For example, it's no surprise that those massive industrial-sized wind turbines that you see on commercials and maybe on some nearby commercial wind farms use materials similar to fiberglass to manufacture their blades.  So if it's good enough for them, why not for your small, modest-sized generator??

Well, the difference is scale.  These giant wind turbines are so big that fiberglass is one of the few materials that can be used economically to support such a large structure and be sufficiently lightweight to turn at all.  In other words, they would use other materials if it was cost competitive, but the simple economic reality is that industrial turbines use reinforced, well-engineered composite materials to construct those massive wind generator blades.  Chances are the company that sells fiberglass blades for your 500-Watt generator have very little in common with the industrial blades.

Besides, a wind farm is generating megawatts of power, and for a utility company managing these wind farms, periodic downtime because of stress fractures in the turbine blades are just a part of the business.  It's not the end of the world when one turbine requires maintenance to repair a broken or cracked blade and in fact, you'll often drive by a wind farm and notice a few turbines simply not spinning--which happens for a variety of reasons.  But you aren't a multi-million dollar company and you probably don't have a wind farm.  And if you do have a wind farm, you probably aren't as willing to constantly commit your time to replacing components on your generator.  

Fiberglass blades will crack and fiberglass blades will break because chances are that your fiberglass blades are inexpensive and weren't designed for industrial-class applications.  Many of the fiberglass blades that we've tried end up being relatively low-quality blades from China that are simply not built to stringent specifications.  The biggest problem we've found is that they are too variable, not sufficiently balanced, and prone to giving out on the first particularly windy day.  

No matter how you cut it in with fiberglass blades, you end up having hidden costs over the long run as you will spend time replacing your blades.  For the commercial wind turbines, they build in redundancy and because of their sheer scale, can accept periodic downtime with their generators.  As a DIYer, you simply do not have that luxury!

Aluminum

Advantages: Commercially available and highly durable; strong and will sustain in winds up to 75 mph!

Disadvantages: Aluminum is heavier than other synthetic materials and therefore limits the size/diameter. 

So aluminum has a lot of qualities that intuitively don't make much sense to a lot of people new to wind power.  Compared to lightweight plastics, aluminum is heavy and hard for the tinkerer at home to shape.  But the dynamics of the homepower movement have changed.  In the years since the first homebrew manuals popped up, there are now literally dozens of companies that are offering world-class components for small-scale wind generators.  Our blades are part of this evolutionary process.  The components available are simply better today, and with all these options comes an important decision--do you want to be a "do it yourselfer" or a "do everything yourselfer"?  If you insist on making your own blades, then obviously aluminum probably won't be your choice.  But we like to remind people that just like you probably won't smelt the steel to make your tower mount, you should consider the advantages of having precision-built and balanced blades that will last you through many strong gusts of wind.

Aluminum blades are weather-resistant and won't warp, bend or mis-shape in different temperatures or humidity. Aluminum, like all metals, is virtually immune to the harsh ultraviolet rays produced by the sun.  Aircraft-grade aluminum alloys used to manufacture blades like our Windy Nation blades have excellent corrosion resistance without applying any type of paint or topcoat to it. That means that from the deserts of Arizona to the rolling hills of Ireland, these blades will spin the same, day after day for many years to come.  

Certainly there are many many challenges to face when it comes to producing reliable, clean and cost-efficient electricity from your wind generator.  It's our belief that the selection of your blades should not be one of those challenges.  When it comes down to it, we believe that the long-life and durability of aluminum blades gives you more time (and more money) to devote towards other important parts of your generator.   

Ron Lin.
WindyNation