From 1900 to 2005, the world population has increased four-fold: there are now 6.445 billion people on the planet. By 2012, there will be 7 billion; by 2025, 7.9 billion. This figure will grow to 8.27 billion by 2030. As these numbers demonstrate, population growth rate has peaked—the world’s population may have grown 12.6% from 1990 to 2000, but this rate will only be 2.6% in the coming decades.

Energy use does correlate to population growth to a certain extent: more people means more energy. From 2005 to 2030, the human population will grow by 1.28 times. In comparison, energy demands over the same time period are projected to grow at a much faster accelerated pace of 1.9 times. Part of the increase in demand will be due to increases in the human population: energy fuels modern society, grows economies, spawns new economies, and gives individuals upward mobility. Using Maslow’s hierarchy of needs, individuals move up the hierarchy of self-fulfillment by first meeting their physiological needs of food, oxygen and water and then their needs for safety and security. Transcending these basic needs, however, requires increasing amounts of energy.