Biofuels journey in Europe: Currently the way to low carbon economy sustainability is still a challenge

The growing need for any type of energy is leading the transport biofuels sector to develop technologies for an energy-efficient future, by using synergistically different forms of energy. Several biofuels are successful in addressing environmental concerns, but some create skepticism on their global sustain ability. This study is built around key topics related to four generation biofuels development, aiming to highlight advantages, drawbacks, negative externalities, and constraints, for their effective commercialization. It offers a short state-of-the-art review of terrestrial and marine biomass conversion into automotive and jet biofuels, and focuses on the biochemical and thermochemical conversion pathways and the role of processing conditions to maximize the production of renewable fuels. It concludes that there is still no clear answer on which generation biofuels meets the global sustainability criteria better. In all cases, it is important to take into account the scale of economy, bioresources availability and planetary boundaries for biomass supply, to design viable technologies and consider the Food-Energy Water and Carbon-Nitrogen Nexus challenges. Although the European Commission is looking at cost-efficient ways to make the European economy more climate-friendly and less energy-consuming by addressing the importance of biomass availability, proper legislation must deal with the multifaceted confrontation of the global sustainability which should also be driven by the socio-economic criteria. (C) 2018 Elsevier Ltd. All rights reserved.