页岩气取代可再生能源行不通

   全世界都在争先恐后地利用可再生能源，美国却落在了后面。页岩天然气工业的异军突起进一步影响了美国可再生能源的前景，并有可能将可再生能源打入冷宫。

    很多有影响力的评论家都对页岩气的低碳排放及其经济潜力大加赞美。即使是一开始支持可再生能源的奥巴马总统也转变了立场，他在2012年的国情咨文中表示要大力发展页岩气，而涉及可再生能源的部分却只有只言片语。

    页岩气之所以在美国受到如此青睐，主要原因包括两个方面。首先，天然气造成的二氧化碳污染是燃煤的一半，天然气正在逐步成为能源工业的燃料选择，这一点毫无疑问。然而，电力行业的二氧化碳排放量大约占全美二氧化碳排放总量的40%，比美国经济领域中的任何一个行业都要多，包括交通运输业。虽然核能发电的二氧化碳排放量要比天然气少得多，但在日本福岛发生核泄漏事故后，核电业遭遇了前所未有的寒冬。

    此外，对于严重依赖传统燃料的交通运输业来说，其二氧化碳排放量占到全国总量的大约30%。要想找到一种既满足大众市场要求，又符合成本效益的替代方案还需要等待很多年。燃煤污染太严重，核能利用与交通运输业又陷入困局，太阳能和风能尚未发展成熟，如此一来，选择天然气也就成了一种对抗气候变化的折衷办法了。

    然而这种设想是否切实有效？《环境研究通讯》（Environmental Research Letters）期刊指出，如果真的要在本世纪内实现给地球降温的目标，就必须尽快大规模综合部署矿藏资源、风能、太阳能和核能，而不是天然气。该刊通过一个例子进一步提醒，假如在未来40年内安装一万亿瓦特的天然气发电厂，到2112年，和燃煤发电厂相比，天然气发电让全球变暖趋势减缓程度也就不到十分之一。

    麻省理工学院（MIT）最近一项研究声称，页岩气的运用抑制了可再生能源的发展，它只能算是向低碳未来前进的一个“短期性”过渡方案。夸大其价值可能会严重妨碍碳收集和碳封存等低排放科技的发展。

    太阳能和风能还未发展到黄金成熟期的想法是一种谬见。美国太阳能产业正在遭遇危机，原因并不是太阳能电池的发展尚未成熟，而是另有原因。一方面，美国人对于新事物的迷恋已经让我们在前沿太阳能科技领域投入了无数资金，成果却并不显著。而另一方面，中国提升了传统多晶硅的能效，并占领了全球太阳能电池50%的市场份额。

    其次，我们没能采纳一种传导性生态系统理念，该系统应该包括长期的行业激励、税收返还和联邦可再生能源配额标准，并在石油和天然气定价时考虑各自的环境成本。第三，坚持在海外生产而非本地生产使得我们仍然能够保持创新力，但这最终也将使得宝贵的知识产权和工作机会流向国外。

    页岩气的迅猛发展也只是最近几年的事。而风力发电之路虽然崎岖，但却卓有成效。一路从明尼苏达到德克萨斯州遍布着的大规模风力发电厂俨然已使美国成为“风能界的沙特阿拉伯”。但联邦政策的不确定性严重制约了风能行业的发展潜力。

   The world is scrambling to deploy renewable sources of energy, but America has fallen behind. The upstart natural gas from shale industry has only further increased the prospect of depressing renewables in America, and potentially shoving them into cold storage.

    Influential commentators have extolled shale gas' low carbon footprint, as well as its economic potential. Even President Obama, who initially embraced renewables, has ardently converted to shale in his 2012 State of the Union address, while throwing renewables a few crumbs.

    Shale gas' allure is two-fold. First, natural gas, which causes about half as much CO2 pollution as coal, is slowly but surely becoming the power industry's fuel of choice. Nevertheless, the electric power sector contributes about 40% of the nation's total CO2 emissions. That total is greater than any other sector of the U.S. economy, including transportation. Nuclear generation, which is much less carbon-intensive than natural gas, is facing a chilly winter post-Fukushima.

    Further, the transportation sector, which accounts for roughly 30% of the country's CO2 emissions, is heavily reliant on conventional fuels. A mass-market, cost-effective alternative to them is many years away. With coal so dirty, and nuclear energy and transportation mired, natural gas is seen as a halfway measure to combat climate change until solar and wind energies mature.

    But how valid is this assumption? An Environmental Research Letters paper argues that to achieve substantial temperature reductions this century, it will take a rapid and massive deployment of a mix of conservation, wind, solar, and nuclear energy -- not natural gas. If a trillion watts of gas-fired generation were installed over the next 40 years, the decline in warming by 2112 would only be within a tenth of a degree of that induced by coal-fired plants, it cautions.

    A new MIT study asserts that shale use suppresses the development of renewables, and that it can only be a "short-term" bridge to a low-carbon future. Treating it otherwise could altogether stunt the development of lower-emission technologies like carbon capture and sequestration.

    That solar and wind are unready for prime time is a myth. Solar energy is facing a crisis in the country, not because solar cells are unproven, but due to other factors. First, America's fascination for the new, new thing has made us sink billions, with few obvious results, into cutting-edge solar technologies. The Chinese, on the other hand, have improved the efficiency of traditional polysilicon, and captured 50% of the world's solar cell market.

    Second, our failure to put in place a conducive ecosystem, whether it includes long-term industry incentives, feed-in tariffs, a federal renewable portfolio standard, or pricing oil and gas fairly by incorporating the costs of their environmental damage. Third, by persisting in manufacturing overseas and not locally, we will still continue to innovate, but end up exporting precious intellectual property and jobs.

    Wind turbines too are rugged and effective. While shale has gushed only in the last few years, a powerful wind corridor has always existed all the way from Minnesota to Texas, making the U.S. the "Saudi Arabia of Wind," but an uncertain federal policy has strangled its potential.