Figure 1 B. Graphs resulting from simulation of the model in Figure 1 A. Available world fuel reserve was taken as 5 X 10 19 kilocalories and energy converted from the solar input and converged into man's productive system of growth and maintenance was 5 X 10 16 kilocalories when structure was 10 18 kilocalories. Peak of structural growth was variable over a 50-year period depending on amounts diverted into waste pathways.