The shale gas "bubble" will soon burst, Alexei Miller says

Shale gas is not economically justified and is not profitable ,  Alexei Miller ,  Chairman of the Board of "Gazprom" , says.
The US government has kept a tight rein on exports since the shale gas boom started more than five years ago. Shale gas exploitation  has been blamed for environmental problems in the US , including water, ground and air pollution and leaks of methane.
Shale gas has brought about a revolution in US energy, with thousands of wells drilled across the country releasing billions of tonnes of fuel. Gas prices have plummeted as a result, to about $2 a unit, compared with about $10 to $12 in Europe and Japan, but those price falls have not yet affected the international market.