Foreword

Energy security is a major present-day global issue. As fossil fuel sources are drying up, there is an urgent need to explore alternate sources of energy. Climate change risk due to GHG emissions and global warming is also a global challenge. Green fuels in gaseous and liquid forms offer a simultaneous solution to both problems of energy security and climate change. Alcoholic biofuels such as bioethanol or biobutanol and biodiesel have emerged as potential green liquid transportation fuels. Gaseous biofuels of biogas and biohydrogen can substitute the conventional CNG in vehicles. Blending of petroleum fuels with liquid biofuels is being practised in several developed and developing economies. In addition to achieving a carbon-neutral fuel, this technique can also reduce the economic burden of oil import in developing countries like India. Despite voluminous research and literature in the areas of green fuels, extensive commercial implementation has not been achieved. Major causes leading to these effects are the high cost of substrates, and production techniques that are energy-intensive and lengthy. Intensification of the production processes is a possible solution for these issues. Ultrasound and cavitation have emerged as effective techniques for the intensification of numerous physical, chemical and biological processes. The application of ultrasound and cavitation in fuel processing has also been a research-intensive area. Essentially, ultrasound and cavitation are new techniques for introducing energy into the processing system. These techniques make energies available on extremely small spatial and temporal scales. Marked enhancement in process kinetics, yield, and efficiency has been observed with the application of ultrasound.

Ultrasound Technology for Fuel Processing is an attempt to bring out the state-of-the-art status of ultrasound-assisted and enhanced fuel processes – with special emphasis on green fuels. The authors of this monograph have touched upon almost all aspects – from fundamental to applied – of ultrasound-assisted fuel processing. Starting with the basic principles of ultrasound and cavitation, the authors have included distinct chapters on biohydrogen, biomass pretreatment, solid waste treatment, 2G/3G liquid fuels from biomass, microbes and microalgae. Other topics such as biodesulfurization, biofuel synthesis with hydrodynamic cavitation, enhanced oil recovery and crude oil upgradation have also been explicitly covered through individual chapters.

I am absolutely sure that a comprehensive collection of expertise from diverse facets of fuel processing in this monograph will be a versatile single source of information to the students and researchers of the multidisciplinary fraternity of biorefineries and chemical/petrochemical engineering. In recent years, many books and monographs have been published in the area of ultrasound, cavitation, sonochemistry, and ultrasound-assisted processes. However, this monograph is perhaps the first of its kind that exclusively addresses applications of ultrasound and cavitation for fuel processing. This monograph could also be a good reference book for undergraduate/graduate level courses on process engineering and intensification.

I have known the editor of this monograph, Dr. Sankar Chakma, for many years since he joined the Indian Institute of Technology Guwahati as an M. Tech. student. I heartily commend him on his efforts in collating and compiling expertise on ultrasound-assisted fuel processing and presenting it in a methodical and articulate manner. I feel convinced that this monograph will prove to be a valuable and lasting contribution to the area of fuel processing.