The leading statement in the “2014 Wind Turbine Buyer’s Guide” (HP161) is right on—“Without question, wind is a tough renewable energy resource to tap.”
I love the Home Power cover shots showing people strapped to a 100-foot tower while a crane, probably another 20 feet over their heads, tries to avoid dropping several hundred pounds of metal on them. Why anyone thinks this is glamorous is completely beyond me. Home-scale wind is dangerous, expensive, takes a lot of real estate, and is so much more involved than PV that—for all but the very few with unlimited time and resources—wind is a no-go. That should tell people capable of looking past the glamour to pass by wind energy.
Yes, I know the arguments about how wind complements PV, but at what cost? At a wind velocity of 11 meters per second, the small Kestrel puts out 1 kW, according to your comparison sheet. That’s about three PV modules—which have a fraction of the cost, little or no maintenance, and 30-plus years of output with a 25-year warranty—not a five-year wind machine warranty.
And why are manufacturers publishing an 11 m/s wind speed’s output—who has that kind of wind? It’s unrealistic and a sad commentary on an industry that can’t compete in the renewable energy business outside of large-scale commercial turbines. How is anyone realistically justifying wind?
Sorry, but this confirms my belief that wind has very little place in small-scale energy production.
Robert Dee • via homepower.com
Small wind is not for the faint of heart. I talk most of my clients out of it, especially as the cost of PV modules continues to drop. For a wind-electric system to make sense, it requires a great wind resource; a dark and windy season (in the case of justifying an off-grid system); or a strong desire to just do it. It is a blast (if you like that sort of thing) to install and keep a system running, but it’s not cheap, easy, or reliable.
One of the presenters at the recent Small Wind Conference gave a presentation titled “Go Big or Go Home,” and I think there’s a lot of logic to that. The economics and the equipment quality both improve as machine size increases.
“Wind complements PV” is a reasonable off-grid approach. On-grid, it’s generally wiser to examine your resources and sink your money into generating energy with the most reliable and abundant resource—be that sun, wind, or falling water. With net metering, there’s little need to have your generating source producing evenly all year. PV can make most of your energy in your sunny season (your utility credits the surplus to your account), and then you can draw on the credit during times of lower production.
I agree that the 11 m/s value is a bit high for a rating—but that is an instantaneous wind speed, not an average. And any instantaneous rating is pretty useless for comparison with PV or with other machines, and for energy predictions. What’s really helpful is an energy rating at various average wind speeds, as shown in the article’s table. Then you can (with luck) find the average wind speed at tower-top height at your site and get a prediction of the kilowatt-hours a given machine may provide each year.
A “1 kW” machine and 1 kW of PV are not comparable. A 1 kW PV system rarely produces at full power, but has a fairly predictable energy (kWh) output if you know the peak sun-hours at the location. A wind turbine rated at 1 kW peak is not similarly predictable, since wind is a cubic resource. For example, cutting the wind speed in half yields about one-eighth the potential power. You’ll need to know the actual tower-top average wind speed to make a reasonable energy prediction.
You are wise to point out that the turbine cost is just one part of the system’s cost. Typically, it’s a small portion—in most cases, the tower and balance-of-system components each cost more than the turbine. Potential wind energy users need good pricing on the installed cost of all of the components before deciding to invest in a wind-electric system. Some will go for it regardless of the economics. In all cases, it’s wise to know the costs and the benefits.
Ian Woofenden • Home Power senior editor