1. How Winds are Created The earth’s winds are caused by pressure differences across the earth’s surface due to uneven heating Local Winds: During the day the air over the land is heated more than the air over the sea. Opposite during the night  Day pattern: Wind blows from sea to land  Night pattern: Wind blows from land to sea

2. How Winds are created Global Winds: Occur due to greater heating of the air near the equator than the poles. Thus wind blows in the direction from the poles to the equator Large ocean and land masses also affect the wind pattern It is important to understand these wind patterns for the evaluation of potential wind sites

3. U.S. Wind Resource Map

4. Classes of Wind Power Density at 10 m and 50 m (a). 10 m (33 ft) 50 m (164 ft) Wind Power Class Wind Power Density (W/m 2 ) Speed (b) m/s (mph) Wind Power Density (W/m 2 ) Speed (b) m/s (mph) 1<100<4.4 (9.8)<200<5.6 (12.5) 2100 - 1504.4 (9.8)/5.1 (11.5)200 - 3005.6 (12.5)/6.4 (14.3) 3150 - 2005.1 (11.5)/5.6 (12.5)300 - 4006.4 (14.3)/7.0 (15.7) 4200 - 2505.6 (12.5)/6.0 (13.4)400 - 5007.0 (15.7)/7.5 (16.8) 5250 - 3006.0 (13.4)/6.4 (14.3)500 - 6007.5 (16.8)/8.0 (17.9) 6300 - 4006.4 (14.3)/7.0 (15.7)600 - 8008.0 (17.9)/8.8 (19.7) 7>400>7.0 (15.7)>800>8.8 (19.7)

5. Modern Wind Turbine Wind power systems are composed of: Tower Rotor with 2 or 3 blades (fiberglass reinforced plastics, epoxy laminates Yaw Mechanism such as a tail vane Low-speed shaft, high-speed shaft, and gearbox (Mechanical Drive Train) Electrical generator Speed sensors and control Modern wind power systems also include: Power electronics Control electronics Batteries to improve the load availability when in stand-alone mode Transmission link connecting to the area grid

6. Characteristic of Wind Turbines Variations in wind speed causes fluctuations in the amount of power produced  Short Term: Gusts and Turbulence  Long Term: Seasonal Changes WTs have a cut-in, cut-out and a peak power output for a given wind velocity Power from the wind is proportional to the area swept by the rotors In practice, the max power efficiency is 45%

7. Global Picture

8. Source: GWEC (Global Wind Energy Council) 2008: http://www.gwec.net/fileadmin/documents/PressReleases/PR_stats_annex_table_2nd_feb_final_final.pdf Wind Power

9. Source: GWEC (Global Wind Energy Council) 2008: http://www.gwec.net/fileadmin/documents/PressReleases/PR_stats_annex_table_2nd_feb_final_final.pdf Wind Power

10. Source: GWEC (Global Wind Energy Council) 2008: http://www.gwec.net/fileadmin/documents/PressReleases/PR_stats_annex_table_2nd_feb_final_final.pdf Top 10 total installed capacityTop 10 added capacity (2008)

11. Total Installed Wind Capacity

13. Cost Analysis Wind energy generation costs have dramatically decreased over the last 25 years from 40 cents/KWh to 4 cents/KWh 20 years from now wind energy is expected to be cheaper than conventional sources of energy

14. Advantages and Disadvantages of Wind Turbines Advantages  Clean Source of Energy  Unlimited Supply  Popular with the Public Disadvantages  How do wind plants impact the power system grid (Not enough data)  Very expensive to install and connect to the power grid

15. Wind Turbine Power: P = 0.5 x rho x A x Cp x V 3 x Ng x Nb P = power in watts (746 watts = 1 hp) rho = air density (about 1.225 kg/m 3 at sea level, less higher up) A = rotor swept area, exposed to the wind (m 2 ) Cp = Coefficient of performance (.59 {Betz limit} is the maximum theoretically possible,.35 for a good design) V = wind speed in meters/sec (20 mph = 9 m/s) Ng = generator efficiency (50% for car alternator, 80% or possibly more for a permanent magnet generator or grid- connected induction generator) Nb = gearbox/bearings efficiency (depends, could be as high as 95% if good)

19. Wind Turbine Noise Levels

20. Electricity Demand Varies throughout the Day Source: ERCOT Reliability/Resource Update 2006 Natural Gas Nuclear Coal Total Coal Capacity

21. Wind and ERCOT daily load Source: Dispatchable Hybrid Wind/Solar Power Plant, Mark Kapner, P.E

22. ERCOT load duration curve 2007 Source: Dispatchable Hybrid Wind/Solar Power Plant, Mark Kapner, P.E

23. Average hourly wind speed Jan.- Nov. 2008 Source: West Texas A &M University http://www.windenergy.org/datasites/1405-olfen/index.htmlhttp://www.windenergy.org/datasites/1405-olfen/index.html

24. GOAL FOR RENEWABLE ENERGY Statutory goal adopted in 1999, revised in 2005 Year GoalActual Non- Wind 200340099045 2005850119045 20071400310077 Today14006450136 20155880 October 15, 2008 24 33 mw biomass; 69 mw landfill gas; 33 mw hydro; 1 mw solar

25. CREZ SCENARIOS Capacity of New CREZ Wind by Scenario (MW) Wind Zone Scen. 1 Scen. 2 Scen. 3 Scen. 4 Panhandle A 1,4223,1914,9606,660 Panhandle B 1,0672,3933,7200 McCamey8291,8592,8903,190 Central1,3583,0474,7355,615 Central West 4741,0631,6512,051 Total*12,05318,45624,85924,419 * Assumes 6,903 MW of existing wind capacity October 15, 2008 25

26. SCENARIO 2 TRANSMISSION PLAN 1,705 miles of new 345-kV double circuits 453 miles of new 345-kV single circuit 371 miles of 345-kV rebuild & upgrade $4.9 billion cost, not including interconnection facilities October 15, 2008 26

27. WHAT’S AHEAD FOR ERCOT WIND DEVELOPMENT Concern about over-development of West Texas wind  Development beyond CREZ plan could reduce market value of all West Texas wind production In next few years, congestion between West Texas and population centers will be significant ERCOT transition to nodal market has been delayed Concerns about reliability with high levels of wind  Forecasting wind, adequate thermal generation to match swings in load and wind generation, cost of load-following services September 10, 2008 27