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We did this in Denmark many, many years ago. It is also significantly cheaper to maintain as you no longer need to manage vegetation around the powerlines, perf

We did this in Denmark many, many years ago. It is also significantly cheaper to maintain as you no longer need to manage vegetation around the powerlines, perform pole / cross-arm inspection etc. In some countries the main hesitation to underground cabling for transmission lines has been up front cost as well as unions (=less maintenance, less work).

urthor 5y ago
Imagine it was significantly cheaper if you measured it over a 3+ year time-span. Not over a 1-2 year time-span. The unwillingness of corporations to minimize OpEx by taking on significant one-time CapEx, in order to pretty the books, lives on in so many domains.
- Consultant32452 5y ago
  Another important factor is that highly regulated local monopolies like power companies may have certain restrictions like only being able to charge a certain % over cost. Well, you'd much rather have 5% of a large number than a small number, so you're incentivized to do the more expensive long term thing.
  - QuercusMax 5y ago
    Health insurance has been doing this too.
  - lazide 5y ago
    It definitely explains a lot of what PG&E has done sometimes - maximum inefficiency and cost in some areas, incredibly (long term destructive) cheap in others.
- bcrl 5y ago
  Minimizing OpEx is one of the main drivers of telcos to switch to fibre. Companies like Bell Canada are telling their shareholders that network maintenance costs will drop as copper is decommissioned and services are migrated to fibre.
bluGill 5y ago
20 years ago my local power company did the math and discovered underground was more expensive to maintain. Underground you don't need to maintain vegetation, but the lines break more often, and are a lot more expensive to replace. This obviously depends on local conditions. Where I lived then there was plenty of water so starting a large fire was not possible. The plenty of water also meant the ground wasn't stable. Of course they did need to maintain vegetation, but that is a known cost.
- orzig 5y ago
  This is very valuable information if true, can you provide some sort of references?
  - abduhl 5y ago
    It’s pretty common sense. Underground breaks cost more to fix because you have to dig the line up both to find the problem and fix it. Above ground problems are visible while underground problems are invisible. Not to mention that above ground lines have slack between poles while underground lines are pulled relatively taut. Any shifting in the ground is going to result in a break underground before a break above ground. Above ground lines are also better founded because the poles are sitting on foundations or driven deep so their ability to resist ground motion is a bit better while electric lines move with the ground around them pretty much in sync. This is particularly important in seismically active areas like CA but underground infrastructure actually typically performs better in actual seismic events.
    - mattferderer 5y ago
      Another 2 cents. Drones are very popular for being able to quickly look at above ground lines. You can easily & quickly determine if parts are in need of repair or soon will be. I don't know if a similar thing exists in underground without building some type of complex tunnel system.
    - lostcolony 5y ago
      "Common sense" does not always equate to facts or relevance. While, yes, the cost to dig up a line is likely to be higher than the cost to repair a hanging line, that's just one cost and consideration. Economic loss due to wildfire as well as rolling brownouts to try and avoid wildfire are both costs you'd need to consider. You also have the cost to maintain vegetation around powerlines, vs basically no pre-emptive maintenance on buried lines (and little to no weathering). And you, of course, have differing likelihoods of the line breaking in any case, which means the per-fix cost is only part of that picture. Lots of potential reasons, but I'd be curious to see a full study on those reasons for both above ground and below ground, their potential solutions, and their potential costs, but without that you have a very fuzzy picture.
bastardoperator 5y ago
They've been doing this in California for the last 40+ years. PG&E is just a prime example of why de-regulation doesn't work. LADWP which is a publicly owned utility ran the Scattergood-Olympic Transmission Line (11 miles) under the city nearly 5 years ago and LADWP actually generates revenue for the city of Los Angeles. Honestly, PG&E needs to die in bankruptcy court.
eastbayjake 5y ago
I thought it was significantly more expensive to bury high-voltage transmission lines because the current corrodes the insulation needed to bury the lines, so you have to dig up and replace every 20-30 years. I was actually quite surprised to learn that above-ground transmission lines in the US are uninsulated for this reason.
- nate_meurer 5y ago
  No, the insulation in a solid dielectric transmission lines is cross-linked polyethylene, or paper in fluid-cooled lines. Lines are designed to operate well within the thermal capabilities of the insulation, and there is no such thing as routine replacement of undamaged underground lines. Above-ground transmission lines are uninsulated because they don't need to be, and the extra weight of the insulation would require more expensive towers.
gaoshan 5y ago
The upfront cost is why we don't generally do this in the US. If we looked at it from a 50 year perspective we'd (probably) do it in a heartbeat but we aren't very good at that sort of planning ahead.
dylan604 5y ago
Yes and no. It's a power company that owns the right-of-way where there lines are located. They will still keep that land cleared of any vegetation they don't want. I'm honestly surprised they don't just use RoundUp over the entire area of their right-of-way.
hattmall 5y ago
If they were managing the vegetation the wildfires wouldn't really be an issue though. It's California though so know doubt a friend of some PGE board member just started a company that buries power lines at an exorbitant cost.
Upitor 5y ago
Did what exactly? Most the transmission grid at least is overhead lines in Denmark. In fact, it is said that putting more than 15% of transmissions lines underground would be irresponsible due to physical limitations of AC lines, which corrupts the transmission system.
- hestefisk 5y ago
  That is true. But the distribution system is largely UGed. My OP was meant to say Dx not Tx.

urthor 5y ago

Imagine it was significantly cheaper if you measured it over a 3+ year time-span. Not over a 1-2 year time-span. The unwillingness of corporations to minimize OpEx by taking on significant one-time CapEx, in order to pretty the books, lives on in so many domains.

Consultant32452 5y ago
Another important factor is that highly regulated local monopolies like power companies may have certain restrictions like only being able to charge a certain % over cost. Well, you'd much rather have 5% of a large number than a small number, so you're incentivized to do the more expensive long term thing.
- QuercusMax 5y ago
  Health insurance has been doing this too.
- lazide 5y ago
  It definitely explains a lot of what PG&E has done sometimes - maximum inefficiency and cost in some areas, incredibly (long term destructive) cheap in others.
bcrl 5y ago
Minimizing OpEx is one of the main drivers of telcos to switch to fibre. Companies like Bell Canada are telling their shareholders that network maintenance costs will drop as copper is decommissioned and services are migrated to fibre.

bluGill 5y ago

20 years ago my local power company did the math and discovered underground was more expensive to maintain. Underground you don't need to maintain vegetation, but the lines break more often, and are a lot more expensive to replace. This obviously depends on local conditions. Where I lived then there was plenty of water so starting a large fire was not possible. The plenty of water also meant the ground wasn't stable. Of course they did need to maintain vegetation, but that is a known cost.

orzig 5y ago
This is very valuable information if true, can you provide some sort of references?
- abduhl 5y ago
  It’s pretty common sense. Underground breaks cost more to fix because you have to dig the line up both to find the problem and fix it. Above ground problems are visible while underground problems are invisible. Not to mention that above ground lines have slack between poles while underground lines are pulled relatively taut. Any shifting in the ground is going to result in a break underground before a break above ground. Above ground lines are also better founded because the poles are sitting on foundations or driven deep so their ability to resist ground motion is a bit better while electric lines move with the ground around them pretty much in sync. This is particularly important in seismically active areas like CA but underground infrastructure actually typically performs better in actual seismic events.
  - mattferderer 5y ago
    Another 2 cents. Drones are very popular for being able to quickly look at above ground lines. You can easily & quickly determine if parts are in need of repair or soon will be. I don't know if a similar thing exists in underground without building some type of complex tunnel system.
  - lostcolony 5y ago
    "Common sense" does not always equate to facts or relevance. While, yes, the cost to dig up a line is likely to be higher than the cost to repair a hanging line, that's just one cost and consideration. Economic loss due to wildfire as well as rolling brownouts to try and avoid wildfire are both costs you'd need to consider. You also have the cost to maintain vegetation around powerlines, vs basically no pre-emptive maintenance on buried lines (and little to no weathering). And you, of course, have differing likelihoods of the line breaking in any case, which means the per-fix cost is only part of that picture. Lots of potential reasons, but I'd be curious to see a full study on those reasons for both above ground and below ground, their potential solutions, and their potential costs, but without that you have a very fuzzy picture.

bastardoperator 5y ago

They've been doing this in California for the last 40+ years. PG&E is just a prime example of why de-regulation doesn't work. LADWP which is a publicly owned utility ran the Scattergood-Olympic Transmission Line (11 miles) under the city nearly 5 years ago and LADWP actually generates revenue for the city of Los Angeles. Honestly, PG&E needs to die in bankruptcy court.

eastbayjake 5y ago

I thought it was significantly more expensive to bury high-voltage transmission lines because the current corrodes the insulation needed to bury the lines, so you have to dig up and replace every 20-30 years. I was actually quite surprised to learn that above-ground transmission lines in the US are uninsulated for this reason.

nate_meurer 5y ago
No, the insulation in a solid dielectric transmission lines is cross-linked polyethylene, or paper in fluid-cooled lines. Lines are designed to operate well within the thermal capabilities of the insulation, and there is no such thing as routine replacement of undamaged underground lines. Above-ground transmission lines are uninsulated because they don't need to be, and the extra weight of the insulation would require more expensive towers.

gaoshan 5y ago

The upfront cost is why we don't generally do this in the US. If we looked at it from a 50 year perspective we'd (probably) do it in a heartbeat but we aren't very good at that sort of planning ahead.

dylan604 5y ago

Yes and no. It's a power company that owns the right-of-way where there lines are located. They will still keep that land cleared of any vegetation they don't want. I'm honestly surprised they don't just use RoundUp over the entire area of their right-of-way.

hattmall 5y ago

If they were managing the vegetation the wildfires wouldn't really be an issue though. It's California though so know doubt a friend of some PGE board member just started a company that buries power lines at an exorbitant cost.

Upitor 5y ago

Did what exactly? Most the transmission grid at least is overhead lines in Denmark. In fact, it is said that putting more than 15% of transmissions lines underground would be irresponsible due to physical limitations of AC lines, which corrupts the transmission system.

hestefisk 5y ago
That is true. But the distribution system is largely UGed. My OP was meant to say Dx not Tx.