Biofuels in Low Carbon Economies and Societies

The current sustainable transition plans seek to pursuit energy supply security with low carbon emissions. Although electrification is presented as a key factor to decarbonize demanding sectors (transport, buildings, and industry), energy provided by fuel combustion will be essential to cope with future demands. In this sense, it is necessary to rely on circular economy models based on low carbon biofuels. During the last decade, the biofuels industry transitioned from being sustainable and socially accepted to a deeply questioned solution due to the food versus energy debate. Therefore, using alternative feedstocks, such as wastes or residual biomass, is convenient to obtain biofuels creating new value chains during the transformation. This chapter is focused on the technologies developed for biofuel production capable of minimizing the carbon footprint. Production methods for gaseous biofuels and liquid biofuels are described. The possible integration of each technology is evaluated considering the availability of feedstocks and the emission savings obtained by main biofuels (bioethanol, biobutanol, and biomethane). This analysis reveals the need for diversification in feedstocks utilization and transformation and the intensification of waste management technologies. In this sense, a case study is presented considering the most extensive wastes produced worldwide (agricultural by-products) and the potential production of regular biofuels (bioethanol, biomethane, and biobutanol). Net energy production as biofuel and emission savings are analyzed for each case. This analysis reveals that bioethanol presents the best performance in terms of carbon neutrality. Finally, a revision of the most recent regulations affecting biomass transformation in biofuels and their role in the circular economy in Europe is included in the last section. This section provides a framework for the application of the technologies and the case study presented.