Emergy-based Simulation to Assess Brazil’s Long-term Carrying Capacity: Environment, Electricity and Population

A macroscopic mini-model of Brazil’s electrical generating capacity (BRAZELECTRIX, Brazilian Electricity Matrix) was developed using the Energy Systems Language and simulated with iconographic Extend® software to explore long-term (200 years) population carrying capacity. South American reserves of natural gas (NG) and Brazilian stream hydro-power potential were assumed as the main inputs to electric power production. Energy values (e.g., kWh, joules) for fuels, electricity and environment were transformed to solar emergy (i.e., solar equivalent joules) to simplify cross comparison with a single metric. BRAZELECTRIX was calibrated using a holistic method that used mean component life-times and conservation of material and energy for each individual unit. Validation of BRAZELECTRIX, based on historical data, gave a root mean square error of 8% for hydroelectricity and 28% for natural gas use. Investments in natural gas infrastructure (e.g., contracts, pipelines, processing plants and electric power plants) accelerated Brazil’s expansion of electrical generating capacity for a finite period, allowing the country to reach its renewable (hydro-power only) carrying capacity 100 years sooner than without (2040 vs. 2140). Brazil has a total of 560 zetta-solar equivalent joules per annum (1 Zseja = 1 ×1021 sej per year) of stream hydro-power potential; 170 Zseja is currently used for electricity generation. According to BRAZELECTRIX, eventually 390 Zseja will be tapped for hydroelectricity. The standard of living, as measured by annual per capita electrical solar emergy, had risen 680% from 166 tera-solar equivalent joules (Tseja) to 1130 Tseja during the 35 year period following 1965 and was predicted to increase another 75% to its maximum (1973 Tseja) in 2050. By comparison, an urbanizing state of the United States (North Carolina) had an annual per capita electrical solar emergy of 7815 Tseja in 1992, indicating that Brazil could reach a living standard, as measured by per capita electricity usage, equal to one-forth the level of United States. Macroscopic mini-models combined with emergy accounting evaluated long-term paths for Brazil’s electricity supply and related it to natural environment trade-offs to demonstrate how sustainable carrying capacity of a developing nation can be forecast.