…In separate filings before the Massachusetts Department of Public Utilities, the Conservation Law Foundation, the Environmental Defense Fund, the Acadia Center and others also challenged need to subsidize a natural gas pipeline that could cost utility customers in excess of $1 billion.Energy efficiency alone probably can’t displace the natural gas pipeline. But it’s clearly an important step in doing so.  With its tremendous push into efficiency, New England could be the proving ground for one of the resource’s biggest promises…