There is considerable uncertainty about the amounts of recoverable shale gas in both developed and undeveloped areas.
The importance of Poland in the Kremlin's eyes has grown along with the prospects of shale gas in the country.
Oil-services firms there pioneered the technique of horizontal drilling, which is used to extract shale gas from America’s vast fields (conventional oil and gas are extracted using vertical wells).
It is true that there are questions about the harm that may be done by the "fracking" process that liberates shale gas; there is an urgent need for systematic before-and-after environmental audits.
Japanese trading houses are hungrily buying energy projects, especially those involving shale gas.
Until America found shale gas, Dow was "progressively shutting factories here and in Western Europe", says Mr Liveris.
New drilling technology has unlocked two vast pockets of shale gas with recoverable reserves of about 70 trillion cubic feet (2 trillion cubic metres).
POLAND may have western Europe's largest reserves of shale gas.
But us researchers found that shale gas Wells leak substantial amounts of methane, a potent greenhouse gas.
Greenhouse gas emissions from shale gas are predominantly down to two things: carbon dioxide produced when the gas is burned, and methane that leaks out while the well is being exploited.
But the extraction of shale gas is controversial.
An area in northwest England may contain 200 trillion cubic feet of shale gas, putting it in the same league as some of the vast shale-gas plays that have transformed the U.S. energy industry.
According to a report released this week by the U. S. Energy Information Administration (EIA), the cost to drill a horizontal shale gas well in China's Sichuan Basin has dropped by 23% since 2013.
Nor is shale gas the only new sort of reserve: "tight gas" in sandstones and coal-bed methane (the sort of gas that used to kill canaries down mines) are also promising.
Methane levels from the hydraulic fracturing of shale gas were 9,000 times higher than previously reported.
Ever-more-available shale gas brought a cheap and reliable alternative route to domestically fuelled electricity.
But the price of LNG has plunged, chiefly because America, now well supplied with shale gas, has stopped importing it.
Environmental worries could stop shale gas dead in places. But although the pace may slow and the road may have bumps, for the moment the revolution looks set to roll on.
By some estimates, shale gas has more than tripled the lifespan of US gas reserves to more than 100 years and experts say there is similar potential in China.
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