The swept area of regular wind turbines seems enormous compared to sheerwind's turbine's. Even the combined area of those 8 entrances look much much smaller. How in the world is this going to compete with those giants? What am I missing?
I can see something like that as a complementary power generator - it is very cheap if produced correctly.
P = 1/2 x ρ x A x v3 where ρ = air density, A = swept area and v = velocity of the wind
These wind towers on the other hand capture and manipulate the whole air flow from the area of their intake, not just the part directly interacting with the blades of a traditional turbine. That's why it is physically possible to extract much more power than with a traditional turbine with an equivalent "swept area".
You are right about the second part, those 'tunnels' do catch all the wind of their area.