coal gasification the clean energy of the future

1、coal gasification: the clean energy of the future?by richard anderson business reporter, bbc news13 april 2014 last updated at 23:10 turning coal into gas is not as environmentally friendly as it sounds dirty it may be, but coal is cheap. for this simple reason, it remains the worlds main source of

2、power, providing a quarter of our primary energy and more than 40% of our electricity. and it will continue to do so for many years to come.the challenge, then, is how to harness coals energy more cleanly. while global attempts to develop carbon capture and storage (ccs) have stalled, a number of co

3、untries are looking at different ways to exploit their abundant coal reserves.not all are motivated by environmental concerns, but are driven instead by economics and a desire for energy independence.old and new the main technology being used is coal gasification - instead of burning the fossil fuel

4、, it is chemically transformed into synthetic natural gas (sng).the process is decades old, but recent rises in the price of gas mean it is now more economically viable. the us has dabbled in the technique, but china is going all out in a bid to satisfy its soaring demand for power and reduce its de

5、pendency on imported liquefied natural gas (lng). the countrys national energy administration has laid out plans to produce 50 billion cubic metres of gas from coal by 2020, enough to satisfy more than 10% of chinas total gas demand.not only does it make economic sense, but it allows china to exploi

6、t stranded coal deposits sitting thousands of kilometres from the countrys main industrial centres. transporting gas is, after all, a lot cheaper than transporting coal.coal gasification can also help address local pollution problems that have in recent months brought parts of the country to a virtu

7、al standstill.but there are two big problems. first, coal gasification actually produces more co2 than a traditional coal plant; so not only will china be using more coal, it will be doing so at a greater cost to the environment.as laszlo varro, head of gas, coal and power markets at the internation

8、al energy agency (iea), says: coal gasification is attractive from an economic and energy security perspective. it can be a nice solution to local pollution, but its overall carbon intensity is worse than coal mining, so it is not attractive at all from a climate change point of view.the us has expe

9、rimented with coal gasification in recent years indeed a study by duke university in the us suggests synthetic natural gas emits seven times more greenhouse gases than natural gas, and almost twice as much carbon as a coal plant.the second problem is water use. coal gasification is one of the more w

10、ater-intensive forms of energy production, and large areas of china, particularly in the western parts of the country that would host new gasification plants, already suffer from water shortages.mr varro says a recent iea report concluded that coal and coal gasification plants would use quite a subs

11、tantial portion of the available water in china.abundant reserves other countries are looking at different ways to get gas from coal. one method, particularly popular in australia, is coal-bed methane, a process allowing access to coal deposits that are too deep to mine. water is sucked out of the s

12、eam and the methane attached to the surface of the coal is freed and then collected. china, indonesia and mozambique are looking at coal-bed methane, while the us and canada also have abundant reserves.very little co2 is emitted, but the process is not without controversy. opponents highlight concer

13、ns about water contamination, land subsidence and disposing of waste water safely, while the water intensive process sometimes involves fracking.and yet coal-bed methane has fundamentally changed the dynamics of the gas industry in australia, according to phil hirschhorn, partner at the boston consu

14、lting groups energy practice in sydney.he says there are 200 trillion cubic feet of coal-bed methane resources in the country, with projects under construction to liquify and export 25 million tonnes of gas every year - equivalent to 10% of the entire global lng market.clean access a very different

15、way to produce gas from coal is known as underground coal gasification (ucg), a process that has been around since the 19th century but which has yet to become commercially viable on a grand scale - there is currently one working facility in uzbekistan and pilot projects in australia and south afric

16、a.heavy pollution has forced china to rethink how it exploits its coal reserves according to julie lauder, chief executive of the ucg association, the process is a new way of harnessing the energy of coal without the usual environmental impacts.technological developments and the rising price of gas

17、mean ucg is now a feasible way of accessing the vast resources of coal that are too deep to mine, she says. indeed, estimates suggest that as much as 85% of the worlds coal resources cannot be accessed through traditional mining techniques.opening them up to exploitation has potentially disastrous i

18、mplications for co2 emissions and climate change, but the industry says these resources can be accessed cleanly.the process involves pumping oxygen and steam through a small borehole into the coal seam to produce a small and controlled combustion. unlike coal-bed methane, therefore, the actual coal

19、is converted from a solid state into gas. the hydrogen, methane, carbon monoxide and co2 is then siphoned off through a second borehole.according to dr harry bradbury, founder and chief executive of uk clean energy company five quarters, this process results in 20% of the co2 produced from tradition

20、al coal mining.but his company is developing a process that requires no burning of coal, and which combines what dr bradbury calls solid state chemical engineering with releasing gases that are trapped not just in the coal, but in the surrounding rocks as well. and all of this takes place offshore,

21、relieving concerns about water contamination and subsidence, he argues.but the real advantage lies in the ability to capture the co2. we need to get more radical - we need to get to zero carbon, dr bradbury says. full carbon capture and storage is absolutely crucial.this can take place through re-in

22、jecting the co2 back into the coal seams, or by converting the carbon into products such as plastics and graphene, he says.the uk government has established a working party to investigate the merits of ucg, undoubtedly excited by the vast resources of coal sitting under the north sea. other governme

23、nts are equally keen to exploit new technologies to access their hidden coal seams.the problem, of course, is that the process depends entirely on wider efforts to develop ccs, efforts that have, so far, singularly failed to find a solution.until one is found, any attempts to gasify coal underground

24、 will either remain theoretical or will exacerbate the already grave problem of co2 emissions. and if recent efforts are anything to go by, we could be waiting a long time.燃煤氣化：未來的清潔能源？譯者：freakymind原文作者：richard anderson煤炭很臟，但是卻很便宜。正因如此，燃煤目前仍然是世界主要的能量來源，它為我們提供了四分之一的主要能源需求以及超過40%的電力。在接下來的許多年里仍將如此。因此，我

25、們面臨的挑戰(zhàn)將是如何以更清潔的方式利用燃煤。盡管全球性的碳采集與儲存(ccs)的嘗試目前停滯不前，仍有一些國家正在探索新的方法來利用他們豐富的燃煤儲量。并非所有這些國家都是出于環(huán)境利益的考量，而可能只是出于經(jīng)濟利益的考慮與能源獨立的需要。老技術(shù)與新方法目前主流的燃煤處理方式是燃煤氣化并非將它燒掉，而是通過化學方法將其轉(zhuǎn)化為人造天然氣（sng）。這項處理方法已經(jīng)沿用了數(shù)十年，但是最近燃氣價格的上漲讓它在經(jīng)濟上更加可行了。美國已經(jīng)開始涉足這項技術(shù)，但是中國正傾盡全力以滿足其迅猛增長的能量需求并減少對進口液化石油氣（lng）的依賴。中國國家能源局已經(jīng)制定出一個要在2020年前利用燃煤生產(chǎn)500億立方

26、米燃氣的計劃，足以滿足中國對燃氣總需求量的10%。這不僅在經(jīng)濟上是可行的，它也讓中國可以將分布在離工業(yè)中心數(shù)千公里遠的地方的煤礦利用起來。畢竟運輸燃氣的成本要比運送燃煤便宜得多。燃煤氣化還有助于解決近幾個月已讓中國部分地區(qū)陷入實質(zhì)上的停滯狀態(tài)的空氣污染問題但是當前這項技術(shù)還有兩大問題。第一個問題是，燃煤氣化比傳統(tǒng)煤炭工廠產(chǎn)生的二氧化碳更多。因此，中國不僅要使用更多的燃煤，還要付出更高的環(huán)境代價。如國際能源署(iea)天然氣、煤炭以及電力部門主管laszlo varro所說：“燃煤氣化從經(jīng)濟及能源安全的角度都看是很吸引力的?！八梢猿蔀橐粋€很好的解決本地污染的解決方案，但是它總體的碳濃度(比煤炭

27、開采)更大，因此從氣候變化的角度來看則一點也沒有吸引力”。實際上，美國杜克大學的一項研究表明人造天然氣的溫室氣體排放比天然氣多七倍，而碳排放量則是煤炭工廠的兩倍。第二個問題則是水的使用。燃煤氣化是耗水較多的能源生產(chǎn)方式中的一種，但中國的大片區(qū)域，尤其是將要建設(shè)氣化工廠的西部地區(qū)，已經(jīng)飽受缺水問題的困擾。varro先生說到一份最近的iea報告得出了一項結(jié)論，煤炭與燃煤氣化工廠會用掉“中國可用水資源的相當大一部分”。豐富的儲量其他國家則在尋找不同的方法來從煤炭中得到燃氣。在澳大利亞比較常見的一種方法是煤層氣法，可以讓人們得以利用埋藏太深而難以開采的煤層。這種方法將水從煤層中抽走，以使附著在煤炭表面的甲烷被釋放出來，再將這些甲烷收集起來。中國，印度尼西亞及莫桑比克都在考慮煤層氣，而美國與加拿大也有豐富的儲量。盡管這種處理流程的二氧化碳排放量很低，但是它的采用也并非沒有異議。反對者們強調(diào)了對水污染，地面沉降和廢水排放方面的擔心，而耗水流程有時又要用到液壓破裂法。而據(jù)波士頓咨詢集團在悉尼的能源業(yè)務(wù)合伙人菲爾赫塞豪恩所言煤層氣已經(jīng)“根本地改變了澳大利亞燃氣行業(yè)的動態(tài)”。他提到，澳大利亞有200萬億立方英尺的煤層氣資源，每年可以從中生產(chǎn)2,500萬噸液化燃氣相當于全球液化天然氣市