Invest in anything that produces energy:

Nocera calculates that if 9 billion people in 2050 used energy at the rate that Americans do today that the world would have to generate 102.2 TW of power—more than seven times current production. If people adopted the energy lifestyle of Western Europe, power production would need to rise to 45.5 terawatts. On the other hand if the world's 9 billion in 2050 adopted India's current living standards, the world would need to produce only 4 TW of power. Nocera suggests, assuming heroic conservation measures that would enable affluent American lifestyles, that "conservative estimates of energy use place our global energy need at 28-35 TW in 2050."  This means that the world will need an additional 15-22 TW of energy over the current base of 13.5 TW.

 

So where will the extra energy come from? Relying on figures from the World Energy Assessment by the United Nations Development Program, Nocera looks at the maximum amounts of power that various non-fossil fuel sources might supply. Biomass could supply 7-10 TW of energy, but that is the equivalent of harvesting all current crops solely for energy. Nuclear could produce 8 TW which implies building 8000 new reactors over the 45 years at a rate of one new plant every two days. Wind would generate 2.1 TW if every site on the globe with class 3 winds or greater were occupied with windmills. Winds at a class 3 site blow at 11.5 miles per hour at 33 feet above the ground. And hydro-power could produce 0.7-2 TW if dams were placed on every untapped river on the earth. Nocera concludes, "The message is clear. The additional energy we need in 2050 over the current 13.5 TW base, is simply not attainable from long discussed sources—the global appetite for energy is simply too great."