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Question

Isn't it time to underground the grid?

Larry Eisenberg's picture
Principal Beezley Energy Advisors

Bringing net zero energy to the built environment and developing utility scale renewable energy projects around the world. Working with cutting edge technologies including solar, wind...

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  • Aug 31, 2021 5:15 am GMT
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OK, how many more climate disasters do we need to collectively experience where a whole city loses electricity, and people die before we agree that putting electric lines on sticks of wood is a cheap and stupid idea, and was from the very beginning? 

How much more money will we spend rebuilding electrical distribution systems in the same way they were built before only to seem them blown down with the next puff of wind? 

Folks climate change is here, strong bad weather will continue, and likely get worse. It is time to redo our electric grid in a way that is completely resilient and can take the worst that Mother Nature has up her sleeve. We rebuild buildings in places where they are going to be wrecked again in the not too distant future. 

The definition of crazy is doing the same thing and expecting a different outcome. Yes, putting the entire high tension to last mile grid underground will be an extremely expensive undertaking.  How much money have we collectively spent to rebuild portions of the grid wrecked by the weather over the last 100 years?  Time to figure out a way to pay for this and get started now.

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Is the energy community ready for the expense? The danger of ground exposed lines surfacing and the headache of repairs to the grid underground will not really change much of the service issues or maintenance needs. Perhaps focusing on reliability progress and safety consciences is a better remedy.

Larry Eisenberg's picture
Larry Eisenberg on Sep 16, 2021

Kimberly and All:  Saw the news yesterday that Hurricane IRA has caused $92 billion in damage.  If Mother Nature keeps it up (which is not in doubt), we will be talking about real money, not to mention the hundreds of billions of damage racked up in the not too recent past.  I would suggest that we need to make an immediate collective commitment to focus the conversation on the resiliency of our national energy supply. For those of you with access to national policymakers, please begin the conversation.  $92 billion would pay for a lot of measures to make our energy supply resilient.

Thank you to all for a great discussion and input. I'd like to add that modern composite core conductors such as ACCC offer greater strength, greatly reduced sag (to reduce transmission line associated fire risk), and can carry twice the power of conventional conductors - which can help reroute power around high-risk or active fire areas.  EPRI also recently demonstrated that the use of stronger steel, wood or composite poles - coupled with relatively weaker cross arms (to serve as a "fuse" when extreme winds are anticipated) - can improve resilience. If you have a minute, please check out this article from 2013 that describes how the ACCC Conductor helped OG&E recover from a direct EF-5 Tornado strike: https://publications.virtualpaper.com/Electric-Energy/eemag_july-august2...

 

A. K. Shyam, PhD's picture
A. K. Shyam, PhD on Sep 13, 2021

Thanks very much Dr. Bryant for sharing the link.  Appreciate it, please.

Bob Meinetz's picture
Bob Meinetz on Sep 14, 2021

"EPRI also recently demonstrated that the use of stronger steel, wood or composite poles - coupled with relatively weaker cross arms (to serve as a "fuse" when extreme winds are anticipated) - can improve resilience."

Dave, wondering if you could expand on this a bit. Cross arms would be designed to break, or simply be more flexible?

Short answer: In some instances, but not all. For details see paper I posted this morning ("Undergrounding Part 2, linked below), but don't read it. Instead start with the "...Part 1" paper that is linked in the Introduction to Part 2, and read that, and then come back to part 2. Also, Linked in the intro of Part 1 is a paper about PG&E handles distribution hardening (very detailed), and how and why they intend to expand undergrounding. 

https://energycentral.com/c/pip/undergrounding-%E2%80%93-part-2

A. K. Shyam, PhD's picture
A. K. Shyam, PhD on Sep 13, 2021

Thanks very much Dr. Benson for sharing the link.  Appreciate it, please.

My understanding is that underground lines are 5x more expensive than overhead lines.  If transmission lines are taken down once every 20 years, then underground would be cheaper.  I live in a residence with underground power lines and like it very much.  However, we had a burnout at a non-accessible location and it took a week to repair.  After 2 days, the utility had to island each street and come in with portable generators.  

I represent Finnish city utility Helen from Helsinki Finland. I have wondered the same issue, why don't you in the US. put the cables underground in the city and urban areas at least? We have in Helsinki 100 % underground cable network in the low voltage and medium voltage networks and partly in high voltage network too. Storms and climate causes are not problem at all for us. Additionally with automation and network redundancy we have managed to reach an excellent reliability level: SAIDI is already less than 3 mins/customer/year. And still the customer tariffs are among the cheapest within EU capital cities. Of course we have started the cabling principles already 100 years ago.

Randy Long's picture
Randy Long on Sep 6, 2021

115kV and above will be very expensive to underground. NIMBY,  NAEP, EIR/EIS, not included. The underground clearance issues would be challenging and would present problems with gas, as well as other utilities. All those towers with thousands of miles can't, "just be put underground." Build your generation closer to the load center, spur development for VPP/MICROGRID. There is no silver bullet.

The first choice of grid transmission is overhead lines because of many advantages that are evident despite severe damage due to natural disasters.  However, underground lines seem to be gaining gradual preference mainly due to minimal disturbance due to natural disasters apart from reduced visibility of electrical structures. Many seem to have found even the cost is affordable compared to the overhead line.  Monitoring issues which was considered serious seems to have been resolved through smart grids.

Underground network systems are categorized as either grid networks or spot networks. They have multiple network vaults (network Centers) connected together on the secondary side to facilitate multiple customer loads. Network Centers are connected together through secondary mains which are typically protected with in line current limiting fuses.

The utility plans to take network protector to next level with remote monitoring and operation for a better knowledge of and control over critical operating equipment.

Since the urban centers need services of many who opt for underground structures for reasons well known since ages, underground network system needs to consider these service lines which demand frequent monitoring.  They could perhaps route it in such a way that they do not disturb any of these service lines.

Whatever urgency one feels about the prospect of climate change, looking ahead, superconducting cables are likely to be an important part of the GRID.  The fist leg of a superconducting cable project by ComEd in Chicago was activated as a permanent part of the GRID just this week.

Of course superconductors can not meet the urgency of those demanding an immediate fix but where underground cable are called for, then superconducting cables should be considered.  The project in Chicago is an AC project designed for implementation to meet growth in dense population areas.

Another use of underground superconducting cables is connecting large scale wind and solar projects to cities.  This could be done with underground DC cables.  Both the AC and DC versions have their engineering issues but one significant "green" advantage is that lose far less energy in the delivery.  

Superconducting cables may not help in burying cables for Louisiana, but they could become practical and widespread in decades to come if they are fostered today.  Superconductor cables, in some specific instances, hold their own on a cost/benefit measure.  The price surely will come come down as they are used more.

 

There have been efforts to harden the above ground distribution systems. Many utilities have forgone the old wooden poles and opted to go with reinforced concrete or steel poles, it all depends on the rating of the pole relative to the amount of damage that may occur during a storm. That is probably the applicable option in most of the distribution areas. Going underground presents a lot of technical challenges as highlighted in previous responses and is incredibly expensive as previously discussed. I don't think the American consumer appreciates the full spectrum of what it would cost to underground most distribution and transmission systems while the country also attempts to decarbonize and build terawatts of renewable resources and terawatts of accompanying storage. It's a price tag that would put electricity out of the reach of a huge chunk of consumers in this country. In this business, one has to learn to walk the tight rope over the flaming pit when trying to balance fiscal responsibility with reliability.

Undergrounding distribution is a very locationally specific challenge, but at least easier to repair.  High voltage transmission is another story, but undergrounding the backbone of the transmission system is actually in sight.  The SooGreen (https://www.soogreenrr.com/)  rail co-located line will prove this by solving the siting challenges and not pinning costs on ratepayers.  This will be the model for the future.

There are so many underground pipeline systems nowadays, such as gas pipelines, water pipelines, telecommunication lines, etc. It's pretty tricky and costly to move the existing electric cables underground, especially in urban cities where the distribution of these underground lines has shaped for years. Plus, the relevant permitting procedure is much more complicated and time-consuming as it involves various stakeholders.

But, for a to-be-developed area or region, this practice is feasible and should be planned ahead.

That quick and dirty approach is a mystery for me as an European.
It creates an exceptional unreliable electricity supply (SAIDI figure >10 times worse than that of Germany).
And it's expensive as it causes that many companies in the US had to buy emergency generators....

 

All: Excellent answers. Thanks for taking the time to share your thoughts in response to my question.  My sense is that there is general consensus on the idea that under grounding does need to be studied and done where appropriate and necessary.

Doug, you are right. I am angry.  Technological development and increasing sophistication in our industry has many of the answers that need to be implemented now. Not tomorrow, not next year. The pace of climate change and vastly altered weather patterns will only accelerate.  We are way past the time for talk, and need specific plans and specific implementation actions in a national and international context.  We need action now.

I have a little grandson. Without immediate collective action based on real science and innovation, all of our grandsons and granddaughters will get an Earth that is not fit for human life.  Sadly, that point is not far off. 

At the same time, I am a wildly enthusiastic optimist.  I am seeing amazing technological development and have a deep belief in "Yankee Ingenuity". I do think that with immediate effort and collective action, we can fix the very large problem that we face, and let all of our grandchildren grow up grateful for the effort we will make.

Larry: It is really tempting to jump on the underground bandwagon, especially here in northern Californian where we have seen PG&E's problems firsthand. The reality, however, is pretty complicated, IMHO. With over 160K miles of transmission lines, the cost runs into the trillions of dollars. Will this stand up to a rigorous, realistic cost-benefit analysis? There is also the problem that underground infrastructure is not a cure-all. I recall working with numerous utilities in my career where there has been a constant challenge with underground utility infrastructure, especially in identifying outages. While I don't suggest that there is a single answer to the problems facing utility executives charged with managing 'the wires' side of the business, there are a few things that might be helpful. First is to leverage available technology to provide better visibility and predictability into the grid. This technology exists at a fraction of the cost of gong all-in with underground. Second, maybe going underground in selective areas is part of the answer, but even this might be cost-prohibitive. Finally, I suggest that utility executives and PUC commissioners rememeber and, to some degree, return to their original mission of providing safe, reliable, affordable electricity. Frankly, I think that there is a focus problem in our industry. Renewables are cool and do solve some business problems (there are some exciting developments in areas like DERMS and long duration storage, for instance), but not at the expense of cratering reliability to the point of killing people and destroying homes, business, and the landscape. It is not a coincidence that a lot of the grid problems we see today have escalated as renewables have also scaled up aggressively. Let's bring some balance back to managing the grid, customers, and energy sources, and get to the zero carbon promised land without killing any more people.

Yes, it is time for planners and engineers to more fully evaluate the 21st century “lifecycle” costs of overhead versus underground electric transmission and distribution.  Indeed, we find ourselves replacing overhead T&D structures and wires time and time again when high impact low probability (HILP) events and major storms wreak havoc in our communities.  We need to seriously count the cost of rebuilding multiple times, loss of local GDP, loss of life and property related to electrical outages and more.  Then, look at the added, but hard to quantify, benefits of underground T&D like safety, resiliency and aesthetics.  

PG&E has finally figured it out.  https://www.pge.com/en/about/newsroom/newsdetails/index.page?title=20210721_pge_announces_major_new_electric_infrastructure_safety_initiative_to_protect_communities_from_wildfire_threat_undergrounding_10000_miles_of_power_lines_in_highest_fire-threat_areas   After decades of senior leadership resistance to underground, the new CEO of PG&E has stated  “It’s too expensive not to do it. Lives are on the line.” with regard to underground and fire mitigation.  Did it take major fire damage, loss of life and bankruptcy to reach this conclusion?  

Many utilities across North America are taking notice.  The latest massive outage in New Orleans (that could last for weeks) is another call for action.  

Keep the pressure on your local utilities to always consider underground options and read my whitepaper, The Case for Distribution Underground, found at https://mikebeehler.com/whitepaper-the-case-for-underground-distribution/

Larry, cheap and stupid might only be halfway there. In the past, cheap was not stupid. The typical number I heard for the cost of underground was 4x the cost and outage time of overhead. That's not really an easy sell. It's certainly not cheap.

I think a lot of utilities are looking at underground more favorably in the last few years. The problem is there is a lot of work to do to get some lines underground. And, if it's not entirely underground, is it really doing anything? And what about substations? And what about meters? You need underground from beginning to end or you've only made your problem smaller. It's not an easy solution but I think it is something worth considering. Even cheap and stupid has a cost.

While I am not plugged into current costs for underground transmission,  we would usually use a factor of 10 for the difference.  So if 115kv overhead costs 1.5 million then the same line underground would be 15 million per mile..That's a major obstacle. However, we do put in underground high voltage lines where there isn't a reasonable alternative.  So the downtown area of Chicago for example is virtually all underground high voltage at either 69kv or 138kv.  

Having said all that,  I have seen some utilities recently moving some lines to underground installations for reliability purposes.  This I suspect is being done strictly because they cannot sustain losing specific lines. 

Under grounding is not the answer for everything. It is mostly on a case by case basis.

According to NERC ES&D database here https://www.nerc.com/pa/RAPA/ESD/Pages/default.aspx

there are 6,800 operating Overhead T lines. Compared to the 100 underground Bulk Electric System lines. There is a reason for that. 

Some of the under construction UG are in the New England area around Boston. Greater Boston – Central and Western Suburbs, Seacoast New Hampshire Solution, Greenwich Area.

 

 Dear Mr. Eisenberg - 

It is clear you are angry and frustrated. I understand your concern and what you are asking. 

Undergrounding is not a magic bullet. It can definitely help in storm events and it should be considered.

However, if you have ever worked on the underground electric system you would understand that a fault can take a lot longer to find than just looking up and seeing the dangling broken line. IN some cases with intermittent faults it can take days to actually find and fix them. Then there are the hungry backhoes of the world that Murphy has put on the planet to dig directly on top of a buried line. Or the very large trees that in the spring tip over root ball and all, dragging the lines out of the ground.

Believe it or not, one-third of all outages in the grid are caused by faults in the underground system according to a study done by the US Department of Energy. Underground distribution makes up less than 20 percent of the grid, so as a percentage of the total faults compared to line miles, undergrounding has more issues. On an average non-storm day, fixing an overhead fault takes about 2 hours, for the same day, and underground fault takes roughly 8 hours.

Some of these underground issues come from burying lines close to the surface, others from issues with the insulation used on direct burial conductors (that happened in the 1960s & 1970s that we are paying for now), some from poor construction standards, and others from the growth of street trees over the last 40-50 years. Some can be fixed; some is just nature.

Better materials and standards reduce the day-to-day failure of conductors, better mapping of where conductor is laid should reduce the location times. Bigger fines for digging without locating first and requiring the plat map for every piece of property to carry location information on all underground utilities would reduce the issues with the dread backhoe and its cousins.

Undergrounding is preferred by homeowners, until they see the costs associated with it, then they are mostly fine with the lower cost overhead. Florida Power and Light has found ways to reduce the cost of undergrounding. PG&E will also find ways to reduce the cost for massive undergrounding.

This is a good time to discuss massive undergrounding, not because of weather issues, but because so much of the distribution grid will require voltage upgrades and larger conductors to support electrification. Doing both at once will be expensive, but not as expensive as doing it twice.

In some areas undergrounding offers massive challenges, some lines run overhead with poles in holes blasted out of pure rock, think about sawing trenches in that rock and how those trenches may become water courses in the rainy season, or undergrounding where the water tables is at or above ground level for miles and miles, meaning submersible equipment, and pad mounted equipment. In those cases, undergrounding may be prohibitively expensive.

The other issue is that underground systems typically need to be replaced every 25-40 years depending on soil pH and other soil related issues.  Overhead systems can be upgraded pole by pole and have an effective life of 50-80 years. Effectively you can knock down the overhead system every decade and still have a lower cost then undergrounding.

The major issue that the regulators do not take into account is the modern issues with outages. The data used in any of the DOE calculators is decades old and does not deal with modern life. They also assume that the customer has access to some other energy source, like propane or natural gas – something that will go away.

Yes, undergrounding is a good idea, but it is not a panacea.

Steve Wickman's picture
Steve Wickman on Aug 31, 2021

Doug has said it very well!  Undergrounding an existing system while it sounds like a great solution does present a different set of issues as mentioned cable faults take much longer to fix than overhead wires down. Underground systems need to have redundant [loop] feeds to restore by switching out the faulted section and feeding the load from "the other end" so to speak until the fault can be repaired.  There are many other factions to look at too that can increase reliability.  Redundant sources from different directions--ie don't put all the transmission circuits feeding a big city on the same transmission tower across a major river!  Microgrids, that can sustain small segments of the populated area by means of co-gen sources, not requiring full time feed from the traditional sources.  There are a myriad of ways to approach the reliability and "storm proof" the electrical grid as we know it today.  Hopefully the New Orleans area will rebuild with a more reliable system that will take in to account ALL the new "tricks" to storm proof the grid in their area.

Michael Keller's picture
Michael Keller on Sep 2, 2021

New Orleans needs to have more generating assets within  the immediate vicinity of the city. Turns out a natural gas plant that many did not want built was instrumental in providing power.

 

Chris Hickman's picture
Chris Hickman on Sep 24, 2021

One of the major problems in our industry is the 'generalizing' we do.  This thread talks about undergrounding like it's relatively the same from 15kV class distribution up to 500kV transmission.  There is a major inflection point above 115/138kV.  So rather than generalizing, about 25 years ago, Colorado Springs Utilities actually built some of this stuff and then made the decision as a community to put everything 115kV and below underground from that point forward.  A plan, wow, what a concept.  And yes, they have lots and lots of rock to blast out or bore through to make this plan happen and their rates are not crazy and their outage statistics are some of the best in the nation.  Lightning has virtually no effect at this point and it's a high lightning area.  They looked at their environment, their costs, what their community wanted and made a plan that clearly said we're going to spend more and here are the reasons.  They set standards, did consistent construction to those standards and bought in for the long haul.  Everyone wants a big bang these days instead of recognizing that planning matters.  It's not about converting everything at once, it's about making a decision with the constituents of the area weighing in and then plodding along the path because we simply have too much to convert in a big bang.

 

Second, I want to give a shout out to Chris Eisenberg at EEI for his miraculous work on mutual assistance to help create a system for us all to help each other.  Many, many others were involved but his tireless efforts have set the foundation.  Now others need to step up.  We need to look at the areas of the country where big storms are wrecking out infrastructure and we need to make a plan.  We need to stockpile more appropriate concrete and metal poles in coastal regions so when mutual assistance crews show up, we rebuild the system in a manner mother nature won't knock it down the next time instead of just slapping stuff back together.  It's a plan, it costs money and all of these utilities need to band together to create this stockpile and work together to build a system that actually does last 50 years in the face of increasing severe weather.  

 

At the same time, all of these communities can take the cue from FP&L and Colorado Springs and make a decision now to say we will put stuff underground.  The technology has come a long way and we can cite examples of outages around the nation because of bad technology, first gen cables and isolated incidents of hard to get to areas as excuses for not doing things.  And then we can use things like social justice as an excuse to say that this policy will unfairly advantage new subdivisions that are out of reach of low income, but that is just part of a plan that says we will start converting some small percentage of the system at the same time and we will focus on these areas.  Is it hard to get everyone in a room and have these conversations, yes.  However, when you look at the stats of people that made a plan and stuck to it, you will find that resiliency in all cases from 138kV and below is better when underground.  

 

The average age of our systems is approaching end of life in many areas and now is the time to have this conversation across each community in our country and making a decision that is meaningful to our future generations.  And folks, there is no future in the next 50 years where the distribution system goes away.  I can cite progress on nuclear fusion and make the case for a future where major transmission networks go away in the next 30 years, but there is no reality without the invention of Mr. Fusion from back to the future that the distribution network goes away.  Electricity is the lifeblood of our world.  It is probably the single thing that allowed America to rise to the level of superpower because a very strong man set a national policy to electrify our nation and our productivity and capability as a nation exponentially increased beyond all others.  Put aside petty partisan politics and the excuses that each special interest brings to the table and actually make a plan to make a difference.  This plan will facilitate the future of electrification for EV's, DER and a better future for even communications because when you have the trench open, you add fiber because it's almost a no cost addition to drop that conduit with fiber in it while you are doing the power.  

 

The only question is whether or not there are strong enough people in each region willing to take on this battle and make it a reality because there are technical or other reasons not to do this in most areas.

 

EHV transmission is a much more challenging discussion but again, I believe in the human spirt of innovation and I believe that small scale, safe, nuclear fission reactors exist today and we should be deploying them.  And in 20 years, small scale nuclear fusion will be a reality.  So the transmission question becomes time related for this type of transport and become an issue for move central station renewables from off shore and from the center of our country to load centers around the country.  

 

If you actually believe the stats for penetration rates of DER and EV's, there really is no discussion or set of excuses that say we don't put a bright shining light on a 30 year plan to reinvest in America's distribution infrastructure and we start today.  

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