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Smart Grid StrategyIsn't it time for the grid to go underground?
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Nov 6, 2012
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By Jesse Berst
Paul Marks, chief technology correspondent with New Scientist, is joining a growing chorus of East Coasters crying for the distribution grid to be buried underground to forestall outages from giant storms like Hurricane Sandy.
My view
I understand the problems and concerns about undergrounding... yet I believe that, as an industry, we overestimate the cost of burial. And that's because we underestimate the potential for cooperation and collaboration with other utilities to do joint undergrounding.
I live in a city served by an IOU that loudly and proudly declaims that it is absolutely, positively impossible to join with telecommunications and cable TV providers. Yet, only a few hundred miles away in the same state, Avista Utilities has been doing exactly that kind of collaboration for at least 15 years. (It also shares other expenses, such as annual updates of the aerial photography that is fed into its GIS system).
With a little coordination, local utilities could come up with a plan to gradually underground all utilities by "piggybacking" on work that was going to be done anyway and then gradually expanding to other areas. Pretending otherwise and presenting overly large estimates of undergrounding costs does our industry a disservice, I believe.
Their view
· Hurricane Sandy cuts power for millions. Why aren't utility lines underground?
· Underground lines not a 'silver bullet' against outages
· Long power outages during storms like Hurricane Sandy could be prevented
· Fixing NYC's underground power grid is no easy task
Your view?
The Talk Back comment form below is ready and waiting for you to tell us what you think about undergrounding. Am I dreaming to think local utilities could get together to make it happen? Is there a better way?
Jesse Berst is the founder and chief analyst of Smart Grid News.com, the industry's oldest and largest smart grid site. A frequent keynoter at industry events in the U.S. and abroad, he also serves on advisory committees for Pacific Northwest National Laboratory and the Institute for Electric Efficiency. He often provides strategic consulting to large corporations and venture-backed startups. He is a member of the advisory boards of GridGlo and Calico Energy Services.
| Sounds good, but..... |
| I work for an electric cooperative in a suburban area and this question comes up periodically. It is normally driven by either a weather event or purely aesthetics. We construct more underground lines than we do overhead, but there are about 7500 miles of overhead left on the system. Our area is primarily sitting on top of one large limestone rock, which makes trenching / blasting quite expensive. We do coordinate with our telephone, cable and fiber companies on both overhead and underground projects and have pretty good relationships. That all works well on new projects. When the subject of placing existing lines underground comes up, though, the conversation is more difficult. We have at least three different business models in play - cooperatives, for profit entities and municipal governments. Each has its own drivers and hoops to jump through, and they rarely line up to the point where a major project like this gets approval from all three. Budget cycles get in the way, as well as trying to get approval for large capital projects from some entities that have home offices in other states and are not really interested in something seen as a local beautification project. And of course, underground electric lines are not a panacea. We had major flooding in our area in 2010 and had to cut the power off to a fairly large area of our system that would have stayed on if it were served overhead. All that being said, certainly we should take opportunities as they arise to improve the reliability of our systems. Underground lines eliminate a lot of tree trimming issues, which is worth a whole lot more than just the dollars you spend. If you have ever talked to a customer about cutting down their trees, you know what I mean. To get back to your point - we have installed over 2500 miles of underground lines, with a good bit of that being large (900 amp) distribution feeders, and we have a good feel for the actual costs. They are generally always seen as excessive for the benefits to be gained. Now, if we had some actual dirt to build in rather than rock, that could change things considerably. That concludes my ramble for the day. |
| Tom Suggs - 11/06/2012 - 07:01 |
| Underground Lines |
| As the writer above points out, topography and geology have a lot more to do with the cost than most people realize. Here in Southeast Louisiana, if you dig a 6-inch hole in the ground, it fills up with water in seconds in most places. That is the antithesis of bedrock but with the same end result. Every time we have a storm here, the citizenry rises up to ask why we don't bury power lines. Well, duh!! |
| M.A. Marullo - 11/06/2012 - 07:42 |
| Right-of-way issues |
| I work for with a municipal type distribution system in Virgina serving suburban type customers. We have done joint projects with other utilities encountering the kinds of issues noted above (budget cycles, approvals, different priorities). One of the issues that really drives cost is the competition for limited right of way. The more utilities in the street or a 10 foot wide utility easement the greater the congestion. Limited space affects coordination during design, working around other utilities during installation and greater ongoing maintenance issues. All this drives costs up. We have found that if we can work with property owners to provide us an easement that is relatively "clean" then costs for single phase underground primary can be comparable to overhead service particularly when tree trimming costs are considered. However when doing similar installations in a congested underground area the costs can easily be 5 to 10 times the cost of overhead. |
| R. Dellinger - 11/06/2012 - 10:26 |
| Undergrounding OH Lines |
| I have worked as a consulting engineer in this field for over 30 years. All comments above have real world merit. Recent experience in a major city downtown area with a network system was revealing. Manholes falling apart, galvanized racks corroded beyond use, cables of different circuits wrapped around each other, and worst of all, communications cables mixed with 15kV cables. The latter is a hazardous situation for unqualified workers. Often cable ownership was missing. This is all to say that undergrounding has issues beyond cost penalties vis a vis overhead construction. And coordination with other utilities for existing systems is not often practical. In one project's case it cost about $800k to go a city block for a complex undergounding situation. To do that overhead would cost maybe $50k, albeit impractical. All materials and equipment for underground systems are more expensive than comparable overhead components. Undergrounding has its place but expect higher costs and not necessarily higher reliability. |
| Paul E. Dorvel - 11/06/2012 - 11:13 |
| Honest question about Europe |
| I do not work in any industry, so my question may seem naive. But I really would like to know why so many European countries are able to underground utilities whereas in the United States it is seen as cost- prohibitive. What is the difference that I'm not seeing? |
| John Sheridan - 11/06/2012 - 15:31 |
| Undergrounding T & D |
| Undergrounding utilities is feasible, and mandated in many cases. The city of San Diego has been burying cables since the 1960's. Many planned developments across the country were designed and built with underground utilities, and a number of jurisdictions require buried electric lines as a condition of approval. I am certain it would be less expensive for the Oil & Gas industry to lay their pipelines on the surface rather than burying them, but that does not make it acceptable. Here is an undergrounding project we were involved with in Snowmass, Colorado: http://www.jkagroup.com/clients/holycross.htm |
| Erik Tilkemeier - 11/06/2012 - 16:40 |
| follow up comments |
| To Mr. Sheridan's question - virtually all new subdivision development in our area is installed underground. Many jurisdictions in our territory require underground for new construction. Since we require the developer to provide the ditch and duct system as a condition of service, the cost to install "normal" underground is very competitive with overhead and is actually less expensive in many cases. The cost issue comes into play in two scenarios. The first is when we have to construct heavy feeder circuits. I am talking about double circuit, 795MCM, 25 KV lines. Combine the costs of blasting through our limestone, installing very large concrete encased duct banks, and providing large copper cables to carry the load, and we routinely see total projects costs of $3,000,000 per mile. That is for new construction across "virgin" land. Equivalent overhead costs us about $175,000 per mile. The other scenario where costs can be prohibitive are areas where existing overhead lines are converted to underground. Even small capacity lines can be very expensive when you factor in the cost of all the moving parts to such a project. These include cutting of roads and associated traffic issues, excavation in established yards, proximity to existing water, sewer, gas, etc. and lack of working space to install power underground. Also, there are the costs of converting the service drops to individual houses and businesses, including changing the meter bases. One other issue that many don't think about are how to deal with trees. People want the lines in front of their house put underground so that their mature trees do not have to be trimmed. However, many times the ditch for the underground will destroy the root system on one side of the tree, either killing it or making it unstable and more likely to fall. We install much more underground than overhead for new construction, but relocation projects are pretty rare for the reasons I listed. |
| Tom Suggs - 11/07/2012 - 06:59 |
| RE:Honest question of Europe |
| I've just gotten back from spending nearly seven weeks in Germany. I can show hundreds of pictures where the local service cables are not underground but on power poles OR they run from roof top to roof top. As mentioned by the earlier posters, it really does depend on the local environment. FWIW, I have lots of pictures from other countries in Europe which show the similar patterns. Often the choice for above ground or underground is dependent prior war(s) damage and the historical nature of the area. Old villages that do not have a significant historical legacy more will more likely have power above the ground. Newer re-developed cities/villages go underground. Pretty much the same as in the US. |
| Dennis Heidner - 11/07/2012 - 19:37 |
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