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The following assumptions were used: 



° Worldwide Population Growth was assumed to level 

 off by 2075 for all scenarios, based on the work 

 of Keyfitz et al .£/ 



° Productivity Growth for labor was assumed to decline 

 for both the high and low scenarios. 



- In the high scenario , the growth rate 

 began at 3.5 percent (per year) in 1980 



and linearly decreased to 2.2 percent by 2100. 



In the low scenario it linearly declined from 

 2.2 percent in 1980 to 1.7 percent by 2100. 



The past 30 years have experienced a higher rate of 

 productivity growth than either of these assumptions. 



° Energy Production Technologies for various 

 fuels were assumed to improve: 



- for the low scenario , a best guess of future 

 technologies and costs was used. 



- for the high scenario the same estimates 

 were used except the cost of nuclear 



energy was assumed to be cut in half in 1983. 



° Fossil Energy Resources were assumed to stay at 

 current levels with no new major discoveries. 



° Energy Use per unit of output (measured in GNP) 

 was assumed to decline by over 60 percent between 

 1975 and 2100, reflecting two assumptions: 

 (1) as economies develop, they will become more 

 service oriented, and (2) energy technologies 

 will become more efficient, partly in response to 

 higher prices. 



A world energy model developed by the Institute for Energy 

 Analysis at Oak Ridge Associated Universities was used to inte- 

 grate the assumptions.^/ The model divides the world into nine 

 regional sectors. Market mechanisms are used to select energy 

 sources and trade supplies in and between each region. CO2 

 emissions are generated by using well-established coefficients 

 for each fuel. 



