1) Water power or electricity
Found on
https://www.crosswordclues.com/clue/white-coal
White coal is a form of fuel produced by drying chopped wood over a fire. It differs from charcoal which is carbonised wood. White coal was used in England to smelt lead ore from the mid-sixteenth to the late seventeenth centuries. It produces more heat than green wood but less than charcoal and thus prevents the lead evaporating. White coal could...
Found on
http://en.wikipedia.org/wiki/White_coal
No exact match found.
