'coal-independent' originates from Modern English, combining the noun 'coal' and the adjective 'independent', where 'coal' referred to the fossil fuel and 'independent' meant 'not dependent'.

'independent' changed from Latin 'independens' (via French 'indépendant') into Middle English and modern English as 'independent'; 'coal' changed from Old English 'col' (from Proto-Germanic *kula) into modern English 'coal', and the compound 'coal-independent' was formed in modern usage by combining these elements.

Initially, the components meant 'coal' (the fuel) and 'not dependent'; combined in modern usage they mean 'not depending on coal' and this core meaning has remained stable in contemporary contexts.