We begin creating the Outlook by looking at fundamental drivers including population, living standards, and consumer preferences.
Then we forecast energy demand across 15 sectors and match the demand for energy services with about 20 types of energy, considering how technology, government policies, and other factors may evolve. We forecast oil and natural gas production from key producing countries/regions, and to estimate energy-related CO2 emissions, we look at historical and projected energy demand and apply an emissions factor for each type.
More information here