**12. Conclusions**

Alcohol fuel is one of the most important source of energy in view of its renewable nature and the abundance of feedstock on earth. Even when many bright prospects of alcohol fuels shed light on possible options for the environmental conscious society, still cost dictates and it will be that way. Carbon taxation might help, but the market might lead to a totally different direction such as hydrogen or green electricity from renewable energy, instead of choosing alcohol fuels. Abundant shale natural gas might play a replacing act of cheap oil that had prevented most of other energy source developments from the 1950s till the 1970s. All these situation point that the future of alcohol fuels depends upon the technological advances in cost and convenience in use.

As discussed in this chapter, the direction of future energy is simple and clear. It is the low-carbon economy using sustainable energy resources but with affordable cost. Alcohol fuels can act as connecting threads between current conventional oil/ gas society and the future hydrogen society in attaining this far-reaching goal.

Current status regarding alcohol fuels can be summarized as stagnant in scale and also in utilizing market. Since bio-ethanol dominates the alcohol fuel market, the

system has an inherently sensitive structure to changes in supply-demand and government's policies. More wide application ranges of alcohol fuels should be sought in areas such as fuel cells, marine ships, and jet fuels. Alcohol fuels must remain as an essential component for the realization of sustainable low-carbon society, and continuous research on key bottlenecks should be pursued systematically.
