The world's population will be 9 billion that double energy consumption by 2050.

Predtechenskiy Michail : scientist
In the early twentieth century, people in the world had two billion and a half years ago, it became seven, and by 2050, predicting that we will be nine billion. The increase in world population by 30 percent with the increase in per capita consumption may give double jump in energy consumption by the middle of the century.