SUSTAINABLE CITIES AND SOCIETY, vol.1, no.1, pp.29-37, 2011 (SCI-Expanded)
The United Nations projects that 60% of the world's population will be living in urban areas by 2030. Cities account for 2% of the world's area but 75% of the world's energy consumption. For over a century, the automobile has offered affordable freedom of movement within urban areas. However, with the current vehicle population exceeding 850 million, almost all of which are powered by internal combustion engines this situation is becoming unsustainable.