Lakota no more!

[Stewart Corman]

Well,
It looks like Dave at True-North has launched his upgraded site:

http://www.truenorthpower.com/index.php?option=com_frontpage&Itemid=1

there are several additions and deletions:
his new design built in Canada ( with some components from China?)
new generator?
no mechical furling (electronic brake)
adjustable pitch ( not variable pitch)
interchangeable larger blades ( coming soon)
only upwind design ( OB1KW/12ft downwind deleted)

Be interesting to see at his pricepoint, how much interest is generated,
being that they should be rolling off the assembly line at Ayr, Ont very soon

If anyone is in the immediate vacinity, why not arrange for a tour/demo??

Stew Corman from sunny Endicott

[Rob Beckers]

Interesting news! I'm glad to see Dave is producing his own turbines now. No prices yet on the site as far as I can tell. The price point will be interesting. I've looked at his (previous) Lakota, and proposed it a few times to customers. It was a tough sell though, since the Bergey XL.1 produced considerably more energy for less money.

I hope the new turbines will do well, it will be good to get a few more options for small wind turbines on the North American market!

-RoB-

[Stewart Corman]

Rob,
If you click on "Arrow" and "brochure", it shows a cost of $2645, avail July '08
Stew

I haven't gotten any details, but IMHO, I'd bet he has some larger blades which can be pitched more for better power at lower WS, and then controlled electrically "furled" to prevent overspeed/overpower??
BTW, I am biased against using only electronics as a governing mechanism ..if/when the electronics fry, the whole unit flies apart in self-destruct mode. Bergey uses a manual reset relay which short circuits all the leads.

Would like to see some performance curves to compare to Skystream.

BTW, I have reviewed the NREL study of Skystream and the numbers are quite good, even tho there was a long discussion on AWEA forum about it only delivering 2/3 of what is shown here (??):
http://www.nrel.gov/docs/fy05osti/38157.pdf

All comments welcome to above

It appears that the newer generation of controllers have less to do with juggling the output voltage/current (for battery charging), but more like a motor speed control, adjust the load to maintain a more uniform rotation speed

unless I am reading wrongly, I see Cp=0.45 at 11mph:

[Rob Beckers]

Hi Stew,

<< getting on my soap box >>

The Skystream is probably the first SWWP design that has some actual engineering behind it. The fact that NREL and Sandia were involved gives some confidence. When I looked at it, it seems well-build and if quality materials are used it should last. From my perspective, I have no issue with the turbine itself.

What I do take issue with is the way SWWP markets the Skystream. There are a couple of problems in their approach: It is advertised and most often installed with their 33 feet (10m) monopole. It is pretty much a guarantee that at 30 feet, and the lower blade tip is at 27 feet, the air will be turbulent. You would have to be at a dead-flat tundra with no vegetation or other obstructions to be above the turbulent air, and even then it's dubious. Any wind turbine placed in turbulent air will not produce much, nor will it live very long because the very nature of turbulent air means it gets wacked around quite a bit (think what it feels like in an airplane when flying through turbulence and you get the idea). There also is not much wind at 10 meters; going up to 20 meters (60 feet - considered the minimum for any turbine) increases energy in the wind by a factor of 1.3x. To give an applicable analogy: Placing a wind turbine on a short tower in turbulent air is the same thing as installing solar panels in the shade. There's no 'fuel' there to extract energy from.

Then there's the fudging of the power curve. If you read their brochure (http://windenergy.com/documents/spec_sheets/0370_skystream_spec.pdf) it shows a curve that hits an unbelievable 2.6 kW at 13 m/s. The 20-second average NREL curve shows 1.8 kW, while a curve through NREL's 1-minute average data also shows around 1.8 kW. Personally I trust NREL more than SWWP's marketing department. Even the NREL data gets abused; SWWP has a brochure somewhere that shows NREL's 20-second averaged data as "the" power curve, while the NREL doc shows that curve to be at the very high side of the 1-minute binned data. It is much more realistic to use a curve fitted through those 1-minute bins, than the 20-second data points, when it comes to predicting production. I have fitted a curve through the 1-minute binned data points, and when I use that curve I get the following production numbers:



Avg. wind speed Rob's Prediction SWWP Claim Difference
m/s kWh/month kWh/month %

3.5 82 100 82%
4.5 173 230 75%
5.5 282 400 71%
6.5 392 500 78%


Those are wind speeds at hub height, and in SWWP's case do not take turbulence into account. Believe me, at 10 meters altitude you are going to loose a great deal of potential production to turbulence!

Then there's the claim that a Skystream will offset 40 - 90% of the electricity use of a home or small business. That is just ludicrous. The average North American household uses 900 kWh/month, and a business won't be any better. Keep in mind that the vast majority of customers that buy this turbine will have less than 4 m/s at 10 meters, not counting the effect of turbulence (which makes it in effect even less).

What it adds up to is two things. First, SWWP is not doing the small wind industry any favors by overhyping a product that can only end up disappointing customers by not living up to the hype. While I am sure that SWWP will do very well and sell lots of turbines, it will give the small wind industry a bad name because they will have sold so many and they will have created a nearly equal number of unhappy customers.

Second, the Skystream really is not a bad turbine and I believe it has merit, if SWWP would be honest about it. Of course, if they were honest their product wouldn't look quite as good compared to the competition, and payback time will be where it is for all small wind turbines (ie. for most places well beyond 20 years).

<< getting off my soap box >>

-RoB-

[Ric Murphy]

Interesting development. I've been dealing with Dave for a little over 3 years now and am currently using a Lakota turbine. He told they were moving the production from China to Ontario but didn't mention it was going to be an all "new" turbine. If you look at the brochure for the Arrow you'll see a reference to EFGEN. I did a search on EFGEN and on their website I found a turbine identical to the Arrow. From what I can see it looks like the Arrow is also sold as the EFGEN 1000.....I'm confused!!!! EFGEN also sells larger turbines up to 15KW. Link to their website below
Ric
http://www.efgen.com/w2w.htm

[Stewart Corman]

Rick,
Great find ..I missed that reference.
Need to do more probing on this.
Note also that the EFGEN site shows downwind turbines as well in the "Proven" line.

Stew Corman