Can coal be clean?
Coal has several advantages as a fuel. It is abundant. It is widely distributed: countries that are short of other fossil fuels, such as Germany and South Africa, have mountains of it. As a result, it is cheap. Even though the price has risen in the past few years, it is still less expensive to run a power plant on coal than on almost anything else.
But coal is also dirty. It releases lots of soot and various noxious chemicals as it burns, and so has fallen out of favour in many Western countries. Worse, coalfired plants produce roughly twice as much carbon dioxide per unit of electricity generated than those that run on natural gas.
The obvious solution is to make coalfired generation cleaner. And that’s what utilities in Western countries have been doing for years, to comply with ever stiffer airpollution standards. Reducing emissions of carbon dioxide, however, is another matter. In Britain, as in most rich countries, the average efficiency of coalfired power stations is about 35%. But Mitsui Babcock, an engineering firm, says its most recent designs can achieve efficiencies as high as 46%. It reckons that switching from an old design to a new one can cut fuel consumption and emissions by 23%.
Many methods can reduce the various emissions produced by coalfired power stations, so that they are at least no worse than gasfired stations. But technologies also exist to make coal cleaner still, by filtering out carbon dioxide from the flue gas and storing it somehow. This is theoretically possible, but expensive. Moreover, unlike modifications that improve efficiency, there are no savings to be had by adding carboncapture technology to a power plant. As a result, no such plants have been built.
How does carbon capture work? Most utilities are eyeing one of three basic designs. The simplest, and easiest to bolt on to existing plants, treats carbon dioxide like any other pollutant, and extracts it from the flue gas. Many firms already use this "amine scrubbing" approach to remove carbon dioxide from natural gas, for example. But it is not so practical for largescale uses, since the amines are expensive, as is heating them to release the captured carbon dioxide.
"Oxy fuel" plants sidestep the difficulties of separating oxygen and nitrogen in the flue gas by burning coal in pure oxygen rather than air. The resulting flue gas is almost pure carbon dioxide. But the energy used to separate oxygen from air before burning is almost as great as that needed to filter out nitrogen afterwards, leading to a similar loss of efficiency.
The third approach, called "integrated gasification combined cycle" (IGCC), also requires oxygen, but for use in a chemical reaction rather than for burning. When heated in oxygen, coal reacts to form carbon dioxide and hydrogen. An amine solution then absorbs the carbon dioxide, while the hydrogen is burnt in a modified furnace. The amine scrubbing is cheaper than usual, since the reaction generates carbon dioxide in a more concentrated form. Engineers are also experimenting with membranes that would allow hydrogen to pass, but not carbon dioxide. There are four IGCC demonstration plants operating in America and Europe, although none currently captures carbon dioxide permanently; instead, it is simply released into the atmosphere. AEP’s planned new plants will follow a similar design.
George Bush is a believer, at any rate. In 2003 he unveiled a subsidised scheme to build a zeroemissions IGCC plant called "Future Gen" by 2013. The European Union, for its part, is giving money to utilities dabbling in oxy fuel, among other schemes. Handouts from the taxpayer are needed, power firms argue, since the technology in question is still young. But it is hard to believe that it will ever grow up unless subsidies give way to stronger measures, such as longterm caps or taxes on carbondioxide emissions. The technology to eliminate such emissions from coalfired plants exists, but it will not be adopted without regulatory incentives from governments.
distribute
v.①分發(fā)，分配;②分布;③配(電);④(over)散布
[真題例句] For example, a grandmotherly woman staffing an animal rights booth at a recent street fair was distributing (①) a brochure that encouraged readers not to use anything that comes from or is tested in animals-no meat, no fur, no medicines.[2003年閱讀2]
[例句精譯] 例如，在近期的一次集市上，一位老奶奶站在動物權利宣傳點前散發(fā)小冊子，規(guī)勸人們不要使用動物制品和動物實驗制品--肉類，毛皮，藥物。
utility
n.效用，有用
[真題例句] Decisions based on utility as opposed to lack of utility are straightforward.[1996年翻譯]
[例句精譯] 根據項目是否有效來做決策簡單明了。
capture
n.捕獲，俘虜;v.①吸引(注意);②記錄;③俘虜
真題例句] Few creations of big technology capture (v.①) the imagination like giant dams.[1998年閱讀1]
[例句精譯] 重大科技創(chuàng)造中很少能像大型水壩這樣讓人癡迷的。
[真題例句] While even the modestly educated sought an elevated tone when they put pen to paper before the 1960s, even the most well regarded writing since then has sought to capture (v.②) spoken English on the page.[2005年閱讀4]
[例句精譯] 在60年代以前，甚至僅受過一般教育的人在下筆時都要尋求一種更高雅的腔調，但在那之后，即使是關注的文章也開始把口語用于寫作。
absorb
v.①吸收;②吸收，使專心
eliminate
v.消除
[真題例句] If the products is in short supply relative to the demand, the price will be bid up and some consumers will be eliminated from the market.[1994年閱讀1]
[例句精譯] 如果商品供不應求，價格就上升，有些消費者就會被排擠出市場。
Little Tips:
由于世界石油和天然氣價格居高不下，全球發(fā)電能源構成正出現(xiàn)重大轉變，煤炭將重新成為新建電廠的首選燃料。當前世界發(fā)電燃料再度轉為以煤為主決非偶然，而是由多種因素促成的。其中最重要的是清潔煤技術的研究發(fā)明，使煤炭利用更加環(huán)保、更為經濟。這不僅是產業(yè)界的重大轉變，更證明了科學技術對于世界能源利用的推進作用。
煤炭可能干凈嗎?
作為燃料，煤炭兼?zhèn)涠囗梼?yōu)勢。首先，它的儲量豐富、分布廣泛：缺乏其他化石燃料的國家，如德國和南非，卻擁有堆積如山的煤炭。因此，煤炭的價格也很低廉。盡管煤炭的價格在過去幾年里有所上浮，但燃煤發(fā)電站的運營成本仍低于幾乎任何一種其他類型的發(fā)電站。
但煤炭也是種污濁不堪的燃料。它會隨著燃燒釋放大量煤煙和有害化學物質，因此許多西方國家已經不再鐘情于它了。更糟的是，燃煤發(fā)電站的單位發(fā)電產生的二氧化碳量幾乎是天然氣發(fā)電站的兩倍。
直接的解決之道是令燃煤發(fā)電變得更加清潔，而且這正是西方國家里的那些公用事業(yè)公司們多年來為達日漸苛刻的空氣污染的標準所不斷努力的方向。
然而，減少二氧化碳的排放量則需另辟蹊徑。同大多數富國一樣，英國燃煤發(fā)電站的平均燃燒效率在35%左右。但是三井巴布科克(Mitsui Babcock)能源有限公司(一家工程公司)宣稱其最新設計的發(fā)電站可以將燃燒效率提升到46%。該公司預計新設計比起舊設計可以令燃料消耗和污染物排放減少23%。
許多方法均能減少燃煤發(fā)電站制造的各類排放物，所以這類燃煤發(fā)電站對環(huán)境的污染至少不會超出燃氣發(fā)電站的水平。但是借由濾除煙道氣體中的二氧化碳并將其儲存起來從而令煤炭更加清潔的各類技術已然出世。雖理論可行，但代價高昂。另外，不同于提升燃燒效率的各種改進，給電站追加捕碳技術根本無利可圖。結果，人們至今沒有建造一座此類電站。
捕碳究竟如何進行呢?大多數公用事業(yè)公司都將目光聚焦在三種基本設計上。同其他污染物一樣對待二氧化碳并將其從煙道氣體中分離出來是改造現(xiàn)有發(fā)電站的設計中最簡單易行的方案。許多企業(yè)已經采用這種"氨凈化"途徑，例如從天然氣中去除二氧化碳。但是，該法還不適于大規(guī)模使用，因為用以吸收并加熱后釋放溶解的二氧化碳的氨溶液較昂貴。
"燃料增氧(Oxyfuel)"電站則通過其他途徑避開了將氧和氮從煙道氣體中分離的難題，即用純氧而非空氣燃燒煤炭，產生的管道氣體幾乎僅僅是二氧化碳。但是燃燒前將氧氣從空氣中分離所需的能源幾乎不亞于上述將氮氣過濾所需的耗費，這就使得兩者在效率損失上不相上下。
第三種途徑稱為"結合氣化的綜合循環(huán)途徑(IGCC)"。該途徑同樣需要氧氣，但這是作為化學反應之用而不是燃料。當煤炭在氧氣中加熱時經化學反應會形成二氧化碳和氫氣。二氧化碳經氨溶液吸收，而氫氣則送往改進型熔爐燃燒。如此，氨凈化的成本將低于普通方法，因為之前化學反應產生的二氧化碳是高濃度的。工程師們也正在用允許氫氣而不允許二氧化碳通過的半透膜做實驗。在美國和歐洲，現(xiàn)有四座IGCC示范電站，盡管目前為止任何一家都無法將碳永久性地封存起來;相反，很容易釋放而進入大氣。AEP計劃的新電站將采用類似的設計。
喬治?布什是一個忠實的信徒。2003年他公布了一項補貼計劃用以建造一座零排放的IGCC電站，該電站名為"Future Gen"，該計劃將歷時十年。就其他方案而言，歐盟正在給予涉足燃料增氧的公用事業(yè)公司財力支持，這是方案中的一部分。電力公司們強調政府的宣傳報道也是必須的，因為這種存在疏漏的技術還很不成熟。但是，很難相信沒有強有力的措施，如制定長期減排目標或對二氧化碳排放征稅等，而僅憑蒼白無力的宣傳就能夠促使該技術不斷成長和發(fā)展。除去燃煤電廠產生的排放物的技術已經出現(xiàn)，但是離開政府的監(jiān)管和激勵后將無人問津。
Coal has several advantages as a fuel. It is abundant. It is widely distributed: countries that are short of other fossil fuels, such as Germany and South Africa, have mountains of it. As a result, it is cheap. Even though the price has risen in the past few years, it is still less expensive to run a power plant on coal than on almost anything else.
But coal is also dirty. It releases lots of soot and various noxious chemicals as it burns, and so has fallen out of favour in many Western countries. Worse, coalfired plants produce roughly twice as much carbon dioxide per unit of electricity generated than those that run on natural gas.
The obvious solution is to make coalfired generation cleaner. And that’s what utilities in Western countries have been doing for years, to comply with ever stiffer airpollution standards. Reducing emissions of carbon dioxide, however, is another matter. In Britain, as in most rich countries, the average efficiency of coalfired power stations is about 35%. But Mitsui Babcock, an engineering firm, says its most recent designs can achieve efficiencies as high as 46%. It reckons that switching from an old design to a new one can cut fuel consumption and emissions by 23%.
Many methods can reduce the various emissions produced by coalfired power stations, so that they are at least no worse than gasfired stations. But technologies also exist to make coal cleaner still, by filtering out carbon dioxide from the flue gas and storing it somehow. This is theoretically possible, but expensive. Moreover, unlike modifications that improve efficiency, there are no savings to be had by adding carboncapture technology to a power plant. As a result, no such plants have been built.
How does carbon capture work? Most utilities are eyeing one of three basic designs. The simplest, and easiest to bolt on to existing plants, treats carbon dioxide like any other pollutant, and extracts it from the flue gas. Many firms already use this "amine scrubbing" approach to remove carbon dioxide from natural gas, for example. But it is not so practical for largescale uses, since the amines are expensive, as is heating them to release the captured carbon dioxide.
"Oxy fuel" plants sidestep the difficulties of separating oxygen and nitrogen in the flue gas by burning coal in pure oxygen rather than air. The resulting flue gas is almost pure carbon dioxide. But the energy used to separate oxygen from air before burning is almost as great as that needed to filter out nitrogen afterwards, leading to a similar loss of efficiency.
The third approach, called "integrated gasification combined cycle" (IGCC), also requires oxygen, but for use in a chemical reaction rather than for burning. When heated in oxygen, coal reacts to form carbon dioxide and hydrogen. An amine solution then absorbs the carbon dioxide, while the hydrogen is burnt in a modified furnace. The amine scrubbing is cheaper than usual, since the reaction generates carbon dioxide in a more concentrated form. Engineers are also experimenting with membranes that would allow hydrogen to pass, but not carbon dioxide. There are four IGCC demonstration plants operating in America and Europe, although none currently captures carbon dioxide permanently; instead, it is simply released into the atmosphere. AEP’s planned new plants will follow a similar design.
George Bush is a believer, at any rate. In 2003 he unveiled a subsidised scheme to build a zeroemissions IGCC plant called "Future Gen" by 2013. The European Union, for its part, is giving money to utilities dabbling in oxy fuel, among other schemes. Handouts from the taxpayer are needed, power firms argue, since the technology in question is still young. But it is hard to believe that it will ever grow up unless subsidies give way to stronger measures, such as longterm caps or taxes on carbondioxide emissions. The technology to eliminate such emissions from coalfired plants exists, but it will not be adopted without regulatory incentives from governments.
distribute
v.①分發(fā)，分配;②分布;③配(電);④(over)散布
[真題例句] For example, a grandmotherly woman staffing an animal rights booth at a recent street fair was distributing (①) a brochure that encouraged readers not to use anything that comes from or is tested in animals-no meat, no fur, no medicines.[2003年閱讀2]
[例句精譯] 例如，在近期的一次集市上，一位老奶奶站在動物權利宣傳點前散發(fā)小冊子，規(guī)勸人們不要使用動物制品和動物實驗制品--肉類，毛皮，藥物。
utility
n.效用，有用
[真題例句] Decisions based on utility as opposed to lack of utility are straightforward.[1996年翻譯]
[例句精譯] 根據項目是否有效來做決策簡單明了。
capture
n.捕獲，俘虜;v.①吸引(注意);②記錄;③俘虜
真題例句] Few creations of big technology capture (v.①) the imagination like giant dams.[1998年閱讀1]
[例句精譯] 重大科技創(chuàng)造中很少能像大型水壩這樣讓人癡迷的。
[真題例句] While even the modestly educated sought an elevated tone when they put pen to paper before the 1960s, even the most well regarded writing since then has sought to capture (v.②) spoken English on the page.[2005年閱讀4]
[例句精譯] 在60年代以前，甚至僅受過一般教育的人在下筆時都要尋求一種更高雅的腔調，但在那之后，即使是關注的文章也開始把口語用于寫作。
absorb
v.①吸收;②吸收，使專心
eliminate
v.消除
[真題例句] If the products is in short supply relative to the demand, the price will be bid up and some consumers will be eliminated from the market.[1994年閱讀1]
[例句精譯] 如果商品供不應求，價格就上升，有些消費者就會被排擠出市場。
Little Tips:
由于世界石油和天然氣價格居高不下，全球發(fā)電能源構成正出現(xiàn)重大轉變，煤炭將重新成為新建電廠的首選燃料。當前世界發(fā)電燃料再度轉為以煤為主決非偶然，而是由多種因素促成的。其中最重要的是清潔煤技術的研究發(fā)明，使煤炭利用更加環(huán)保、更為經濟。這不僅是產業(yè)界的重大轉變，更證明了科學技術對于世界能源利用的推進作用。
煤炭可能干凈嗎?
作為燃料，煤炭兼?zhèn)涠囗梼?yōu)勢。首先，它的儲量豐富、分布廣泛：缺乏其他化石燃料的國家，如德國和南非，卻擁有堆積如山的煤炭。因此，煤炭的價格也很低廉。盡管煤炭的價格在過去幾年里有所上浮，但燃煤發(fā)電站的運營成本仍低于幾乎任何一種其他類型的發(fā)電站。
但煤炭也是種污濁不堪的燃料。它會隨著燃燒釋放大量煤煙和有害化學物質，因此許多西方國家已經不再鐘情于它了。更糟的是，燃煤發(fā)電站的單位發(fā)電產生的二氧化碳量幾乎是天然氣發(fā)電站的兩倍。
直接的解決之道是令燃煤發(fā)電變得更加清潔，而且這正是西方國家里的那些公用事業(yè)公司們多年來為達日漸苛刻的空氣污染的標準所不斷努力的方向。
然而，減少二氧化碳的排放量則需另辟蹊徑。同大多數富國一樣，英國燃煤發(fā)電站的平均燃燒效率在35%左右。但是三井巴布科克(Mitsui Babcock)能源有限公司(一家工程公司)宣稱其最新設計的發(fā)電站可以將燃燒效率提升到46%。該公司預計新設計比起舊設計可以令燃料消耗和污染物排放減少23%。
許多方法均能減少燃煤發(fā)電站制造的各類排放物，所以這類燃煤發(fā)電站對環(huán)境的污染至少不會超出燃氣發(fā)電站的水平。但是借由濾除煙道氣體中的二氧化碳并將其儲存起來從而令煤炭更加清潔的各類技術已然出世。雖理論可行，但代價高昂。另外，不同于提升燃燒效率的各種改進，給電站追加捕碳技術根本無利可圖。結果，人們至今沒有建造一座此類電站。
捕碳究竟如何進行呢?大多數公用事業(yè)公司都將目光聚焦在三種基本設計上。同其他污染物一樣對待二氧化碳并將其從煙道氣體中分離出來是改造現(xiàn)有發(fā)電站的設計中最簡單易行的方案。許多企業(yè)已經采用這種"氨凈化"途徑，例如從天然氣中去除二氧化碳。但是，該法還不適于大規(guī)模使用，因為用以吸收并加熱后釋放溶解的二氧化碳的氨溶液較昂貴。
"燃料增氧(Oxyfuel)"電站則通過其他途徑避開了將氧和氮從煙道氣體中分離的難題，即用純氧而非空氣燃燒煤炭，產生的管道氣體幾乎僅僅是二氧化碳。但是燃燒前將氧氣從空氣中分離所需的能源幾乎不亞于上述將氮氣過濾所需的耗費，這就使得兩者在效率損失上不相上下。
第三種途徑稱為"結合氣化的綜合循環(huán)途徑(IGCC)"。該途徑同樣需要氧氣，但這是作為化學反應之用而不是燃料。當煤炭在氧氣中加熱時經化學反應會形成二氧化碳和氫氣。二氧化碳經氨溶液吸收，而氫氣則送往改進型熔爐燃燒。如此，氨凈化的成本將低于普通方法，因為之前化學反應產生的二氧化碳是高濃度的。工程師們也正在用允許氫氣而不允許二氧化碳通過的半透膜做實驗。在美國和歐洲，現(xiàn)有四座IGCC示范電站，盡管目前為止任何一家都無法將碳永久性地封存起來;相反，很容易釋放而進入大氣。AEP計劃的新電站將采用類似的設計。
喬治?布什是一個忠實的信徒。2003年他公布了一項補貼計劃用以建造一座零排放的IGCC電站，該電站名為"Future Gen"，該計劃將歷時十年。就其他方案而言，歐盟正在給予涉足燃料增氧的公用事業(yè)公司財力支持，這是方案中的一部分。電力公司們強調政府的宣傳報道也是必須的，因為這種存在疏漏的技術還很不成熟。但是，很難相信沒有強有力的措施，如制定長期減排目標或對二氧化碳排放征稅等，而僅憑蒼白無力的宣傳就能夠促使該技術不斷成長和發(fā)展。除去燃煤電廠產生的排放物的技術已經出現(xiàn)，但是離開政府的監(jiān)管和激勵后將無人問津。