This chart shows how much greenhouse gas is emitted during the life cycles of the fuels listed below. These emissions (in CO2 equivalents) are broken down into four steps:
1. Extraction - production of the raw material
2. Treatment - processing the raw material into the final form in which the fuel is used
3. Transportation - transporting the fuel to the locations at which it is used
4. Conversion - use of the fuel for production of heat or electricity for example
The last steps also includes any emissions occurring during waste treatment or storage.
The numbers and references used to quantify the fuel chain emissions can be found in a document that can be downloaded from here.