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Vertical Axis Wind Turbines

November 15, 2013
Glen Lux

Rebuttal to Another Eggbeater Oh My--Saskatoon’s Lux

Thank you for your critique on the CBC article. I do not expect to get praise or support from anyone in the wind industry for the efforts that I have made, but I do wish you and others, would keep an open mind to a turbine design that has so much potential.

When you said I 'have a very flimsy design', you could not be further from the truth.  Are you familiar with the structure called the 'geodesic dome'.  Buckminster Fuller coined the phrase 'to build more with less'.  Even though my turbine is light and flimsy looking it is actually very rugged.  The dome uses triangular shapes to provide structural integrity which is very similar to my turbine design.

This is a rebuttal to my article Another Eggbeater Oh My--Saskatoon’s Lux: More Over-the-top VAWT Hype. I am posting it here in fairness to Glen. Unlike most of the inventors I critique, his reply was reasonable and reasoned.

If you look at the video on my website or the video on the 'Create the Future' website, about 1/3 of the way in we show the cross cables highlighted with the blades.  The cables are highlighted because in a scaled view they are not visible.  This image is full of triangular shapes similar to the geodesic dome, hence the rigid structure.

The report from the NRC offers the blade deflection and stresses on a 40m diameter, 1MW computer model at extreme wind speeds of 59.5 m/s (IEC lla standard).  The maximum blade displacement is 17.6 in and the maximum stress on the blades is 11.9 ksi.  In operation at wind speeds of 21.99m/s and a rotational speed of 21 rpm, the maximum blade displacement is 6.4 in and the maximum stress on the blades is 6.2 ksi.  As you can see the maximum deflection of the blades is very small in comparison to the blade length of 220 feet.  Try building a 220 foot fence and be within 6.2 in without using surveying equipment or GPS.  Also, the low operational blade stresses is the reason why the life expectancy is measured in centuries.  Similar numbers were achieved when the design was scaled to 160m in diameter with a power output of 16MW.

We installed strain gauges on one prototype and used radio frequency equipment from the NRC to gather stress data while the turbine was in operation.  The results showed very low blade stresses which is in line with the computer models from the NRC.

Just one other point I would like to make.  At the awards night last Friday, in New York, an extremely interesting speaker from NASA listed some of the most successful endeavours that they have had over the past years.  He mentioned the hugely successful software program called NASTRAN and everyone at our table were scratching their heads in confusion.  I explained that this was the program used by the NRC when they analyzed my turbine.

I strongly agree that more 3rd party testing is required and concrete proof will only come through larger prototype operation and testing.  You should continue to discredit dodgy wind turbine designs that are not worth the paper they are written on but please be careful when choosing which designs fall into this category.  I do believe you made an error this time.  

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