The first commenter above is right to point out an error in George Wagner's quote "as far as I know there's no other (VAWT) wind company with years of field testing and international patents." He meant to say that we know of no company pursuing the understory market of commercial wind farms. The VAWTs we have seen are either for home/rooftop use and are small, less than 10 kW or, if they are large, they are designed to be put on towers. An understory VAWT has to be short and they need to be placed closely together to maximize the use of land and reduce costs. WHI's "coupled vortex" patent (http://www.wipo.int/pctdb/en/wo.jsp?wo=2003064852) will prevent VAWT competitors from placing their turbines close together such that the neighboring turbines create additional lift and torque on each other. VAWTs in the understory will need to withstand much more turbulence that when they are in smoother more laminar winds higher above the ground. Any new turbine model entering the commercial wind market takes years of field testing, multiple iterations and a great deal of experience.