Harvesting Megawatts From Tidal Lagoons
潟湖潮汐提供大量電力
By Beth Gardiner

LONDON – The development of a new generation of sea-based power arrays lags far behind more widely used renewable technologies like wind and solar.
新一代海基發電陣列的發展，目前仍遠落後於使用更廣泛的再生能源技術，例如風力與太陽能。

But the company pushing a new project on the coast of Wales thinks its update of traditional dam-based hydropower will be much easier to bring to fruition.
不過，在威爾斯海岸推動一項新計畫的這家公司，認為將傳統以水壩為基礎的水力發電加以升級，可讓海基發電的成果更容易實現。

Tidal Lagoon Power Limited says the approach, known as tidal lagoon generation, could provide as much as 10 percent of Britain’s power from six of its projects within a decade. That is an optimistic. Still, those hoping the seas will become an energy source will be watching Swansea Bay, Wales, where the company hopes to get approval this spring to build the first lagoon.
「潮汐潟湖電力有限公司」表示，透過該公司的6項計畫，10年內，這種名為潮汐潟湖發電的方法，最高可望提供英國10%的電力。這項說法十分樂觀。儘管如此，期待海洋能成為能源來源的人，將會密切觀察威爾斯天鵝海灣的發展。該公司希望今春能獲准於該地打造第一座潟湖。

“If it’s put together and it’s a success, people will look for other similar areas where there’s some development opportunity,” said Douglas J. Arent of the National Renewable Energy Laboratory in Colorado. Because it needs a large difference between the levels of high and low tides, tidal lagoon power is likely workable in few places, like Alaska’s Cook Inlet and parts of South Korea. Mr. Arent said it could still be useful because, unlike the wind and sun, tides are predictable.
美國科羅拉多州「國家再生能源實驗室」的道格拉斯．艾倫特說：「若能建造完成，成功發電，人們會開始尋找有開發機會的其他類似地區。因為它需要海水漲退潮時有極大水位差，潮汐潟湖發電只能在少數幾個地方行得通，如阿拉斯加庫克灣與南韓部分地區。但是艾倫特說它仍有用處，因為它和風能、太陽能不同，潮汐是可以預測的。

The Swansea Bay plan is estimated to cost 1 billion pounds, or $1.6 billion. Engineers would build a large holding pool along the shore, contained by a seawall. When the tide rises, water levels become higher outside the pool than in. Gates open to let water enter, turning turbines. When the tide recedes, the levels are higher inside than outside, and the water, when released, turns the turbines in the other direction. In principle, it is not so different from projects like the barrage at the mouth of the Rance river in France, or the Sihwa Lake station in South Korea. Because they often block estuaries, though, such plants raise worries about environments damage. The lagoon approach seeks to minimize such impact.
天鵝海灣計畫估計造價10億英鎊，合16億美元。工程人員將沿著海岸建造一個大型蓄水池，以海堤圍起。漲潮時，池外海水水位高於池內。打開閘門，讓潮水流入，推動渦輪。退潮時，池內水位高於池外。將海水洩出時，從相反方向推動渦輪。原則上，它和法國蘭斯河口或南韓始華湖潮汐電廠的堰壩差不多，但因它們經常封住河口，這類電廠引來破壞環境的憂慮。潟湖的作法尋求將這項衝擊降至最小。

Worldwide, plants in the broader category of tidal range now have about 500 megawatts of power-generating capacity, and that could rise to 800 megawatts by 2020, experts say. That is tiny compared, for example, to global solar panel capacity, which grew by an estimated 100 megawatts every day in 2013.
廣義而言的潮汐發電，全球目前發電總容量約為500百萬瓦，專家表示，這項產能可望在2020年提高到800百萬瓦，與其他發電形式相比算是小兒科。且以全球太陽能板發電為例，2013年產能每天約成長100百萬瓦。

The biggest concern for the project, energy experts say, is its high cost, and the fear of budget overruns, in part because of the need for a 10-kilometer seawall. A report that Tidal Lagoon Power commissioned from the consulting firm Poyry estimated that the Swansea lagoon would require a price of 168 pounds per megawatt hour, just above the guarantee provided to offshore wind farms, considered very expensive. The five projects the company hopes to build subsequently would bring the cost down to 92 pounds per megawatt hour.
能源專家說，這項計畫最令人擔心之處是成本高昂，而且預算可能超支，部分是因它需要建造長10公里的海堤。「潮汐潟湖電力」委託顧問公司「貝利」所做的報告估計，天鵝海潟湖每百萬瓦小時電力的成本價是168英磅，略高於提供給離岸風力發電場的擔保價格，十分昂貴。公司希望後續建造的5個計畫，能將成本降至每百萬瓦小時92英鎊。

“If you are serious about decarbonizing your electricity supply, frankly you need all the technologies available, whether that’s wind, solar, nuclear,” or anything else, said Ali Lloyd, one of the authors of the Poyry report. “There’s a role for all of them.”
貝利報告的作者之一艾里．勞依德說：「在電力供應上，如果你想認真看待去碳這件事，坦白說，你需要所有可用的技術，無論是風能、太陽能、核能，或任何其他能源。所有能源都有它的一角。」

原文參照：
http://www.nytimes.com/2014/10/29/business/energy-environment/swansea-bay-generating-power-from-tidal-lagoons.html

2015-01-20聯合報/G5版/UNITED DAILY NEWS 王麗娟譯 原文參見紐時週報十二版下