Matthew Wald in his New York Times blog, has more information about the construction of the Electric Superhighway up and down Delaware’s coast.
Onshore, we use an AC grid, or one based on alternating current. But the link in the Atlantic would have to be buried, and alternating current does not work well in long cables that are enclosed because the interaction between the current and the cable casing drives up voltage to unwanted levels. So the system has to be direct-current.
The cost of putting a cable under water can be lower than burying cables on land, because workers can lay the cables from giant reels, allowing stretches of more than a mile with no splices. But underwater lines are still more expensive than lines on transmission towers. Much of the cost in each case is to transform the electricity to direct current, a form that is easier to use in buried cables.
New technology offered by two European companies, Siemens and ABB, has lowered the cost for some direct current projects, and shrunk the size of the terminals where alternating current is converted to direct current and back, a crucial consideration in urban projects.
One of those companies Siemens, has a plant here in Glasgow, Delaware. Recently, European transmission experts were in town to deliberate.
The cable itself, weighing about 30 pounds a foot, would be lowered into a shallow trench that would be blasted by a device called a jet plow that squirts ocean water into the soil. The cable goes into the trench and is gradually covered over with sediment.
The cable itself is copper, with 1.75 to 2 inches of insulation and multiple shielding layers. It may have a steel outer guard. The outer diameter would be about six inches.
But beyond three miles from shore, no matter where it goes, the cable has a major advantage over cables on land: it faces only one landlord at the outset, the Department of Interior. And the department is sympathetic to wind.
This is a wake up call for Delaware. Governor Markell, Congressman-elect John Carney, Senator-elect Chris Coons, and Senators Ted Kaufman and Tom Carper, all need to get moving on this opportunity now, if only to head off those other states who will be trying to muscle in… These next 24 hours are critical.
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October 12, 2010 at 10:55 am
Duffy
Do not underestimate lower Delawarean’s ability to whine about anything the might alter their precious ocean view. Even something as small as the platform you’re proposing would be a never ending source of complaining. I doubt you’d be able to see it on all but the clearest of days but that doesn’t matter. They’ll still whine.
October 12, 2010 at 12:10 pm
kavips
I don’t think they will… They’re not Massachusetts blue bloods. They don’t really care about their view, especially when it enhances their beaches, making them a tourist mecca for every environmental energy enthusiast living east of the Mississippi…..
October 13, 2010 at 12:38 pm
Duffy
That does not match my personal experience. I work with a guy who’s from Lewes and the first thing he said was something about ruining our view.
October 15, 2010 at 10:18 pm
kavips
He will have to drive down to Rehoboth if he wants to see them.. and only then,… on a clear day…