|
The ratio between energy produced per unit of carbon dioxide released for various fuels is shown on this diagram.
Natural gas (which is primarily methane) produces the least amount of CO2 per unit of energy released, at around 0.54 kg/kWh. Other gaseous fuels are similar.
The liquid fuels (such as automotive fuel) produce between 0.65 and 0.8 kg/kWh.
Coal produces between 0.93 and 1.0 kg/kWh, the worst offender being lignite coal—which produces almost twice as much CO2 per unit of energy released as does methane.
Burning wood is worse still, but that is offset by the fact that wood is part of the fast carbon cycle.
The CO2 emission-levels of the fuels are generally comparable to their rates of emission of other pollutants, such as nitrous oxide and sulphur dioxide. In other words, natural gas is relatively clean, while coal and wood are dirty