A lot of cool air?

I hadn't heard of SheerWind until they started following me on Twitter. They offer, they say, a 'better way to harvest wind'. Their technology, which seems to be to do with accelerating wind down a tube, and using the Venturi effect before it goes through a generator, claims to work at relatively low wind speeds, and not to need huge wind turbines but just some relatively low interventions. I don't know if birds could fly in. I don't know how much electricity would be generated and if it is significant.

All I know is that they are American, that their apparatus looks a bit Heath Robinson, and that they have some great testimonials and supporters - and that it sounds exciting. Does anybody know any more?