v in v out P out ©2014 David Laino

14 MYTH: “Breakthrough: 3x – 50x Energy Output!!!” C P = P captured / P wind Power Coefficient Turbine efficiency NO turbine can exceed the Betz Limit Modern designs perform admirably No room for “breakthroughs” IEC Tested SWTPeak C P 7.42 m 2 VAWT m 2 HAWT m 2 HAWT m 2 HAWT m2 HAWT0.36

15 MYTH: Ducted Turbines are Special A FACT: “Swept Area” includes the duct Venturi effect is real Velocity increases in a nozzle Works well for constrained flow ©2014 David Laino

16 Reality: Wind is Lazy The math looks promising P wind  v 3 But … Wind turbine’s job is to slow the wind, and Wind is NOT constrained inside a hose Wind takes the path of least resistance ©2014 David Laino

17 Myth: More Blades = More Energy Myth: Propeller turbines let most of the wind pass between the blades Reality: Space between spinning blades is small. Fewer blades is better High-speed propeller strikes the proper balance between slowing the wind (its job) and letting it pass (so it doesn’t stop) wind speed Blade rotational speed Blade 1 track Blade 3 track Blade 2 track Blade track ©2014 David Laino

18 If High Solidity is Better, May I suggest… ©2014 David Laino

19

20 MYTH: Revolutionary Technology New Boat Propeller Slow, quiet operation Fish-friendly Pushes more water Revolutionary design New Wind Turbine Slow, quiet operation Bird-friendly Catches more wind Revolutionary design 9 th century Persian Panemone ©2014 David Laino

21 Four factors affect wind energy capture potential: 1.Air density 2.Wind speed 3.Overall turbine efficiency 4.Swept area E =  t ½ VV 3 C P A dt Factors in Wind Turbine Effectiveness ©2014 David Laino

22 Where else will advances come from? Economics: cost of energy Ease of installation t = $ Materials >m = >$ Reliability  = $ Architecture Mo’ parts = mo’ $ ©2014 David Laino


Download ppt "Wind Energy: The Myths and the Math SWC 2014, Stevens Point- June 18, 2014 Dr. David J. Laino Principal Engineer Endurance Wind Power"

Similar presentations


Ads by Google