A rapid increase in shale gas output helped US to raise natural gas supplies to a high level in recent years thus allowing the country sustain adequately low prices and enhancing the country's energy independence. US natural gas storage approached to record of 3.852 trillion cubic feet, reported the Energy Information Administration. The expansion of shale gas production can result in revolution in energy sector but at the moment it is in the early stage, said Chris Mayer, editor of Capital & Crisis.