Already in 1874, Jules Verne, in his novel The Mysterious Island, lets the engineer Cyrus Harding reply when asked what mankind will burn instead of coal, once it has been depleted:

Today's energy and transport system, which is based mainly on fossil fuels, can in no way be evaluated as sustainable. In the light of the projected increase of global energy demand, concerns over energy supply security, climate change, local air pollution and increasing prices of energy services are having a growing impact on policy making throughout the world.

At present, oil, with a share of more than one third in the global primary energy mix, is still the largest primary fuel and covers more than 95% of the energy demand in the transport sector. With continued growth of the world's population and industrialisation of developing nations, such as China and India, accompanied by an increasing ‘automobilisation’, a surge in global demand for oil is expected for the future. A growing anxiety about the economic and geopolitical implications of possible shortcomings in the supply of oil as a pillar of our globalised world based on transportation is increasingly triggering the search for alternative fuels.