Algal Biodiesel Production Research Articles

A zero discharge, carbon-neutral bi-fuel production process for algal biodiesel and renewable hydrogen

This work proposes a novel zero discharge, carbon-neutral bioprocess for the simultaneous production of algal biodiesel and renewable hydrogen. This innovative bi-fuel production process (BiFPP) consists of five units connected in series for biodiesel production, biodiesel purification, glycerol separation, glycerol steam reforming and hydrogen purification. To assess the techno-economic feasibility, the genetic algorithm based multi-objective optimization strategy is developed to minimize the total annual cost and CO2 emission level, and maximize the fuel purity. The optimal BiFPP scheme yields 97.3 mol % biodiesel and 98.8 mol % hydrogen, and thereby meets the standard specifications, ASTM D6751 and EN 14214. A heat exchanger network is designed with thermal coupling to secure the energy savings of 79.5% (heating load) and 50% (cooling load), leading to 93% reduction in utility cost. To achieve carbon neutrality, a CO2 sink for algae cultivation is finally proposed to integrate with this industrial-scale BiFPP process that overall yields a novel zero discharge bi-fuel production technology.

A novel solar reactive distillation based production of algal biodiesel: Retrofitting, carbon cost and process economics

In this contribution, solar power driven reactive distillation based process is developed for the production of algal biodiesel. For industrial scale operation, the conventional reactive distillation (cRD) is designed to retrofit with a parabolic trough collector (PTC) that yields cRD-PTC based scheme. To serve the same purpose, we have subsequently proposed a solar reactive distillation based configuration. The optimal design and operating conditions of both processes are determined with two conflicting objectives: minimising the total annual cost (TAC) and maximising the purity of biodiesel. For this, the optimisation is performed by the technique for order of preference by similarity to ideal solution embedded non-dominated sorting genetic algorithm-II. Further, we evaluate those process units in terms of the emission trading system based carbon pricing (ETS-CP) and social cost of carbon (SCC) considering the availability of solar energy during day time only. The attractiveness of the proposed solar reactive distillation based process lies in its total annual cost savings of 9.92% (ETS-CP) and 19.06% (SCC), whereas they are 6.67% (ETS-CP) and 16.14% (SCC), respectively for the conventional reactive distillation coupled with parabolic trough collector (cRD-PTC) process. It is further investigated that the total annual cost savings comes down when the proposed configurations are operated with solar (2000 working hours/year) and thermal energy (6000 working hours/year) throughout the year. Finally, the economic feasibility of the biodiesel production processes is studied with the usage of solar heat for the entire operating time.

Valorization of lignocellulosic wastes for low-cost and sustainable algal biodiesel production using biochar-based solid acid catalyst

Recently, carbon-based solid acid catalysts have come into prominence among different types of catalyst for production of biodiesel. Solid acid catalysts can be produced from carbon based materials such as biomass wastes by reducing the cost. Utilization of these wastes to prepare solid acid catalyst provides solid waste management and the potential greenhouse gas emissions decreases. Since algal biodiesel production is not so economical and needs to be improve, using these catalysts produced from waste biomass can be promising for making the process more cost effective and a low cost applicable zero-waste biorefinery approach can be put forth. In this study, walnut shell, olive stone and macroalgae were utilized to produce biochar based solid acid catalyst to be evaluated in microalgal biodiesel production. Walnut shell carbonized at 500 °C and then sulfonated by sulfuric acid was selected for biodiesel production due to having higher sulfonic acid density (0.35 mmol/g) and preferable structural properties. The statistical evaluation of transesterification parameters effect on microalgal biodiesel yield were evaluated and yield of 82% was found as the highest which was obtained by using 5 wt% catalyst, 12:1 methanol/oil molar ratio at the reaction time of 60 min. Stability test also showed the catalyst can be re-used up until the 5th cycle. Low cost feedstock and reusability of the catalyst presented a simple, cost-effective and environment-friendly process. At last, lignocellulosic wastes can be suggested for not only as biochar production also can be evaluated as solid acid catalyst and provide a cost-efficient biodiesel production.

Screening of wastewater Oedogonium oblangum algae for hyper-oil transformation into biodiesel by response surface methodology

The algae have gained more significance as a renewable third-generation feedstock for being easily available and a hyper-production source for lipids and biodiesel. Sustainable and cost-effective production of algal biodiesel requires screening and optimization of various culture conditions. Screening of algae on the basis of its lipid content is crucial for exploring its potential for production of biodiesel. In the current study, the screening of six indigenous algal strains was performed based on lipid contents, out of which Oedogonium oblangum (O. oblangum) exhibited hyper-lipid content (15.76%). Bold basal media and wastewater media were compared as culture media to evaluate the growth of O. oblangum; the respective strain showed better growth on wastewater media, therefore, this media was used for further experimentation. A laboratory-based integrated approach was used to enhance production of algal lipids by applying the effects of temperature, pH, and wastewater dilutions. The oil contents were interestingly improved under the optimal culture conditions of temperature (25°C), pH (6.5), wastewater dilution (45%) with oil contents of 18.35%, 17.15%, and 17.95%, respectively. The extracted oil was transformed into biodiesel by alkali-mediated transesterification reactions using four factors (Oil/methanol ratio, temperature, time, and catalyst) by response surface methodology (RSM). The RSM successfully optimized the transesterification reactions with 86.73% of biodiesel under optimal conditions of oil/alcohol ratio (1:7.6 v/v), temperature (60.5°C), time (59 ​min), and catalyst (0.53 ​wt. %). Physical properties of biodiesel (kinematic viscosity; 5.17; acid value; 0.63; flash point; 152; specific gravity; 0.74; calorific value; 42.11; and water contents; 0.03) comply with the ASTM standards and lead to enhance the quality of produced biodiesel. The optimized culture conditions, transesterification reactions, and wastewater medium can be employed for the economically production of biodiesel at commercial scale. Overall, the results showed that biodiesel derived from an indigenous novel algal strain, O. oblangum, has the potential to compete and replace commercially available petro-diesel using wastewater media. It might contribute to resolve the energy challenges being faced by Pakistan and the entire world.

The role of microtubules in microalgae: promotion of lipid accumulation and extraction

BackgroundMicrotubules in cells are closely related to the growth and metabolism of microalgae. To date, the study of microalgal microtubules has mainly concentrated on revealing the relationship between microtubule depolymerization and synthesis of precursors for flagellar regeneration. While information on the link between microtubule depolymerization and biosynthesis of precursors for complex organic matter (such as lipid, carbohydrate and protein), is still lacking, a better understanding of this could help to achieve a breakthrough in lipid regulation. With the aim of testing the assumption that microtubule disruption could regulate carbon precursors and redirect carbon flow to promote lipid accumulation, Chlorella sorokiniana SDEC-18 was pretreated with different concentrations of oryzalin.ResultsStrikingly, microalgae that were pretreated with 1.5 mM oryzalin accumulated lipid contents of 41.06%, which was attributed to carbon redistribution induced by microtubule destruction. To promote the growth of microalgae, two-stage cultivation involving microtubule destruction was employed, which resulted in the lipid productivity being 1.44 times higher than that for microalgae with routine single-stage cultivation, as well as yielding a desirable biodiesel quality following from increases in monounsaturated fatty acid (MUFA) content. Furthermore, full extraction of lipid was achieved after only a single extraction step, because microtubule destruction caused removal of cellulose synthase and thereby blocked cellulose biosynthesis.ConclusionsThis study provides an important advance towards observation of microtubules in microalgae through immunocolloidal gold techniques combined with TEM. Moreover, the observation of efficient lipid accumulation and increased cell fragility engendered by microtubule destruction has expanded our knowledge of metabolic regulation by microtubules. Finally, two-stage cultivation involving microtubule destruction has established ideal growth, coupling enhanced lipid accumulation and efficient oil extraction; thus gaining advances in both applied and fundamental research in algal biodiesel production.

A review on biodiesel production by algal biomass: Outlook on lifecycle assessment and techno-economic analysis

Depletion of fossil fuels and the need for an eco-friendly substitute has resulted in utilizing biological materials for producing biofuels. Algae is one of the biological species that act as beneficial biomass for producing biodiesel, a toxic-free alternative to commercial transportation fuels. Algae seem to be the most promising species for biodiesel production with merits such as easy cultivation, large biomass production, adaptability, etc. The main concern is the production cost and environmental conditions. This review focuses on the production of biodiesel production using algal species. The parameters affecting the algal growth such as pH, temperature, light source, and nutrient availability are discussed in detail. In addition, the factor that influences biodiesel production like oil to alcohol ratio, secretion of lipid content, nature, and catalyst type is analyzed in detail. Lifecycle assessments (LCA) on cultivation system, mode of algal growth like heterotrophic and autotrophic, and nutrient availability in the medium have been discussed in detail. The economic concerns and ecological impacts have been elaborated that resolve the challenges in algal biodiesel production. The algal community proves to be safe, non-toxic, and effective in producing biodiesel. There still exists a challenge limiting its development to large-scale commercialization.

Optimizing algal biodiesel production from a novel reactive distillation based unit: Reducing CO2 emission and cost

The algal biodiesel as a potential alternative to conventional petroleum fuel and first-generation biofuel has been explored extensively but the efficacy of its production in a reactive distillation (RD) unit is yet to be analyzed thoroughly. In this contribution, the performance of the RD column is enhanced by process intensification and optimization. A multi-objective optimization (MOO) strategy is framed for optimizing the RD column for three conflicting objectives. For this MOO, the elitist non-dominated sorting genetic algorithm (NSGA-II) is employed. From the obtained Pareto-optimal front, one optimal solution for RD design is selected using the technique for order of preference by similarity to ideal solution (TOPSIS) with entropy information for weighting of objectives. To further reduce the environmental impact and optimal usage of internal energy, a novel thermally coupled reactive distillation (TCRD) column is suggested. Finally, a biodiesel production unit is developed by integrating a decanter with the TCRD column, to produce biodiesel product of 99.45 wt.% purity. Performance of the TCRD column is better than the conventional RD column, in terms of CO2 emission reduction (14.49%) and total annual cost savings (3.72%). Energetic sustainability of the proposed biodiesel process is determined by net energy ratio (NER) of 1.79, net energy value (NEV) of 18.2 and net renewable energy value (NREV) of 41.4 MJ/kg.

Optimal reflux splitting reactive distillation for algal biodiesel Production: Waste heat recovery through vapor recompression and organic Rankine cycle

Algal biodiesel is widely accepted as a sustainable and alternative transportation fuel. This study aims at exploring the integration of multiple thermal intensification strategies to improve the energetic, economic and environmental performance of an optimal continuous flow algal biodiesel process. For this, a reflux splitting reactive distillation (RSRD) column is proposed for heterogeneous transesterification reaction. To enhance the biodiesel purity, the bottom stream of this RSRD scheme is subsequently proposed to treat in a decanter. A multi-objective optimization (MOO) technique, namely elitist non-dominated sorting genetic algorithm (NSGA-II) is employed to get the optimal configuration. The MOO problem is formulated with multiple conflicting objectives to optimize the biodiesel purity (maximize), total annual cost (minimize) and CO2 emissions (minimize). The technique for order of preference by similarity to ideal solution (TOPSIS) with entropy information as a weighting criterion is used to select the final optimal point. Then a vapor recompression scheme is introduced to enhance the energetic performance of the proposed RSRD column, which is here named as side vapor recompressed-reflux splitting RD (SVR-RSRD) configuration. Finally, the residual heat is proposed to recover by organic Rankine cycle (ORC) with selecting R245fa as a working fluid to further reduce the degree of heat irreversibility of the proposed configuration. Overall, 39.07% savings in energy consumption, 1.3% in total annual cost (TAC) within a payback period of 5 years (45.38% savings within a payback period of 10 years) and 40.01% reduction in CO2 emission with biodiesel purity of 93.5 mol% make this optimal integrated RSRD configuration attractive from energetic, economic and environmental perspective.

Multiobjective optimization of ultrasound intensified and ionic liquid catalyzed in situ algal biodiesel production considering economic, environmental and safety indicators

The current study focuses on the multiobjective optimization of an ultrasound intensified and ionic liquid catalyzed in situ transesterification of wet microalgae for renewable biodiesel production. The process is developed and simulated in Aspen Plus V10 simulator and an excel based multiobjective optimization (EMOO) programme for the elitist non-dominated sorting genetic algorithm-II is used for optimization. Total Annual Cost, i.e. TAC (representing economics), organic waste (representing cleaner production), individual risk, i.e. IR (representing risk to the human capital), and CO2 emission (representing environment) are chosen as the objectives for the constrained optimization of this process. The results show that the TAC reduces with the increase in the generation of organic waste, CO2 emission and IR. This article contemplates and articulates the reasons for the obtained trade-offs between objectives. The quantitative trade-offs between objectives aid to the better decision making about the process design and operation while satisfying economic, environmental and safety concerns. Finally, net flow method (NFM) has been implemented for the identification of best suitable solution in the Pareto-optimal fronts. Simultaneous optimization of all four objectives resulted in the impressive savings in TAC (∼15%), organic waste (∼33%), IR (∼9%), and CO2 emission (∼37%).

PROSPECTIVE ANALYSIS OF ALGAL BIODIESEL PRODUCTION

This article aims to carry out an initial patent mapping of algal biodiesel. The production of algal biodiesel is one of the forms of third generation biodiesel; it is an environmentally friendly alternative energy whose main advantage is that it does not compete with food, as the algal biodiesel is produced from synthesized lipids by algae in growth using sunlight. The methodology used was the patent mapping by activity having as search criteria: the Espacenet database (“worldwide”); and, the keyword: biodiesel and algae and algal biodiesel. It was observed that about 80% of the family of patent documents referring to this technology were applied between 2007 and 2016 and that these documents were published mainly in China (34% of patent documents), followed by the United States (25% of patent documents) and thirdly, the World Intellectual Property Organization (WO), that is, the PCT's international patent application, which indicates an interest in protection in several countries (15% of patent documents). Concluding that China and the United States are the countries that invest the most in the development and protection of technologies related to the production of algal biodiesel, however, the interest in protection goes beyond these countries, since the interest in alternative energies is worldwide.

Dry route process and wet route process for algal biodiesel production: A review of techno-economical aspects

In this study, two approaches for biodiesel production from microalgae, one through a dry route (using dried microalgae) and another through a wet route (using wet microalgae), are critically assessed. Analysis suggests that although both routes yield biodiesel of similar quality, there is a considerable difference in overall energy consumption, energy-intensive steps, and size of equipments for processing the same amount of lipids. This review depicts that both routes demand significant amount of energy, i.e. up to 120 MJ per kg of biodiesel that amounts to nearly three times the energy obtained from it. Also, the cost of production for one kg of biodiesel is high, i.e. up to $25 and $12 in dry and wet route respectively. This review article aims to present comprehensively and coherently the technical aspects of these two routes and their attributes in terms of energy consumption, manufacturing cost, and capital investment.

Impact of hydrogen peroxide on microalgae cultivated in varying salt-nitrate-phosphate conditions

Microalgal biomass has received a great deal of attention as renewable and environmental-friendly biofuel feedstock as a rebuttal to climate change, energy crisis, and global warming. To improve the commercial viability of algal biodiesel production, the rise in lipid accretion and the enrichment of algal fatty acid profile are of utmost importance. In this experiment, lipid content and fatty acid methyl ester profiling of the microalgal strain, Scenedesmus sp. is done to understand the intercalating effect of different media composition for its suitability in context to biodiesel production. Various nutrient combinations (sodium nitrate, NaNO3) and di-potassium hydrogen phosphate, (K2HPO4) were incorporated along with salinity (sodium chloride) exposure for first 48 h stage of algal cultivation, followed by oxidative stress via hydrogen peroxide (H2O2) for the second 24 h stage of cultivation. The results show that the presence of 100 mM NaCl, 35.29 mM NaNO3, and 5.74 mM K2HPO4 followed by the addition of 10 mM H2O2 (S100H10N35.29P5.74) to the algal growth media led to the accumulation of maximum total lipid content (226.49 ± 16.6 μg/mg). Another nutrient combination, S0H10N35.29P0, increased the saturated fatty acid composition (C16:0) to 31.7%. Principal component analysis (PCA) also demonstrated the combined effect of multiple nutrient components and their relative concentrations on the growth parameters and algal biochemical profile, such as biomass, chlorophyll, lipid, carbohydrate, alongwith fatty acid profiling. Hence, this study demonstrate the potential of Scenedesmus sp. in response to a multi-component stress environment that has influenced the fate of fatty acid methyl esters (FAME) composition and significantly improved the quality of algal biofuels produced over a short period.

Nano-catalytic heterogeneous reactive distillation for algal biodiesel production: Multi-objective optimization and heat integration

This work proposes a novel reactive distillation (RD) column for the production of algal biodiesel by the use of a heterogeneous nano-catalyst, Ca(OCH3)2. The elitist non-dominated sorting genetic algorithm (NSGA-II) is employed to optimize the design of this RD column to maximize biodiesel purity while minimizing total annual cost and CO2 emissions. The optimal point is recommended by a Pareto ranking method, namely, technique for order of preference by similarity to ideal solution (TOPSIS) with entropy information for the weighting of objectives. To improve biodiesel purity, a decanter is proposed to couple with the RD column at the bottom. Subsequently, performance of the optimal RD column is further improved by retrofitting it with the vapor recompression arrangement. In this proposed intensified configuration, a reactive stage is thermally integrated with the reboiler to constitute a side vapor recompressed RD (SVRRD) column. Finally, a comparative study is performed to quantify the performance improvement of the proposed SVRRD column over the conventional RD column. It is found that there is a 34.6% reduction in CO2 emissions with a payback period of 4.54 years for the vapor recompressor. Hence, the proposed SVRRD is attractive with better performance in terms of energetic, environmental and economic perspectives.

Design and retrofitting of ultrasound intensified and ionic liquid catalyzed in situ algal biodiesel production

Although biodiesel synthesis has been widely studied, the use of wet microalgal feedstock for biodiesel synthesis using ionic liquid catalyst and ultrasonication is scarce to find, especially pertaining to economic viability and environmental impact. In this study, new processes are designed based on the experimental results for ultrasound assisted in situ algal biodiesel production using an ionic liquid catalyst. Process retrofitting is then conducted using a divided-wall column (DWC) and multistage vapor recompression (MVR). Later, comparative analyses in terms of capital cost, cost of manufacturing (COM), cost of biodiesel, specific energy consumption (SEC) and carbon emission is presented. The process with DWC and MVR resulted in a significant saving in COM (13.84%), biodiesel cost (18.24%), utility cost (45.44%), SEC (29.15%) and carbon emissions (38.15%) than those in its counterpart. This study shows that the biodiesel cost is linearly dependent on the cost of feedstock and process economics can be improved by converting glycerol to triacetin. Major contributions of this work are (1) experimental and process design for a novel ultrasound assisted and ionic liquid catalyzed algal biodiesel production, (2) retrofitting using DWC and MVR and (3) investigation of the uncertainty in the thermodynamic property. This study is significant as it designs processes based on the experimental outcomes and investigates designs for their economic as well as environmental merits.

The Roles of Cullins E3 Ubiquitin Ligases in the Lipid Biosynthesis of the Green Microalgae Chlamydomonas reinhardtii.

Microalgae-based biodiesel production has many advantages over crude oil extraction and refinement, thus attracting more and more concern. Protein ubiquitination is a crucial mechanism in eukaryotes to regulate physiological responses and cell development, which is highly related to algal biodiesel production. Cullins as the molecular base of cullin-RING E3 ubiquitin ligases (CRLs), which are the largest known class of ubiquitin ligases, control the life activities of eukaryotic cells. Here, three cullins (CrCULs) in the green microalgae Chlamydomonas reinhardtii were identified and characterized. To investigate the roles of CrCULs in lipid metabolism, the gene expression profiles of CrCULs under nutrition starvation were examined. Except for down-regulation under nitrogen starvation, the CrCUL3 gene was induced by sulfur and iron starvation. CrCUL2 seemed insensitive to nitrogen and sulfur starvation because it only had changes after treatment for eight days. CrCUL4 exhibited an expression peak after nitrogen starvation for two days but this declined with time. All CrCULs expressions significantly increased under iron deficiency at two and four days but decreased thereafter. The silencing of CrCUL2 and CrCUL4 expression using RNAi (RNA interference) resulted in biomass decline and lipids increase but an increase of 20% and 28% in lipid content after growth for 10 days, respectively. In CrCUL2 and CrCUL4 RNAi lines, the content of fatty acids, especially C16:0 and C18:0, notably increased as well. However, the lipid content and fatty acids of the CrCUL3 RNAi strain slightly changed. Moreover, the subcellular localization of CrCUL4 showed a nuclear distribution pattern. These results suggest CrCUL2 and CrCUL4 are regulators for lipid accumulation in C. reinhardtii. This study may offer an important complement of lipid biosynthesis in microalgae.

Chemical Characterization of Algae Oil and Optimization of Transesterification Parameters for Boosting of Algal Biodiesel Production from Spirulina Wild Stuff Explored in the Natural Habitation

The investigation on standardizing the parameters for achieving biodiesel production from a distinctive approach where the identified wild stuff of algal biomass (Spirulina maxima) grown at its natural conditions was considered. The composed algal wild stuff was subjected to extraction of the crude lipids using a flawless solvent system coupled with the soxhlet method. The accumulation of lipid contents was expansively analyzed and the oil obtained from lipid content was subjected to transesterification using both acid (H2SO4) and base (KOH) catalysts for its analogous fatty ester which is the potential way out to the high viscosity elements that ultimately converted algal oil into biodiesel. Further, the optimization of transesterification parameters for boosting algal biodiesel production at variable reaction factors was carried-out with respect to; molar ratio, temperature, reaction time, stirring speed, and amount of promising catalysts were also evaluated. In the acid esterification process, the acid value (AV) was reduced from 11.43 to 0.52 mg KOH/g of the feedstock and, the most favorable conditions for the highest yield of esterified oil were found at the molar ratio 8:1, temperature 650C, catalyst concentration 1% (wt%) H 2 SO 4 and the stirring speed of 600rpm for a reaction time of 90th minute. Whereas in the alkali transesterification, the optimum biodiesel (96.6%) was achieved, and promising conditions were recorded at molar ratio 6:1, temperature 60OC, stirring speed of 500 rpm, catalyst concentration 0.3% (wt%) of KOH for a reaction time of 60th minute. The produced algal biodiesel was evaluated in contrast to ASTM standard specification and all the results within standards limit were observed. The Physico-chemical properties of biodiesel-derived crude glycerol samples were also determined and the compositional analysis of crude glycerol was found to be significant in crude glycerol. Besides, the work-out on the effectiveness of capital and operating costs are found to be rational and this certainly makes algae fuel production commercially viable. However, the novelty of this study is to explore the wild stuff of S.maxima algae from its natural habitat for biodiesel production is significantly cost-effective which is possible by omitting the algal culturing segment in vitro.

Two-step microalgal (Coelastrella sp.) treatment of raw piggery wastewater resulting in higher lipid and triacylglycerol levels for possible production of higher-quality biodiesel

Microalgal treatment of undiluted raw piggery wastewater is challenging due to ammonia toxicity and a deep dark color hampering photosynthesis. To overcome these problems, (1) a microalga (Coelastrella sp.) was isolated from an ammonia-rich environment, (2) the wastewater treatment was divided into two steps: a heterotrophic process followed by a mixotrophic process, and (3) a narrower transparent photobioreactor was employed with higher light intensity in the mixotrophic process. Coelastrella sp. removed 99% of ammonia, 92% of chemical oxygen demand (COD), and 100% of phosphorus during the 4-day process. Acetate in the wastewater relieved the ammonia stress on microalgae and promoted algal lipid and triacylglycerol productivity. Oxidative stability and low-temperature fluidity of triacylglycerols in lipids were improved by means of an altered fatty acid profile. Aside from the overall microalgal treatment performance, the proposed processing of piggery wastewater yielded a material suitable for possible production of algal biodiesel of better quality.

A strategy for lipid production in Scenedesmus sp. by multiple stresses induction

Microalgae are rich source of lipids and are one of the promising feedstocks for biofuel production, whereas enhancement of lipid, carbohydrate, and biomass production is crucial for commercialization of algal biofuels. Nutrients/salinity stresses are important to increase the synthesis of lipid. In the present study, Scenedesmus sp. is treated with a varying combination of sodium nitrate (NaNO3), dipotassium hydrogen phosphate (K2HPO4), and sodium chloride (NaCl) to improve lipid accumulation. Results indicate that the modified media comprising of NaCl (100 mM), NaNO3 (0 mM), and K2HPO4 (0.22 mM) (S100N0P0.22) accumulated higher quantities of lipid (385.4 ± 34.2 μg/mg) along with considerable biomass (537.0 ± 22.3 μg/mL), chlorophyll “a” (6.2 ± 0.08 μg/mL), and palmitic acid (32.6%). Apart from biochemical analysis, stress-induced biomarker such as hydrogen peroxide (H2O2) was observed maximum for same combination (10854 μmolH2O2/g), with low lipid peroxidation (3.2 μmol/g). Catalase (CAT) and superoxide dismutase (SOD) activity were further studied to monitor the impact of reactive oxygen species (ROS) on lipid accumulation. This study revealed a better combination in terms of lipid and biomass profile, which can further be investigated for large-scale production. Multi-stress-driven lipid production is one of the significant outputs of the current study, which can further be explored in detail. Insight such interactions may provide directions for economical production of algal biodiesel.

The Perspective of Large-Scale Production of Algae Biodiesel

We have had high expectations for using algae biodiesel for many years, but the quantities of biodiesel currently produced from algae are tiny compared to the quantities of conventional diesel oil. Furthermore, no comprehensive analysis of the impact of all factors on the market production of algal biodiesel has been made so far. This paper aims to analyze the strengths, weaknesses, opportunities, and threats associated with algal biodiesel, to evaluate its production prospects for the biofuels market. The results of the analysis show that it is possible to increase the efficiency of algae biomass production further. However, because the production of this biodiesel is an energy-intensive process, the price of biodiesel is high. Opportunities for more economical production of algal biodiesel are seen in integration with other processes, such as wastewater treatment, but this does not ensure large-scale production. The impact of state policies and laws is significant in the future of algal biodiesel production. With increasingly stringent environmental requirements, electric cars are a significant threat to biodiesel production. By considering all the influencing factors, it is not expected that algal biodiesel will gain an essential place in the fuel market.

Cobalt-doped CaO catalyst synthesized and applied for algal biodiesel production

Microalgal biomass is a potential feedstock for biofuel production because of its oleaginous nature and fast growth rate. Furthermore, its cultivation does not compete with crop producing land and thereby eliminating food vs. fuel dilemma. This study describes a low-cost nutrient mediated cultivation method for growing lipid enriched algal biomass from Scenedesmus quadricauda in BG11 media in a raceway pond. A renewable heterogeneous catalyst is synthesized using calcium oxide obtained from calcination of waste egg shells and modified using cobalt nitrate hexahydrate by co-precipitation method. The synthesized catalyst is characterized by XRD, SEM, EDX, FTIR, TEM techniques. Lipid extracted from the biomass is converted to biodiesel using the synthesized catalyst. The formation of biodiesel is confirmed using 1 H NMR, 13C NMR and GC-MS techniques. The result demonstrated that the CaO–Co catalyst has very high catalytic activity for biodiesel production. The integrated process described in this study has potential for producing environmentally benign fuels and a heterogeneous catalyst from renewable sources. • The microalgae Scenedesmus quadriacuda is a good candidate for biofuel production. • KNO 3 helps in lipid enhancement. • The catalyst CaO-Co is renewable in nature. • The algal biodiesel yield is 98%.