Catching the Sun’s Rays And Using Later
貯存多餘太陽能支援電網
By Matthew L. Wald

WASHINGTON – Solar power is growing so fast in California – with installations by customers increasing tenfold since 2006 – that it is turning the state’s power system upside down.
太陽能發電在加州迅速成長，從2006年迄今客戶裝設數量已增加10倍，正使加州的電力系統全盤變動。

In a twist that is being closely watched by power companies around the United States, California utilities will install massive banks of batteries and other devices to store the power surplus created by solar panels in the afternoon, when the sun’s rays are strong.
有一項轉變全美各大電力公司都在密切觀察，就是加州電力業者將設置大量的電池與其他電力貯存設備，把每天下午日照強勁時太陽能板所生產的多餘電力貯存下來。

The batteries are then to begin discharging power into California’s electric grid in the early evening, around sunset, when the solar generation of energy dies down but demand rises as millions of people get home and turn on air-conditioners, televisions and other electricity gobblers.
到黃昏日落之際，再把這些電池貯存的電力下載到加州的電網，此時太陽能所產生的電力下降，但電力需求卻上升，因為數百萬民眾都已回家，打開空調、電視及其他大量耗電的電器。

The new system is the opposite of an idea utilities have considered for years: Use batteries to store power at night from traditional sources, like natural gas and coal, and run them down in the peak heat of late afternoon.
這套新系統與電力公司多年來考慮的構想背道而馳：業者原本打算利用電池，把晚間由天然氣、燃媒等傳統能源所產生的電力貯存下來，以因應下午天氣最熱時的電力需求。

“It is the reverse of the way we’ve always thought of storage,” said Gregory Reed, director of the Electric Power Initiative at the University of Pittsburgh in Pennsylvania.
賓州匹茲堡大學電力計畫召集人芮德說：「這與我們一向所思考的貯存模式完全相反。」

The relatively new idea of using batteries – which could be bundled in packs, each about the size of an 18-wheel truck trailer – to store electricity during the day and discharge it in the evening is aimed at coping with rapid changes in supply and demand. The expense of the batteries, possibly in the billions of dollars for California, has limited their use.
這種利用電池在白天存電、黃昏放電的新構想，目的在於因應電力供給與需求的迅速變化。這些電池可以綁在一起，大小與18輪大拖車差不多。電池成本昂貴，可能使加州居民多負擔數十億美元，因此應用程度原本相當有限。

But booming solar power in California has changed the equation and made the California Public Utilities Commission take a different path.
但加州太陽能發電盛行已使情況改觀，而加州公共電力委員會也因而採取了不同的作法。

At the end of October, the commission ordered the utility companies it regulates to install some form of energy storage equipment – exactly what was not specified – in the first such mandate in the country. A critical purpose of the storage is to allow generators, which in California run largely on natural gas, to keep operating in the late afternoon, when the output from solar panels eliminates the need for their electricity.
去年十月底，委員會指示所管轄的各電力公司裝設一些能源貯存設備，但不明確規定何種設備，而這項強制作法在美國實屬首見。裝設電力貯存設備的重要目的之一，是允許加州以燃燒天然氣為主的各發電廠，在每天下午太陽能電力供給增強、對電廠的電力需求減少時，仍繼續發電。

With so many solar panels in California, “we may find ourselves in periods of time when we have oversupply, overgeneration,” said Clyde Loutan, senior adviser for renewables integration at the California Independent System Operator, which runs the state’s grid. That is just as destabilizing as shortage, he said.
負責加州電網運作的加州獨立系統操作處再生能源整合資深顧問魯坦表示，由於加州裝設大量太陽能板，「我們可能發現自己在某些時段會供給過剩，發電量過多」。他說，這跟電力短缺同樣都是一種不穩定。

The point of keeping the generators running is that they will be needed immediately after the sun sets, but the problem is that they cannot start instantly. By 2020, planners estimate, it will be difficult to balance supply and demand at sunset, because the combination of the sun setting and evening demand picking up will create the instant need for a vast amount of power. The system would have to double its output in about three hours, faster than it can now manage.
讓電廠發電機繼續運作的原因在於，日落之後立即需要電廠供電，而電廠卻無法立即開始運轉。規畫人員估計，到2020年時日落時分的電力供需將難以平衡，因為太陽下山及晚間電力需求激增兩項因素加在一起，將使立即性的電力需求大增。在大約三小時的時間內，電力系統的供電量須提高一倍，而目前電力系統無法如此迅速地增加供電。

The problem is acute in California because the demand for power is concentrated in a narrow coastal band that runs north and south. “The sun sets on all of it at about the same time,” said Philip Undercuffler of Outback Power, a battery company.
加州的問題相當尖銳，因為電力需求集中在從南到北一條狹長的海岸區。電池業者奧巴克電力公司主管安德卡夫勒說：「整個地區太陽幾乎同時下山。」

The utilities commission’s order for storage, which will be phased in starting this year, represents shifting needs, said Laura Wisland of Concerned Scientists. “We’re shifting from a need for capacity on the system to a need for flexibility on the system.”
科學家關注聯盟成員蘿拉．魏斯蘭說，電力委員會下達的電力貯存命令從今年起逐步實施，這表示需求有了改變。「我們正由要求供電系統必須有能力供電，轉變為要求系統必須更有彈性」。

原文參照：
http://www.nytimes.com/2013/12/24/business/energy-environment/catching-some-rays-in-california-and-storing-them.html

Graphic：Solar Power Reshapes the California Grid
http://www.nytimes.com/interactive/2013/12/24/business/solar-power-reshapes-the-california-grid.html

2014-01-28聯合報/G9版/UNITEDDAILYNEWS 任中原譯 原文參見紐時週報七版左