This design looks dead brilliant. From the company site:
The ridgeblade is a cross flow turbine fitted on the ridge line at the top of a building and uses the existing roof area to collect and focus the wind. This is where the wind is forced to travel over the roof surface, accelerating the airflow though the turbine. And whilst the unit is fixed to the roof and doesn’t turn to face the wind, the advanced blade design means that it works in 70% of wind directions.
The ridgeblade is an innovative, affordable and effective way of harnessing the wind's power to produce renewable electricity.
The ridgeblade addresses the issues associated with traditional micro-wind generation technologies.
The unique design means it can reliably produce electricity in low or variable wind conditions whilst creating very little visual impact.