Wind turbines often don’t work well on top of buildings. With all the other structures in the way in urban areas, the wind speeds aren’t fast enough, and the blades fail to turn. You sometimes get the feeling the developer put the thing there not to generate power, but to make some kind of environmental statement.
The WindRail is different because it was designed specifically for buildings and takes advantage of its air flows. Developed in Zurich, it’s a combination wind turbine and solar system that sits between a building’s facade and the roof edge. It could be a way of generating power on buildings that aren’t suitable for conventional solar panels or turbines, which is plenty of them.
“When wind flows around the building, it creates a pressure difference between the facade and the rooftop. The facade has a higher wind pressure,” explains Sven Koehler, CEO of Anerdgy, the company behind the Windrail. “Because we are channeling the wind and making a connection between the high and low pressure areas, the speeds are faster and we have more energy.” Koehler says the pressure effect accounts for 50% of the power the WindRail generates.
The device comes in two meter modules and can generate 1,500 to 2,000 kilowatt hours (kWh) a year. A whole rooftop could therefore generate enough power for all a building’s needs in some cases. The average U.S. home uses 10,837 kWh a year.
Koehler, who worked at energy solutions giant Alstom before starting Anerdgy, argues the system offers flexibility depending on the weather conditions and time of day. In sunny, clear weather the PV-back to the WindRail generates electricity like any solar panels. At night and in poor weather, the wind part takes over.
The WindRail also doesn’t need a wide area, like solar panels, and can be integrated to most construction. “Often there’s a shadowing and there are chimneys and other obstructions. This is on the corner edge where there’s nothing else,” he says.
Last year, Anerdgy successfully tested a prototype on top of some grain silos outside Zurich. It will make its first real installation this year, starting with a furniture warehouse. Koehler thinks airports and office buildings could be particularly suitable. The cost is $3,000-$4,000 for the two meter module.
“We are comparable with solar power in costs, but the functionality is better. You can also use our tool as a design element,” he says.