Wind Turbine Payback in Cape Girardeau County, MO
Wind turbine payback in Cape Girardeau County
No. The turbine wears out before it pays for itself.
At 30 m, the height a home turbine tower usually reaches, the wind in Cape Girardeau County, MO averages 4.69 m/s (10.5 mph). A 10 kW turbine there would make about 10,508 kWh a year, worth $1,501 at MO's 14.28¢/kWh. Against an installed cost of about $100,000, that is a payback of 67 years, and the turbine is built to last about 20.
What to do in Cape Girardeau County
A home turbine is not worth buying for savings in Cape Girardeau County unless your spot is far windier than the county average, 8.2 m/s at the hub against 4.69 m/s here. Per kW, solar panels would make about 1,241 kWh a year here against the turbine's 1,051, so get a solar quote first.
What would have to change
- Power would have to cost 48¢/kWh, 3.3 times what MO pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 4.69. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of MO
Cape Girardeau County is the 1,626th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in MO is Atchison County at 6.17 m/s, payback 33 years.
Month by month in Cape Girardeau County
March is the strongest month here, at 5.50 m/s and about 1,362 kWh. July is the weakest, 3.50 m/s and 369 kWh, so the best month makes 3.7 times the worst. November to March brings in 55% of the year's output in Cape Girardeau County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 5.37 m/s | 1,283 kWh | $183 |
| February | 5.42 m/s | 1,187 kWh | $170 |
| March | 5.50 m/s | 1,362 kWh | $194 |
| April | 5.56 m/s | 1,353 kWh | $193 |
| May | 4.68 m/s | 886 kWh | $127 |
| June | 3.94 m/s | 516 kWh | $74 |
| July | 3.50 m/s | 369 kWh | $53 |
| August | 3.55 m/s | 386 kWh | $55 |
| September | 3.90 m/s | 499 kWh | $71 |
| October | 4.69 m/s | 890 kWh | $127 |
| November | 5.10 m/s | 1,084 kWh | $155 |
| December | 5.11 m/s | 1,130 kWh | $161 |
What a taller tower would buy
Measured at 10 m the wind in Cape Girardeau County averages 3.36 m/s; at 50 m it is 5.47 m/s. That gives a shear exponent of 0.303, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 7,322 to 15,821 kWh a year, 116% more, before counting the extra cost of the taller tower. Why tower height decides it explains the shear behind these numbers.
| Hub height | Average wind | Output | Payback |
|---|---|---|---|
| 20 m | 4.14 m/s | 7,322 kWh | 96 years |
| 30 m | 4.69 m/s | 10,481 kWh | 67 years |
| 40 m | 5.11 m/s | 13,300 kWh | 53 years |
| 50 m | 5.47 m/s | 15,821 kWh | 44 years |
Counties around Cape Girardeau County
3 of the 6 closest counties are windier at turbine height; the windiest, Jackson County, averages 5.34 m/s.
- Bollinger County, MO: 4.46 m/s, 9,100 kWh, payback 77 years (19 mi)
- Alexander County, IL: 5.23 m/s, 14,116 kWh, payback 37 years (23 mi)
- Perry County, MO: 4.46 m/s, 9,100 kWh, payback 77 years (23 mi)
- Scott County, MO: 5.23 m/s, 14,116 kWh, payback 50 years (24 mi)
- Union County, IL: 4.69 m/s, 10,508 kWh, payback 50 years (25 mi)
- Jackson County, IL: 5.34 m/s, 14,892 kWh, payback 35 years (32 mi)
Sun versus wind in Cape Girardeau County
Cape Girardeau County gets 4.25 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,241 kWh a year; one kW of the turbine above makes 1,051. Kilowatt for kilowatt, panels make 1.2 times as much here as the turbine. Panel output assumes an 80% system performance ratio. Wind or solar runs the same comparison for every county.
How this is worked out
Wind is NASA's Power climate record, the 2001-2025 average at 10 m and 50 m for the county's centre, carried to 30 m with this county's own measured wind shear and spread into hours with a Rayleigh distribution. The turbine is a generic 10 kW, 7 m rotor machine with 10% losses. Cost is $10,000 per kW installed with no tax credit, because the federal one ended in 2025. One county-centre number cannot see your hilltop or your tree line, so treat it as the starting point for a site survey, not a substitute. The full method and its weak spots are in how the numbers are made.