There's a little more to it than that.  Fracking currently beat coal in part because it's much cheaper.  I'm not ignoring the potential ills of that process, but I found it odd that 2-3 debates ago, Warren and Sanders were practically falling over themselves to say they would countenance NO drilling, NO mining, etc.  My thought was, "none?"  Ever?  Anywhere?  All that would do would be to push the issues elsewhere.  Incentivizing movement toward renewables, however, is not only something I support, but it is part of the field in which I work.  We have a a bunch of investments in fuels-from-waste technology, including one that is just about ready to go live.  (IH2 if you want to Google).  That is a little different than a full renewable, but it is a strong step in that direction.  There's a lot more, but I don't have time to detail now.