Wind Turbine Payback in Cowlitz County, WA
Wind turbine payback in Cowlitz 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 Cowlitz County, WA averages 2.96 m/s (6.6 mph). A 10 kW turbine there would make about 2,484 kWh a year, worth $358 at WA's 14.42¢/kWh. Against an installed cost of about $100,000, that is a payback of over 100 years, and the turbine is built to last about 20.
What to do in Cowlitz County
A home turbine is not worth buying for savings in Cowlitz County unless your spot is far windier than the county average, 8.1 m/s at the hub against 2.96 m/s here. Per kW, solar panels would make about 1,013 kWh a year here against the turbine's 248, so get a solar quote first.
What would have to change
- Power would have to cost 201¢/kWh, 14.0 times what WA pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 2.96. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of WA
Cowlitz County is the 3,076th 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 Cowlitz County
January is the strongest month here, at 3.71 m/s and about 444 kWh. August is the weakest, 2.45 m/s and 106 kWh, so the best month makes 4.2 times the worst. November to March brings in 64% of the year's output in Cowlitz County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.71 m/s | 444 kWh | $64 |
| February | 3.31 m/s | 277 kWh | $40 |
| March | 3.08 m/s | 243 kWh | $35 |
| April | 2.78 m/s | 163 kWh | $24 |
| May | 2.53 m/s | 119 kWh | $17 |
| June | 2.52 m/s | 114 kWh | $16 |
| July | 2.49 m/s | 114 kWh | $16 |
| August | 2.45 m/s | 106 kWh | $15 |
| September | 2.65 m/s | 138 kWh | $20 |
| October | 3.00 m/s | 222 kWh | $32 |
| November | 3.47 m/s | 347 kWh | $50 |
| December | 3.61 m/s | 405 kWh | $58 |
What a taller tower would buy
Measured at 10 m the wind in Cowlitz County averages 1.87 m/s; at 50 m it is 3.67 m/s. That gives a shear exponent of 0.419, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 1,351 to 5,034 kWh a year, 273% 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 | 2.5 m/s | 1,351 kWh | over 100 years |
| 30 m | 2.96 m/s | 2,492 kWh | over 100 years |
| 40 m | 3.34 m/s | 3,729 kWh | over 100 years |
| 50 m | 3.67 m/s | 5,034 kWh | over 100 years |
Counties around Cowlitz County
3 of the 6 closest counties are windier at turbine height; the windiest, Multnomah County, averages 3.39 m/s.
- Columbia County, OR: 3 m/s, 2,601 kWh, payback over 100 years (26 mi)
- Lewis County, WA: 2.94 m/s, 2,427 kWh, payback over 100 years (30 mi)
- Clark County, WA: 2.96 m/s, 2,484 kWh, payback over 100 years (31 mi)
- Wahkiakum County, WA: 2.89 m/s, 2,287 kWh, payback over 100 years (36 mi)
- Skamania County, WA: 3.12 m/s, 2,970 kWh, payback over 100 years (37 mi)
- Multnomah County, OR: 3.39 m/s, 3,905 kWh, payback over 100 years (47 mi)
Sun versus wind in Cowlitz County
Cowlitz County gets 3.47 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,013 kWh a year; one kW of the turbine above makes 248. Kilowatt for kilowatt, panels make 4.1 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.