The following is from the Energy Information Administration:
Different fuels emit different amounts of carbon dioxide in relation to the energy they produce. To compare emissions across fuels you must compare the amount of CO2 emitted per unit of energy output or heat content. Pounds of CO2 emitted per million Btu of energy for various fuels:
- Coal (anthracite) 228.6
- Coal (bituminous) 205.7
- Coal (lignite) 215.4
- Coal (subbituminous) 214.3
- Diesel fuel & heating oil 161.3
- Gasoline 157.2
- Propane 139.0
- Natural gas 117.0
The amount of CO2 produced when a fuel is burned is a function of the carbon content of the fuel. The heat content or amount of energy produced when a fuel is burned is a function of primarily the carbon (C) and hydrogen (H) content of the fuel. Heat is produced when C and H combine with oxygen (O) during combustion. Because natural gas is primarily methane, or CH4, it has a relatively high energy content relative to other fuels, and thus a relatively low CO2 to energy content. Water and various elements such as sulfur and non-combustible elements in some fuels reduce their heating values and increase their CO2 to heat contents.
