Microalgae-Based Biofuels and Bioproducts
10 - Biodiesel from microalgae
Abstract
This chapter focuses on the production of microalgae-based biodiesel, which has been the most studied biofuel from this promising feedstock. This chapter highlights the advantages of the microalgal biomass to produce third-generation biodiesel compared to oleaginous crops (first generation) and to other raw materials (second generation). The differences between the microalgae-based biodiesel's properties with other feedstock are presented as well as the way to enhance the biomass and lipid productivities, the innovative methods/methodologies to lower production cost in all production steps, and a case study from the Eastern Mediterranean, and future trends.
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Life cycle assessment with the transition from lignocellulose- to microalgae-based biofuels: A review
2024, Journal of Industrial and Engineering ChemistryThe main issue in our environment today is the rapid increase in greenhouse gases (GHGs), which is mainly caused by emissions from transportation and industries. Therefore, biomass-based biofuels are considered promising solutions for the reduction of GHGs owing to their carbon neutrality. This review presents an environmental impact analysis of different biofuels derived from different types of biomass. The characteristics of sustainable biodiesel are analyzed in this review. From the perspective of the existing cycle, it is important to evaluate and quantify the environmental effects of biofuel synthesis, such as biodiesel and bioethanol. The goal of this study was to foster a life cycle analysis information database for biofuels obtained from various types of biomass by utilizing the life cycle concept. The effect on climate was found to be the highest during the development stage compared to the other biomass life cycle stages. The variation in feedstock quality and contributions from various other components of life cycle assessment (LCA) cause a variation in GHG emissions, along with the use of different technologies for the conversion of biomass to biofuel. Biofuel technology development, enhanced energy efficiency and biomass agriculture management are significant measures that moderate the effects of existing biofuel patterns on the climate.
UiO-66-NH2@MnFe2O4 was synthesized and used as a novel nanocatalyst to generate biodiesel from utilized edible oil (UEO) in a microwave reactor. Several analyses were utilized to characterize the catalyst structure, including SEM, EDX, FTIR, Raman, CO2-TPD, TGA, VSM, BET, TEM, and XRD. Central composite design (CCD) was employed for optimizing impressive variables on biodiesel synthesis. The utmost biodiesel yield using UiO-66-NH2@MnFe2O4 under optimal conditions (e.g., nanocatalyst concentration of 2.89%, methanol/UEO proportion of 9.43:1, stirring rate of 833.89 rpm, and microwave time of 6.37 min) was 97.81%, which is a considerable yield. Moreover, the aforementioned nanocatalyst was utilized in 7 reusing cycles with high performance, so that after the 7th cycle, its biodiesel yield was more than 90%, demonstrating the high recyclability of the nanocatalyst. Furthermore, the activation energy (47.32 kJ/mol) and frequency factor (10.2 × 105) demonstrate that the UiO-66-NH2@MnFe2O4 nanocatalyst has sufficient kinetic energy to do the transesterification reaction. Besides, the reaction between alcohol and UEO was endothermic. The influence of adding biodiesel to petrodiesel in various ratios (B0–B20) on a CI diesel engine was investigated, and satisfactory outcomes were attained in terms of emissions (e.g., reducing CO and UHC concentrations) as well as engine performance.
Conversion of waste ship-oil sludge into renewable fuel: Assessment of fuel properties and techno-economic viability of supplementing and substituting commercial fuels
2023, Journal of Cleaner ProductionWaste ship-oil sludge (WSOS) is considered as a hazardous waste as it affects the aquatic and dependent ecosystems. However, energy-rich fuels can be obtained upon treating this waste instead of discharging into the sea. Pyrolysis of oily wastes yields a higher proportion of energy-rich fuel when compared to solid wastes. This study provides an insight into the production of different products at various stages of thermal decomposition of completely mixed WSOS and compares its fuel properties such as calorific value, acid content, flash point, distillation, etc. with commercial diesel and aviation fuels. Non-combustible phenol-rich liquids were obtained at a temperature of 220 °C–300 °C (stage – 1) and 300 °C–400 °C (stage – 2). The stage – 2 product contained octa atomic sulphur and the concentration of sulphur in the subsequent stages increased consequently. Stage 3 (475 °C–550 °C) and stage 4 (550 °C–650 °C) products were analysed for commercial fuel properties and compared to conventional diesel and aviation fuels as they contained 45.79% and 56.29% of diesel-equivalent (C13 – C18) hydrocarbons respectively. Stage 3 corresponded well with Grade No.1 diesel fuel according to the ASTM D-975-19 standards and exhibited better properties in comparison with the stage 4 product. An inductive method of techno-economic analysis was carried out. The analysis returned a positive net present value (69,142.49), a high internal return rate (53.78%), and a payback period of 13.52 months, indicating that the sale of pyrolyzed WSOS as commercial fuel will be profitable.
This study presents an economic assessment of an up- and downstream process (USP and DSP) using P. tricornutum in flat-panel airlift photobioreactors (FPA-PBRs) with artificial illumination. Depending on the solvent, it is possible to obtain separately a crystalline fucoxanthin and eicosapentaenoic acid-rich (EPA) oil or a fucoxanthin- and EPA-rich oleoresin. The objective was to investigate the potential of optimizing light supply during USP and changing the extraction solvent during DSP to reduce fixed capital investment (FCI) and production costs. Comprehensive experimental data on the cultivation of P. tricornutum and the extraction and separation of the products were used to perform techno-economic assessments (TEA) and profitability analyses of different scenarios. In the first part, six scenarios were developed to determine the economic performance with a biomass concentration (c0) of either 3.0 or 6.0 g l−1 and a specific light availability (Ispec) of 2.0, 5.0 or 8.0 μmolphotons g−1 s−1 during the annual production of 10.0 t fucoxanthin ((component of biomass) until harvest. In the second part, the scenario with the economically most favourable results served as the basis for TEA depending on the solvent. It was demonstrated that production costs of dry weight biomass (CX) could be reduced from 644.31 to 184.30 € kgDW−1 by increasing Ispec and volumetric biomass productivity (QX) with the lowest biomass yield on light energy (YX,ph). A sensitivity analysis was performed to evaluate the possibilities of reducing costs and increasing profitability. Increasing QX proved to be the most effective, resulting in a decrease in CX of up to 20.1 %. Subsidising the FCI was most effective in reducing FCI, resulting in a decrease of up to 49.6 %. By using ethanol instead of a nonpolar solvent, the specific production costs of fucoxanthin (CFx) could be decreased by 60.0 % from around 39,825 € kgFx−1 to 16,111 € kgFx−1.
Experimental and modeling study on the autoignition characteristics of methyl stearate in a rapid compression machine
2023, Combustion and FlameWith the extensive exploration of advanced combustion modes and the increasing demand for engines with extremely high efficiency and low emissions, biodiesel has garnered significant attention and research as a renewable fuel source that boasts a wide range of raw materials. The ignition delay times (IDT) of methyl stearate, one of the main components in biodiesel, were measured in a new heated rapid compression machine (RCM). The data were obtained for the equivalence ratio of 0.3–0.8 and the compressed temperatures ranging from 820 K to 1000 K under three different pressures of 8, 10, and 12 bar. The influence of compressed temperature, compressed pressure, equivalence ratio, and oxygen mole fraction on ignition delay times was systematically discussed under experimental conditions, revealing the autoignition characteristics of methyl stearate in intermediate temperatures. Besides, the CRECK model and a skeletal model were verified against the experimental results, revealing that the model obtained by analogy significantly overestimates the low-temperature reactivity of methyl stearate. Furthermore, appropriate adjustments were made to the pre-exponential factors for the low-temperature elementary reactions in the CRECK model based on sensitivity analysis. The results indicate that the present model with optimization can well capture the dependence of the IDTs on the operating parameters under the investigated conditions, and the simulation results are in satisfactory agreement with the experimental data. Finally, the optimized model was verified against the experimental data from both the shock tube and jet-stirred reactor. To the authors' knowledge, this study represents the first gas-phase RCM experiment conducted on pure methyl stearate, which is a waxy solid at room temperature.
Fuel characterization, engine performance characteristics and emissions analysis of different mustard seed biodiesel: An overview
2023, Journal of BiotechnologyThe current new technology in the automotive sector depends on the primary energy source because the power source is from the secondary energy source. Besides, the interest in biofuels is increasing due to the weaknesses of fossil fuels that have been voiced for years. The feedstock is important in biodiesel production and its use in the engine. Mustard oil is non-edible, high mono-unsaturated fatty acid value, conveniences in cultivation conditions, and worldwide use that offer significant advantages to biodiesel producers. The presence of erucic acid, which forms the basis of mustard biodiesel, makes itself felt in the prevention of the fuel-food debate, its effect on biodiesel fuel properties, and its relationship to engine performance and exhaust emissions. Along with the minuses of mustard biodiesel in kinematic viscosity and oxidation ability, the problems experienced in engine performance and exhaust emissions compared to diesel fuel offer new studies to policymakers, industrialists and researchers. Accordingly, this review focuses on the recent finding in fuel properties, engine performance and emission characteristic of mustard seed biodiesel as well as its types, geographical distribution, and biodiesel production. It can be stated that this study will be an important supplementary reference to the above-mentioned groups.