美联储主席格林斯潘回忆录--动荡年代:勇闯新世界-127:THE LONG-TERM  ENERGY SQUEEZE-4

天然气（英语：natural gas）是一种主要由甲烷组成的气态化石燃料。它主要存在于油田以及天然气田，也有少量出于煤层，因此天然气是火力发电的一种燃料，发电时虽比煤炭发电好、但发电过程中也会制造一定程度的碳排放。

当非化石的有机物质经过厌氧腐烂时，会产生富含甲烷的气体，这种气体就被称作生物气体。生物气的来源地包括森林和草地间的沼泽、垃圾堆填区、下水道中的淤泥、粪肥，由细菌的厌氧分解而产生。生物气还包括胃肠涨气（例如：屁）。

当甲烷（生物气）溢散到大气层中时，它将是一种直接促使全球变暖化愈演愈烈的温室气体。

这种飘散的甲烷，经过有效的处理，就不会被视作一种污染物，而是一种有用的再生能源、虽说如此，天然气依旧不是洁净能源、也非绿能。

然而，在大气中的甲烷一旦与臭氧发生氧化反应，就会变成二氧化碳和水，因此排放甲烷所导致的温室效应就会以二氧化碳的方式继续延长下去。而且就燃烧而言，天然气要比煤这类石炭纪燃料产生的二氧化碳要少得多。

甲烷的重要生物形式的来源是白蚁、反刍动物（如牛羊）和人类对水稻的耕种。据估计，这三者的散发量分别是每年15、75和100百万吨（年散发总量约为1亿吨）。

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This effect was quite dramatic. 

For example, based on then-recent trends in petroleum use, the U.S. Department of Energy projected in 1979 that world oil prices would reach nearly $60 per barrel by 1995—the equivalent of more than $ 150 in 2006 prices. 

The failure of oil prices to rise as projected is a testament to the power of markets and the new technologies they fostered. 

Since oil use is less than two-thirds as important an input into world GDP as it was three decades ago, the effect of the oil price surge on the world economy during the first half of 2006, though noticeable, proved significantly less consequential to economic growth and inflation than the surges in the 1970s. 

Throughout 2006, it was difficult to find serious evidence of any erosion in world economic activity as a consequence of sharply higher oil prices. 

Indeed, we have just experienced one of the strongest global economic expansions since the end of World War II. 

The United States, especially, was able to absorb the implicit tax of rising oil prices 

through 2006. 

Nonetheless, holders of private inventories of oil, both industry and investors, apparently foresee little likelihood of a change in petroleum supply/demand fundamentals sufficient to alter long-term concerns. 

This does not mean that oil prices will necessarily move higher. 

If the market is efficient, then all knowledge affecting the prospective future supply/ 

demand balance ought already to be reflected in the spot prices of crude oil.* 

*Spot prices in principle embody the market participants' knowledge not only of the forces setting spot prices but also of those setting futures prices. 

In fact, when the market participants perceive a forthcoming very large rise in price, long-term futures prices will rise and pull up the spot price with them. 

If the spot price is below longer-term futures by more than the carrying cost of inventories, speculators can buy spot oil, sell the distant futures, store the spot oil, pay interest on the money borrowed to hold the oil, and, at the expiration of the contract, deliver the oil and pocket the profit. 

This arbitrage will go on until the spot price is brought up to the distant future price less carrying costs of inventory. 

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THE AGE OF TURBULENCE 

Many analysts saw spot prices of early 2007 embodying a large "terrorist" risk premium. (Middle East peace would doubtless initiate a sharp drop in oil prices.) 

To move crude-oil prices would require a change, or the threat of a change, to the prospective supply/demand balance. 

History tells us that will happen—that the balance will shift often and in either direction. 

Technology cannot prevent that. But it can assuage the cost and price impacts 

that such tight markets foster. 

The hit-or-miss exploration and development of oil and gas during the petroleum industry's early years have given way to a more systematic approach. 

Dramatic changes in technology in recent years have made existing oil reserves stretch further while keeping the costs of oil production lower than they otherwise would be. 

Seismic imaging and advanced drilling techniques are facilitating the discovery of promising deepwater reservoirs, 

especially in the Gulf of Mexico, and making possible the continued development 

of mature onshore fields. Accordingly, one might expect that the cost of developing new fields would have declined. 

But development-cost reductions have been overwhelmed by shortages and higher prices of drilling rigs, as well as escalating wages of skilled oil workers.*

Technology has not been able fully to counter those factors. 

Much of the innovation in oil development outside OPEC has been directed at overcoming increasingly inhospitable and costly exploratory environments, 

the consequence of more than a century of draining the more immediately accessible sources of crude oil. 

Still, consistent with declining long-term marginal costs of extraction, distant futures prices for crude oil moved lower, on net, during the 1990s. 

Prices of the most-distant (sevenyear) futures fell from a bit more than $20 per barrel before the first Gulf War to less than $18 a barrel on average in 1999.

Between 1991 and 2000, although spot prices ranged between $11 and $35 per barrel, distant futures exhibited little variation. 

It appeared for a while that we had reached the long-term price-stability nirvana that oil companies have sought since the days of John D. Rockefeller.

*The long period (1986-99) of subdued oil prices lessened the need for and the attraction of oil industry jobs. The number of employees engaged in oil and gas extraction fell from a peak of 271,000 in July 1982 to 118,000 by the end of 2003. Employment recovered markedly through 2007. 

Labor supply has not caught up to demand; thus, since the fall of 2004, average 

hourly earnings of oil industry workers have risen far faster than those of the nation as a whole. 

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THE LONG-TERM ENERGY SQUEEZE 

But it was not to be. 

Long-term price stability has, of course, eroded noticeably since 2000. 

Distant futures prices have risen sharply. 

In June 2007, prices for delivery in 2013 of light sweet crude exceeded $70 per barrel. This surge arguably reflects the growing presumption that increases in crude-oil capacity outside OPEC will no longer be adequate to serve rising world demand, especially from emerging Asia. 

Additionally, the longer-term crude price has presumably been driven up since 2000 by renewed fears of supply disruptions in the Middle East and elsewhere. 

Because of the geographic concentration of proved reserves (threefifths in the Middle East, three-fourths in OPEC), much of the investment in crude-oil productive capacity required to meet future demand, without prices rising unduly, will need to be undertaken by national oil companies in OPEC and other developing economies.

Meanwhile, productive capacity does continue to expand, albeit gradually, and exploration and development activities are ongoing, even in developed industrial countries. 

Conversion of the vast Athabasca oil sands reserves in Canada to actual productive capacity, while slow, has made this unconventional source of oil competitive at recent market prices. 

However, despite improved technology and high prices, proved reserves in the developed countries are being depleted because additions to these reserves have not kept pace with oil extraction. 

Before I borrow the oracle's crystal ball to peer into the future of petroleum, 

we must survey the rest of the energy complex with which oil is inextricably intertwined. 

Compared with oil, the natural-gas industry is relatively new. 

Through much of the early history of petroleum exploration, drillers could not tell 

whether a successful hit would turn up valuable crude oil or natural gas, 

which was wastefully "flared," or burned off, for lack of transport facilities. 

But after many of the transportation hurdles had been surmounted, gas production for market surged more than sixfold between 1940 and 1970. 

In recent decades, natural gas has blossomed into a major source of energy, 

reflecting its myriad new uses in industry and as a clean-burning source of electric power.

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THE AGE OF TURBULENCE 

 In 2005; natural gas supplied nearly three-fifths as much energy as oil. In contrast to oil, the natural gas consumed in the United States is almost solely produced in the United States and Canada, from which in 2006 the United States imported a fifth of its twenty-two trillion cubic feet of consumption. 

The reason for the emphasis on domestic production is that natural gas is still much harder to handle than oil. 

It is difficult to transport in its gaseous form through pipelines and is particularly challenging in its cryogenic form when transported as liquefied natural gas (LNG). It is also difficult to store: in gaseous form, it requires deep salt caverns. 

At times, in recent years, supply has not kept pace with the growth of 

demand. Indeed, the inventories of natural gas held in storage caverns were 

drawn down to record lows during the winter of 2003. 

As a consequence, spot prices of gas spiked. The very technologies that have improved our oil and gas drilling success rates have also enabled us to drain newly discovered gas reservoirs at an increasingly rapid pace. 

Data for Texas, for example, 

show that since 2000, output from new wells declined by more than 60 percent after one year of operation. That compares with roughly 25 percent in the early 1980s. As a result, merely to hold net marketed gas production 

stable, new discoveries and the drilling activity associated with them have had to rise. 

The combination of demand for gas in our power plants—where its use tends to be less damaging to the environment than the burning of coal or oil—and continued demand from households, commercial establishments, and industry has put significant pressure on the natural-gas reserve base. 

Until recently, virtually all new electric power facilities on the drawing board 

had been gas-fired or "dual-fired," able to burn gas or oil. 

To meet higher anticipated needs, the always-present tension between energy requirements and environmental concerns will doubtless grow in the years ahead. 

U.S. natural-gas prices, even seasonally adjusted, have historically displayed 

far greater volatility than prices of crude oil. 

Doubtless this reflects, in part, the relatively primitive state of global trade in natural gas—oil's broader and more diverse market tends to damp down wild swings in price. 

Over the past few years, despite markedly higher U.S. drilling activity, the U.S. natural-gas industry has been unable to expand production noticeably, 

and we have also been unable to increase imports from Canada.* 

Significant pressure on prices has ensued. 

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THE LONG-TERM E N E RG Y S O U E E Z E 

(未完待续, To be contd)
 

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