ROOF-CAPTURE · Innovative Design for Wind Energy Capture in Urban Environments

We propose a new approach for urban wind power to help the EU to meet renewable energy targets and make micro–generation acceptable in environmentally sensitive areas. Typically, the wind around buildings is too turbulent and slow to be of much use. Normal turbines need to be placed high above them which is expensive and attracts planning objections. If buildings could be used to augment turbine airspeeds, it’s estimated that the potential for energy capture in the built environment could exceed 10 TWh, creating CO2 savings of approximately 4 Megatonnes by 2020. We will develop a retro-fittable roof-mounted module that will be almost invisible from street level. It will accentuate the low pressure zone over a flat roof parapet and link it to high-pressure static air beneath using a tapered duct. The air speed in such a duct has been shown to exceed the free wind by more than 30%. Power increases with the square of air velocity, so a turbine in this region will generate more than double the power of a conventional turbine, and as a ducted fan it will cause significantly less noise and vibration. Further, we will use passively-warmed air injection to create a vortex in the duct, raising generator output by another 40%. The vortex can heat or chill air directly which, coupled to powered passive ventilation, might augment a building’s air conditioning and offset power consumption, cutting payback time still further. The potential EU market for building integrated wind turbines is €345m and we believe that we can capture a high proportion (20%) of it. Conventional wind turbines typically have payback periods of 15-30 years (depending on location) and our system has the potential to reduce this to 5 years. Regardless of the level of augmentation, this approach will significantly improve urban wind power viability and make wind power possible in wind-rich but planning-sensitive areas such as seaside towns and national park hillsides for the first time.