Abstract

Bioenergy is a very heterogeneous aggregation of different feedstocks, conversion technologies and end-uses, and are often promoted as a "green" alternative to fossil fuels. In the case of fossil fuels, extraction energy costs would become higher than the actual energy yield due to increased energy costs for research, deep drilling, as well as to the lower quality and accessibility of the still available oil storages. The objective of this manuscript is to discuss the main myths, challenges, biotechnology progress and emerging possibilities about the bioenergy sources throughout the world. Bioenergy production systems are sometimes claimed to be able to fill the future fossil fuel shortages as well as to decrease carbon dioxide emissions and global warming. The success of bioenergy production depends on the quantity and quality of biomass available and the ability to cost effectively utilize it for energy production. The global effects of the development of biofuel production will depend crucially on where and how feedstocks are produced. Advances in biotechnology are needed to develop bioenergy crops more adapted to adverse environmental conditions with higher growth rate and high caloric value. Life-cycle analysis and evaluation of external costs are important for assessing the social and environmental advantages and disadvantages of bioenergy system.

Key words: Renewable energy, biomass, biofuel, environment, fossil fuel.