Of the fourteen models participating in the EMF 12 exercise, three agreed to participate in an exercise analyzing the sector- and service-specific fuel switches and efficiency improvements that lead to carbon reductions. Fossil2, Gemini, and Markal contain enough technology specific detail to allow such analysis. A list of the major technologies included in each of the three models is included as an appendix. The analysis was confined to results for the United States over the next few decades.
The goal of the exercise was to, first, describe the source of the emissions reductions and then explain the differences among the model forecasts. We were able to accomplish the first goal, i.e., describe the differences in the sources of reductions among models. We were able to explain some, but not all, of these differences.