Wind Turbine Payback in Pierce County, WA
Wind turbine payback in Pierce 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 Pierce County, WA averages 2.87 m/s (6.4 mph). A 10 kW turbine there would make about 2,232 kWh a year, worth $322 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 Pierce County
A home turbine is not worth buying for savings in Pierce County unless your spot is far windier than the county average, 8.1 m/s at the hub against 2.87 m/s here. Per kW, solar panels would make about 999 kWh a year here against the turbine's 223, so get a solar quote first.
What would have to change
- Power would have to cost 224¢/kWh, 15.5 times what WA pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 2.87. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of WA
Pierce County is the 3,117th 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 Pierce County
January is the strongest month here, at 3.72 m/s and about 448 kWh. July is the weakest, 2.05 m/s and 50 kWh, so the best month makes 9.0 times the worst. November to March brings in 71% of the year's output in Pierce County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.72 m/s | 448 kWh | $65 |
| February | 3.35 m/s | 288 kWh | $42 |
| March | 3.26 m/s | 291 kWh | $42 |
| April | 2.79 m/s | 166 kWh | $24 |
| May | 2.38 m/s | 95 kWh | $14 |
| June | 2.31 m/s | 82 kWh | $12 |
| July | 2.05 m/s | 50 kWh | $7 |
| August | 2.08 m/s | 54 kWh | $8 |
| September | 2.40 m/s | 96 kWh | $14 |
| October | 2.93 m/s | 204 kWh | $29 |
| November | 3.56 m/s | 375 kWh | $54 |
| December | 3.62 m/s | 411 kWh | $59 |
What a taller tower would buy
Measured at 10 m the wind in Pierce County averages 1.95 m/s; at 50 m it is 3.44 m/s. That gives a shear exponent of 0.353, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 1,329 to 4,094 kWh a year, 208% 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 | 2.49 m/s | 1,329 kWh | over 100 years |
| 30 m | 2.87 m/s | 2,239 kWh | over 100 years |
| 40 m | 3.18 m/s | 3,163 kWh | over 100 years |
| 50 m | 3.44 m/s | 4,094 kWh | over 100 years |
Counties around Pierce County
3 of the 6 closest counties are windier at turbine height; the windiest, Kitsap County, averages 2.97 m/s.
- Thurston County, WA: 2.81 m/s, 2,073 kWh, payback over 100 years (33 mi)
- King County, WA: 2.75 m/s, 1,920 kWh, payback over 100 years (34 mi)
- Lewis County, WA: 2.94 m/s, 2,427 kWh, payback over 100 years (34 mi)
- Kitsap County, WA: 2.97 m/s, 2,513 kWh, payback over 100 years (47 mi)
- Mason County, WA: 2.6 m/s, 1,565 kWh, payback over 100 years (52 mi)
- Cowlitz County, WA: 2.96 m/s, 2,484 kWh, payback over 100 years (64 mi)
Sun versus wind in Pierce County
Pierce County gets 3.42 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 999 kWh a year; one kW of the turbine above makes 223. Kilowatt for kilowatt, panels make 4.5 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.