At present and in the near future, the significantly growing energy demand in the transport sector will mainly be covered by crude oil, with a production peak showing up within the next decade. This future fuel supply situation is likely to produce instabilities in ecological, economic and political terms. An increase in fuel prices and the necessary reduction of traffic-induced climatically relevant emissions and associated secondary pollutants will intensify the pressure on road traffic with respect to consumption and emission reductions.
This leads to the research of solutions for the restriction of global warming, relaxation of the dependence on oil, reduction of fossil energy carriers, improvement of local air quality. The solutions can be found increasing the efficiency of "clean" drive systems, developing new and more efficient power trains, introducing new energy carriers into the market. A wide range of solutions has been proposed based on the improvements of conventional power trains, novel sources of energy for conventional power trains (like natural gas, hydrogen, biofuels, synthetic fuels). In addition, almost all automobile manufacturers are developing vehicles with electric power trains including batteries and fuel cells as well as (plug-in) hybrid drives with combustion engines or fuel cell systems and electric motors.
This large spectrum of solutions requires to carry out comprehensive analysis to evaluate and compare them. To look only at what happens on the vehicle is not enough to evaluate the impact of the new solution on the energy and climatic issues explained above. It is necessary to consider the whole energy conversion chains from the source of the primary energy up to its use in the vehicle, i.e. the Well-to-Tank step and the Tank-to-Wheel step - in sum, the Well-to-Wheel chain. For further information see the links above.