Power Lines Going Underwater

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The US, in keeping with most developed societies, faces a dilemma in securing reliable power delivery. On the one hand, the country needs new power lines to bring renewable energy and new power plant supply from remote areas to the metropolitan areas. On the other hand, there is growing opposition from the public to unsightly and allegedly health damaging overhead power lines.  But a solution to these conflicting pressures has resulted in a quiet revolution in power transmission laying power lines under water. OK you say that’s fine between offshore wind farms and the mainland or between adjacent islands as in say Hawaii, but what relevance does it have on the continental mainland?

Well not all locations can be served in this way but certainly many projects are either under construction or on the drawing boards that make use of rivers and lakes to lay power cables relatively cheaply and with the minimum of disruption.

In a New York Times article Edward M. Stern, president of PowerBridge, a company that built a 65-mile offshore cable from New Jersey to Long Island, summed up the issue of gaining approval for new power lines by saying “The fish don’t vote.

Underwater lines are still more expensive than overhead lines hung from transmission towers. Mr. Stern’s 65-mile Neptune Cable, which runs from Sayreville, N.J., to Levittown, N.Y., on Long Island cost about $600 million, and a 53-mile cable under San Francisco Bay cost about $505 million. 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.

Standard lines hung on towers run from $1 million to $4 million a mile, depending on terrain and other factors, but as Donald G. Jessome, the president of Transmission Developers is quoted as saying, “If you can’t get them built, because the communities you want to serve don’t want them, then in our opinion they are infinitely expensive. His firm is seeking approval for an even more ambitious project. Beginning north of the Canadian border, a 370-mile line would run along the bottom of Lake Champlain, down the bed of the Hudson all the way to New York City. It would continue under Long Island Sound to Connecticut. If built, it would be one of the longest submarine power cables in the world. It would bring hydroelectricity to the power-thirsty New York City market. It would also break a stalemate; New York has not had a major new overhead power line in 20 years.

The metals markets are not gong to see a discernible difference in demand. Volumes used in power transmission although significant are not going to be impacted overnight by such a switch from overhead which generally uses aluminum for lightness and cost, to copper, generally used underground for longevity and transmission capacity.

Even environmental groups, some environmental groups anyway, are supporting projects on the grounds it is better to have power lines out of sight at an affordable cost, especially if it supports investment in renewable or less polluting power sources.

–Stuart Burns

Comment (1)

  1. Undergrounding is the replacement of overhead cables providing electrical power or telecommunications, with underground cables. Undergrounding can increase the initial costs of electric power transmission and distribution but may decrease operational costs over the lifetime of the cables.

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