The following is an excerpt from an article I've posted on this topic.
"I’ve avoided comment on SheerWind and its Invelox device previously—I can’t really call it a wind turbine—because I’ve debunked similar claims for other devices many times before. I only mention SheerWind in passing in my 560-page book on wind energy. I include it in a litany of ducted wind turbine flops that failed to meet Carl Sagan’s skeptic’s credo that “extraordinary claims demand extraordinary proof.” In this case, SheerWind made extraordinary claims, but offered no proof that its Invelox device could do what it promised—and it still doesn’t.
I wouldn’t have bothered looking into it even now until links to news articles about a furor in Denmark were thrown over my digital transom. Denmark? Surely, they know better? And that was why the flap was resonating in both the local and engineering press. Danes were asking how this could happen in the land where modern wind energy was born. Now SheerWind’s design was more than a “industry-changing” or “revolutionary” invention as such hucksters are won’t to call them. It was an international scandal involving so-called “American” technology. "
In short, the thing doesn't work.
You can read the rest on my web site at SheerWind-Invelox--Is the End Nigh for Another Ducted Turbine?