The shift from our current fossil fuel based economies to sustainable renewable energy economies is usually presented as a great challenge. That is also the message coming from the UN Climate Conference in Copenhagen. Oil companies tell us that it can be done but that we need decades to get there. The numbers tell a bit of a different story. Total world energy consumption is about 15 terawatts (2005).
All that energy can be generated by today’s solar panel technology on a sunny piece of land of about 550 by 550 kilometers (340 square miles). That is for instance about 3 percent of the surface of the United States and China, 4 percent of the surface of Australia, 3.5 percent of Brazil and 9 percent of India. And we just need to capture about 20 percent of the solar energy that hits such an area. Of course the beauty of solar energy is that it can be generated locally. So we are not going to see such a centralized production. But the numbers clearly convey that the challenge is not as huge as it is often presented.
Some people argue that renewable energy is not always available where it is needed. That is true. There are places where there is not enough sunshine, not enough wind etc. But again that challenge is not as big as it is made out to be. Scientific American recently calculated the renewable power available in readily accessible locations. The numbers are staggering: there is 2 terawatts (TW) hydro energy easily available, 40-85 TW wind energy and 580 TW solar energy. So there is about 40 times more clean energy available than we need for the present world consumption. All that energy can be captured with technology that already exists! From that perspective the generation of renewable energy is hardly the huge challenge that we are told it is.