Would the ionic wind power fence actually work?

Question

Described here and in the references (patent, patent), the idea is to use a large fence as a grid electrode. Spray water droplets near a high voltage to charge them, and then the wind blows them away, converting wind pressure into electric potential?, then they hit another electrode or the Earth to complete the circuit.

The scientific basis for this is shown in FIG. 9 which shows charged particles 16, 16' removed toward infinity from a single isolated conducting sphere 17 of radius r₀ According to the principles of electrical physics, work W=QV is done in removing the charges to infinity.

Would such a device actually work? If so, why isn't it built or used? Can the energy output be estimated and compared to a traditional wind turbine?

Some simple calculations:

According to the patent, the pylons to support the fence in the image are 1 km apart and 150 m high, and a 100,000 m² section of this size would produce 45 MW. This would be 450 W/m². The largest turbine in the world is the German RePower turbine producing 5 MW while sweeping an area of 12,000 m² = 401 W/m², so not much of an improvement?

Answer 1

I am extremely skeptical of this design, and I don't think that there is any chance that the practical problems can be surmounted. If a generator like this can work, it will probably only be a novelty device, like the Kelvin thuderstorm, and it will only work in very unlikely conditions (like already highly ionized air). The Kelvin machine only works because water is a conductor, while air is an insulator.

ionization can't work

There is a huge gap between the ionization energy of a molecule and its kinetic energy, even in the strongest wind. The ionization energy is measured in eV per molecule, while the kinetic energy in an insanely strong wind of 300m/s is .04 eV. This means that you need to extract the ionization energy you use to make the ions when the molecules de-ionize with an impossible efficiency of 96% to have any hope of getting any energy out. This is certainly practically impossible.

Charging small spheres is difficult.

The problem with using wind to move spheres (like droplets) up a potential well is not that the droplets have to be charged up and discharged--- this can be done relatively cheaply. The problem is that air is an insulator, so the droplets have to transfer their charge by contact. The Kelvin thunderstorm works only because water has enough ions to be a conductor.

In order to get the wind to push the droplets, they must be actively sprayed into the wind. You won't be able to charge them up efficiently by just applying a potential, because they would have to touch the wire to charge up, then blow off with the wind. But the mesh will disrupt the wind, most of the wind will not want to go through a mesh barrier. So you have to charge and spray, the spraying will cost energy.

If you charge up water, then spray it into a region with a field, then let the wind blow it towards higher potential, you still need to gather up the charge at the higher potential region in an efficient way. This has to be a physical contact mechanism too, like a wire mesh, but you might be able to get away with letting the droplets fall by gravity onto a plate. Behind the mesh, you need to make an electric field using a gigantic fine charged wire-mesh which doesn't disrupt the wind.

The issues in this are all of scale: this thing has to be enormous! You need a big wire mesh to set up the electric field so that it is approximately opposite the wind, you need a sprayer to throw droplets in the air, and you need a big plate to gather up the droplets. The bigger the droplets, the more effective the system, because you don't have self-capacitance costs, so you are best off using one giant droplet.

But one giant droplet might as well be a traditional turbine, because you are back in the moving-parts bird-killing regime.