Energy experts predict that total global consumption of primary energy--energy used for space heating, transportation, and generating electricity--will double or triple over the next 50 years, from about 400 exajoules (EJ) per year in 1998 to 800--1,200 EJ per year in 2050. (An exajoule is a billion billion joules. One exajoule is about equal to the energy content of 30 million tons of coal, or the gasoline consumed by a million automobiles during their lifetimes, or the annual energy consumption of West Virginia or Portugal.) Fossil fuel consumption would have to be limited to about 300 EJ per year in 2050 to permit stabilization of anthropogenic greenhouse gases at an equivalent doubling. Carbon-free energy sources would then have to supply the difference: 500--900 EJ per year. That's daunting. In 1998, carbon-free sources supplied less than 60 EJ. Carbon-free energy would need to grow tenfold over the next 50 years--from 15 percent of the total commercial supply to 60--75 percent in 2050.
(An exajoule is a billion billion joules. One exajoule is about equal to the energy content of 30 million tons of coal, or the gasoline consumed by a million automobiles during their lifetimes, or the annual energy consumption of West Virginia or Portugal.)
Fossil fuel consumption would have to be limited to about 300 EJ per year in 2050 to permit stabilization of anthropogenic greenhouse gases at an equivalent doubling. Carbon-free energy sources would then have to supply the difference: 500--900 EJ per year.
That's daunting. In 1998, carbon-free sources supplied less than 60 EJ. Carbon-free energy would need to grow tenfold over the next 50 years--from 15 percent of the total commercial supply to 60--75 percent in 2050.
