Why Aren't Powergrids Underground? 556
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?
DC (Score:5, Interesting)
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. (Score:5, Interesting)
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... (Score:4, Interesting)
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:It costs money? (Score:2, Interesting)
What about in the long term, though? Rather than putting a powerline underground, put in a conduit. Workers can work down there without the need for expensive cherry pickers, having to haul equipment up to polls, without affecting traffic. Work would probably be easier and more efficient. Need to run fiber optic/cable/whatever? No problem - the conduit is already there. Much cheaper. What about losses from power outages? What about gains from beautification? There are all kinds of benefits and a lot of them result in changed costs. So, like I said, I'd like to see some figures as to weather it would really be more expensive.
Two words: Fire Ants (Score:3, Interesting)
Re:Water (Score:5, Interesting)
Here's a link to the article summary, [chireader.com] though you'd have to pay $2 to actually read it.
Just an Electrical Contractors point of view... (Score:3, Interesting)
DIffers (Score:4, Interesting)
Here in Japan, on the other hand, it's all above ground. In part because of the relative lack of zoning laws (Japanese city architecture is delightfully, ah, surprising as a result), but according to people here it's mosty because of the prevalence of earthquakes, the one thing buried cables are not protected against. Sure, overhead cables will break too, but it'll be easier to fix.
I can understand the situation here in Japan, but really, it's a pretty hideous sight. So your power may end up getting slightly more expensive as a result (though this is dwarfed by other factors), but it's worth it. If saving money is all there is about city living, why not allow people to dump their trash in the street as well?
Re:what about liability? (Score:2, Interesting)
Nowadays, most telecoms cables are buried, which puts them witin reach of problems you'd probably not consider likely.
Termites, we discovered, will eat lead sheathing and just about anything else. So will rats. In fact rats will gnaw at anything. Then there are chemicals in the ground. Water is an issue. All our cables were pressurised with air to keep the water out. In short, you can't just bury cables and ignore them.
Re:It costs money? (Score:1, Interesting)
I'd love to see the look on the workers' faces when told they have to tunnel through miles of this to put in a conduit for utilities. I'm not sure if providing cost numbers is even needed.
Here's the answer straight from the guys who know. (Score:1, Interesting)
His point was this -- when an overhead line has issues, they average a 30 minute recovery time. When an underground line is out, it can take days for them to dig it up and figure out where the problem is. Especially since they are in the midwester US where the ground is frozen for months at a time, it is simply impractical for them to do that much digging.
I asked why it wasn't possible to use some technology to have the system report exactly what lines are non-function (surely there is some easy way to do this?). His answer was that there is some of that, but not to the level of precision needed to avoid digging.
Apparently the cost to dig vs. string overhead is negligible.
Re:Introducing other dangers (Score:5, Interesting)
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.
Buried Cable is Trouble (Score:1, Interesting)
When an outage occurred at home, it took at two days for cables to be unburied, repaired, and reburied. Road traffic was disrupted, Lawns torn up. And NO POWER!
At work we found the cable was not where it was supposed to be. Mislabeled drawings over 20 years old.
Farms had overhead cables were repaired in hours!
In flood areas, buried power cables will float to the survace.
Re:what about liability? (Score:3, Interesting)
Power Sink (Score:3, Interesting)
If New Orleans didn't learn to do it different before Katrina, why should we learn to do it different after Katrina?
Re:I can tell you why Nashville has overhead lines (Score:2, Interesting)
Re:DC (Score:4, Interesting)
That's insane! The law is clear: if you called (and hand dig in the indicated areas,) the utilities are responsible for the damage and repairs. But if you didn't call and you cause damage by digging, the repair bill is 100% yours.
I've had them out to mark my lot three times in the last three years for various projects and home improvements. The service is completely free, and they guarantee all utilities will be marked within 48 hours. I can't imagine the amount of stupidity required to assume the risks of both injury and liability just because someone is too lazy to dial an f'ing telephone number.
Re:It costs money? (Score:4, Interesting)
http://205.243.100.155/frames/longarc.htm#500_kV_S witch [205.243.100.155]
High Tension underground in Sydney, too (Score:2, Interesting)
Re:It costs money? (Score:5, Interesting)
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...
Re:It costs money? (Score:3, Interesting)
Costco gets hassled for paying their employees more than the industry avg, giving them benefits packages above the industry avg and for not charging consumers more on the goods they sell.
Wal*Mart, is quite possibly going to run its suppliers out of existence because of the razor thin profit margins it allows them. Wal Mart also happens to save massive amounts of cash (which go directly to the bottom line) by not providing any meaningful benefits to their employees.
It's not just upkeep... (Score:3, Interesting)
Underground wires will require insulated wire to replace much of the uninsulated wire used in overhead lines.
Underground wires will require that thousands of miles of trenches be dug.
Underground lines will require that houses have power inlets underground rather than on the roof, as present.
Underground lines will require that Millions, if not billions, of towers and poles be constructed.
Underground lines will require pole-top transformers be moved to ground level or below.
The costs of converting are staggering, and will take probably at least a decade.
As a resident of the DC suburbs (southern MD to be precise) we aren't having too many power outages due to these recent storms. Mostly flooded roads.
Re:Simple physics (Score:2, Interesting)
Where I live we have a 60MW/90KV DC transmission cable that runs over 30 miles under the sea to France. That is one way of sorting the inductance problem. I couldn't say how this compares with the cost of overhead transmission, but the total cost of the link was about £30million. (But that would include switching equipment at both ends, and the fact that the cable has been laid underwater and in a much more hostile environment than would be the case on land.
see http://www.electricity.gg/about/companyhistory/th
I believe there is a similar 2000MW link between the UK and France acorss the English Channel.
And if you think backhoe fade is a problem, just think what a trawling fishing boat could do to your power cable.
Time to string them back up. (Score:2, Interesting)
Put fiber optics underground, and no matter how well you try, someone is going to hit them. Whether by contractor laziness/mistake, or due to utility locates being off by more than 20 feet, it's going to happen. Also, you have the problem of lazy install contractors who will find the softest dirt, and bury fiber optics right smack dab on top of existing utilities. And repairing overhead is more cost efficient than repairing underground utilities. I work in this field, so I know what I'm talking about.
In my opinion, string that garbage up in the air where it can be seen, and make a "treefall" zone around any above ground utility (nothing shall remain standing that can at any time fall and interupt service. There are plenty of trees, and what would be cut can be replaced).
Why do we use fiber optics anyway when there's wireless? The only thing that should be in the ground are gas, storm drains, and water and sewer lines.
This experiment in burying wires has gone on long enough, time for it to end.
Re: shared costs (Score:3, Interesting)
That might suggest that a single US utility consumer might be paying for a bit more infrastructure.
It is not the full 9x factor that the numbers imply since you can localize your sources, but it is a SIGNIFICANTLY larger distance that must be covered to convey the same service.
This is true of highways.
I find it absolutely amazing that our prices are even in the same ball park as those of Europe on goods and services that are impacted by population density. In most cases in the US it is cheaper even if you do not take government subsidies into consideration.
Ok, train travel is MUCH cheaper in Europe, but electricity, water, septic, garbage, postal, trucking, auto and air are all cheaper in the US.
Re:It costs money? (Score:3, Interesting)
Re:It costs money? (Score:2, Interesting)
The utilities probably used the fiber for their scada systems but I hope they do more than that with it now.
Re:It costs money? (Score:4, Interesting)
Even if you add up the costs over, say, twenty years and find you've spent more under the above ground scenario, it may still cost more if you include "opportunity costs". Suppose I could spent $25M to put in an above ground transmission system in an area, and pay out $25M over twenty years, vs. spending $50M for underground and for sake of argument 0 for maintenance of the same period. It's not a wash, because in the second scenario you have $25M in your pocket you can invest; in the first scenario you miss out on the interest.
There's an even simpler explanation as well. There is no market for power distribution. If you are dissatisfied by the reliability of your electrical grid, you cannot switch to a competitor's grid. The owners of the grid will charge you the cost of running the grid plus as much as they can get away with over that. They have no incentive to take their money and, effectively, bury it in the ground to give you another sigma of reliability. All they have to do is get you enough power so they can charge you, and not get nationalized by a furious public. Which might not be a bad thing, if you compare the interstate highway system to the electrical grid.
The most amazing thing about the electrical grid is that it works at all. And indeed most of the time it works well when compared to, say, Iraq. But although it works in routine cases, it does not work in even moderately exceptional cases, such as peak demand for air conditioning. And it certainly does not work to address problems like the California power crisis of several years ago.
Looking forward two to three decades, the electrical grid is probably the single most important piece of infrastucture to improve if the US is to remain a viable economic power. As oil production drops, and world demand rises, prices will rise. The grid is critical in enabling us to respond by bringing more diverse energy sources on line. The roblem is that many of these sources: wind, solar, tidal, geothermal etc. aren't located where the power must be consumed. And others, such as nuclear, are not politically practical to place neir population centers. And you can't build them overnight. Although we can see a trend of increasing oil prices into the future, when it comes it probably won't be smooth upward ratcheting off prices. It will probably come as a series of shocks (if it hasn't started already).
Re: Long-term cost (Score:2, Interesting)
Underground conduit laying robots exist today (Score:3, Interesting)
And another about a robot for laying conduit in sewers. [telephonyonline.com]
And those are just the first two hits on a google search for "underground conduit robot."
You proved another point. (Score:3, Interesting)
Burying cables makes them harder and more expensive to upgrade, so it brings a risk of inadequate capacity planning.
Exactly, so indirectly the parent to your post is in fact correct. If Georgetown did not bury its transmission lines they could've afforded to upgrade them as peak demand increased. Now, these people face the prospect of digging a very large trench and causing a very long, very intrusive disruption to the area where the cable is buried...or they could just build another (overhead) transmission line.
This is TRANSMISSION.... (Score:3, Interesting)
Part of the thing *not* discussed here is that there are huge amounts of the power distro system in DC which *is* underground
That is because the *distribution* systems are not even part of this discussion. Transmission lines present a whole different set of challenges. Firstly, they are longer, second they are MUCH higher voltage--hundreds of kV, and third a transmission line serves a much larger area than distribution lines.
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...
Thus these problems are magnified orders of magnitude for transmission lines. Working with live transmission lines requires very specialised safety equipment--expensive and bulky. With lower voltage distribution lines it is merely cumbersome to open a manhole and crawl into a confined space--with transmission lines the practical constraints as well as the increased danger make it basically impossible to repair or upgrade without digging out a big pit. In any case not much could be done live so they'd have to disconnect the line...and when you suddenly disconnect a transmission line you don't take down city blocks...you yould take out *cities*.
I think there are a few people with experience in transmission that appreciate what is involved in the installation and maintenance of high-tension lines, however I don't think the general public really has a grasp of it--they aren't the same as telephone or the power lines coming into your house. Very high power, high current electricity behaves very strangely sometimes.