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

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

U.S. Wind Resource Map

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/m2) Speed(b) m/s (mph) 1 <100 <4.4 (9.8) <200 <5.6 (12.5) 2 100 - 150 4.4 (9.8)/5.1 (11.5) 200 - 300 5.6 (12.5)/6.4 (14.3) 3 150 - 200 5.1 (11.5)/5.6 (12.5) 300 - 400 6.4 (14.3)/7.0 (15.7) 4 200 - 250 5.6 (12.5)/6.0 (13.4) 400 - 500 7.0 (15.7)/7.5 (16.8) 5 250 - 300 6.0 (13.4)/6.4 (14.3) 500 - 600 7.5 (16.8)/8.0 (17.9) 6 600 - 800 8.0 (17.9)/8.8 (19.7) 7 >400 >7.0 (15.7) >800 >8.8 (19.7)

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

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%

Global Picture

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

Total Installed Wind Capacity

Total Installed Wind Capacity

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

Advantages and Disadvantages of Wind Turbines 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

Wind Turbine Power: P = 0.5 x rho x A x Cp x V3 x Ng x Nb P = power in watts (746 watts = 1 hp) rho = air density (about 1.225 kg/m3 at sea level, less higher up) A = rotor swept area, exposed to the wind (m2) 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)

Wind Turbine Noise Levels

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

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

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

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

GOAL FOR RENEWABLE ENERGY October 15, 2008 Statutory goal adopted in 1999, revised in 2005 Year Goal Actual Non-Wind 2003 400 990 45 2005 850 1190 2007 1400 3100 77 Today 6450 136 2015 5880 ERCOT wind, per planning report 5871 mw SPP wind, per Class4Wind conference, 430 mw Non-wind, per texasrenewables.org, 136 mw Pre-2002 resources: 297 total; 179 hydro; 116 wind 24 33 mw biomass; 69 mw landfill gas; 33 mw hydro; 1 mw solar 24

Capacity of New CREZ Wind by Scenario (MW) CREZ SCENARIOS October 15, 2008 Capacity of New CREZ Wind by Scenario (MW) Wind Zone Scen. 1 Scen. 2 Scen. 3 Scen. 4 Panhandle A 1,422 3,191 4,960 6,660 Panhandle B 1,067 2,393 3,720 McCamey 829 1,859 2,890 3,190 Central 1,358 3,047 4,735 5,615 Central West 474 1,063 1,651 2,051 Total* 12,053 18,456 24,859 24,419 * Assumes 6,903 MW of existing wind capacity 25 25

SCENARIO 2 TRANSMISSION PLAN October 15, 2008 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 26 26

WHAT’S AHEAD FOR ERCOT WIND DEVELOPMENT September 10, 2008 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 27