DyoCore and Why the Rating of Small Turbines Remains a Black Art

By Paul Gipe

Despite my best efforts, I’ve been dragged into the DyoCore flap here in California. I successfully ignored Mick Sagrillo’s plea to write something. I successfully ignored DyoCore’s request to get involved on their behalf. Now the staff of the California Energy Commission (CEC) has weighed in asking me to clarify my statements.

Ok I give up. I can’t stay on the sidelines any longer. (Isn’t there someone else out there qualified to debunk all these “inventions” that plague us?)

Possibly as many as two dozen Dyocore 1.2 m diameter wind device atop adjoined buildings in Morro Bay, California.

My policy is to only comment on the most egregious examples of flim-flammery or when–for whatever reason–I’ve become personally involved. This can be as simple as being barraged with email requests of “Wow, what do you think of this super duper little turbine?”‘ or seeing my colleague’s efforts at real renewable energy development getting sideswiped by the “Why do we need big (that is, real) windmills when this little one will do everything we ever need?” crowd.


Dyocore markets a micro wind turbine, the SolAir, 1.2 meters in diameter. This puts the DyoCore into the same category as the Ampair 300 or the Air Breeze. All intercept about 1.1 m² of the wind stream.

The San Diego, California company has sold a slew of their turbines in the sate where there is a subsidy under the CEC’s Emerging Renewables Program. The subsidy is based on the turbine’s power “rating” in watts or kilowatts.

The Ampair 300 is rated at 300 watts, the Air Breeze at 200 watts. (My tests indicate the Air Breeze is a reliable 150 W turbine.) However, DyoCore “rates” their turbine at–are you ready for this–1,600 watts, or 1.6 kW.

Thus, the DyoCore turbine qualifies for a hefty subsidy in California that essentially pays for the turbine.

Apparently getting the state of California to give you a free windmill is appealing to a lot of people and DyoCore “sold” a slew of machines potentially exhausting the funds in the subsidy program.

The CEC staff–playing Hamlet–felt something was rotten in DyoCore’s marketing and called a halt to the program and is taking action against DyoCore.

There are a few more twists and turns in the tale, but that’s the gist of it.


Who is responsible for this mess? Let’s just list them

  • The Small turbine industry,
  • The California Energy Commission,
  • DyoCore, and
  • Consumers.

The small turbine industry is partly to blame because if they’d listened to Mike Bergey 30-years ago–yes, that long ago–and had implemented a small turbine rating standard we wouldn’t keep having this problem. They are also to blame for being in love with subsidy programs that base their payments on installed capacity, the watts or kilowatts that the turbine is presumed to produce. See New Federal Subsidies Distort the US Small Wind Market: Or How to Increase the Power of the Skystream 3.7 with the Stroke of a Pen. The state of California is at fault for not understanding wind energy and falling back on outdated policy–subsidies on installed capacity–that was proven ineffective and prone to abuse–again–30 years ago.

DyCore of course. Their turbine is wildly overrated, but more on that in a moment.

And consumers are to blame for not doing their homework (that includes not reading books on wind energy–some of which I’ve written), and for succumbing to the greed of “getting something for nothing.” As the US Postal Service warns, “If it’s too good to be true, it probably is.”

Power Ratings

Do I really have to go over this again? See my books. See my other articles on various small wind turbines. See Testing the Power Curves of Small Wind Turbines, and especially note the sections Power Curves and The Rating Game where I first explain then rail against the power at wind speed system of rating small wind turbines.

To summarize, until very recently there was no “standard rating” of wind turbines–small or large. DyoCore’s contention on this point is correct. Wind turbines can be “rated” at wind speeds from 9.5 m/s (~20 mph) to 15 m/s (~35 mph) or even higher. In wind energy, the difference between 10 m/s and 15 m/s is huge–5³ or 125 times.

In part to remedy this problem, I began using what I call a “standard power rating” of my own creation. At the time (2000) there was little prospect of the industry reaching any kind of consensus. My intent was to provide consumers with an easy way to compare small wind turbines for those who were metrically challenged since we report swept area in m².

A decade later, the industry is finally getting its act together but some newcomers are reluctant to play by the new rules and we continue to have the same problems we had three decades ago.

Gipe’s Standard Power Rating

What is my “standard power rating”? It’s not very sophisticated, it’s simply the product of the swept area times 200 W/m² of rotor loading. Why 200 and not some other value? Before the dominance of rare-earth magnets in small wind turbines, most small wind turbines that were rated at a reasonable wind speed had rotor loadings that hovered around that value.

For example, at my “standard rating” the Ampair 300 is “rated” at 230 W, the Air Breeze at 210 W.

Today with rare-earth magnets, and their greater power density, that standard rating could move up some. However, I have no plans to change it. Why? Remember, I based this value on the manufacturer’s “rating” of their own products. My tests at the Wulf Test Field found that all the turbines I tested, save one, substantially failed to meet their proffered power curves. The Air Breeze, for example, at the manufacturer’s specified rated speed should be rated at 150 W, which is less than the 210 W in my “standard rating system”.

Where does DyoCore fit in the “Gipe standard rating system”? Since it’s the same size as the Ampair 300, the DyoCore would be rated at 230 W. The manufacturer’s “rating” of 1.6 kW is nearly seven times greater than in my system.

DyoCore’s Rating

DyoCore’s web site says that their turbine will generate 1.6 kW in a wind of 8 m/s, that is, the turbine is “rated” at 1.6 kW at 8 m/s (visited 20 September, 2011).

Can it do that? Not on this planet. The 1.6 kW rating at 8 m/s is more than four times the energy in the wind at that speed. Forget the Betz Limit, there is simply not the energy in the wind to do what DyoCore says its turbine will do.

DyoCore is now saying privately that the turbine will generate 1.6 kW at 17 m/s (38 mph). Can it do that? Possibly, it is at least back in the realm of the real world.

Nevertheless, DyoCore’s web site was still reporting the 8 m/s wind speed and that’s what consumers must go on.

In the end, the DyoCore rating flap is a distraction. Ratings are only useful for a crude comparison among turbines. The flap is only important because the CEC pays out subsidies on “ratings” and the DyoCore turbine is outrageously over-rated.

In the over-rating sweepstakes, DyoCore ranks right up there with inventors of Diffuser Augmented Wind Turbines (DAWT) or wind turbines that use shrouds. DyoCore’s rotor loading at rated power of 1,400 W/m² is just shy of the world record for wind turbine hype now claimed by Geneva’s Elena Energie (see Elena Diffuser Augmented Wind Turbine (DAWT): Have Parisians Drunk the Coolaid?) of 2,100 W/m². DyoCore just edges out Wind Cube’s 1,300 W/² (see Wind Cube Squarely Over the Top) to take the number two slot.

Energy Estimates Out of This World

What really matters of course is how much electricity these little devils produce. All the rest is puffery and marketing.

The good news is that the DyoCore’s estimates of Annual Energy Production, or the Annual Energy Output of earlier days, are not as outlandish as their power ratings.

Alas, DyoCore’s estimates can’t be met on this planet, possibly on another planet with a thicker atmosphere, but then we don’t live there and certainly the CEC gives subsidies only for wind turbines installed in California.

At an annual average wind speed of 4 m/s, the turbines are advertized to generate 2 times the energy in the wind.

At an annual average wind speed of 4.9 m/s, the turbines are advertized to generate 1.6 times the energy in the wind.

At an annual average wind speed of 5.4 m/s, the turbines are advertized to generate 1.4 times the energy in the wind.

Solution to the Rating Black Art

The solution should be fairly obvious, don’t base payments for small wind turbines on installed capacity.

In a subsequent post, I’ll try to explain why the CEC and California should simply exclude small wind from the Emerging Renewables Program. Instead, small wind should be paid its cost of generation, that is, a rate per kWh of actual generation. The small wind industry won’t like it. They’ll fight it, but it’s the only sure way for the small wind industry to mature. If the British can do it, so can we.