Why Aren't Powergrids Underground?

jonging asks: "It is common knowledge that an underground power grid is less susceptible to the effect of a large thunderstorm. The American Transmission Company cites numerous reasons why it (and other power companies I assume) do not bury their transmission lines underground (e.g. environmental concerns, cost of installation and repair, etc.). Exactly how detrimental are underground transmission lines to the environment? Wouldn't the time spent without a power outage generate more than enough revenue to offset initial costs? Aren't the need for repairs in cities with successful underground power grids rare?" The linked article goes into extensive detail about the disadvantages in initial costs of putting in underground lines, but doesn't go into any detail about the maintenance costs of either option. With storms getting worse and worse (Maryland, DC and Northern Virginia have weathered torrential downfalls this week), might underground lines prove more resistant to storm-related power outages?

Comments

DC

[Southpaw018]

Though I'm not addressing TFA directly, let me comment on the DC thing. Yes. We have been utterly hammerered unto oblivion with rain in the last 5 days. But even at that, the power grid in DC is remarkably stable.

My office, which is about 3 blocks from the White House, has never had a major event that would have an effect on our network. In about 10 months of running monitoring 24/7 on our UPS, I've never seen a major "power event" (outage, surge, something else big). I've never seen a big spike or dip. Hell, I've barely seen any variation at all in the signal.
Perhaps it's a function of living in the big city. Perhaps it really is the fact that I'm on the same power grid as the White House. Perhaps it's just a coincidence and some really nice wiring, and me with a little too much tinfoil in my hat. Regardless, I think something is special about the power grids in the DC area.

I can tell you why Nashville has overhead lines.

[justchris]

The workers prefer overhead lines.

It's true that underground lines require less maintenance. A lot less maintenance. If we changed all our lines from overhead to underground, NES would have to layoff 4/5 of their maintenance team. Rather than realizing that it would take years to convert every powerline in Nashville from overhead to underground so they'd have excellent job security until they retired, they have decided not to convert to underground lines. I wouldn't be surprised if this is true in other areas, but I know that's the deal here. So everytime there's a thunderstorm the power goes out, and the cable goes out with it, cause the cable lines follow the powerlines.

Interesting Story...

[chriswaclawik]

I live in Madison, which is near Spring Green, which is where Taliesin is located. For those not in the know, Taliesin was the home/studio of world famous archictect Frank Lloyd Wright. When driving up to his house for a tour, I noticed the highways near it looked a little "bare." Later on, I discovered that Frank Lloyd Wright not only owned the house/studio, but acres and acres of land around it. And he HATED power lines, because the way that they disturbed the natural prarie. And since he was infamous for not caring about budgets and practicality, he paid to have every single power line on his estate buried.

And you know what? I'd say it looked pretty damned nice.

You know what else? I sound like a old rambling grandpa. I remember in my day to get to Taliesin we had to walk 5 miles uphill both ways in the snow...

Re:Water

[CerebusUS]

There was an article in the Chicago Reader a couple of weeks ago about pets (and people) getting electrocuted from lines that were buried 40 or more years ago and were now corroding or fraying. It can actually cause wet concrete to basically act like a large shock plate. Not fun. It's also very hard to detect.

Here's a link to the article summary, though you'd have to pay $2 to actually read it.

Re:Introducing other dangers

[whoppers]

I've been building power plants and other industrial projects for 15 years now. We encase all cabling in ductbanks (conduit & rebar in concrete, usually dyed red) and only a determined idiot will knock these lines out of service.

To address the issue with power loss through induction, yet it happens and it's dangerous. We had a run of pipe being welded up directly under a 100+ kV line leaving a substation. After getting several hundred feet welded up, they started having spot fires in the area. After several calls to the local FD, the FD Chief was getting pissed so they were walking the area down, heard a zzzzzssshhhtt (best I can describe) and sure enough the lines were inducing a current into the pipe (creating a large cap) and once the charge was large enough it arced to the ground, sometimes in a area with dry leaves & pine needles.

Also on another project we had a 12kV line in a ductbank piggybacking a 100pr data cable which fed our T1/T3 lines and we kept blowing the phone companies coils on their end and causing havoc with our digital phone system. Finally one day I was re-wiring the phone system and got zapped. Voltmeter showed 60V, not sure of amerage but it smarted. Idiots who installed the 12kV line didn't bond the shield so we had a current inducted into the 100pr.

So, yes power can be run underground but you better encase it and know what you're doing or hire someone who does.

Re:It costs money?

[caseydk]

Part of the thing *not* discussed here is that there are huge amounts of the power distro system in DC which *is* underground. The problem that they've run into - and I've had conversations with the people maintaining them - is that maintenance is a nightmare.

Getting to the underground lines is a bear and then making any changes is even worse. In most scenarios, they actually wait for the equipment to fail (eg. ignite and/or blow up) before they can do anything because the alternative is that they take down multiple city blocks for hours...