A company in New Hampshire called Solar Aero Research has patented an improvement on an idea first devised by Nikola Tesla in 1913. A Tesla turbine has a stack of parallel disks connected to a central shaft with airfoil-shaped spacers arranged around the edge. Air enters the turbine at the edge of the disks and flows over the airfoil shaped peripheral spacers, turning the shaft. The lift produced boosts the turbine efficiency.
As a result of air flowing over these airfoil shaped peripheral spacers, the turbine generates more mechanical power, for a given flow of air, than would be produced by a prior-art turbine.
The peripheral spacers are aligned in columns of such peripheral spacers extending through the entire turbine. But it is also possible to arrange the peripheral spacers in other patterns, or randomly, without any particular alignment.
Solar Aero’s completely enclosed model avoids drawbacks of bladed turbines such as noise, radar interference, visual pollution and wildlife injuries — while retaining high efficiency ratings. The unit's driveshaft is the only one rotating component so there are no heavily loaded bearings. The company claims the turbine can deliver power at a cost comparable to coal-fired power plants.
A point in the design's favor is that all generation equipment can reside at ground level while the turbine sits on magnetic bearings, thus eliminating the need to climb 20-story towers for routine maintenance. Yaw bearings will be permanently lubricated, the company says.
The turbine is efficient over a wider range of fluid flow rates than conventional turbines because of the airfoil-shaped spacers. This feature makes the turbine especially useful for generating power from wind, as well as from from relatively low-temperature geothermal sources.
You can view the Solar Aero patent here:
http://www.freepatentsonline.com/7695242.html
The company Web site is here: