Fungal communities represent the majority of root-specific transcripts in the transcriptomes of Agave plants grown in semiarid regions

The aim of this chapter is to contextualize second-generation ethanol considering civilization’s needs for fuel, jobs, and sustainability, under the logics of the Bioeconomy. We will briefiy refiect on the evolution of energy use, the entry of fossil fuels into our lives and the need to move efficiently to a new energy matrix. It is in this matrix that ethanol can assume the role of a global liquid fuel. With this goal in mind, we are going to present the possibilities of producing ethanol in the necessary volume from various sources of biomass, whose use should be optimized through second-generation technologies and bioeletrification. Thus, we will explore the reasons that led to the development of the first second-generation ethanol plants, the technologies developed, and the challenges faced by the pioneers of the sector, particularly the fact that all underestimated the specific characteristics of straw and bagasse, which resulted in serious pretreatment failures. We will briefiy touch on themes that will be covered in detail in other chapters of this book, such as biomass, bioelectrification and the carbon credit system, subjects that are essential to the world expansion of 2G ethanol.