Carbon Dioxide from the Energy of a Fuel (IPCC Emission Factor)

This is the Tier 1 method of the Intergovernmental Panel on Climate Change: the carbon dioxide from a fuel is taken as its energy times a default emission factor per unit of energy, $m_{CO_2} = E\,EF$. Here $E$ is the net calorific value of the fuel burned, its heat content, and not the electricity that came out of it; for a power plant, the heat rate page turns electricity into fuel energy first. $EF$ is entered in kilograms of carbon dioxide per gigajoule.

The defaults are in the 2006 IPCC Guidelines, volume 2, chapter 2, Table 2.2, for stationary combustion, and the table prints them in kilograms per terajoule on a net calorific basis. A terajoule is 1 000 gigajoules, so natural gas at 56 100 per terajoule is 56.1 per gigajoule, the number this page takes. The others in the table are crude oil 73 300, gas or diesel oil 74 100, residual fuel oil 77 400, motor gasoline 69 300, jet kerosene 71 500, liquefied petroleum gases 63 100, anthracite 98 300, sub-bituminous coal 96 100 and lignite 101 000. Divide any of them by 1 000 for the page.

In the page's examples, 1 000 gigajoules of natural gas at 56.1 kg/GJ makes 56.1 t of carbon dioxide, 1 000 gigajoules of diesel oil at 74.1 makes 74.1 t, and 1 000 gigajoules of anthracite at 98.3 makes 98.3 t. The 73 780 gigajoules of natural gas that a plant burned in a year therefore made 4 139 tonnes. The same relation solves for the energy that a known mass of carbon dioxide implies, or for the factor itself from a mass and an energy.

A default is a default. The table gives a range for each factor, for natural gas 54 300 to 58 300 per terajoule, and that range is the real uncertainty of the number. Methane and nitrous oxide from combustion are separate factors in the same table and are not in this one, so the result is carbon dioxide only.