Wind turbines

[Gill Catton]

Originally Posted by Tormentil

Each wind turbine requires roughly 0.1 square kilometres of unobstructed land, as far as I can ascertain.

The ones I've seen have proper tarmacaddamed service access "roads" to each turbine. Presumabley all the power lines from each turbine are placed under ground to substation that will then connect to the national grid.

The ones I have seen have gravel and recycled compacted hardcore tracks and yes I think you're right about the power lines but I think these run under the tracks.

[John D]

Originally Posted by Coley

I mean each as an individual unit. If you calculated the combined areas they don't take up as much space as a power station, car parks for the workers and the new road for the workers to get to the station. Well at least that is what my Environmental Science tutor told me when I was doing my A level on the subject.

I think you should have a look for yourself at a wind turbine site and compare it with that of a 'conventional station' site. There are several wind turbine sites near where I am and each covers a site much larger than a conventional station based on Mw output per metre squared.
In my previous posting based on 71 wind turbines generating a maximum 213mw is less than a tenth of a conventional coal fired station such as Longannet (output 2304Mw) which is on a smaller site.
Access to wind turbine sites are also very extensive in comparison as each turbine requires access over and above the main site access. Many accesses being through land that is full of wild life or green belt with scenic beauty.
The best site for land based wind turbines are unfortunately in higher remoter parts out in the country
John D

[John D]

Originally Posted by Gill Catton

The ones I have seen have gravel and recycled compacted hardcore tracks and yes I think you're right about the power lines but I think these run under the tracks.

It is not practical, efficient or economic to transmit large electrical loads underground. Large electrical loads are transmitted at 'high voltage' on overhead transmission systems.
John D

[Tormentil]

Originally Posted by John D

It is not practical, efficient or economic to transmit large electrical loads underground. Large electrical loads are transmitted at 'high voltage' on overhead transmission systems.
John D

But you don't see many "overhead wires" on a wind farm !!

[JennyS]

It is not practical, efficient or economic to transmit large electrical loads underground. Large electrical loads are transmitted at 'high voltage' on overhead transmission systems.

I've a feeling (though I could be wrong) thats there is an EU Directive due to come into force in the next few years compelling power companies etc to put the high voltage lines underground rather than overground. At least they are much better insulated when underground, don't require creosoted poles that need replacement/repair, and remove the eyesore of power lines.

[kshotton45]

High voltage electricity can be routed underground with modern insulators. I think that the main drawback is the cost - it's about 10-15 times more expensive than overhead wires. About 5% of power is distributed this way at the moment in the UK.

Keith.

[John D]

Originally Posted by Tormentil

But you don't see many "overhead wires" on a wind farm !!

Underground cables can be used for transmission from individual turbines but for the final on connection of the windturbine farm to the Grid, when generated output is in MWs. then overhead Lines will be used. In smaller installations where total output is in KWs or say less than 20MWs underground cables may be used.
John D

[John D]

Originally Posted by kshotton45

High voltage electricity can be routed underground with modern insulators. I think that the main drawback is the cost - it's about 10-15 times more expensive than overhead wires. About 5% of power is distributed this way at the moment in the UK.

Keith.

Yes I agree. High voltage can be transmitted by means of underground cables but with limitations. Limitations include transmission voltage,load, terrain and as you say cost.
Much more efficient to transmit by overhead since conductors can be much smaller, no conductor insulation required (the surrounding air space acts as the insulater between conductors), more easily installed, more easily maintained thus overall less costly by far. If it were possible to underground it would be done. There is no doubt pylons and overhead lines are an eyesore!
John D

[John D]

Originally Posted by JennyS

I've a feeling (though I could be wrong) thats there is an EU Directive due to come into force in the next few years compelling power companies etc to put the high voltage lines underground rather than overground. At least they are much better insulated when underground, don't require creosoted poles that need replacement/repair, and remove the eyesore of power lines.

Creosoted poles are only used when transmission is around 33KV or less. Transmission from larger wind farms is normally at higher voltages. The grid (ie what you see on steel pylons) is 132Kv to 400Kv. It is by way of the grid that ultimately most power that is generated is transmitted.
One of the problems that was causing delay in the go ahead of the proposed wind farms in the Western Isles was the route the HV Transmission lines would take as the made their way South to Central Scotland.
Can you imagine UNDERGROUNDING all that way????????????????. A mind boggling thought even if it was technically possible.
Better insulated from what?

John D

[Jez]

I remember many moons ago on Tomorrows World around 1995/6 they showed a concept of putting mass turbines up into the sky & anchored to terrafirma. They were going to be so high up it possibly couldn't seen by the naked eye? And be superbly effiecent. What ever happened to that idea? Sounded genius to me.