A research company in New Hampshire recently announced the patent of their bladeless wind turbine, which is based on a patent issued to Nikola Tesla in 1913. The Fuller Wind Turbine developed by Solar Aero has only one rotating part, the turbine-driveshaft. The entire assembly is contained inside a housing, so that this turbine offers several advantages versus blade-style (primarily horizontal-axis type) turbines. With a screened inlet and outlet, this turbine does not present a danger to wildlife such as bats and birds. To an outside observer, the only movement visible is the entire turbine housing as it adjusts to track the wind. This also makes it a good candidate for use near military surveillance and radar installations, where moving blades would otherwise cause difficulties.
According to the company, the turbine is expected to deliver power at a cost comparable to coal-fired power plants. Total operating costs over the lifetime of the unit are expected to be about $0.12/kWh. The turbine also should have fewer maintenance requirements, leading to lower lifetime operating costs. The turbine itself can also be supported on magnetic bearings, and all of the generating equipment kept at ground level, which will also make maintenance easier. The company estimates "final costs will be about $1.50/watt rated output, or roughly 2/3 the cost of comparable bladed units."
The Tesla turbine operates using the viscous flow of a fluid to move the turbine and thereby produce energy. The Tesla turbine "consists of a set of smooth disks, with nozzles applying a moving gas to the edge of the disk. The gases drag on the disk by means of viscosity and the adhesion of the surface layer of the gas. As the gas slows and adds energy to the disks, it spirals in to the center exhaust. Since the rotor has no projections, it is very sturdy." Disks in the turbine need to be closely spaced in order to capture the viscous flow,. In order to be effective, the Tesla turbine also needs to have extremely thin disks to minimize turbulence at the edges. Tesla was not able to find metals of sufficient quality to make this work effectively, but apparently, nearly a century later, those limitations have been overcome.
Solar Aero's current example is an unassuming trailer-mounted unit, but a unit the size of the one pictured (see website) "should be capable of 10kW output with no problem," according to the inventor. The number of disks determines the amount of power that can be produced. It will be interesting to see if this technology takes off, and if the technology is something that can be scaled up to provide utility level power production, or if it is only a niche system. In any case, it is interesting to see alternatives to bladed wind turbines.
Link: Solar Aero