REVOLT opposing unnecessary, excessive and intrusive powerline development

opposing unnecessary, excessive and intrusive powerline development

REVOLT Newsletter 246

Revolt news 4/1/2008

1.  This year will see the first windfarm proposals for Hambleton District coming through. Not a natural target for wind power, Hambleton has political targets imposed through the new regional political system. While Hambleton’s targets are disproportionately high, similar processes will be emerging across the country.

2.  As announced in the press on 20 December 2007, under cover of the holiday period as many such announcements seem to be timed, a new windfarm proposal for Seamer will be the subject of consultation in 2008 with a view to lodging a planning application in the summer. The developers’ website is http://www.seamerwindfarm.co.uk 

3. The developers of Seamer Windfarm have kindly agreed to meet me to discuss details. In my view it is better to engage the affected public fully and early, to seek a genuine mutual understanding. That may help a developer to decide between projects, although the prospect for significant change to proposals may be very limited.

4.  I am asking Hambleton for a list of all approaches by windfarm developers, whether for exploratory discussions, for anemometer masts or for windfarm proposals. Citizens concerned for local environmental impact, perhaps suspicious of windfarm policy and its likely significance or not for climate change, may like to make similar enquiries in other areas.

5.  In the last ten years a “new” damaging impact of power lines has been identified and researched. That is AC induced corrosion, particularly of underground pipelines (APPENDIX A). A concerned resident near Swansea writes to ask would anyone in REVOLT know of cases where powerlines have actually caused corrosion on metallic objects above ground such as fences in close proximity for a prolonged period of time – please let me know of any such cases.

6.  Meath Pylon Pressure held a mass rally at Bective Abbey on Sunday 30 December. A photo of a human circle around “NO PYLONS HERE” spread across the field can be seen at their web site

http://www.pylonpressure.ie 

7.  Following news245.3 on the new Dutch pylon design, we have confirmation from the designers that it does indeed use passive-loop conductors and shorter insulated cross-arms. These are designed to cope with normal weather in the Netherlands comparably with standard designs. The design reduces the distant EMFs but not necessarily those close to the line. That may suit the Netherlands if their lines don’t pass over houses. In the UK, we would need to remove those cases over homes first.

8.  One version of the Dutch design is pasted at APPENDIX B. Revolt would be pleased to hear of readers’ reactions. Please let me know if you have difficulty receiving this picture.

9.  The Welbury Christmas Lecture mentioned in last email news was attended by about 30 people in the village hall on 29th December. I am compiling some notes which will be available by email on request.

*****

APPENDIX A   AC induced corrosion.

AC induced corrosion:  Notes 30-12-07

1. Extracts from Roger Ellis, Shell UK, pdf report 2001:

www.ukopa.co.uk/publications/pdf/020034.pdf 

AC induced corrosion is a significant threat to integrity of buried pipelines, due to its very high localized corrosion rate. It can and has resulted in metal loss of more than 1 mm per year.

Whilst the mechanism of ac corrosion is not fully understood the mitigation measures are. The pipeline needs to be earthed using a system compatible with the cathodic protection system such that the ac current densities are reduced below 20 A/m2. The risk of ac corrosion occurring should be reduced to a tolerable level.

Mitigation Measures have been implemented by the installation of earthing systems. This earthing comprises 150m length of zinc ribbon installed parallel to the pipe 2.5m from the pipe centre line.

Conclusions.

AC induced corrosion is a potentially serious phenomena and could lead to failure of a buried pipeline.

AC corrosion can however be predicted and the following are considered to be the main ingredients.

A source of induced AC

A coating of high dielectric strength

A soil of low resistivity or good earth.

Small coating defects.

A high current density.

Monitoring an data logging of induced AC and current densities running to earth should form an integral part of pipeline integrity management

Mitigation in areas of high susceptibility can be achieved by installation of a preferential earthing system.

2.  Extracts from the Journal of Corrosion Science and Engineering 2004:

www.jcse.org/Volume4/Preprints/V4Preprint16.pdf 

In this paper, the alternating current corrosion cases since 1986 have been reviewed by summarizing the general characteristics of the alternating current corrosion shown in the surveyed literature.

The first corrosion failure on a pipeline that was attributed to the alternating current corrosion was in 1986. And since then, substantial research and development on the alternating current corrosion have been carried out.

[Several examples from different countries of pipeline failure attributed to AC corrosion within from 1 to 6 years of installation are described, along with other examples much later (e.g. over 20 years) in the pipeline’s life.]

There is no standard measure against the AC corrosion so far. The only possible way is keeping the induced AC voltage under the limit, which can’t cause the AC current density of 20[A/m2] or more.

*****

 

APPENDIX B   One example of new Dutch low-EMF pylon design


(artist’s impression)

 

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