'coal-based' originates from the English word 'coal,' which comes from the Old English 'col,' meaning 'mineral of fossilized carbon,' and 'based,' from the Old French 'basse,' meaning 'foundation or support.'

'coal' changed from the Old English word 'col' and eventually became the modern English word 'coal.' 'Based' evolved from the Old French 'basse' to the modern English 'based.'

Initially, 'coal' meant 'mineral of fossilized carbon,' and 'based' meant 'foundation or support.' Over time, 'coal-based' evolved to mean 'relating to or derived from coal.'