Energy source	External cost (in Euro cents/kWh)
Coal	3-8 cents
Gas	1-3 cents
Nuclear	0.2-0.5 cents
Wind	up to 0.25 cents

Source : European Commission, Externe Study, revised 2003 edition, "External Costs - Research results on socio-environmental damages due to electricity and transport", see : also http://www.externe.info