Wind Turbine Payback in Grant County, WA
Wind turbine payback in Grant 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 Grant County, WA averages 4.55 m/s (10.2 mph). A 10 kW turbine there would make about 9,641 kWh a year, worth $1,390 at WA's 14.42¢/kWh. Against an installed cost of about $100,000, that is a payback of 72 years, and the turbine is built to last about 20.
What to do in Grant County
A home turbine is not worth buying for savings in Grant County unless your spot is far windier than the county average, 8.1 m/s at the hub against 4.55 m/s here. Per kW, solar panels would make about 1,200 kWh a year here against the turbine's 964, so get a solar quote first.
What would have to change
- Power would have to cost 52¢/kWh, 3.6 times what WA pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 4.55. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of WA
Grant County is the 1,719th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in WA is Columbia County at 5.18 m/s, payback 50 years.
Month by month in Grant County
March is the strongest month here, at 5.11 m/s and about 1,129 kWh. August is the weakest, 4.09 m/s and 599 kWh, so the best month makes 1.9 times the worst. November to March brings in 47% of the year's output in Grant County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 4.59 m/s | 839 kWh | $121 |
| February | 4.80 m/s | 861 kWh | $124 |
| March | 5.11 m/s | 1,129 kWh | $163 |
| April | 4.83 m/s | 937 kWh | $135 |
| May | 4.41 m/s | 749 kWh | $108 |
| June | 4.45 m/s | 742 kWh | $107 |
| July | 4.20 m/s | 647 kWh | $93 |
| August | 4.09 m/s | 599 kWh | $86 |
| September | 4.31 m/s | 675 kWh | $97 |
| October | 4.58 m/s | 835 kWh | $120 |
| November | 4.73 m/s | 885 kWh | $128 |
| December | 4.54 m/s | 812 kWh | $117 |
What a taller tower would buy
Measured at 10 m the wind in Grant County averages 3.51 m/s; at 50 m it is 5.14 m/s. That gives a shear exponent of 0.237, typical of ordinary open country. Going from 20 m to 50 m takes output from 7,283 to 13,490 kWh a year, 85% 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 | 7,283 kWh | 95 years |
| 30 m | 4.55 m/s | 9,664 kWh | 72 years |
| 40 m | 4.88 m/s | 11,703 kWh | 59 years |
| 50 m | 5.14 m/s | 13,490 kWh | 51 years |
Counties around Grant County
4 of the 6 closest counties are windier at turbine height; the windiest, Lincoln County, averages 4.88 m/s.
- Douglas County, WA: 3.61 m/s, 4,778 kWh, payback over 100 years (38 mi)
- Adams County, WA: 4.83 m/s, 11,407 kWh, payback 61 years (47 mi)
- Franklin County, WA: 4.61 m/s, 10,008 kWh, payback 69 years (54 mi)
- Lincoln County, WA: 4.88 m/s, 11,734 kWh, payback 59 years (55 mi)
- Kittitas County, WA: 3.56 m/s, 4,570 kWh, payback over 100 years (57 mi)
- Benton County, WA: 4.84 m/s, 11,472 kWh, payback 61 years (68 mi)
Sun versus wind in Grant County
Grant County gets 4.11 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,200 kWh a year; one kW of the turbine above makes 964. 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.