The fertility rate for women and the related population growth rate, for numerous developing (transitional) countries, show a downward trend with increasing annual per capita energy use. On the assumption that such trends will continue, estimates are made for some simple cases of the energy demands required to stabilize the world's population in the period 2100 to 2150.

An assessment is made of how these energy demands might be met, capitalizing as much as possible on the indigenous energy resources for each of the ten major regions of the world – North America, Latin America, Europe OECD, Former Soviet Union and Central and Eastern Europe, China, Pacific OECD, East Asia, South Asia, Africa, and the Middle East. Consideration is also given to the potential need to limit carbon emissions because of global warming concerns.

The study highlights the crucial nature of energy efficiency improvements and the need to utilize all energy sources, including nuclear energy, if the world is to find a sustainable future with a much improved standard of living in the developing world.

The deployment of more fission power can build upon the existing successes. The availability of fusion power will depend upon the pace of the development program and, in principle, fusion power deployment might start around the middle of the twenty first century.