Wind Turbine Payback in Petroleum County, MT
Wind turbine payback in Petroleum 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 Petroleum County, MT averages 5.89 m/s (13.2 mph). A 10 kW turbine there would make about 18,890 kWh a year, worth $2,669 at MT's 14.13¢/kWh. Against an installed cost of about $100,000, that is a payback of 38 years, and the turbine is built to last about 20.
What to do in Petroleum County
A home turbine is not worth buying for savings in Petroleum County unless your spot is far windier than the county average, 8.2 m/s at the hub against 5.89 m/s here. Per kW, solar panels would make about 1,168 kWh a year here against the turbine's 1,889, so get a solar quote first.
What would have to change
- Power would have to cost 26¢/kWh, 1.9 times what MT pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 5.89. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of MT
Petroleum County is the 1,001st windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in MT is Fallon County at 6.64 m/s, payback 29 years.
Month by month in Petroleum County
January is the strongest month here, at 6.72 m/s and about 2,125 kWh. July is the weakest, 5.00 m/s and 1,067 kWh, so the best month makes 2.0 times the worst. November to March brings in 49% of the year's output in Petroleum County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.72 m/s | 2,125 kWh | $300 |
| February | 6.04 m/s | 1,534 kWh | $217 |
| March | 6.06 m/s | 1,709 kWh | $241 |
| April | 5.99 m/s | 1,616 kWh | $228 |
| May | 5.78 m/s | 1,537 kWh | $217 |
| June | 5.33 m/s | 1,219 kWh | $172 |
| July | 5.00 m/s | 1,067 kWh | $151 |
| August | 5.09 m/s | 1,118 kWh | $158 |
| September | 5.46 m/s | 1,292 kWh | $183 |
| October | 6.20 m/s | 1,798 kWh | $254 |
| November | 6.52 m/s | 1,934 kWh | $273 |
| December | 6.45 m/s | 1,954 kWh | $276 |
What a taller tower would buy
Measured at 10 m the wind in Petroleum County averages 4.52 m/s; at 50 m it is 6.66 m/s. That gives a shear exponent of 0.241, typical of ordinary open country. Going from 20 m to 50 m takes output from 14,894 to 24,582 kWh a year, 65% 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 | 5.34 m/s | 14,894 kWh | 48 years |
| 30 m | 5.89 m/s | 18,879 kWh | 38 years |
| 40 m | 6.31 m/s | 22,013 kWh | 32 years |
| 50 m | 6.66 m/s | 24,582 kWh | 29 years |
Counties around Petroleum County
5 of the 6 closest counties are windier at turbine height; the windiest, Garfield County, averages 6.41 m/s.
- Musselshell County, MT: 5.95 m/s, 19,334 kWh, payback 37 years (45 mi)
- Fergus County, MT: 6.18 m/s, 21,039 kWh, payback 34 years (48 mi)
- Garfield County, MT: 6.41 m/s, 22,743 kWh, payback 31 years (58 mi)
- Golden Valley County, MT: 6 m/s, 19,704 kWh, payback 36 years (69 mi)
- Treasure County, MT: 5.74 m/s, 17,785 kWh, payback 40 years (78 mi)
- Phillips County, MT: 6.17 m/s, 20,965 kWh, payback 34 years (78 mi)
Sun versus wind in Petroleum County
Petroleum County gets 4 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,168 kWh a year; one kW of the turbine above makes 1,889. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.6 times. 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.