On Feb 20, 2009, at 4:04 AM, Terry Blanton wrote:
On Thu, Feb 19, 2009 at 11:12 PM, Horace Heffner
<hheff...@mtaonline.net> wrote:
I don't understand why power
companies, even here, fight underground transmission so adamantly.
Underground power cables are far more expensive to purchase, install
and maintain. They usually need wholesale replacement in 20 to 30
years.
If true, then this is clearly a design flaw that should be fixable.
Why should cable need wholesale replacement in that short a time frame?
If underwater cable is economic then underground should also be
economic. I think there hasn't been enough motivation to do research
or to improve the engineering in this filed.
I found this study on the web:
http://buckplanning.blogspot.com/2009/02/underground-cables-would-
cost-500m-more.html
http://snipurl.com/capzd [buckplanning_blogspot_com]
I'm sure overhead cable maintenance in Alaska is higher than Ireland;
but, I doubt it outweighs the capital cost factor. Our utility's rate
is a function of their capital cost. They are allowed something on
the order of 13% ROI per annum.
Terry
Well, the article points out that this is still a controversial subject.
"NEPP rejected PB Power’s findings yesterday and claimed that they
were fundamentally flawed."
NEPP statement: “The report grossly overestimates the cost of
operating an underground system and goes in the face of international
expert opinion that, while underground may be more costly to build,
it is always cheaper to operate than overhead,” the group’s statement
said.
Underground DC power transmission at that distance may also be a
possibility. BTW, there is a slowly oscillating multi-conductor (3
wire I think) version of DC transmission (under 1 Hz) that
periodically permits arc free switching. It slowly switches the
power from one conductor to another in a complimentary fashion, yet
sustains full uniform power transmission at all times. I don't
recall now where I saw it.
My feeling is that the cost argument is a red herring, because a
power company here fought underground transmission even though
surveys showed the customers preferred to pay the extra to get rid of
overhead lines. Another power company fought even placing a few
hundred feet of 7,500 V line underground at the end of a runway
because they felt it would set a bad precedent.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
