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Thread: FYI: Northern Pass High Voltage Transmission Project

  1. #1
    Senior Member Waumbek's Avatar
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    FYI: Northern Pass High Voltage Transmission Project

    I am just getting wind of this project and do not find mention of it in a forum search. Nor do I know much about it yet other than the fact that the HV lines aim to transmit power from Quebec to NH/New England. There's a first public meeting on Monday in Sugar Hill and Franconia; presumably the company will pitch the project. Maps can be found at

    http://www.northernpass.us/maps/Proj...Map_101410.pdf

    The "preferred route" in this area cuts right through the Rocks Estate (SPNHF) in Bethlehem and uses an existing ROW in the WMNF; it crosses the AT on the Kinsman Ridge between Mt Wolf and Eliza Brook shelter and goes down through the lower section of Franconia Notch (see pg. 2 of the pdf maps). The alternative route, not preferred by the company, takes the line west of the WMNF and Franconia Notch and then heads east again lower down through the Plymouth area, thus bypassing the Notch area. This alternate would be roughly along the old rail route "bypass" into the north country.

    Is it feasible, technologically and economically, to bury these lines in sensitive areas?

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    Senior Member MichaelJ's Avatar
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    That appears to be exactly the route of the existing power line corridor, at least from 302 Bethlehem through Rocks, Sugar Hill, over Kinsman ridge, and down past 112, so I'm not sure what impact there would be.

    A neat idea, to take a high-voltage DC line from Hydro Quebec right down into Southern NH to feed the grid. Environmentally, however, I have no idea.
    May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view. May your mountains rise into and above the clouds. - Edward Abbey

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    Member Lou Hale's Avatar
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    Burying lines is very expensive I think the last person I talked to said 10X the cost but that's as un official as estimates get. I think its also way more intrusive to install and repair buried lines.

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    Senior Member Craig's Avatar
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    I'm not sure they can bury a 300KV transmission line. Those high voltage overhead transmission lines are steel uninsulated cable. Additionally, those voltages put off a significant EMF. I wonder if the EMF would be too strong (for living things) at ground level.

    <drift>
    The original engineered plan for supplying 15KV power to MW Obs was to install conduit on the side of the cog trestle. There was to be separate conduit for the power and fiber optic cable. This was the most cost effective way to get power and communication to the summit. Unfortunately, the engineer couldn't demonstrate code compliance so that scenario was scrapped.

    Eventually they engineered direct burial 15KV cable for power and buried conduit to install the fiber optic cable. This method was vastly more expensive (monitarily & enviromentally) but was code compliant and will probably last a lot longer than exposed conduit.
    </drift>

    I know they are developing direct submersion cable for the use in the distribution of offshore wind power. Not sure what voltages those will be rated for.

    Hold on tight, you're going to see more and more above ground transmission projects in the future as we move away from a fossil fuel economy. I believe they've already started a few large ones out west.
    Enjoy your best

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    Senior Member Fitz's Avatar
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    Dams

    Not to mention many proposed dams in Canada to feed our needs.

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    Member Lou Hale's Avatar
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    Quote Originally Posted by Craig View Post
    I'm not sure they can bury a 300KV transmission line. Those high voltage overhead transmission lines are steel – uninsulated cable. Additionally, those voltages put off a significant EMF. I wonder if the EMF would be too strong (for living things) at ground level.

    <drift>
    The original engineered plan for supplying 15KV power to MW Obs was to install conduit on the side of the cog trestle. There was to be separate conduit for the power and fiber optic cable. This was the most cost effective way to get power and communication to the summit. Unfortunately, the engineer couldn't demonstrate code compliance so that scenario was scrapped.

    Eventually they engineered direct burial 15KV cable for power and buried conduit to install the fiber optic cable. This method was vastly more expensive (monitarily & enviromentally) but was code compliant and will probably last a lot longer than exposed conduit.
    </drift>

    I know they are developing direct submersion cable for the use in the distribution of offshore wind power. Not sure what voltages those will be rated for.

    Hold on tight, you're going to see more and more above ground transmission projects in the future as we move away from a fossil fuel economy. I believe they've already started a few large ones out west.
    more drift on your drift. I didn't think engineers needed to demonstrate code compliance and if so I wonder what the specific issue is 15KVish is a pretty common supply voltage and should have lots of off the shelf solutions

    I think they can bury 300KV cables its just unimaginably expensive. The real worry for me would be current leakage 300K volts can overcome a lot of resistance
    Last edited by Lou Hale; 11-07-2010 at 08:45 PM.

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    Senior Member Craig's Avatar
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    Quote Originally Posted by Lou Hale View Post
    more drift on your drift. I didn't think engineers needed to demonstrate code compliance and if so I wonder what the specific issue is 15KVish is a pretty common supply voltage and should have lots of off the shelf solutions
    I can see folks eyes glassing over so I PM'd you.
    Enjoy your best

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    Senior Member DougPaul's Avatar
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    Quote Originally Posted by Lou Hale View Post
    more drift on your drift. I didn't think engineers needed to demonstrate code compliance and if so I wonder what the specific issue is 15KVish is a pretty common supply voltage and should have lots of off the shelf solutions
    15KV is too low for long-distance lines. Think more like 345KV. There are also 765KV lines. (The Soviet Union once operated a 1150KV line.) The higher the voltage, the lower the losses, but the more clearance required. However, for a given amount of power, the higher voltage line requires less horizontal space than multiple lower voltage lines. (Example: one 765KV line requires a 200ft cut, but the six 345KV lines required to carry the same amount of power would require a total of 900ft of cut.)

    DC lines also have some advantages over AC lines.

    Ref: Wald, Matthew L., "How to Build the Supergrid", Scientific American, Nov 2010, pp 57-61. http://www.scientificamerican.com/ar...-the-supergrid

    My eyes hadn't glazed over and I didn't get the PM, so I figured I post...

    Doug

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    Senior Member MichaelJ's Avatar
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    There are certainly 100kV and higher lines under the streets of Boston and surrounding towns. However, and I don't know what is the controlling factor, some of them are oil-filled.

    But as Doug points out ... this is a DC transmission line. It doesn't need three-phase lines spread out across the arms of a tower, there's no phase. It needs only one line, but hopefully they'll use two, as there are detrimental environmental effects to having voltage return through the ground. Voltages can be up to the 600kV range.

    One thing I didn't know until researching this was that a steady wind across a DC transmission line can produce a corona effect, losing voltage and producing ozone. There are ways to mitigate this, of course, and the number one is burying. In fact, buring an unshielded return cable is much cheaper than a second shielded cable, but will mitigate the effects of having a ground return.
    May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view. May your mountains rise into and above the clouds. - Edward Abbey

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    Senior Member Davehiker's Avatar
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    It's interesting to me that much of the "Central Section First Alternative," and the "Preferred Route" parallels an existing high-voltage right of way from near Bath as far south as Salisbury, crossing it in Bath, and again in Groton. I seem to remember that that existing line comes from Quebec to the Comerford converter station in Monroe, and continues at least as far as Manchester. I wonder if it's more cost effective to build a new right of way than to share one with another company.

    I'm a layman and have little knowledge of power transmission, but it seems to me that a significant advantage of small solar and wind power projects is that the power is produced closer to where it's used, reducing the need for long-range transmission lines. As long as we continue to use more electricity, the infrastructure must grow to continue reliable service.
    -Dave

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    Senior Member DougPaul's Avatar
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    Quote Originally Posted by MichaelJ View Post
    But as Doug points out ... this is a DC transmission line. It doesn't need three-phase lines spread out across the arms of a tower, there's no phase. It needs only one line, but hopefully they'll use two, as there are detrimental environmental effects to having voltage return through the ground. Voltages can be up to the 600kV range.
    Actually, one can use two DC phases: plus and minus...

    With two wires, one can be run positive (+1/2) and the other negative (-1/2) (or +1 and -1 to double the effective voltage) which has advantages over running a hot wire (+1) and a ground (-0).

    That said, I don't know what industry practice is with regard to single vs double wire DC transmission systems.


    There is a bunch of general info at http://en.wikipedia.org/wiki/Electri...r_transmission.

    Doug

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    Senior Member DougPaul's Avatar
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    Quote Originally Posted by Davehiker View Post
    I'm a layman and have little knowledge of power transmission, but it seems to me that a significant advantage of small solar and wind power projects is that the power is produced closer to where it's used, reducing the need for long-range transmission lines. As long as we continue to use more electricity, the infrastructure must grow to continue reliable service.
    One of the problems with solar and wind is that the best locations for the power generators tend to be far from the consumers. Thus a high-capacity power grid will be required if they are ever to produce large fractions of the power used by consumers.

    And integrating wind generators into the power grid can actually increase the overall CO2 output because of changes that must be made elsewhere to handle the unpredictable variable output of wind generators. I read recently that while Denmark has about 20% of its power generated by wind there is no overall reduction of CO2 production.

    Doug

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    Senior Member el-bagr's Avatar
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    I'm interested to see this discussion here -- dealing with transmission lines from Canada, and their policy implications, is part of what I do for work. Canadian generators (like Hydro-Quebec and Nalcor) have large amounts of hydropower and other generation north of the border, far in excess of local demands. In fact, last Friday I met with Canadian developers in Boston, many of whom were very eager and open about wanting to supply power to New England and the US.

    Personally, I think Lou Hale is right when he suggests that the costs of burying any significant length of a 1200 MW HVDC line are staggering. Northern Pass proposes to construct a single circuit ~345kV HVDC above-ground transmission line. Generally, towers for that size of line are mounted about 90 feet to 135 feet tall. It proposes to acquire a 150' wide right of way from the border in northern Cos County to the Lost Nation substation in Northumberland 45 miles away. From the Lost Nation substation south to a converter station in Franklin, Northern Pass's proposed new line would be located largely within an existing transmission ROW. They can deviate from that initial route, but generally in so doing incur higher costs or environmental consequences.

    Davehiker, you're right that distributed generation can play a role in meeting electric demand requirements while minimizing transmission costs. There are federal and state policies that promote distributed generation for just those reasons. On the other hand, the magnitude of the Canadian renewable generation is so large that developers argue that it is less costly and less environmentally harmful, even though it requires expensive transmission lines.

    Keeping this thread germane: I suspect many of us have crossed part of the transmission system in question, hiking along the AT from Mount Wolf north to the Kinsmans. According to Guy Waterman, Nathan Kinsman settled in the Easton Valley in 1782 and cut a cart path over the Kinsman Ridge through a notch where the present power line and the Reel Brook Trail cross. Perhaps it's only natural that this route would be attractive to a transmission developer today.

    Fascinating to see this discussion here. I write a daily blog about energy policy issues, like Canadian power imports. If you're interested, you can read it here:
    http://www.energypolicyupdate.blogspot.com/

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    Senior Member RoySwkr's Avatar
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    Quote Originally Posted by el-bagr View Post
    Keeping this thread germane: I suspect many of us have crossed part of the transmission system in question, hiking along the AT from Mount Wolf north to the Kinsmans. According to Guy Waterman, Nathan Kinsman settled in the Easton Valley in 1782 and cut a cart path over the Kinsman Ridge through a notch where the present power line and the Reel Brook Trail cross.
    Apparently this was originally called Kinsman Notch, with the notch to S being Lost River Notch

    The present powerline location was also proposed as a route for I-93 with many AMC officials preferring it to Franconia Notch, but as we know it didn't happen

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    Senior Member Waumbek's Avatar
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    So how does the argument in this link relate to the discussion at hand about the prohibitive expense of burying the Northern Pass HVDC line?

    http://www.renewableenergyworld.com/...an-ugly-towers

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