This column highlights the most interesting and useful business and financial commentary on energy from around the Web every Tuesday.   Seeking Alpha Link: Delta Refinery Deal All About Southwest "Delta Airlines' (DAL) agreement to buy a ConocoPhillips (COP) refinery in Pennsylvania is all about Southwest Air (LUV). Delta's ongoing battle with Southwest is about costs. Delta's hub-and-spoke system is inherently less efficient than Southwest's network of short flights that just go back-and-forth. But because Southwest has now been around for a generation and accepted unions while Delta has always pushed back against workers it may actually have an advantage in labor costs." (Also read Within A Month ...