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When loss is more (for transmission towers)

By | August 31, 2011, 5:18 AM PDT

Contrary to popular belief, transmission towers cost more than underground power lines. That’s partially because in the long term, pylons lose more electricity than do buried cables.

So suggests Britain’s Defense Secretary Liam Fox, who is leading his own defense of the countryside in Britain, battling against plans to construct some 400 miles of gargantuan transmission towers in scenic areas of the UK.

The company that would build them, National Grid, has said that burying cables underground costs 12-to-17 times more than stringing them along new pylons.

But Fox claims the opposite, noting that underground cables could in fact cost half of a pylon scheme.

In a letter to Energy and Climate Secretary Chris Huhne leaked to the press, “Dr. Fox cites research suggesting the lifetime cost of pylons could be double that of underground cables over 40 years,” the UK’S Daily Mail reports.

Fox did not elaborate on “lifetime costs”, but Tessa Munt, a Member of Parliament from Wells, England who also opposes pylons, did.

Appearing on a BBC radio call-in show in support of underground lines, she noted, “It’s absolutely clear from the figures that I’ve seen that the whole life costs are actually cheaper. Using underground methods, you can actually save energy. You can save about 5% of the losses that occur on overhead lines.”

Both Munt and Fox are MPs (in Britain’s parliamentary system, MPs serve in the government cabinet) who represent constituencies that are part of a planned 37-mile network of pylons that would connect England’s Hinkley Point nuclear plant on the southwest coast to an industrial port at Avonmouth. Munt and Fox view underground cables as well as subsea cables as viable alternatives.

Among their concerns is that the 150-foot pylons – far taller than the norm in Britain – would ruin scenery and destroy tourism. Munt says the towers would threaten 26,000 tourism-related jobs in her area, Somerset. She and Fox also say maintenance costs would be higher for pylons than for underground lines.

“My principle objection to pylons is they’re an old technology and we should be modernizing what we’re doing,” Munt said. “They’re not the solution for the next century, that’s for sure.” On a separate BBC radio show, she defended underground schemes. “This is the greenest way of doing things, it’s the most cost-effective way of doing things, and actually yes of course will protect the tourism that is absolutely critical in parts of the country that are going to be smashed to pieces by having these ghastly towers.”

The countrywide plans for more pylons coincide with efforts to connect alternative energy sources like wind and nuclear to the grid and shrink Britain’s carbon footprint by reducing its substantial reliance on fossil fuels. They are facing heated opposition in other regions as well.

The pylons have gained support from some quarters, including from groups who believe that they are aesthetically pleasing.

Earlier this year the Royal Institute of British Architects and the Department of Energy and Climate Change launched a competition for creative transmission tower designs.

As the debate rages about how to transmit the new power that many people agree the country needs, one dearly departed physicist is probably turning in his grave. Over a century ago, Nikola Tesla advocated wireless transmission of electricity. While that idea has caught on as a way to power cordless toothbrushes and possibly electric cars, it still seems over the hills and far away from the public grid.

Photo: Toshihiro Oimatsu/Flickr

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Mark Halper

About Mark Halper

Mark Halper is a contributing editor for SmartPlanet.

Mark Halper

Mark Halper

Contributing Editor

Mark Halper has written for TIME, Fortune, Financial Times, the UK's Independent on Sunday, Forbes, New York Times, Wired, Variety and The Guardian. He is based in Bristol, U.K.

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Mark Halper

Mark Halper

Mark has no financial holdings in the companies he writes about. He occasionally travels at the expense of companies or their press relations agencies in order to report on a company or industry event related to it; Mark will prominently disclose this information when appropriate. This relationship will have no influence on his coverage. Companies he covers do not get to review columns in advance, or select or reject topics.

He writes for SmartPlanet and is not an employee of CBS.

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+1 Vote
+ -
Will someone please explain why...
...underground cables would be so much more efficient? The story didn't. Electrons moving through copper really don't care either way.
Posted by JohnMcGrew@...
31st Aug 2011
+1 Vote
+ -
Manpower And Maintenance issues
Cost Efficency - towers though not very often have to be maintained; painted, bolts tightened, and insulators replaced . ice, hurricanes, and trees (less likely on high voltage transmission lines) can bring down above ground power lines.

Flooding, Leeching ground water (fills manholes) and earthquakes are the biggest problems for below ground.

Below Ground needs Less Maintenance.
Posted by d_resz
31st Aug 2011
+2 Votes
+ -
But that's not he argument he's making.
He says "Using underground methods, you can actually save energy. You can save about 5% of the losses that occur on overhead lines.??? I'd like to know why.

And underground lines do require maintenance, albeit of a different nature and frequency. (Having had experience with an underground line literally exploding underneath a former residence) Although overhead lines require more frequent maintenance, underground ones require much more expensive maintenance. I honestly do not know how the costs compare over the long term. But I suspect that if it was competitive, then utilities would already be putting them underground more than they currently do.
Posted by JohnMcGrew@...
31st Aug 2011
+1 Vote
+ -
Well sir, let me tells ya...
It's because an electric current does not move through the conductor but around it. This is why large tansformers and high voltage lines can interfere with radio for example. The losses are less because the earth is a better insulator than the air.
Posted by shaunehunter
31st Aug 2011
+1 Vote
+ -
electrons don't care...
actually, they do. remember that electrons don't stay in the wire and are affected by external EMF and conductors.
Posted by wizoddg
16th Oct 2011
+1 Vote
+ -
Total life costs
If you live in an area that is subject to intense weather (hurricanes, tornados or similar) consider the cost of replacing above-ground equipement, including towers and cables, as often as the weather events pass through. The East Coast of the U.S. is going through that exercise this week. For most areas involved, this is not the first, nor the worst, they have experienced. Underground electricity distribution would have been largely unaffected.

Also remember that AC electricity is subject to the same considerations as radio frequency transmission lines. The effiency is affected by changes in impedance, which can be affected when the air around above-ground transmission lines change in humidity, and temperature to a lesser extent. Undeground the area around the lines remains unchanged, yielding consistent efficiencies. It is applied physics.
Posted by JimWillette
31st Aug 2011
+4 Votes
+ -
Not being discussed.
Both forms of cables lose significant power due to inherent line resistance that they convert to heat. However, under ground cables are not weight restricted in the higher conductive alloys they can use - unlike the highly wt. sensitive aerial lines. So, underground lines have a potentially much higher conductive efficiency and less exposure to physical risks (as pointed out above).

Probably the greatest difference between aerial and underground power transmission though is that with aerial lines the resistance power loss is extremely impractical if not impossible to recover. However, an underground system has the ability to recover some of the lost energy as heat captured by the conduits already required for burying and then to used as heat for public building heating purposes or industrial purposes - all of which offsets the otherwise required fossil fuel usage.

Aerial systems are only attractive because the lower upfront capital costs, but which costs are lost in electrical inefficiency and maintenance cost over their comparative shorter lives. Once again we face the problem of our technically incompetent political leadership only looking at short term solutions - even knowing over the long term they will cost us more.
Posted by dduggerbiocepts
Updated - 31st Aug 2011
+1 Vote
+ -
Thank you. This was the answer I was interested in.
Although since these proposed lines are mostly intended for the boonies in support of wind farms, I doubt it will be practical to recapture heat loss for industrial purposes.
Posted by JohnMcGrew@...
31st Aug 2011
+1 Vote
+ -
Thermal issues
Also the heating in aerial lines can cause them to sag under extreme load conditions and this sometimes causes other problems, such as shorting or total failure. in simple terms current is carried mostly on the surface of the conductors. Since there is no tensile strength issue with buried cable the conductor bundle can be much larger and less current limiting.
Posted by zclayton3
Updated - 31st Aug 2011
+1 Vote
+ -
Incorrect
It's because an electric current does not move through the conductor but around it. This is why large tansformers and high voltage lines can interfere with radio for example. The losses are less because the earth is a better insulator than the air.
Posted by shaunehunter
31st Aug 2011
+1 Vote
+ -
Other than better insulation
The lower cost is obvious since it's less work and uses less resources to dig a hole and throw something in it than suspend it 150 feet in the air.
Posted by shaunehunter
31st Aug 2011
+1 Vote
+ -
â??My principle objection to pylons is theyâ??re an old technology and we shoul
perhaps the worst justification for change ever put forth...for it's own sake.

'old' tech is not necessarily 'poor' tech and 'new' tech isn't necessarily an improvement.

new because it's new is no better (and actually worse) than the argument that "old, reliable, tested," is best.

If you want the 'best' ignore relative age--concentrate upon functional & cost analysis.

For truly 'new' go back to Tesla broadcast w/ NO transmission lines....no lines, no towers, no right-of-ways, no accidental electrocutions, no lines in need of relocation....


To sum up what's wrong with our society: We invented the automatic throttle 40 years before the automatic brake.

With centuries of experience that drinking exacerbates all problems, it's still the single most popular and dangerous social activity. And we let people legislate under the influence....
Posted by wizoddg
16th Oct 2011
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