Wind Turbines on Power Lines?

Another cool wind power idea. Very similar to the French idea of putting wind turbines in broken-down or ailing electrical towers.



The design concept comes from Nils Uellendahl, working at the Victoria University of Wellington, New Zealand, and calls for a series of helical (spiral) wind turbines mounted on power lines which generate energy through electromagnetic induction and transmit it directly into the grid while simultaneously reversing the inevitable energy losses (estimated at 7 percent) which affect long-distance transmission lines.

Link: http://www.energyboom.com/wind/wind-turbines-power-lines

Dual purpose of a necessary structure.

Great idea.

great idea!

to power lines that are already under a considerable amount of stress.

Barrel turbines on poles might be an alternative.

When I saw this I thought "brilliant"! Dana : )

Just because a structure exists doesn't mean it is a good idea to attach a turbine to it. Saving money on a tower doesn't justify spending money on generators that don't perform. Unless these type plans can get the center of the rotor up to about 200 feet high in an area with GOOD WINDS then it is an interesting idea but a waste of money and effort.

There are three basic problems, all having to do with the power contained in wind. What most people don't realize is that small increases in wind speed result in non-linear increases in power. If you double wind speed, the power doesn't double, it increases 8X. Besides the geographic setting ruling out probably 90% of the locations because of basic lack of suitable wind, there is the fact that the altitude where winds are located in GOOD areas is up around 200 feet. I'm not an expert on power lines, but I doubt if most lines are above 60 feet. This means they are in close enough proximity to the ground that it acts to induce a drag on the available wind.

Finally you have another vital factor related to the physics of harnessing the power in the wind - the swept area of the rotors. You can only extract energy from the wind your rotor touches.

Say each of the turbines on the wire is 3 feet in diameter. The area would be 3.14(1.5^2) about 7 square feet. Compare that to a *small* commercial turbine with a diameter of 90 feet (large ones are about 350ft and ones in testing are about 500 feet dia.).

I selected the 90 foot one because it would be on a tower of similar height to the electric wires on a transmission (not distribution) line. 3.14(45x45) is about 6,358 ft^2. That means you'd have to string up 908 of these small turbines to equal the productive power of one SMALL regular turbine. It also means you have to build, weatherproof, install and maintain 908 separate units.

In the end, it will be a cost benefit calculation. If the devices can be produced, installed and serviced for a price that is low enough to compensate for extremely low productivity, then the technology will proceed. I personally don't think that C/B equation will work out, but we won't know for sure until there is a lot more data on price and productivity.

A high voltage transmission line is an engineered system. The stringing tension in the line is based on the weight of the cables alone - add the weight of the turbines and the sag will likely be too great and the line will be too close to the ground. To fix that, new and stronger cables would be needed. The cables need a certain minimum separation from each other. Unless the the turbines are perfectly insulated (a trick in itself on a high voltage line), you may wind up with phase to phase faults, particulary on windy days when the cables will be swaying. I'll spare you a discussion about overturning moments, but the towers are not designed for the extra forces that the turbines would place on them and would likely need to be replaced.

In my opinion, such a system would need to be built from scratch. Retrofitting an existing line would be prohibitively expensive.

(Turns out that I'd misread the OP ... :blush: )