From the Guest Editor’s desk: biofuels from biomass and wastes

Waste biomass is unanimously recognised as the most abundant renewable feedstock for bioenergy generation worldwide. Conversion of biomass to biofuels is possible either through biochemical (anaerobic digestion and anaerobic fermentation) or thermochemical (pyrolysis and gasification) pathways or their hybridisation. Waste biomass is converted to various second-generation biofuels, namely, bioalcohols (bioethanol, biobutanol and higher alcohols), biohydrogen, biomethane, bio-oil and bio-syngas, etc., through employment of either the biochemical or thermochemical route or hybrids. The hybrids are useful in the production of a plethora of platform chemicals along with biofuels, introducing the concept of biorefinery. Accordingly, biorefineries are globally contemplated as the viable platforms for the highly anticipated transition from ‘fossil-based economy’ to the ‘biobased economy’. Vigorous effort is currently being made for upgradation of the existing biorefinery frameworks to fully achieve the sustainability standards required to ensure their full-scale implementation in near future. As a consequence of introducing the sustainability goals into the concept of biorefinery and the ever-increasing concern for the glaring ‘food-fuel conflict’, the second generation (2G) of biorefineries has garnered worldwide popularity over their first-generation counterparts. Utilisation of fully renewable lignocellulosic biomass (LB), derived from various waste streams in place of exhaustible petro-fuels, is the most vital factor favouring the widespread acceptance of 2G biorefineries from social–economical–environmental aspects. Significant technological progress is presently being made in the field of 2G biorefineries, converting LB to different liquid and gaseous biofuels. This has incremented the efficacy of the end-use of the LB manifolds. The implementation of hybrid strategies further strengthens the sustainability of biorefineries using waste biomass. This Special Issue of Indian Chemical Engineer (ICE) comprises research articles focussed on the exploration of some interesting hybrid technologies for the production of biofuels and biochemicals from the LB feed-stocks, using the 2G-biorefinery concept. The articles, in general, highlight biochemical–thermochemical hybrid bioenergy systems, producing various bioenergy vectors from different LBs. The integration techniques of these hybrid processes with an overall assessment of their better attributes with respect to their individual counterparts have been discussed as well. The articles have also underlined the challenges involved in the way of further advancement of these technologies. One expects that the knowledge base, created by virtue of these research articles, will be of great relevance to the existing body of the available information on 2G biorefineries, using hybrid platforms. Selected articles, presented in an International Seminar on Sustainable 2-G Biorefinery Platforms (ISS2-GBP) and an International Workshop on Hybrid Technologies for Conversion of LB to Biofuel (IWHTCLBB), have been selected for publication in this Special Issue. ISS2-GBP and IWHTCLBB were organised by the Chemical Engineering Department of Jadavpur University, India, during 10–12 December and 11–13 December 2019, respectively. The sponsor of ISS2-GBP was RUSA-2, Jadavpur University. IWHTCLBB was sponsored by CONVER-B (Inno-Indigo) project of DST, India. A total of 100 registered participants from European institutes, namely, UFZ, Germany and Indian academic and Research institutions, namely, IIT Kharagpur, NIT Durgapur, Jadavpur University as well as industry houses like Indian Oil Corporation, attended the events. To celebrate the extensive development and growth of Chemical Engineering education in India, we would like to dedicate this Special Issue of ICE to the Chemical Engineering Department of