Recent studies have shown strong evidence of human activity impact on the climate of the planet. higher temperatures and intensification of extreme weather events such as hurricanes are among the consequences. this scenario opens up several possibilities for what is now called "green" or low carbon economy. we are talking about creating new businesses and industries geared to develop products and services with low consumption of natural resources and reduced greenhouse gases emission. within this category of business, biofuels is a highlight and the central theme of this book. the first section presents some research results for first generation ethanol production from starch and sugar raw materials. chapters in the second section present results on some efforts around the world to develop an efficient technology for producing second-generation ethanol from different types of lignocellulosic materials. while these production technologies are being developed, different uses for ethanol could also be studied. the chapter in the third section points to the use of hydrogen in fuel cells, where this hydrogen could be produced from ethanol.