Why no widespread underground power utilities?

Regarding post 90 in the current Hurricane Ian thread:

I don’t want to hijack that thread with my question so I’ll start this new thread: why aren’t power utilities laid underground? Regarding the above comment, it looks like areas of Florida have spent nearly two decades replacing the power poles with taller, more robust versions of the same in an attempt to protect the lines from the dangers of storms, floods, and similar bad weather. It seems to me that, especially in new construction, it would be easy to avoid the dangers and inconviniece of having the power grid basically up in the sky and instead protect it by putting it underground: lay some sort of reinforced corrosion-proof conduit underground, buried deep enough to avoid the usual wayward shovels and similar dangers (say, 8 feet) and run the power lines through those. Transformers could be placed in some sort of reinforced enclosure on the surface. I don’t know how difficult it would be to retrofit an existing neighborhood with his new power infrastructure but it would probably be one-and-done situation: the next hurricane or tornado or huge blizzard or whatever comes along that usually takes out the power grid would have much less of an impact if indeed it had one at all.

Utility companies around here – western Oregon – have dedicated crews that keep lines clear of trees, brush, and debris. Our neighbor did that for a long time and he was not only always busy but there was always some crisis the crew had to go deal with: a downed tree hitting a line, brush that had grown into the line and suddenly caused a problem, some idiot homeowner who cut a tree down and hit a power pole, and on and on. Disasters like wildfires, something one would not immediately associate with a downed power grid, were a constant problem in the summer. He would travel all over the west coast working with other crews to keep lines clear. I’m sure that’s the case for most of the country. It seems to me that avoiding that would save utilities money in the long run.

What I know about electricity I could write on a postage stamp with a Sharpie so I’m sure there is something I’m missing here.

Primarily cost, it appears. Various web sites I’m finding suggest that running power lines underground is roughly 10x the cost of stringing above-ground lines.

My understanding is that, once buried, they’re obviously less likely to fail, but more expensive to conduct maintenance or repairs when such are actually needed, due to having to dig them back up.

That’s what our local electric company said a few years ago after a huge storm knocked power out for days. The utility spokesperson said the cost of burying lines in rights-of-way the power company already owned would run about one million dollars per mile. Plus there’d have to be new rights of way to pass under streets and around obstacles. Finally, there’s the not-insignifican problem of the telephone and cable companies having to negotiate all new agreements for the underground rights, instead of just hanging their lines off poles.

And that’s the costs in most of the US, not in Florida. In Florida, everything underground is more expensive than it is elsewhere, due to the entire state being pretty much one giant sand bar.

We’ve lived in three different subdivisions in three different areas over the last 30+ years and all of them had buried power lines. I don’t think the cost is anywhere near 10x if the underground wiring is installed along with the rest of the utilities (water, sewer, gas) before the streets are even graded, let alone paved.

That said, we were still dependent on above-ground wiring bringing electricity from the substation to the subdivision. Part of this is because these feeders run along existing roads so would require retrofitting. Burying the higher voltage feeder lines is also more difficult than the lower voltage “last mile” lines.

You also have a problem with dissipating generated heat in high-voltage transmission lines.

Doing the math from kenobi’s link gives four million dollars a mile. Of course, all estimates rest on a pile of assumptions and utility companies will always choose the ones that drive up the totals.

We do this thread after every hurricane and the answers have always been the same: cost, maintenance, inconvenience, and leakage. Mostly cost. Who will pay the trillions of dollars needed for the conversion? Utility companies certainly can’t, their customers will absolutely refuse, and governments don’t have that kind of money and if they did who would vote for it? The damages from Hurricane Ian were $50 billion at last estimate, spread across several states. That’s small change in the greater scheme of things and comes out of many pockets who are all directly affected. That’s the kind of logic America runs on.

Somebody needs to tell Elon Musk to forget his Boring machine for cars and turn that into a boring machine to run electric cable for $400,000 a mile. Money is out there to be made.

But underground electrical lines are just less efficient than overhead lines, due to leakage and capacitance effects. So they waste more electricity in transmission losses. And that’s a continuing loss – it occurs every minute the line is in use.

How many additional power plants would we have to build if all electric transmission line were underground? Even Elon Musk can’t change the physical laws that cause this.

All the new subdivisions I’ve seen bury the local transmission lines. (and cable, and phone). Every dozen houses or so, some lucky homeowner has a green utility box about half the size of a fridge on the lawn by the road. Feed to the houses is also buried. I assume since they have dug up the entire area for sewer and water and natural gas, it makes sense at the same time to add the cabled utilities. (The same applied IIRC when I visited relatives in Idaho) But I haven’t seen a major move to retrofit the much older neighborhoods, and repairs due to trees are frequent. Trees seem to have this bad habit of growing. A few neighborhoods the trees look really funny -they are almost directly under the power lines, and have been trimmed that they grow in a Y shape.

A year or two ago, the phone company had been replacing old copper distribution with fibre, and there were crews wandering the neighbourhoods with those horizontal drilling machines, and messing up people’s lawns to run the distribution cables. I assume that would have been the case where it would have been far cheaper to string it on poles, but in those areas there were no poles. Nor attach points on houses to string a wire to - they all came up from underground conduits. I’m sure some of these new half-million dollar houses would be thrilled to find someone sticking poles though their back yards and drilling anchor holes in the stucco exterior.

I do note too that when some of our main streets are rebuilt (when their time comes) the utilities are also moved from poles to underground. But the long distance high voltage distribution lines are still all above ground.

So short answer - if it is built that way from the beginning, it’s a lot cheaper than retrofitting. And you have to think that in terms of available money and priorities, it’s cheaper to not have to change things once they are in place so they just leave things as they are.

I live in downtown Chicago and all power lines are buried. Indeed, they seem to be buried for most of the more urban areas near downtown.

I only see the above ground stuff in the suburbs (with the caveat that I certainly have not been everywhere in Chicago).

Maybe the density means they cannot string power lines above ground. They would be too big. Just guessing though.

Likewise, you do not see above ground power in Manhattan.

In most rural and suburban areas, service points are fed by radial feeders. A feeder is a series of lines (overhead or underground) running from a given substation to a set of customers. In a radial model, at any given moment, each house (and maybe its neighbors) is fed by one transformer, itself fed by a sequence of line segments tracing back to one substation. Conceptually similar to how each power outlet in your home is fed by a 3-conductor wire which may feed other outlets, but ultimately can be traced back to a single breaker. The utilities place switches at certain points that can link together portions of different feeders when needed, providing some redundancy and flexibility. Radial feeders typically have wires running along roads and streets, either on poles or underground.

Downtown areas in large cities are often served by secondary network grids, a more complex arrangement where there can be multiple transformers serving multiple customers. The transformers and switchgears to make this happen are typically underground, as are the cables feeding the customers.

In a lot of downtown areas, it’s not so much that the utilities are underground, as that the streets are about ten feet above the “ground”. They put everything on the ground, and then built the streets over them.

In an urban area like Manhattan, there is an amazing amount of stuff going on below the ground; subway tunnels, tunnels delivering water from upstate, water mains, gas lines, sewer lines, steam pipes (some buildings still have utility-supplied steam heat), electrical wires, telephone/cable/data wires, etc. Digging up a street involves a careful dance around all of these.

That’s not really accurate.

Thank you; that illustrates the point I was making. It’s really busy down there.

Depends on the city, I imagine. In significant sections of downtown Chicago, “street level” is, in fact, between four and fourteen feet above ground level (an effort which was apparently originally made to build a sewer system above the swampy ground).

Didn’t they also “lift” Seattle? I seem to remember something about an old Seattle underground from an ancient Kolchak documentary.

A lot of these replies conform my original suspicion: utility companies consider the added upkeep and maintenance costs of overhead lines to be more cost-effective than burying lines.

Thanks all.

Yeah, I used to work for a utility (in IT, though), and they always said it was the expense.

Yes, they did.