...both candidates are playing up the ascendant  role of commercially untested and so far economically nonviable ways of  converting America's plentiful coal supplies into electricity without spewing  massive quantities of heat-trapping greenhouse gases." 
 "US Democratic presidential hopefuls Hillary  Clinton and Barack Obama are talking more about 'clean coal' and less about  global warming as they woo voters in West Virginia and Kentucky -- two states  that sit at the heart of the nation's coal economy. In a bid to draw voters  ahead of Democratic primaries.