From Machine Design: New Device for Extracting Energy from Wind
Here’s a renewable energy idea that frequent commenter Tim Kingston sent me. It doesn’t seem reasonable, but I thought I’d ask the physicists out there to comment. It’s a device that emits tiny droplets of water from electrical conductors (copper pipes with thousands of tiny holes?) that are placed in the wind. The droplets pick up electrical charge, and, when they’re blown away, cause the conductor to take on the opposite charge.
There is nothing theoretically impossible about this, and I love the concept that it doesn’t have moving parts that wear out. But the electrical field that is created (and thus the electrical energy that can be derived from it) comes from the kinetic energy of the wind. You’re not going to get more energy out of this than the theoretical maximum (as prescribed by Betz’ Law) regardless of what device you insert into the path of the wind. Am I not right? And how much of that total energy can be converted into blowing droplets off their pipes? I would think it would be a minute fraction. What am I missing?
Whether it would I don’t know, but I do have doubts.
The maximum power generated could not be more than a wind turbine of the same area which has an efficiency of 100% which, of course, they do not have. In all likelihood, the system described would have a lower efficiency and, in addition, would require water for its operation.
Testing the concept should be easy. The device would be easy to make. Just make a very small one and test it with an electric fan. If it delivered significant power, then means could be devised to test its efficiency.
If you were already using evaporation for cooling in a dry climate, perhaps the electricity generation might be useful if you were in an off-grid situation, perhaps. But even in this case I can’t see it being cost effective.
Possibly a reworking of the concept might be possible involving a coil of electromagnets in a tidal current – generating electricity by induction as sea water flows through the coil
That would work, although it’s doubtful that enough power could be generated to justify the investment.
Instead of electromagnets, it would be better to use permanent rare earth magnets and pick up the current from the sea water with electrodes as it flows through the magnetic field.
Something similar was tried with plasmas created by burning a fossil fuel. The problem which they never overcame was rapid corrosion of the electrodes.