Wind power is often used as an example of how we are becoming a greener society. If you travel along the highways of Pennsylvania all the way to Oregon, you’ll pass some of the largest wind farms in America. Acres of these mammoth turbines pay homage to our changing value system. While these large scale turbines have proved their worth, smaller residential systems still haven’t.
Why Residential Rooftop Wind Turbines Aren’t On Every Roof
To understand why you don’t see turbines on every roof, it’s important to understand how they work. Turbine blades are placed in a circular orientation around a central hub. The wind pushes these blades in succession, rotating the central hub and the shaft it is connected to. This shaft is surrounded by a ring of coiled wire and two magnets. When the shaft rotates, the magnets push electrons down the length of the wire generating an electrical current.
Wind turbines need to be pushed by a consistent wind of 10 mph or greater to start producing an electrical current. Wind at roof top levels is rarely this high for any extended period of time. Winds don’t start reaching a consistent energy producing level until they are about 30 feet higher than the highest tree or roof top in the area and at least 300 feet away from any obstructions. This would necessitate a pole mounted turbine on at least an acre of land.
Even if you are the 1 in 10,000 existing homes that does fall into an area where you receive winds of the needed level, a roof mounted turbine will give you a maximum of about 100 Kilowatt hours of electricity every month (10% of the average home bill). With a life expectancy of about 20 years and a huge initial
purchase cost, a residential wind turbine, although a green choice, isn’t a very good economical one.
What Will It Take to Get Them There?
Before roof mounted residential turbines are viable, a radical new design will need to be developed. The current bladed models are simply not efficient enough to produce a meaningful amount of electricity from a roof mounted position. Bladeless designs based on one of Nikola Tesla’s mock ups or the Saphon Zero Blade (seen in the video below), are not only more than twice as efficient than the traditional models but much cheaper to produce as well.
If newer designs can start to harness wind energy at wind speeds in the range of 5 to 7 mph it will open up a much larger portion of the country to rooftop wind turbines. Hopefully, they will also eliminate one of the major concerns with turbines – noise.
The unfortunate truth is that you are better served by putting your money into a rooftop solar array instead of a turbine system. Solar arrays are cheaper, more efficient and able to harness energy more of the time than wind turbines.
What do you think? Is there a future in rooftop wind turbines and their technology, or will large windfarms be our only option for harnessing the wind?