Volume 2: Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae

Konur, O., ed. 2021. Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae: Science, Technology, Health, and Environment. Boca Raton, FL: CRC Press. https://doi.org/10.1201/9780367456207

This second volume of the Handbook of Biodiesel and Petrodiesel Fuels presents a representative sample of the population papers in the field of feedstock-specific biodiesel fuels.

The research on feedstocks for biodiesel fuels has first focused on the edible oils as first-generation biodiesel fuels. However, the public concerns about the competition with foods based on these feedstocks and adverse impact on the ecological diversity and deforestation have resulted in the exploration of nonedible-oil-based biodiesel fuels as second-generation biodiesel fuels in the first instance.

Due to the ecological and cost benefits of treating wastes, waste oil-based biodiesel fuels as third-generation biodiesel fuels have emerged. Furthermore, following a series of influential review papers, the research has focused on the algal oil-based biodiesel fuels in recent years. Since the cost of feedstocks in general constitutes 85% of the total biodiesel production costs, the research focused more on improving biomass and lipid productivity in these research fields. Furthermore, since water, CO₂, and nutrients (primarily N and P) have been major ingredients for the algal biomass and lipid production, the research has also intensified in the use of wastewaters and flue gases for algal biomass production to reduce the ecological burdens and the production costs.

Part 1 presents a representative sample of the population papers in the field of edible oil-based biodiesel fuels covering major research fronts. It covers soybean oil-based biodiesel fuels, palm oil-based biodiesel fuels, and rapeseed oil-based biodiesel fuels as case studies besides an overview paper.

Part 2 presents a representative sample of the population papers in the field of nonedible oil-based biodiesel fuels covering major research fronts. It covers Jatropha oil-based biodiesel fuels, polanga oil-based biodiesel fuels, and moringa oil-based biodiesel fuels as case studies besides an overview paper.

Part 3 presents a representative sample of the population papers in the field of waste oil-based biodiesel fuels covering major research fronts. It covers wastewater sludge-based biodiesel fuels, waste cooking oil-based biodiesel fuels, and microbial oil-based biodiesel fuels as case studies besides an overview paper.

Part 4 presents a representative sample of the population papers in the field of algal oil-based biodiesel fuels covering major research fronts. It covers algal biomass production in general, algal biomass production in wastewaters, algal lipid production, hydrothermal liquefaction of algal biomass, algal lipid extraction, and algal biodiesel production besides an overview paper.

This book will be useful to academics and professionals in the fields of Energy Fuels, Chemical Engineering, Physical Chemistry, Biotechnology and Applied Microbiology, Environmental Sciences, and Thermodynamics.

Ozcan Konur is both a materials scientist and social scientist by training. He has published around 200 journal papers, book chapters, and conference papers. He has focused on the bioenergy and biofuels in recent years. In 2018, he edited ‘Bioenergy and Biofuels’, that brought together the work of over 30 experts in their respective field. He also edited ‘Handbook of Algal Science, Technology, and Medicine’ with a strong section on the algal biofuels in 2020.

Part 5. Edible oil-based biodiesel fuels

Chapter 21. Konur, O. 2021. Edible oil-based biodiesel fuels: A scientometric review of the research. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae: Science, Technology, Health, and Environment, ed. O. Konur. Boca Raton, FL: CRC Press.  Edible Oil-based Biodiesel Fuels | 2 | A Scientometric Review of the R (taylorfrancis.com)

Crude oils have been primary sources of energy and fuels, such as petrodiesel. However, significant public concerns about the sustainability, price fluctuations, and adverse environmental impact of crude oils have emerged since the 1970s. Thus, biooils have emerged as an alternative to crude oils in recent decades. In this context, edible oil-based biodiesel fuels have also emerged as a viable alternative to crude oil-based diesel fuels. However, for the efficient progression of the research in this field, it is necessary to develop efficient incentive structures for the primary stakeholders and to inform these stakeholders about the research. This chapter presents a study of the scientometric evaluation of the research in this field using two datasets. The first dataset includes the 100-most-cited papers (n = 100 sample papers) whilst the second set includes population papers (n = over 2,650 papers) published between 1980 and 2019. This complements the chapters on crude oil-based petrodiesel fuels and other biooil-based biodiesel fuels. The data on the indices, document types, authors, institutions, funding bodies, source titles, ‘Web of Science’ subject categories, keywords, research fronts, and citation impact are presented and discussed.

Chapter 22. Westbrook, C. K. 2021. Chemistry of biodiesel fuels based on soybean oil. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae, ed. O. Konur. Boca Raton, FL: CRC Press. Chemistry of Biodiesel Fuels based on Soybean Oil | 3 | Biodiesel Fuel (taylorfrancis.com)

The chemistry of biodiesel fuels is discussed, using soybean oil biodiesel fuel as the specific example. The presence of only five unique methyl ester molecules in a biodiesel fuel is shown to be a major simplifying factor in understanding and using detailed chemical kinetic modeling to describe its combustion. The number and location of C=C double bonds in these component molecules is shown to be a dominant factor in distinguishing ‘soy biodiesel’ (SBD) fuel from biodiesel fuels produced from other vegetable oils and for predicting the combustion properties of soybean oil diesel fuel. The monosaturated component of soybean oil, methyl oleate, is shown to have an optimal structure as a diesel fuel in terms of minimizing pollutant emissions, maximizing diesel cetane number of the fuel, and limiting fuel thermal stability. Ongoing research to improve the oxidation stability of soybean oil in food applications, by increasing the oleate fraction in soybean oil, is shown to also be improving the combustion properties of biodiesel fuels, properties that will be based on future soybean oil.

Chapter 23. Konur, O. 2021. Palm oil-based biodiesel fuels: A review of the research. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae, ed. O. Konur. Boca Raton, FL: CRC Press. Palm Oil-based Biodiesel Fuels | 4 | A Review of the Research | Ozcan (taylorfrancis.com)

Crude oils have been primary sources of energy and fuels, such as petrodiesel. However, significant public concerns about the sustainability, price fluctuations, and adverse environmental impact of crude oils have emerged since the 1970s. Thus, biooils and biooil-based biodiesel fuels have emerged as alternatives to crude oils and crude oil-based petrodiesel fuels, respectively, in recent decades. Nowadays, although petrodiesel fuels are still used extensively, biodiesel fuels are being used increasingly in the transportation and power sectors. Therefore, there has been great public interest in the development of edible oil-based biodiesel fuels as the first generation of such fuels. ’Palm oil-based biodiesel’ (POBD) fuels have been among the most-produced and marketed edible oil-based biodiesel fuels. Although there have been a number of reviews and book chapters in this field, there has been no review of the 25-most-cited articles in this field. Thus, this chapter reviews these most-cited articles by highlighting the key findings of these studies on the production and properties of POBD fuels. Then, it discusses these key findings.

Chapter 24. Konur, O. 2021. Rapeseed oil-based biodiesel fuels: A review of the research. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae, ed. O. Konur. Boca Raton, FL: CRC Press. Rapeseed Oil-based Biodiesel Fuels | 5 | A Review of the Research | Oz (taylorfrancis.com)

Crude oils have been primary sources of energy and fuels, such as petrodiesel. However, significant public concern about the sustainability, price fluctuations, and adverse environmental impact of crude oils have emerged since the 1970s. Thus, biooils and biooil-based biodiesel fuels have emerged as alternatives to crude oils and crude oil-based petrodiesel fuels, respectively, in recent decades. Nowadays, although petrodiesel fuels are still used extensively, biodiesel fuels are being used increasingly in the transportation and power sectors. Therefore, there has been great public interest in the development of edible oil-based biodiesel fuels as the first generation of biodiesel fuels. Rapeseed oil-based biodiesel (ROBD) fuels have been among the most-produced and marketed edible oil-based biodiesel fuels. Although there have been a number of reviews and book chapters in this field, there has been no review of the 25-most-cited articles. Thus, this chapter reviews these articles by highlighting the key findings of these most-prolific studies on the production and properties of ROBD fuels. Then, it discusses these key findings.

Part 6. Nonedible oil-based biodiesel fuels

Chapter 25. Konur, O. 2021. Nonedible oil-based biodiesel fuels: A scientometric review of the research. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae: Science, Technology, Health, and Environment, ed. O. Konur. Boca Raton, FL: CRC Press. Nonedible Oil-based Biodiesel Fuels | 7 | A Scientometric Review of th (taylorfrancis.com)

Crude oils have been primary sources of energy and fuels, such as petrodiesel. However, significant public concern about the sustainability, price fluctuations, and adverse environmental impact of crude oils have emerged since the 1970s. Thus, biooils have emerged as an alternative to crude oils in recent decades. In this context, nonedible oil-based biodiesel (NOBD) fuels have emerged as a viable alternative to crude oil-based diesel fuels. However, for the efficient development of the research in this field, it is necessary to develop efficient incentive structures for the primary stakeholders and to inform these stakeholders about the research. This chapter presents a study of the scientometric evaluation of the research in this field using two datasets. The first dataset includes the 100-most-cited papers (n = 100 sample papers) whilst the second set includes population papers (n = over 2,150 population papers) published between 1980 and 2019. This complements the chapters on crude oil-based petrodiesel fuels and other biooil-based biodiesel fuels. The data on the indices, document types, authors, institutions, funding bodies, source titles, ‘Web of Science’ subject categories, keywords, research fronts, and citation impact are presented and discussed.

Chapter 26. Banapurmath, N. R., M. E. Soudagar, S. V. Ganachari, P. S. Kulkarni, N. K. Kumar, and V. S. Yaliwal. 2021. An exhaustive study on the use of Jatropha based biodiesel for modern diesel engine applications. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae: Science, Technology, Health, and Environment, ed. O. Konur. Boca Raton, FL: CRC Press. An Exhaustive Study on the Use of Jatropha Based Biodiesel for Modern (taylorfrancis.com)

Recent investigations on fuel additives have suggested that the presence of nanosized carbon particles in diesel–biodiesel fuel blends enhance the overall engine characteristics. This work includes approaches for nanofluid preparation using ultrasonic probe and bath sonication methods, the stability improvement of nanofluids by the addition of surfactants, numerous characterization techniques to estimate ‘nanoparticle’ (NP) shape and size, dispersion stability, and the chemical bonding of nanoadditives in liquid fuel. Jatropha oil has been converted into its biodiesel called ‘Jatropha oil methyl ester’ (JOME) and blended with diesel to obtain its B20 blend. Further improvement in the fuel properties of the B20 blend has been realized with the addition of graphene NPs as fuel additives with their dosage varying at 15, 20, and 30 mg respectively. Accordingly, JOMEB20Gr20 represents a B20 blend of JOME with a 20 mg dosage of graphene NPs. The stability of nanoadditive–fuel blends has resulted in their improved thermophysical properties. Further, their use in high pressure assisted ‘common rail direct injection’ (CRDI) diesel engines has resulted in a higher heat transfer rate and higher in-cylinder pressures. ‘Brake thermal efficiency’ (BTE) increased and ‘brake specific fuel consumption’ (BSFC) reduced, while the exhaust emissions of carbon monoxide (CO), ‘unburned hydrocarbons’ (UHC), and ‘nitrogen oxide’ (NO) decreased, depending on the dosage of NPs in the fuel.

Chapter 27. Dandu, M. S. R., K. Nanthagopal, and B. Ashok. 2021. The effects of additives with Calophyllum inophyllum methyl ester (CIME) in CI engine applications. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae: Science, Technology, Health, and Environment, ed. O. Konur. Boca Raton, FL: CRC Press. The Effects of Additives with Calophyllum inophyllum Methyl Ester in C (taylorfrancis.com)

Biodiesel is a promising and best substitute for fossil fuel for automobile applications around the globe. Nowadays, biodiesel from vegetable feedstocks is gaining much attention, significantly raising plantation awareness which relates to environmental concerns. In this chapter, the different production structures for Calophyllum inophyllum feedstock is considered for maximum yield rate. The produced biodiesel is treated as one of the best alternative energy sources for ‘compression ignition’ (CI) engine applications through various categories such as property assessment and utilization in diesel engines. This chapter summarizes the recent research output on the effect of various higher alcohol ‘oxygenated additives’ (OAs), ethers, and ‘nanoparticles’ (NPs) with ‘Calophyllum inophyllum biodiesel’ (CIBD) fuel at various concentrations.

Chapter 28. Niju, S. and G. Janani. 2021. Moringa oleifera oil as a potential feedstock for sustainable biodiesel production. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae, ed. O. Konur. Boca Raton, FL: CRC Press. Moringa oleifera Oil as a Potential Feedstock for Sustainable Biodiese (taylorfrancis.com)

Biodiesel has been gaining huge attention as an alternative to petrodiesel over the past decades, mainly due to its striking economic and environmental benefits. An integrated feedstock supply chain and production technology play a crucial role in a sustainable and economically feasible biodiesel adoption all over the world. Biodiesel can be produced from various vegetable oils, animal fats, and microbial oils, but when it comes to economic and commercial production, second generation feedstock becomes the major choice of raw material. Moringa oleifera is one such promising feedstock for biodiesel production due to its high ‘cetane number’ (CN), high oxidation stability, and low iodine value with a large fraction of unsaturated fatty acids, and its widely distributed perennial tree. But the high acid value makes it unfit for direct transesterification. This chapter highlights the available feedstocks as well as the potential of ‘Moringa oleifera oil’ (MOO) for biodiesel production and efficiency of ultrasonication; a case study is performed on the ultrasound assisted acid catalyzed esterification of MOO.

Part 7. Waste oil-based biodiesel fuels

Chapter 29. Konur, O. 2021. Waste oil-based biodiesel fuels: A scientometric review of the research. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae: Science, Technology, Health, and Environment, ed. O. Konur. Boca Raton, FL: CRC Press. Waste Oil-based Biodiesel Fuels | 12 | A Scientometric Review of the R (taylorfrancis.com)

Crude oils have been primary sources of energy and fuels, such as petrodiesel. However, significant public concerns about the sustainability, price fluctuations, and adverse environmental impact of crude oils have emerged since the 1970s. Thus, biooils have emerged as an alternative to crude oils in recent decades. In this context, ‘waste oil-based biodiesel’ (WOBD) fuels have also emerged as a viable alternative to crude oil-based diesel fuels. However, for the efficient development of the research in this field, it is necessary to develop efficient incentive structures for the primary stakeholders and to inform these stakeholders about the research. This chapter presents a study on the scientometric evaluation of the research in this field using two datasets. The first dataset includes the 100-most-cited papers (n = 100 sample papers) whilst the second set includes population papers (n = over 2,150 population papers) published between 1980 and 2019. It complements the chapters on crude oil-based petrodiesel fuels and other biooil-based biodiesel fuels. The data on the indices, document types, authors, institutions, funding bodies, source titles, ‘Web of Science’ subject categories, keywords, research fronts, and citation impact are presented and discussed.

Chapter 30. Siddique, M. N. and S. Rohani. 2021. Biodiesel production from municipal wastewater sludge - Recent trends. Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae: Science, Technology, Health, and Environment, ed. O. Konur. Boca Raton, FL: CRC Press. Biodiesel Production from Municipal Wastewater Sludge | 13 | Recent Tr (taylorfrancis.com)

Municipal wastewater treatment plants produce huge amounts of sludge, which is expected to increase with the advancement of modern society. Sludge management is expensive and challenging for any wastewater treatment plant. Different approaches are being considered to reduce waste management cost and to produce valuable fuels and chemicals. As municipal sewage sludge is a good source of lipids and phospholipids, it is a potential source for biodiesel (‘fatty acid alkyl ester’) production. Biodiesel, a key alternative of petrodiesel, is produced via esterification and transesterification. It receives huge attention as it is renewable and environmentally viable and can be used either directly as a fuel or as a blend with petrodiesel without any engine modification. But biodiesel production is not economically viable mainly due to the higher raw material cost and edible sources that compete with food materials. Hence, it is important to find an alternative, inexpensive, and readily available raw material source. Sewage sludge can play a vital role in biodiesel production to mitigate the production cost and environmental footprint. Biodiesel production from wastewater sludge has been widely investigated over the last two decades. This chapter highlights the recent advances, challenges, and economic analysis of biodiesel production from municipal sewage sludge.

Chapter 31. Castanheiro, J. E. 2021. Heterogeneous acid-catalysts for biodiesel production from waste cooking oil. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae: Science, Technology, Health, and Environment, ed. O. Konur. Boca Raton, FL: CRC Press. Heterogeneous Acid Catalysts for Biodiesel Production from Waste Cooki (taylorfrancis.com)

Biodiesel is a green fuel, because it is biodegradable and reduces the emission of greenhouse gases. In the first generation of biofuels, the biodiesel is produced from edible oils. However, due to the high cost of biodiesel production and social problems, the use of ‘waste cooking oils’ (WCO) can improve the economics of first generation biodiesel. Traditionally, biodiesel production has been performed using homogeneous catalysts (NaOH, KOH). However, these homogenous catalysts have some disadvantages, such as difficulty in separation from reaction products and corrosiveness. The use of heterogenous catalysts can be a solution to the problems associated with homogeneous catalysts. These catalysts have some advantages such as easy separation from the reaction mixture and the material can be reused and regenerated. The aim of this chapter is to review biodiesel production from second generation WCO in the presence of heterogeneous solid acid catalysts. Biodiesel production from WCO is done using zeolites, polymers, heteropolyacids, activated carbons, metal oxides, and composite catalysts.

Chapter 32. Satyannarayana, K. V. V., R. Singh, G. Moorthy, and R. V. Kumar. 2021. Microbial biodiesel production using microbes in general. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae: Science, Technology, Health, and Environment, ed. O. Konur. Boca Raton, FL: CRC Press. BioMicrobialdiesel Production using Microbes in General | 15 | Biodies (taylorfrancis.com)

This chapter discusses the role of microbes (oleaginous microbes), namely microalgae, bacteria, fungi, or yeast, through the transesterification process used in the production of biodiesel. At present, the most extensively used biofuels are bioethanol and biodiesel. Biodiesel production through a microbial system is consequently receiving growing concentration as sustainable, alternative, and cost-effective. Microbial lipids have the high content of a saponifiable material and a suitable fatty acid profile for biodiesel production. Biodiesel fuel is better than petrodiesel in many characteristics, for instance, it is environmentally friendly, has reduced emissions, improved lubricity, a higher combustion efficiency, renewability, and safer. The physical and chemical properties and characteristics of microbial biodiesel are discussed in this chapter. In addition, it provides complete details about the importance, methods of production, applications, and benefits of microbial biodiesel.

Part 8. Algal biodiesel fuels

Chapter 33. Konur, O. 2021. Algal biodiesel fuels: A scientometric review of the research. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae: Science, Technology, Health, and Environment, ed. O. Konur. Boca Raton, FL: CRC Press. Algal Biodiesel Fuels | 17 | A Scientometric Review of the Research | (taylorfrancis.com)

Crude oils have been primary sources of energy and fuels, such as petrodiesel. However, significant public concerns about the sustainability, price fluctuations, and adverse environmental impact of crude oils have emerged since the 1970s. Thus, biooils have emerged as an alternative to crude oils in recent decades. In this context, algal biodiesel fuels have also emerged as a viable alternative to petrodiesel fuels. However, for the efficient progression of the research in this field, it is necessary to develop efficient incentive structures for the primary stakeholders and to inform these stakeholders about the research. Scientometric analysis offers ways to evaluate the research in a respective field. However, there has been no current scientometric study of this field. This chapter presents a study of the scientometric evaluation of the research in this field using two datasets. The first dataset includes the 100-most-cited papers (n = 100 sample papers) whilst the second set includes population papers (n = over 15,000 population papers) published between 1980 and 2019. The data on the indices, document types, authors, institutions, funding bodies, source titles, ‘Web of Science’ subject categories, keywords, research fronts, and citation impact are presented and discussed.

Chapter 34. Konur, O. 2021. Algal biomass production for biodiesel production: A review of the research. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae, Ed. O. Konur Boca Raton, FL: CRC Press. Algal Biomass Production for Biodiesel Production | 18 | A Review of t (taylorfrancis.com)

Crude oils have been primary sources of energy and fuels, such as petrodiesel. However, significant public concerns about the sustainability, price fluctuations, and adverse environmental impact of crude oils have emerged since the 1970s. Thus, biooils and biooil-based biodiesel fuels have emerged as alternatives to crude oils and crude oil-based petrodiesel fuels, respectively, in recent decades. Nowadays, although petrodiesel fuels are still used extensively, biodiesel fuels are being used increasingly in the transportation and power sectors. Therefore, there has been great public interest in the development of algal biodiesel fuels as the fourth generation of biodiesel fuels. However, it is necessary to reduce the total cost of biodiesel production by reducing the feedstock cost through the improvement of the biomass productivity of algal biomass. Furthermore, for the efficient progression of the research in this field, it is necessary to develop efficient incentive structures for the primary stakeholders and to inform these stakeholders about the research. Although there have been a number of reviews and book chapters in this field, there has been no review of the 25-most-cited articles. Thus, this chapter reviews these articles by highlighting the key findings of these most-prolific studies on algal biomass production for algal biodiesel production. Then, it discusses these key findings.

Chapter 35. Konur, O. 2021. Algal biomass production in wastewaters for biodiesel production: A review of the research. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae, ed. O. Konur. Boca Raton, FL: CRC Press. Algal Biomass Production in Wastewaters for Biodiesel Production | 19 (taylorfrancis.com)

Crude oils have been primary sources of energy and fuels, such as petrodiesel. However, significant public concerns about the sustainability, price fluctuations, and adverse environmental impact of crude oils have emerged since the 1970s. Thus, biooils and biooil-based biodiesel fuels have emerged as alternatives to crude oils and crude oil-based petrodiesel fuels, respectively, in recent decades. Nowadays, although petrodiesel fuels are still used extensively, biodiesel fuels are being used increasingly in the transportation and power sectors. Therefore, there has been great public interest in the development of algal biodiesel fuels as the fourth generation of biodiesel fuels. However, it is necessary to reduce the total cost of biodiesel production by reducing the feedstock cost through the use of wastewater instead of fresh water. Although there have been a number of reviews and book chapters in this field, there has been no review of the 25-most-cited articles in this field. Thus, this chapter reviews these articles by highlighting the key findings of these most-prolific studies on algal biomass production and nutrient removal in wastewaters for algal biodiesel production. Then, it discusses these key findings.

Chapter 36. Konur, O. 2021. Algal lipid production for biodiesel production: A review of the research. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae, Ed. O. Konur Boca Raton, FL: CRC Press. Algal Lipid Production for Biodiesel Production | 20 | A Review of the (taylorfrancis.com)

Crude oils have been primary sources of energy and fuels, such as petrodiesel. However, significant public concerns about the sustainability, price fluctuations, and adverse environmental impact of crude oils have emerged since the 1970s. Thus, biooils and biooil-based biodiesel fuels have emerged as alternatives to crude oils and crude oil-based petrodiesel fuels, respectively, in recent decades. Nowadays, although petrodiesel fuels are still used extensively, biodiesel fuels are being used increasingly in the transportation and power sectors. Therefore, there has been great public interest in the development of algal biodiesel fuels as the fourth generation of biodiesel fuels. However, it is necessary to reduce the total cost of biodiesel production by reducing the feedstock cost through the improvement of lipid productivity of algal biomass. Furthermore, for the efficient progression of the research in this field, it is necessary to develop efficient incentive structures for the primary stakeholders and to inform these stakeholders about the research. Although there have been a number of reviews and book chapters in this field, there has been no review of the 25-most-cited articles. Thus, this chapter reviews these articles by highlighting the key findings of these most-prolific studies on algal lipid production for algal biodiesel production. Then, it discusses these key findings.

Chapter 37. Koley, S., S. Sonkar, and N. Mallick. 2021. Bio-oil production from microalgae: Current status and future prospective. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae, ed. O. Konur. Boca Raton, FL: CRC Press. Biooil Production from Microalgae | 21 | Current Status and Future Per (taylorfrancis.com)

Depleting stocks of fossil fuels encourage the development of sustainable biofuels. Microalgae, among other biomass, have the potential to become a primary energy source in the future. Despite the various advantages, microalgal biofuels still need some of their constraints resolving. In this chapter, the authors provide a short overview of how these hurdles can be overcome and how the ‘hydrothermal liquefaction’ (HTL) of biomass can offer a unique inexpensive way of biooil production by replacing the energetic and cost-intensive drying and transesterification processes. Hydrothermal processing has the ability to process biomass at a wide range of moisture levels. The present scenario focuses primarily on the process factors, which can enhance the yield of biooil from microalgal biomass. The effect of a catalyst is also observed to enhance the yield of biooil. Biooil has a high heating value in the range of 30–38 MJ/kg, and thus can be used with the processing of conventional crude. The upgrading of biooil needs to be performed to meet the characteristics of conventional crude. The current study also focuses on effectively using all the extract of HTL. Finally, based on the findings obtained from the literature review, directions for future research are suggested.

Chapter 38. Krishnan, S., J. Jeevanandam, C. Acquah and M. K. Danquah. 2021. Extraction of algal neutral lipids for biofuel production. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae, ed. O. Konur. Boca Raton, FL: CRC Press. Extraction of Algal Neutral Lipids for Biofuel Production | 22 | Biodi (taylorfrancis.com)

Lipids represent a major algal biochemical with an extensive range of applications including biodiesel synthesis. Biodiesel constitutes ‘fatty acid methyl esters’ (FAME) arising from the transesterification of lipids. Among algal lipids, neutral or true lipids such as ‘triacylglycerols’ (TAGs) are important for generating high quality and stable biodiesel fuel with enhanced calorific value. New and improved physicochemical lipid extraction methods are highly important to enable the selective generation of true lipids from algal biomass. This chapter presents an overview of the diverse conventional and advanced extraction methods used as efficient approaches for lipid extraction from algae. The impact of nanotechnology for enhanced lipid extraction is discussed.

Chapter 39. Sivaramakrishnan, R. and A. Incharoensakdi. 2021. Microalgal biodiesel production. In Handbook of Biodiesel and Petrodiesel Fuels: Science, Technology, Health, and Environment. Volume 2. Biodiesel Fuels based on the Edible and Nonedible Feedstocks, Wastes, and Algae, ed. O. Konur. Boca Raton, FL: CRC Press. Microalgal Biodiesel Production | 23 | Biodiesel Fuels Based on Edible (taylorfrancis.com)

Replacing fossil fuel with a suitable and sustainable fuel source is necessary to address the issue of global warming. Biodiesel can be considered as an alternative solution due to its non-toxic and eco-friendly nature. Among the different feedstocks, microalgae have been considered as a potential candidate for biodiesel production. Microalgae can be cultivated in non-arable land which requires less cropland when compared to other conventional crops as microalgal feedstock does not compete with the food supply. Microalgae have a high growth rate and high lipid content. Moreover, microalgal biodiesel production is less energy intensive and economically feasible. However, the commercialization of microalgal biodiesel production is still confronted with numerous challenges in practice. Selection of microalgae is very important to achieve high biomass and lipid yield. A microalgal cultivation system is one of the crucial factors for achieving sustainable microalgal production which can undoubtedly affect the biomass and lipid yield. In this chapter, lipid extraction and biodiesel production methods are discussed. The findings provided in this chapter could be described as a roadmap in acquiring the knowledge required for microalgal biodiesel production and future microalgal biodiesel development.