Turbines on Pylons?

Rather disappointingly this is the reply I got from National Grid:

This is a question we often get asked and I'm afraid it is not practical on a number of engineering and safety fronts, not least that pylons are not designed to bear the stresses from having a wind turbine installed.

Regards

Stewart

Stewart Larque

UK Media Relations Manager

Corporate Affairs

National Grid

Hi - been thinking about this a bit lately too. Some of the issues raised, are non issues such as:

1. Blades interfering with cables. There are vertical axis turbines, which would not cause a problem.

2. Accessing the grid. Turbines could only be placed within a reasonable distance to a town or village - therefore enabling any variable low voltage to be dropped into the local distribution networks grid supply points.

I really think this idea is viable - and would love to see some further investigation.

Retrofitting turbines onto pylons in my view would be a structural nightmare. However, a big cost of wind farm construction is the infrastructure that's required to connect to the National Grid; pylon locations, especially in remote locations like Scotland, might provide solutions and also help to resolve some of the strategic, environmental and rural community issues:

1. Turbines can be built alongside pylons thus reducing National grid connection costs.

2. Maintenance of pylons and turbines can be managed together, thus reducing costs further.

3. The visual impact will be minimal in that pylons are already a blot on the landscape, majestic turbines migh even improve the view.

4. I don't know if the National Grid pay ground rent to the landowners for pylons, but rural turbine contractors typically pay farmers around £20,000 a year per turbine. This commercial reality drives costs up and the at the end of the day, end-users and the environment pick up the tab... this is a complex issue, but if farmers and other land owners, etc., only got paid a nominal amount, which I think is the case for Pylons, the whole dynamic would change.

Your idea sounds obvious and sensible. I too have wondered about this. I can imagine that the principle objections would be:

1. Safety: turbines have to turn with the wind so the turbine tower would have to be considerably higher than the top of the pylon to avoid blade strikes of high voltage lines. Worse, the extra loading that this imparts to the pylon, and the inevitable vibrations from the turbine motion, means that the pylon itself could collapse since pylons are designed solely to carry static transmission lines. And it a turbine failed - fell apart in a gale, say - then imagine the damage which could be done!

2. Transmission lines commonly operate at anything up to half a million volts. This would make transforming the tiny input from a single turbine (per pylon) - say, 20 kilovolts - prohibitively expensive. As Nick Burch says, the only way the turbine output could realistically be used would be as part of an entirely separate low voltage local network since many generate at between 240 and 400 volts.

So I have to conclude that the idea sounds great and obvious but is hopelessly impractical. Any other views out there from electrical engineers?

I received this interesting response from Nck Burch:

I’d guess the main problem would be the transformers and the links. Pylons normally carry very high voltage current, and the grid tends to be very careful about voltage + phase etc to ensure minimal energy loss. I’m not sure that it’d be very easy to drop the variable (but low voltage) power of a wind turbine in.

You might have more luck installing wind turbines on pylons when they go near to existing energy users. In that case, you’d be using the pylon to hold the turbine, but just feeding the (variable, low v) enery into the local 415/240V grid, rather than the kV grid the pylon’s actually carrying.