美發現超大「甲烷熱點」 年洩漏量超標3倍 | 環境資訊中心
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美發現超大「甲烷熱點」 年洩漏量超標3倍

2014年10月14日
摘譯自2014年10月10日ENS美國,加州,帕薩迪納報導;姜唯編譯;蔡麗伶審校

美國太空總署(NASA)和密西根大學合作的衛星資料研究顯示,西南部一處「甲烷熱點」所製造的溫室氣體甲烷濃度不但全美最高,甚至高過標準地面估計值的3倍以上。

美國太空總署NASA衛星資料發現一處巨大「甲烷熱點」。(來源:NASA/JPL-Caltech/University of Michigan)

天然氣生產設備處置不當 年洩漏量超乎預期 

此甲烷熱點位於亞利桑那州、科羅拉多州、新墨西哥州和猶他州4州的交界,面積2,500平方英哩(6,500平方公里)。

研究主要作者、密西根大學學者Eric Kort說,研究的時間點早於熱點附近廣泛的水力裂解活動。這表示並非裂解造成甲烷釋放,而是新墨西哥州聖胡安盆地天然氣生產處理設備洩漏的關係,而該處是美國最活躍的煤炭層甲烷產地。

根據2003年至2009年間每年進行的研究,該地區釋出約59萬噸的甲烷進入大氣,是歐盟常用的全球大氣研究排放數據估計值的3.5倍。

「結果顯示,石化燃料採集技術所排放的比所儲藏的還要多。」Kort說。

儀器偵測二度驗證 甲烷熱點一直都在

甲烷無色無味,沒有科學儀器難以偵測其洩漏。

在這項發表於「地質物理研究快訊」的研究中,科學家用歐洲太空總署的「大氣製圖用掃描影像吸收光譜儀」(Scanning Imaging Absorption Spectrometer for Atmospheric Cartography, SCIAMCHY)進行觀測。

2002至2012年間,SCIAMCHY就曾被應用於測量溫室氣體。研究期間,該甲烷熱點便一直存在著。由美國能源部洛斯阿拉莫斯國家實驗室(Los Alamos National Laboratory)運作的一總碳柱觀測網絡地面觀測站(Total Carbon Column Observing Network)已獨立驗證了該測量數據。

計算熱點甲烷排放速度需要觀測大氣中甲烷濃度,研究人員用化學運輸模型進行高解析度的區域模擬,這種方法也用於模擬氣候變化和空氣中化學物質的改變。

甲烷洩漏有爆炸疑慮 氣體溫室效果更強於二氧化碳

甲烷跟二氧化碳一樣,會在地球表面聚熱,造成全球暖化。不過甲烷的溫室效果是二氧化碳的22倍。一般天然氣成分有95%~98%是甲烷。

1970年代美國能源危機後,從煤礦採集甲烷的技術問世,被用於開發燃料。2012年,「煤炭層甲烷」佔全美天然氣供給的8%。煤炭層甲烷是充滿煤炭孔隙的氣體,在地下煤礦中是一種危險氣體,每年都因滲漏引起致命的爆炸意外。

Huge U.S. Methane ‘Hot Spot’ Detected From Space
PASADENA, California, October 10, 2014 (ENS)

Just one location in the U.S. Southwest is responsible for producing the largest concentration of the greenhouse gas methane seen over the United States – more than triple the standard ground-based estimate, according to a new study of satellite data by scientists at NASA and the University of Michigan.

Methane traps heat in the Earth’s atmosphere and, like carbon dioxide (CO2), it contributes to global warming. But methane is 22 times more potent as a greenhouse gas than is CO2.

The “hot spot,” near the Four Corners intersection of Arizona, Colorado, New Mexico and Utah, covers about 2,500 square miles (6,500 square kilometers).

In each of the seven years studied from 2003-2009, the area released about 0.59 million metric tons of methane into the atmosphere.

This is almost 3.5 times the estimate for the same area in the European Union’s widely used Emissions Database for Global Atmospheric Research.

The study’s lead author, Eric Kort of the University of Michigan says the study period predates the widespread use of hydraulic fracturing, known as fracking, near the hot spot.

This indicates that the methane emissions should not be attributed to fracking but instead to leaks in natural gas production and processing equipment in New Mexico’s San Juan Basin, which is the most active coalbed methane production area in the country.

Natural gas is 95 to 98 percent methane. Methane is colorless and odorless, making leaks hard to detect without scientific instruments.

“The results are indicative that emissions from established fossil fuel harvesting techniques are greater than inventoried,” Kort said.

Coalbed methane is gas that lines pores and cracks within coal. In underground coal mines, it is a deadly hazard that causes fatal explosions almost every year as it seeps out of the rock.

After the U.S. energy crisis of the 1970s, techniques were invented to extract the methane from the coal and use it for fuel. By 2012, coalbed methane supplied about eight percent of all natural gas in the United States.

In the study published online today in the journal “Geophysical Research Letters,” researchers used observations made by the European Space Agency’s Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument.

SCIAMACHY measured greenhouse gases from 2002 to 2012. The atmospheric hot spot persisted throughout the study period. A ground station in the Total Carbon Column Observing Network, operated by the Department of Energy’s Los Alamos National Laboratory, provided independent validation of the measurement.

To calculate the emissions rate that would be required to produce the observed concentration of methane in the air, the authors performed high-resolution regional simulations using a chemical transport model, which simulates how weather moves and changes airborne chemical compounds.

※ 全文及圖片詳見:ENS

作者

蔡麗伶(LiLing Barricman)

In my healing journey and learning to attain the breath awareness, I become aware of the reality that all the creatures of the world are breathing the same breath. Take action, here and now. From my physical being to the every corner of this out of balance's planet.