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  • What is hydraulic fracturingor fracking ?

  • Since the industrial revolution our energy consumption has risen unceasingly.

  • The majority of this energy consumption is supplied by fossil fuels like coal or natural gas.

  • Recently there has been a lot of talk about a controversial method of extracting natural gas:

  • Hydraulic fracturing or fracking.

  • Put simply, fracking describes the recovery of natural gas from deep layers inside the earth.

  • In this method, porous rock is fractured by the use of water, sand and chemicals

  • in order to release the enclosed natural gas.

  • The technique of fracking has been known since the 1940s.

  • Nonetheless, only in the last ten years has there been quite a “fracking boom”,

  • especially in the USA.

  • This is because most conventional natural gas sources in America and on the European continent have been exhausted.

  • Thus prices for natural gas and other fuels are rising steadily.

  • Significantly more complicated and expensive methods, like fracking, have now become attractive and profitable.

  • In the meantime, fracking has already been used more than a million times in the USA alone.

  • Over 60% of all new oil and gas wells are drilled by using fracking.

  • Now let’s take a look at how fracking actually works:

  • First, a shaft is drilled several hundred meters into the earth.

  • From there, a horizontal hole is drilled into the gas-bearing layer of rock.

  • Next, the fracking fluid is pumped into the ground using high-performance pumps.

  • On average, the fluid consists of 8 million liters of water

  • which amounts to about the daily consumption of 65,000 people.

  • plus several thousand tons of sand and about 200,000 liters of chemicals.

  • The mixture penetrates into the rock layer and produces innumerable tiny cracks.

  • The sand prevents the cracks from closing again.

  • The chemicals perform various tasks

  • among other things, they condense the water,

  • kill off bacteria

  • or dissolve minerals.

  • Next, the majority of the fracking fluid is pumped out again.

  • And now the natural gas can be recovered.

  • As soon as the gas source is exhausted, the drill hole is sealed.

  • As a rule, the fracking fluid is pumped back into deep underground layers and sealed in there.

  • However, fracking is also associated with several considerable risks.

  • The primary risk consists in the contamination of drinking water sources.

  • Fracking not only consumes large quantities of fresh water,

  • but in addition the water is subsequently contaminated and is highly toxic.

  • The contamination is so severe that the water cannot even be cleaned in a treatment plant.

  • Even though the danger is known and theoretically could be managed,

  • in the USA already sources have been contaminated due to negligence.

  • No one yet knows how the enclosed water will behave in the future,

  • since there have not yet been any long-term studies on the subject.

  • The chemicals used in fracking vary from the hazardous to the

  • extremely toxic and carcinogenic, such as benzol or formic acid.

  • The companies using fracking say nothing about the precise composition of the chemical mixture.

  • But it is known that there are about 700 different chemical agents which can be used in the process.

  • Another risk is the release of greenhouse gases.

  • The natural gas recovered by fracking consists largely of methane,

  • a greenhouse gas which is 25 times more potent than carbon dioxide.

  • Natural gas is less harmful than coal when burned.

  • But nonetheless, the negative effects of fracking

  • on the climate balance are overall greater.

  • Firstly, the fracking process requires a very large consumption of energy.

  • Secondly, the drill holes are quickly exhausted and it is necessary to drill

  • fracking holes much more frequently than for classical natural gas wells.

  • In addition, about 3% of the recovered gas is lost in the extraction and escapes into the atmosphere.

  • So how is fracking and its expected benefits to be assessed

  • when the advantages are balanced against the disadvantages?

  • When properly employed, this technique offers one way

  • in the short to medium term for meeting our demand for lower-cost energy.

  • But the long-term consequences of fracking are unforeseeable

  • and the risk to our drinking water thus should not be underestimated.

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What is hydraulic fracturingor fracking ?

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頁岩法取油:是機會或危機? (Fracking explained: opportunity or danger)

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    Kwan Kuo 發佈於 2014 年 05 月 22 日
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