水力压裂技术是上天的恩赐

    美国环境组织塞拉俱乐部（Sierra Club）执行董事和壳牌（Shell）公司高管之间能够达成什么样的共识？答案是，天然气可以作为美国的一种过渡性燃料，逐步让美国从依赖石油转变为广泛使用可再生能源。

    现在争论的重点是，这个过渡期将会持续多久。

    本周二，对水力压裂技术持不同意见的双方齐聚加利福尼亚举办的《财富》绿色头脑风暴（Fortune's Brainstorm Green）大会，共同探讨美国天然气能源的未来。

    联邦能源管委会（the Federal Energy Regulatory Commission）前任主席、目前担任Wood3能源公司负责人的帕特•伍德表示，美国在理想情况下最终将转向包括核能、太阳能和风能在内的清洁能源。他说：“那一天到来之前，上天恩赐给了我们一份大礼，那就是水力压裂技术。”

    水力压裂是开采天然气时采用的一种油气井增产技术。石油和天然气公司从上世纪五十年代就开始在垂直井中采用这种技术。然而2003年哈里伯顿公司（Halliburton）开始在水平井采用这种方法，结果开采量大大超乎预想。

    简单点来说，水力压裂技术能够让天然气井附近的页岩层产生裂缝，接着向岩石裂缝注入混合着砂质的水，将天然气挤压出来，进入气井。

    水力压裂和天然气钻探已经在全美引发了争议。一些美国人，尤其是那些住在东北部马塞勒斯页岩气田附近的人声称水力压裂已经对他们的水源造成了污染，最起码影响到了他们的生活质量。马塞勒斯页岩气田所处的两个州，也就是纽约州和新泽西州，已经暂时禁用水力压裂技术。

    壳牌美洲上游业务部陆上天然气业务副总裁拉斯•福德称：“真正的问题在于，如何妥善建设天然气井。”他说，所谓的水压压裂技术带来的污染大部分都是由于一些公司没有正确地使用天然气井。他说，如果天然气井建设合理（一般来说确实如此），水力压裂技术是安全的。

    他说，实际上，天然气足够安全，有能力在未来的美国能源结构中占据更大的比重。他很乐意用天然气来替代污染严重的燃煤。

    但塞拉俱乐部执行董事麦克•布鲁尼称，这可能依然解决不了美国非清洁燃料的问题。塞拉俱乐部的长期目标是到2030年让美国三分之一的燃煤发电厂停止运营。布鲁尼表示，这段时间内，理想状态下，天然气产量如果没有轻微下滑的话将会保持稳定，直到人们掌握了更多的信息，进一步名曲天然气开发的安全性，以及天然气到底是否真正属于绿色燃料。

    但如果你询问天然气业内人士，你会发现，努力使天然气成为全球主要燃料来源的系统已开始运转。而根据伍德和其他人的观点，水力压裂技术是保证该系统状态良好、运转顺利的关键所在。

    译者：李玫晓/汪皓

    What can the executive director of the Sierra Club and a Shell executive agree on? That natural gas can serve as a bridge fuel in the United States, carrying the country from its dependence on oil to a widespread use of renewables.

    The main point of contention is the length of that bridge.

    Panelists on both sides of the fracking divide gathered Tuesday at Fortune's Brainstorm Green conference in California to discuss the future of natural gas in the U.S.

    Ultimately, the country will ideally transition to clean fuels including nuclear energy, solar and wind power, says Pat Wood, former chairman of the Federal Energy Regulatory Commission and currently a principal at Wood3 Resources. "Between now and then, God gave us a great big gift here with fracking."

    Fracking is a well-stimulation method used when drilling for natural gas. Oil and gas companies have used the method on vertical wells since the 1950s. But in 2003, Halliburton (HAL) started fracking along horizontal wells, allowing companies to extract much more natural gas than previously conceived.

    In simple terms, fracking creates fissures in the shale rock alongside a well, then floods those fissures with a mixture of sand and water to push gas out of the cracks and up the well.

    Fracking and gas drilling have caused controversy across the country. Some Americans, especially those living near the Marcellus Shale in the northeast, have claimed that fracking has poisoned their water, or, at the very least, their quality of life. Two states that touch the Marcellus – New York and New Jersey – have temporarily banned fracking.

    "The real issue is how you properly construct a well," says Russ Ford, the vice president of onshore gas, upstream Americas for Shell's exploration and production arm. Most of the pollution problems attributed to fracking happen when companies don't line their wells properly, he says. Ford claims that when wells are properly built, as they usually are, fracking is safe.

    Safe enough, in fact, to become an even greater portion of the U.S. energy portfolio going forward. Ford would be happy, he says, to displace dirty coal with natural gas.

    That may not solve America's unhygienic fuel problem, says Mike Brune, the executive director of the Sierra Club. The Sierra Club's long-term goal is to retire one-third of U.S. coal plants used for power generation by 2030. Over that period of time, Brune says, natural gas production will ideally remain stable if not decline slightly until more information is available on the safety of natural gas drilling, and whether natural gas is truly a green fuel.

    But if you ask the industry, the wheels making natural gas a major global fuel source are already in motion. And fracking, according to Wood and others, is the blessing keeping those wheels good and greased.