Preface

The increasing demand for energy worldwide, together with the depletion of crude oil reserves, environmental threats due to greenhouse gas emissions and new national and international legislation, is resulting in the imperative for petroleum-derived fuels to be complemented or substituted by biofuels. Such an alternative, renewable, biodegradable and nontoxic biofuel is biodiesel.

The book "Biodiesel: Feedstocks and Processing Technologies" is intended to provide a professional look on the recent achievements and emerging trends in biodiesel production. It includes 21 chapters, organized in two sections.

The first book section: "Feedstocks for Biodiesel Production" covers issues associated with the utilization of cost effective non-edible raw materials and wastes, and the development of biomass feedstock with physical and chemical properties that facilitate it processing to biodiesel. Chapter 1 is focused on the possible use of *Brassicaceae* spp., namely *B.juncea* in biodiesel production, and demonstrates the sustainability of an agronomic rotation between *Brassicacea* and *nicotiana tabacum* to produce vegetable oil from marginal soils. Chapter 2 comments on waste cooking oils transesterification to produce biodiesel, identifying the main types of cooking oils and supplying production process details. The generation of animal fat wastes in Brazil, their characterization and use for biodiesel synthesis is summarized in Chapter 3. The current knowledge advances in oleaginous fungi metabolism, physiology, and strain improvement are discussed in Chapter 4. Oleaginous fungi, and particularly yeasts, are considered as very efficient in the accumulation of intracellular triacylglycerols and it is expected that they will be exploited by the biofuel industry in the future. In continuation of the topic, Chapters 5-9 provide an overview on the various aspects of the use of microalgae as a source of oil for biodiesel, focusing on: a description of algae and their properties with regards to oil production, requirements and key factors in microalgal cultivation, methods and challenges in harvesting and processing of algal biomass, economic and environmental feasibility of microalgal biodiesel, mechanisms to enhance lipid productivity of microalgae, and future research directions. Finally, Chapter 10 discusses the implementation of an integrated waste-free biomass utilization system for an increased productivity of biofuel and bioenergy.

The second book section: "Biodiesel Production Methods" is devoted to the advanced techniques for biodiesel synthesis. Chapters 11 and 12 discuss the technological aspects of the process of supercritical transesterification in biodiesel production, highlighting the effect of the reaction parameters, and the operational conditions. The economical feasibilities and the chemical limitations of supercritical transesterification, as well as process improvements and prospective are commented in details. Chapter 13 reports some alternative methods for biodiesel production reducing the reaction time, the reactive ratio, the quantity of the by-products, and the energy consumption. These include microwaves, radio frequency and ultrasound techniques. Biodiesel production efficiency improvement applying reactive distillation, and optimized transesterification processes are commented in Chapters 14 and 15. Recent advances in solid catalyst method for biodiesel production are reported in Chapters 16-18. Catalyst synthesis and characterization, as well as catalytic mechanism and catalytic activity are discussed, making use of research results. Chapters 19 and 20 comment on some aspects of the enzymatic approach to biodiesel production. Chapter 19 provides an overview on the use of immobilized lipases in biodiesel production, the techniques applied for enzyme immobilization, and the factors affecting the process. Chapter 20 is focused on a case study, namely the transesterification of rapeseed oil with immobilized yeast lipase. Biodiesel refining process is the subject of Chapter 21. The theoretical and practical aspects related to the functioning, design and operation of adsorbers and their application to the purification of biodiesel product and feedstocks are comprehensively reviewed.

The adequate and up-to-date information provided in this book should be of interest for research scientist, students, and technologists, involved in biodiesel production.

All the contributing authors are gratefully acknowledged for their time and efforts in preparing the different chapters, and for their interest in the present project.

> **Margarita Stoytcheva Gisela Montero**  Mexicali, Baja California Mexico
