Deep underground lies stores of once inaccessible natural gas.
地下深层有着曾经不可触及的天然气。
This gas was likely formed over millions of years
这些气体很可能是在数百万年的时间里，
as layers of decaying organisms were exposed to intense heat and pressure under the Earth's crust.
由于地壳下一层层腐烂的生物体暴露在高温和高压下而形成的。
There's a technology called hydraulic fracturing, or fracking,
有一种新的技术，叫做水力压裂，或是压裂法，
that can extract this natural gas, potentially powering us for decades to come.
可以开发出这些天然气，并可能为我们继续提供数十年的能源。
So how does fracking work, and why it is a source of such heated controversy?
那么水力压裂究竟是怎么工作的呢，为什么它招来了许多争议？
A fracking site can be anywhere with natural gas, from a remote desert to several hundred feet from your backyard.
水力压裂点可以建在任何有天然气的地方，可以建在遥远的沙漠，也可以建在离你家后院几百英尺的地方。
It starts out with a long vertical hole known as a wellbore drilled down through layers of sediment.
一开始，要在数层沉积物中钻一个竖长的孔，即井眼。
When the well reaches 2500-3000 meters, it's at its kickoff point where it can begin the process of horizontal drilling.
当井深到达2500到3000米时，就到了开采点，可以开始横向的钻井。
It turns 90 degrees and extends horizontally for about 1.5 kilometers through a compressed black layer called the shale rock formation.
井的方向调转90度，在一个被称作页岩形成区的压缩黑色层横向蔓延将近1.5公里。
A specialized perforating gun is then lowered and fired,
一种专门的钻孔枪被运送到地下，开始运行，
creating a series of small, inch-long holes that burst through the well's casing into the rock layer.
在井壁上钻出一系列细小的、直径只有几英尺的小孔。
About three to four months after the initial drilling, the well is ready for fracking to begin.
在开始钻井后约三到四个月，这口井就可以开始被液压破碎了。
Fracking fluid is pumped down into the well at a pressure so high,
液压液体以以如此高的压力喷射到井内，
it cracks the shale rock, creating fractures through which the trapped gas and oil can escape.
击碎页岩，形成断裂层，使得困住的气体和石油可以出来。
The fluid itself is more than 90% water. The rest is made up of concentrated chemical additives.
这个液体90%都是水。剩下的由浓缩的化学添加剂构成。
These vary depending on the specific characteristics of the fracking site,
液压液体依据水力压裂点的具体特征而变化，
but usually fall into three categories: acids for clearing debris and dissolving minerals,
但一般分为三类：用于清除碎石、溶解矿物的酸性物质，
friction-reducing compounds to create a slippery form of water known as slickwater, and disinfectant to prevent bacteria growth.
用于形成润滑状态的水的降摩擦化合物，也被称作压裂液，用于防止细菌滋生的消毒剂。
Sand or clay is also mixed into the water to prop open the fissures
沙石也被混入水中，用来填充裂缝，
so the gas and oil can keep leaking out, even after the pressure is released.
所以在压力释放完之后，天然气和石油还可以继续流出。
It's estimated that all of fracking's intense pumping and flushing uses an average of 3-6 million gallons of water per well.
据估计，每口井平均需要3到6百万加仑的水，来完成水力压裂所需要的注射和冲刷。
That's actually not a lot compared to agriculture, power plants, or even golf course maintenance,
相比农业、发电厂、甚至高尔夫球场的保养，这点水不算什么，
but it can have a notable impact on local water supply.
但是它会对当地供水形成明显的影响。
And disposing of used fracking water is also an issue.
而且如何处理用过的压裂水也是个问题。
Along with the trapped gas that's pumped up to the surface, millions of gallons of flow-back liquid come gushing up.
数万加仑的液体随着压回地面的天然气一起涌了上来。
This liquid containing contaminants like radioactive material,
这些液体包含着许多污染物，比如放射性物质、
salts, heavy metals, and hydrocarbons, needs to be stored and disposed of.
盐类、重金属、烃类，需要被贮藏和处理。
That's usually done in pits on-site in deep wells or off-site at water treatment facilities.
这些污染物要么贮藏在现场的深井中，要么到别处的水处理设备进行处理。

Another option is to recycle the flow-back liquid,
另一个选择是再利用回流液体，
but the recycling process can actually increase levels of contamination since the water is more toxic with each use.
但是回收利用的过程事实上恶化了污染程度，因为随着每一次的使用，水会变得更有毒。
Wells are typically encased in steel and cement to prevent contaminants from leaking into groundwater.
一般来说，井会密封在钢铁或水泥之中，以防止污染物泄露到地下水中去。
But any negligence or fracking-related accidents can have devastating effects.
但是任何不小心或是与水力压裂相关的事故都会造成毁灭性的结果。
Fracturing directly into underground water hazardous underground seepage and leakage,
裂缝直接打入地下水层、危险的地下渗透和泄露、
and inadequate treatment and disposal of highly-toxic waste water can potentially contaminate drinking water around a fracking site.
以及对剧毒污水的不恰当处理，都可能污染当地的饮用水。
There's also concern about the threat of earthquakes and damaged infrastructure from pressure and waste water injection.
还要考虑地震的威胁，以及由压力和污水注射引起的基础设施损坏。
Links between fracking and increased seismic activity
水力压裂和越来越多的地震运动之间的关联，
leave unresolved questions about long-term pressure imbalances that might be happening deep beneath our feet.
也给我们留下了关于我们脚下可能发生的长期压力不平衡的疑问。
Fracking's biggest controversy, though, is happening above the ground.
但是，水力压裂最大的争议是在地上。
The general consensus is that burning natural gas is better for the environment than burning coal
一般认为，相比燃烧煤矿，燃烧天然气对环境更友好，
since the gas collected from fracking emits only half the carbon dioxide as coal per unit of energy.
因为从水力压裂收集的天然气的每单位能源和煤矿相比只释放一半的二氧化碳。
The pollution caused by the fracking itself, though, isn't negligible.
但是，由水力压裂造成的污染不容忽视。
Methane that leaks out during the drilling and pumping process is many times more potent than carbon dioxide as a greenhouse gas.
在钻井和抽送过程中泄露的甲烷作为一种温室气体，比二氧化碳的危害大数倍。
Some scientists argue that methane eventually dissipates, so has a relatively low long-term impact.
有些科学家称甲烷最终会消散，所以长期来看影响相对较低。
But a greater question hangs in the air.
但是仍存在一个更大的问题。
Does fracking take time, money, and research away from the development of cleaner renewable energy sources?
水力压裂是否和更清洁的可再生能源，抢夺了时间、金钱和研究呢？
Natural gas is non-renewable, and the short-run economic interests supporting fracking may fall short in the face of global climate change.
天然气是不可再生的，而支撑水力压裂的短期经济利益可能在全球气候变化面前不再成立。
Experts are still examining fracking's overarching effects.
专家仍在研究水力压裂的长久影响。
Although modern fracking has been around since the 1940s, it's boomed in the last few decades.
尽管现代水力压裂从上世纪四十年代兴起，但这种技术是在近几十年才发展起来的。
As other sources of natural gas decrease,
随着其他天然气资源减少，
the costs of non-renewable energies rise, and cutting-edge technologies make it so accessible.
不可再生能源的成本提高，而尖端技术使天然气变得重新可得。
But many countries and regions have already banned fracking in response to environmental concerns.
但是很多国家和地区因为环境因素已经禁止了水力压裂。
It's undeniable that fracking has reshaped the energy landscape around the world, but for what long-term benefit and at what cost?
不可否认，水力压裂改变了能源在世界的分布，但是长期收益如何，成本又如何？