The future of fusion

The population of the world is increasing, mainly in the developing world, and is projected to saturate within about 100 years at up to twice the pres ent population of 6 billion people (Bos et al., World Population Projection s: 1994-95 Edition, Published for the World Bank). Studies (Goldemberg and Johansson (Eds.), Energy as an Instrument for Socio-Economic Development Un ited Nations Development Programme, New York, 1995, p. 9; United Nations St atistical Yearbooks, 10th issue; 1965; 20th issue; 1975, 22nd issue, 1977; 32nd issue, 1987; and 39th issue 1994, United Nations Publications; Sheffie ld, J. Technol. Forecasting Social Change 59 (1998) 55.) show that, histori cally, the population growth rate has varied inversely as the annual per ca pita energy use in most parts of the developing world, where per capita ene rgy use is typically less than 1 t of oil equivalent energy per year. Howev er, in areas with more than 2-3 t of oil equivalent of energy use per year per person, the growth rate is around zero. If this trend continues, a stab le world population will require, allowing for energy efficiency improvemen ts, some 2-3 times the present annual energy use. There is an abundance of energy in the world both exploited and potential to meet this need - fossil , fission, and renewables - but it is not evenly distributed, some are cost ly, and there are issues of environmental pollution in present use, that ma y limit use. Fusion energy is a potential longer-term source with attractiv e environmental features. It is the least-developed energy option and still faces a challenging development path, but there are many areas of the worl d that would benefit hugely from its deployment from the later part of the 21st century onward, and it is important to consider how it might be deploy ed. Most fusion power plant options considered today show an economy of sca le, owing to the fixed distance needed for shielding fusion neutrons, triti um breeding and handling the heat loads. One interesting approach is to use the power plant to co-produce electricity and hydrogen to facilitate the i ntroduction of lower cost of electricity, multi-gigawatt power plants (Shef field et al., A study of options for the deployment of large fusion power p lants, 2000, to be published). Published by Elsevier Science B.V.