A Floating Tower of Wind Power Sets Sail
浮動風力發電塔上場了
By Matthew L. Wald

One reason that offshore wind has not caught on as a source of power in the United States is the steep cost of erecting a tower in the water, but researchers at the University of Maine tried another approach recently by launching a floating wind machine. It is the first offshore wind installation in United States waters, according to the Energy Department.
離岸（或稱近海）風力至今未能成為美國電力的一個主要來源，原因之一是在水面上安裝電塔太花錢。緬因大學的研究人員最近嘗試另外一種方法：投放一部浮動風力機。美國聯邦能源部表示，這是在美國水域的第一個離岸風力發電設施。

The tower, launched in Brewer, Maine, sits on three hollow concrete tubes and will be anchored in the Gulf of Maine. It is a mere 20 kilowatts in capacity, an amount of power that could be soaked up by a handful of big suburban houses on a hot summer day. But it is one-eighth the dimensions of the one the researchers hope to deploy in the next few years, a gigantic 6-megawatt model, with each blade as long as the wingspan of a Boeing 747.
這座發電塔已在緬因州的布魯爾下水，底部是三根中空的水泥管，預定在緬因灣固定。它的發電容量只有20瓩，小到幾個大型郊區住家一個燠熱的盛夏日子就可以耗盡。然而它的大小僅為研究人員希望未來幾年可以實際部署的大型發電設施的1/8。後者的發電容量可達6000瓩，每一個葉片的長度相當於波音747客機的翼展。

Because of its site, it will have two big advantages over machines on land, according to Habib J. Dagher, a professor of civil engineering at the university. Onshore wind machines produce most of their energy at night, when it is least valuable to utilities buying the power, but this one will catch the predictable, strong breezes that come up every sunny summer afternoon, he said, when the sun heats the land more than the sea, creating an onshore breeze.
緬因大學土木工程學教授達格爾表示，它的位置使它相對於陸上風力發電設施而言，享有兩大優勢。陸上風力機發電時段多數是在夜間，對購買電力的公用事業而言電力價值最低。達格爾指出，緬因灣的這座電塔可以利用陽光普照的夏季午後吹往岸上的可預期強風。每年的這個時節，在太陽照射下陸地溫度高於海面，形成吹向陸地的風。

Over a year, onshore machines in the Eastern United States produce only about a third as much electricity as would result if they ran at full tilt every hour of the year, but this one will produce 40 percent to 50 percent as much, he said, because winds offshore are stronger.
他表示，美國東部岸上風力發電設施一年生產的電力，約僅為全年全力運轉的1/3，緬因灣的海上風力發電塔生產的電力則可達40%至50%，因為岸外的風力比較強。

The engineering, though, is tricky; for one thing, the tip of the tower will swing on the waves. But the platform is designed to rock at a slower rate than the waves to lessen their impact.
癥結是，工程問題相當棘手。電塔的頂部會在波浪中搖晃。不過它的平台搖動速率設計成可低於波浪，以降低波浪的影響。

The project is one of seven sponsored by the Energy Department under a $168 million program. Three are floating, four are fixed, and this is the first to be put into use, said Jose Zayas, director of the department’s Wind and Water Power Technologies office.
這是美國能源部以1.68億美元贊助的七個風電機計畫之一，三座浮動式，四座固定式。能源部所屬「風力及水力技術辦公室」主管沙亞斯表示，緬因灣的風力發電塔是第一個啟用的設施。

The project is small but “it’s important to recognize it is at a relevant scale,” he said. “It does represent the behaviors and dynamics of a large machine.”
他表示，這項計畫的規模很小，然而各界必須明白，「它的規模具實用意義」。他說：「它代表一部大型機器的行為模式與力學。」

Among the issues is durability; Mr. Dagher said the concrete would not corrode and should last 60 years.
耐用性是問題之一。達格爾表示，水泥不會腐蝕，應該可以使用60年。

“The beauty of the floating technology is it doesn’t care what the water depths are,” he said.
他說：「浮動技術的迷人之處是，它不在乎水有多深。」

Water is shallow off most of the East Coast but not off Maine, and not off much of California’s coast, experts say.
專家表示，美國東岸外海大多是淺水域，緬因州外海則是深水域，加州外海也以深水域居多。

Peter Mandelstam, a wind developer and longtime chairman of the American Wind Energy Association’s offshore group, said, “We and other developers want this technology developed on both coasts.”
擔任美國風力能源協會離岸小組主席的風力開發商曼德爾史坦姆說：「我們與其他開發商都希望能夠在美國東西兩岸發展這種技術。」

原文參照：
http://www.nytimes.com/2013/06/01/business/energy-environment/a-floating-wind-tower-is-launched-in-maine.html

2013-06-18聯合報/G5版/UNITEDDAILYNEWS陳世欽譯 原文參見紐時週報八版下