Abstract
Soaring crude oil prices has suggested that we have to consider not only CO2 but also security as discussing energy in future. Alternative fuels like bio fuels, natural gas, hydrogen, electricity, and so on will be key players to solve these issues. However, too much diversity of fuels should be avoided from the viewpoint of vehicle technology. The opimum fuel mix should be selected for transportation sectors meet the requirement of CO2 reduction, energy security and avoiding soaring fuel price. Considering that the internal combustion engine (ICE) will be main stream well into this century, it must be first to improve fuel efficiency to reduce crude oil consumption. For this purpose, hybrids and plug-in hybrids have large potential of improving fuel efficiency and these technologies will become core technologies for ICE. The next step to consider is the diversity of energy source for these engines. In various application, bio fuels and natural gas will be favorable alternative fuels from the viewpoint of supply potential and vehicle technologies in short term. Biofuels are especially promising as alternative fuels, since existing vehicles and infrastructure can incorporate them with little or no change. Considering the next generation biofuels, there is a large supply potential and possibility to mitigate GHG emissions. Since the technology of natural gas vehicle is matured, natural gas can expand quickly if governments support it through energy policies. Fuel Cell Vehicles and Electric Vehicles are still in their early development stages, but it is expected that hydrogen and electricity will be a major energy source in long term.
Keywords: Energy, Alternative fuel, CO2, GHG