Areas of industrial wind facilities*
facility capacity/area† acres/MW
Mojave Co., Ariz. 425 MW/24,527 acres 58
Snowflake, Ariz. 99 MW/7,000 acres 71
Altamont Wind Resource Area, Calif. 580 MW/50,000 acres 86
Fountain Wind, Shasta Co., Calif. 347 MW/37,436 acres 108
Keyhole Wind, Kern Co., Calif. 100 MW/3,920 acres 39
Montezuma Hills, Calif. 180 MW/6,800 acres 38
Morro Bay (off shore), Calif. 3 GW/399 mi2 85
Pine Tree Wind Farm, Tehachapi Hills, Calif. 135 MW/8,000 acres 59
Tule Wind Project, East County, Calif. 131.5 MW/12,000 acres 91
Cheyenne Ridge Wind Project, Colo. 500 MW/100,000 acres 200
Colorado Green, Lamar 162 MW/11,840 acres 73
Niyol, Logan Co., Colo. 200.8 MW/39,314 acres 196
Prairie Wind, Colo. 69 MW/7,000 acres 101
Twin Buttes, Colo. 75 MW/9,000 acres 120
Winergy offshore, Del. 1,101 MW/67 mi2 40
Cassia County, Idaho 200 MW/4,500 acres 23
Boone County, Ill. 27 MW/800 acres 30
Baileyville Wind Farm, Ogle County, Ill. 80 MW/5,000 acres 62
Big Sky, Ill. 75 MW/10,000 acres 133
Bishop Hill, Ill. 400 MW/25-30,000 acres 62-75
Crescent Ridge, Ill. 54.5 MW/2,200 acres 40
LaSalle Country, Ill. 384.5 MW/25,000 acres 65
Mendota Hills, Ill. 50.4 MW/3,500 acres 69
Rail Splitter, Ill. 100.5 MW/11,000 acres 109
Twin Groves Wind Farm, McLean County, Ill. 396 MW/21,000 acres 53
Walnut Ridge, Bureau County, Ill. 225 MW/14,000 acres 62
Jordan Creek Wind Farm, Warren County, Ind. 300 MW/27,000 acres 90
Cerro Gordo, Iowa 42 MW/2,110 acres 50
Franklin County, Iowa 200-300 MW/40,000 acres 133-200
Pomeroy Wind Farm, Pocahontas County, Iowa 198 MW/8,200 acres 41
Elk River, Kan. 150 MW/8,000 acres 53
Ford County, Kan. 100.5 MW/5,000 acres 50
Smoky Hills, Kan. 100.8 MW/20,000 acres 198
Spearville, Kan. 100 MW/10 mi2 64
Beacon Wind (off shore), Mass. 2,430 MW/128,000 acres 53
Cape Wind (off shore), Mass. 420 MW/24 mi2 37
Harvest Wind Farm, Mich. 53 MW/3,200 acres 60
Huron County, Mich. 48 MW/4,700 acres 98
Muskegon, Mich. 31.5 MW/8,000 acres 254
Goodhue Wind Project, Minn. 78 MW/32,700 acres 419
Grand Meadow Wind Farm, Dexter, Minn. 100.5 MW/10,000 acres 100
Palmer’s Creek Wind Farm, Minn. 44.6 MW/6,150 acres 138
Pleasant Valley Wind Farm, Minn. 300 MW/80 mi2 171
Trimont Area Wind Farm, Minn. 100.5 MW/8,900 acres 89
Bluegrass Ridge, Mo. 56.7 MW/7,000 acres 123
Judith Gap, Mont. 135 MW/8,300 acres 61
Pierce County, Mont. 150 MW/72 mi2 307
Ainsworth, Nev. 59 MW/11,000 acres 185
Colfax County, N.M. 20 MW/800-1,200 acres 20
Grant County, N.M. 2150 MW/25 mi2 64
Cherry Valley, N.Y. 60 MW/1,200 acres 40-60
Fenner, N.Y. 30 MW/1,500 acres 50
Gore Mountain, N.Y. 27.5 MW/1,700 acres 62
High Sheldon, N.Y. 112.5 MW/10,000 acres 89
Long Island Sound (off shore), N.Y. 140 MW/8 mi2 37
South Fork Wind (off shore), N.Y. & R.I. 130 MW/13,700 acres 105
Pasquotank and Perquimans Counties, N.Car. 208 MW/34 mi2 105
Pierce County, N.Dak. 150 MW/72 mi2 307
Velva, N.Dak. 12 MW/3 mi2 160
Wilton Wind Energy Center, N.Dak. 49.5 MW/8,000+ acres 162
Black Fork Wind Farm, Ohio 201.6 MW/46,000 acres 228
Blue Canyon V, Okla. 99 MW/12 mi2 78
Arlington, Ore. 104 MW/14,000 acres 135
Biglow Canyon, Ore. 350-450 MW/25,000 acres 56-71
Elkhorn Valley, Ore. 101 MW/10,000 acres 99
Shepherds Flat, Ore. 750 MW/32,000 acres 43
Forkston Twp., Pa. 75-125 MW/7,400 acres 59-99
Block Island, R.I. >1,000 MW/>260 mi2 166
Titan I, Hand County, S. Dak. 25 MW/7,500 acres 300
Galveston Offshore, Texas 150 MW/11,355 acres 76
Desert Sky, Texas 160.5 MW/15 mi2 60
Horse Hollow, Texas 735 MW/47,000 acres 64
Pampa Wind Project, Texas 4,000 MW/400,000 acres 100
Stanton, Texas 100 MW/12,000 acres 120
Wildorado Wind Ranch, Texas 161 MW/16,000 acres 75
Milford Wind Corridor, Utah 300 MW/40 mi2 85
Sheffield, Vt. 52 MW/3,000 acres 58
Big Horn, Wash. 200 MW/15,000 acres 75
Desert Claim, Wash. 180 MW/5,237 acres 29
Hopkins Ridge, Wash. 150 MW/11,000 acres 73
Kittitas Valley, Wash. 181.5 MW/6,000 acres 34
Klondike II, Sherman County, Wash. 75 MW/6,400 acres 98
Linden Wind Farm, Wash. 50 MW/1,800 acres 36
Lower Snake River, Wash. 1,250 MW/94,900 acres 76
Nine Canyon, Kennewick, Wash. 63.7 MW/5,120 acres 80
Wild Horse, Wash. 64 MW/7,500 acres 118
Mountaineer, W.V. 66 MW/4,400 acres 67
Bent Tree, Freeborn County, Wis. 200 MW/32,000 acres 160
Forward Wind Energy Center, Wis. 200 MW/32,400 acres 162
Kewaunee County, Wis. 11 MW/603 acres 54
Monroe County, Wis. 80 MW/10,000 acres 125
Evanston, Wyo. 144 MW/7,800 acres 54
Campbell County, Wyo. 199.5 MW/14,000 acres 70
Converse County, Wyo. 200 MW/17,000 acres 85
Naikun Offshore, Hecate Strait, Br. Col. 396 MW/100 km2 62
Blue Highlands, Ont. 49.5 MW/4,500 acres 91
Sederglan Wind Farm, Alb. 70.5 MW/3,900 acres 131
St. Joseph Wind Farm, Man. 138 MW/125 km2 224
Prince I & II Wind Energy Project, Ont. 189 MW/10,000 hectares 55
Thunder Bay, Ont. 100 MW/8,000 acres 80
Anse-a-Valleau, Que. 100.5 MW/4,800 hectares 118
Stanstead Station, Que. 62 MW/920 hectares 37
Eurus wind park, Juchitán, Oaxaca 250.5 MW/6,178 acres 25
Codrington, Australia 18.2 MW/240 hectares 33
Dollar Wind Farm, Australia 79.2 MW/2,000 hectares 62
East Otago, Australia 650 MW/300 mi2 295
Macarthur, Australia 334 MW/5,500 hectares 47
Ruševo-Krmpotsko, Croatia 90 MW/27 km2 74
Senj, Croatia 156 MW/65 km2 103
Horns Rev (off shore), Denmark 160 MW/24 mi2 96
Horns Rev II (off shore), Denmark 209 MW/35 mi2 107
Baltic Eagle (off shore), Germany 476 MW/43 km2 22
Butendiek (off shore), Germany 240 MW/35 km2 36
Duddon Sands (off shore), U.K. 500 MW/66 km2 33
London Array, Thames Estuary (off shore), U.K. 1,000 MW/245 km2 61
Hornsea One (off shore), U.K. 1,218 MW/407 km2 83
Hornsea Two (off shore), U.K. 1,320 GW/462 km2 86
Norfolk Boreas (off shore), U.K. 1.8 GW/725 km2 96
Outer Dowsing (off shore), U.K. 1.5 GW/116 mi2 49
Walney (off shore), U.K. 450 MW/74.5 km2 41
Walney Extension (off shore), U.K. 659 MW/145 km2 54
E. Ayrshire, Dumfries, Galloway, Scotland 300 MW/8,000 hectares 67
Beinn Ghlas, Scotland 8.4 MW/300 hectares 88
Braes of Doune, Scotland 72 MW/1,000 acres 14
Lewis, Scotland 600 MW/45 mi2 50
Novar, Scotland 17 MW/300 hectares 44
Sutherland, Scotland 50 MW/2,731 hectares 135
Windy Standard, Scotland 21.6 MW/350 hectares 40
Carno, Wales 33.6 MW/600 hectares 44
Makara Hills, New Zealand 210 MW/55 km2 65
Quartz Hill, New Zealand 210 MW/3,000 hectares 35
Egypt (off shore) 2200 MW/1,600 km2 180

* The data are gathered mostly from news articles, some from government and company documentation. The list includes proposed (and possibly rejected) as well as operating facilities. Ridgeline facilities described only by length instead of the whole area taken are not included. An August 2009 study for the National Renewable Energy Laboratory examined land-use data for 172 projects, representing about 80% of the installed and targeted wind capacity in the U.S., and found an average area of 85 acres/MW.

According to "Permitting setbacks for wind turbines and the blade throw hazard," by Scott Larwood, presented at the 2004 California Wind Energy Collaborative Forum, University of California, Davis, the distance that turbines should be from each other for minimal wind interference is 3 rotor diameters when aligned perpendicular to the wind and 10 rotor diameters when parallel to the wind. This is also the spacing described by the New York State Energy Research and Development Authority and others. The minimum area required (where d is the rotor diameter) around each turbine in a single line where the wind is generally from one direction would therefore be 13d (10d fore and 3d aft) × 3d, with an extra 1.5d at each end. The minimum area in an array would be 10d × 10d, with an extra 5d border.

For a stand-alone turbine, the area required would be a 13d × 6d oval at a site where the wind is generally from one direction and up to a 20d-wide circle to use the wind from any direction. Depending on surrounding features, very tall towers allow reducing the area for a stand-alone turbine or a single line to some extent.

The GE 1.5-MW turbine, with a 70.5-m rotor span, therefore requires at least 38 acres per tower in a single line perpendicular to the wind (25 acres/MW) or 96 acres per tower in an array (64 acres/MW). Each Vestas V90 1.8-MW turbine, with a 90-m rotor diameter, requires 61-157 acres (34-87 acres/MW). Tom Gray of the American Wind Energy Association has written, "My rule of thumb is 60 acres per megawatt for wind farms on land."

That may still not be enough for maximum efficiency. More recent research at Johns Hopkins University by Charles Meneveau suggests that large turbines in an array need to be spaced 15 rotor diameters apart, increasing the above examples to 145-197 acres required per installed megawatt in an array.

Note that larger turbines are not substantially more efficient than small ones, because they require proportionally more space.

† Remember that capacity is different from actual output. Typical average output is only 25% of capacity, so the area required for a megawatt of actual output is four times the area listed here for a megawatt of capacity. And because three-fifths of the time wind turbines produce power at a rate far below average, even more (2.5×, perhaps, for a total of 10×) -- dispersed across a wide geographic area -- would be needed for any hope of a steady supply.

1 km2 = 100 hectares = 247.1 acres = 0.386 mi2
1 mi2 = 640 acres = 259 hectares = 2.59 km2


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