Biorefinery Scheme Research Articles

Evaluation of fractionation and delignification efficiencies of deep eutectic solvents on oil palm empty fruit bunch

Deep eutectic solvent (DES) has been introduced as a new generation green solvent for lignocellulosic biomass pretreatment in recent years. In the current study, six DES varying from acidic to basic nature were synthesized and applied on oil palm empty fruit bunch (EFB) in a single step fractionation and delignification process. The effect of the properties of DES on its fractionation performance was assessed. Mass balance performed on the pretreatment process reveals that pH of DES has a significant impact on biopolymer fractionation efficiency. The dissolution trend of acidic and basic DES resembles those in the conventional acid and alkaline pretreatments. The pretreatment energy requirement for the DES used ranged from 2087 to 2451 J/g. The acidic choline chloride:lactic acid DES succeeded in achieving 100% hemicellulose extraction, 88% delignification and 50% lignin pellet extraction from EFB. Thus, it is feasible for acidic DES to be considered in a biorefinery scheme for biomass fractionation.

Economic analysis of a biorefinery process for catechol production from lignin

Abstract Recently, the valorization of the lignin fraction in the biorefinery scheme is getting more and more attention as the use of this component for the production of bio-based chemicals is crucial for the success of the integral development of lignocellulosic biorefinery processes. The present work includes the exergy performance and the economic analysis of a process for catechols production using lignin extracted from olive tree pruning. Energy and exergy calculations were obtained from the process simulation with Aspen Plus®. The exergy analysis was applied to identify the units associated with the main irreversibilities and exergy losses. The process investment and operating costs were determined as well as the derived catechol market price. The calculated total plant capital investment was about 4.9 M$ for a plant capacity of 2544 kg feedstock/day. The estimated catechol price was 1100 $/t with a valorization ratio of 3.02. These results place the product in a competitive position in the market.

Green biorefinery of larch wood biomass to obtain the bioactive compounds, functional polymers and nanoporous materials

The first green biorefinery of larch wood based on the fractionation of biomass into dihydroquercetin (DHQ), arabinogalactan (AG), microcrystalline cellulose (MCC) and soluble lignin (SL) is reported. The new green method of one-step isolation of DHQ and AG from larch wood by ethanol–water solution was developed. The first results of kinetic studies and optimization of the process of extracted larch wood peroxide fractionation into MCC and SL in acetic acid–water medium in the presence of green TiO2 catalyst are described. The products obtained from larch wood were characterized by FTIR, NMR, XRD, AFM and chemical methods. The scheme of larch wood biorefinery is suggested which integrates the developed processes of woody biomass fractionation into DHQ, AG, MCC and SL. All developed methods use non-toxic and less-toxic reagents, such as water, ethanol, hydrogen peroxide and acetic acid.

Integral use of plants and their residues: the case of cocoyam (Xanthosoma sagittifolium) conversion through biorefineries at small scale.

During last decades, there has been a growing interest of decreasing the environmental impact generated by humans. This situation has been approached from different perspectives being the integral use of raw materials as one of the best alternatives. It was estimated that 3.7 × 109tonnes of agricultural residues are produced annually worldwide. Then, the integral use of feedstocks has been studied through the biorefinery concept. A biorefinery can be a promissory option for processing feedstocks in rural zones aiming to boost the techno-economic and social growth. However, many plants produced at small scale in rural zones without high industrial use contribute with residues usually not studied as raw materials for other processes. Cocoyam (Xanthosoma sagittifolium) is a plant grown extensively in tropical regions. Nigeria, China, and Ghana are the main producers with 1.3, 1.18, and 0.9 milliontonnes/year, respectively. In Colombia, there are no technified crops, but it is used where it is grown mainly as animal feed. This plant consists of leaves, stem, and a tuber but the use is generally limited to the leaves, discarding the other parts. These discarded parts have great potential (lignocellulose and starch). This work proposes different processing schemes using the parts of the plant to obtain value-added products, and their techno-economic and environmental assessment. The simulation was performed with Aspen Plus and the economic package was used for the economic assessment. For the environmental assessment, Waste Algorithm Reduction of the U.S. EPA was implemented. The obtained results showed that the integral use of plants under a biorefinery scheme allows obtaining better techno-economic and environmental performance and that small-scale biorefineries can be a promissory option for boosting rural zones.

Recalcitrance Assessment of the Agro-industrial Residues from Five Agave Species: Ionic Liquid Pretreatment, Saccharification and Structural Characterization

Agave has recently shown its potential as a bioenergy feedstock with promising features such as higher biomass productivity than leading bioenergy feedstock while at the same time being drought-resistant with low water requirements and high sugar to ethanol conversion using ionic liquid (IL) pretreatment. IL pretreatment was studied to develop the first direct side-by-side comparative recalcitrance assessment of the agro-industrial residues from five Agave species [Agave americana (AME), A. angustifolia (ANG), A. fourcroydes (FOU), A. salmiana (SAL), and A. tequilana (TEQ)] using compositional analysis, X-ray diffraction, and the lignin syringyl/guaiacyl subunit ratio (S/G) by pyrolysis molecular beam mass spectrometry (PyMBMS). Prominent calcium oxalate peaks were found only in unpretreated AME, SAL, and TEQ. The S/G ratios of all five unpretreated Agave species were between 1.27 and 1.57 while the IL-pretreated samples were from 1.39 to 1.72. The highest overall sugar production was obtained with IL-pretreated FOU with 492 mg glucose/g biomass and 157 mg xylose/g biomass at 120 °C and 3 h using 1-ethyl-3-methylimidazolium acetate ([C2C1Im][OAc]). An estimated theoretical ethanol yield from the studied agro-industrial residues from the five Agave species was in the range of 1060 to 5800 L ethanol/ha/year. These comparison results demonstrate the potential of the Agave spp. as a suitable biofuel feedstock which can be employed within a biorefinery scheme.

Bioaugmentation with Clostridium tyrobutyricum to improve butyric acid production through direct rice straw bioconversion

One-pot bioconversion is an economically attractive biorefinery strategy to reduce enzyme consumption. Direct conversion of lignocellulosic biomass for butyric acid production is still challenging because of competition among microorganisms. In a consolidated hydrolysis/fermentation bioprocessing (CBP) the microbial structure may eventually prefer the production of caproic acid rather than butyric acid production. This paper presents a new bioaugmentation approach for high butyric acid production from rice straw. By dosing 0.03 g/L of Clostridium tyrobutyricum ATCC 25755 in the CBP, an increase of 226% higher butyric acid was yielded. The selectivity and concentration also increased to 60.7% and 18.05 g/L, respectively. DNA-sequencing confirmed the shift of bacterial community in the augmented CBP. Butyric acid producer was enriched in the bioaugmented bacterial community and the bacteria related to long chain acids production was degenerated. The findings may be useful in future research and process design to enhance productivity of desired bio-products.

Mechanical deconstruction of corn stover as an entry process to facilitate the microwave-assisted production of ethyl levulinate

In this study, ball milling was applied as a pretreatment to promote the production of ethyl levulinate (EL) from corn stover under microwave irradiation. The experiments showed mechanical grinding significantly increased the EL yields by 31.23 and 23.31% at 160 and 170 °C, respectively. To further understand the influence of ultrafine grinding on alcoholysis process, we have presented a series of physicochemical and morphological analysis for the ball milled corn stover. The characterization indicated that ball milling sharply reduced the particle size to cellular scale and the intact, smooth surface changed to an open, porous structure during ball milling. It also resulted in the disruption of crystalline cellulose to amorphous state and the depolymerization of polysaccharides with an increase in reducing-ends. In general, mechanical processing approach could efficiently modify the corn stover and facilitate the EL production in the following three ways: firstly, the reduction in particle size with increased surface increased the reaction accessibility of cellulose; secondly, the destruction of compact cellulose crystal structure conduced to the reduction of alcoholysis energy barrier; moreover, the depolymerized polysaccharides resulted in the increase of the reaction sites, which further improved the reaction activity and promote EL conversion. The mechanical processing approach could well hold the key to a better use of the mechanical forces in the alcohol reaction system, providing an environment-friendly method into lignocellulosic biorefinery schemes.

Assessment of the Influence of the Temperature in the Microwave-Assisted Alkaline Delignification of Vine Shoots

The limitation of the fossil-resources has led the research to focus on the production of biomass-based fuels from lignocellulosic agricultural residues, as it is the case of the bio-ethanol. Due to the complex and heterogeneous structure of these residues, a delignification stage is usually necessary prior to a simultaneous saccharification and fermentation treatment (SSF) for the production of bio-ethanol. In a previous work, an alkaline delignification of hydrothermally pretreated vine shoots using conventional heating was carried out in order to obtain a solid residue with low lignin and hemicellulosic content, which could be further subjected to a SSF treatment. However, when this biorefinery scheme was evaluated by a Life Cycle Assessment it was observed that the energy and chemical requirements of the delignification stage needed to be reduced. Therefore, in this work the assistance of the alkaline delignification stage by microwave was studied. The treatments were carried out at different temperatures, in order to study its influence on the lignin removal. It was observed that the microwave assistance could permit the improvement of the delignification treatments not only by increasing the delignification yield but also by reducing the temperature, time and NaOH concentration used in the treatments. The strong influence of the temperature on the chemical composition, structure and crystallinity of the delignified solids was also appreciated during this study. The solid residues obtained under the most severe conditions of the microwave-assisted alkaline delignification treatment (125 °C) could be a promising solid for the employment in a SSF treatment due to its low lignin and hemicellulosic content (16.68 % and 0.01 % respectively) and its high glucan content (50.75 %), although it presented a higher crystallinity index than the hydrothermally pretreated vine shoots.

Succinic Acid Production across Candidate Lignocellulosic Biorefinery Feedstocks

Non-food lignocellulosic crops with both high biomass yields and superior adaptation to marginal lands have significant potential as biofuel feedstocks that can replace fossil fuels. Deployment of dedicated crops into single biofuels, however, has been reduced by conversion technology costs and low petroleum prices. Integrated biorefinery strategies, in which value-added coproducts are generated in conjunction with biofuels, by comparison offer opportunities to overcome this economic disadvantage. The objective of this research was to evaluate succinic acid accumulation across candidate lignocellulosic feedstocks. Feedstock entries included pearl millet x napiergrass hybrids (“PMN”; Pennisetum glaucum [L.] R. Br. × P. purpureum Schumach.), napiergrass (P. purpureum Schumach.), annual sorghum (Sorghum bicolor [L.] Moench), pearl millet (P. glaucum [L.] R. Br.), perennial sorghum (Sorghum spp.), switchgrass (Panicum virgatum L.), sunn hemp (Crotalaria juncea L.), giant miscanthus (Miscanthus × giganteus J. M. Greef & Deuter) and energy cane (Saccharum spp. L.). Replicated field plots, as well as an independent greenhouse trial, were characterized for succinic acid content. The PMN, napiergrass, sunn hemp and energy cane entries had greater (P ≤ 0.05) succinic acid yields, up to 556 kg·ha-1, in field trials. Napiergrass and PMN entries similarly had higher succinic acid yields under greenhouse conditions; however, irrigation treatments did not alter succinic acid accumulation in this study. Napiergrass, PMN, and energy cane thus are promising biorefinery feedstocks.

Green catalytic processing of native and organosolv lignins

Two ways of catalytic depolymerization of native and isolated wood lignins are described: the peroxide delignification of hardwood (aspen, birch) and softwood (abies) in the medium of acetic acid – water over TiO2 catalyst and the thermal dissolution of organosolv lignins (ethanol-lignin and acetone-lignin) in supercritical alcohols (ethanol and butanol) over solid Ni-containing catalysts.The catalyst TiO2 in rutile modification has the higher activity in wood peroxide delignification at 100 °C as compared to TiO2 in anatase modification. The results of kinetic studies and optimization of the processes of peroxide depolymerization of hardwood (aspen, birch) and softwood (abies) lignins in the medium of acetic acid – water over catalyst TiO2 (rutile) at mild conditions (≤100 °C, atmospheric pressure) are compared. The catalyst TiO2 initiates the formation of OH and OOH radicals from H2O2 which promote the oxidative fragmentation of wood lignin. In this case, the peroxide depolymerization of softwood lignin, constructed from phenylpropane units of guaiacyl-type proceeds more difficult than the hardwood lignins, mainly containing syringyl-type units.The solid and soluble products of peroxide catalytic delignification of wood under the optimized conditions were studied by FTIR, XRD, GC–MS and chemical methods. Regardless of the nature of wood the cellulosic products have a structure similar to microcrystalline cellulose. The soluble products mainly consist of monosaccharides and organic acids. Aromatic compounds are present only in a low amount which indicates the oxidative degradation of aromatic rings of lignin phenylpropane units under the used conditions of wood catalytic delignification.The processes of thermal dissolution of acetone-lignin and ethanol-lignin from aspen-wood in supercritical ethanol and butanol over Ni-containing catalyst (NiCu/SiO2, NiCuMo/SiO2) are compared. The composition, structure and thermal properties of organosolv lignins were studied with the use of FTIR, GPC, 1H – 13C HSQC NMR, DTA and elemental analysis.The influence of a composition of Ni-containing catalyst on the thermal conversion in supercritical butanol and ethanol of ethanol-lignin and acetone-lignin was established. The highest conversion of lignins (to 93% wt.) in supercritical alcohols and the highest yield of liquid products (to 90% wt.) were achieved at 300 °C in the presence of catalyst NiCuMo/SiO2.Scheme of green biorefinery of wood based on the use of non-toxic and low-toxic reagents (H2O2, H2O, acetic acid, ethanol, butanol) and solid catalysts (TiO2, NiCuMo/SiO2) is suggested.

Improving economics of lignocellulosic biofuels: An integrated strategy for coproducing 1,5-pentanediol and ethanol

A biorefinery strategy for the coproduction of ethanol and 1,5-pentanediol (1,5-PDO), which can be used as polyester and polyurethane component, from lignocellulosic biomass is proposed. This strategy integrates biomass fractionation with simultaneous conversion of hemicellulose and cellulose constituents into 1,5-PDO and ethanol, respectively. An experimentally-based process model is developed to determine the economic potential of the integrated strategy. The coproduction strategy becomes competitive with the ethanol-only strategy when 1,5-PDO can be sold at $1140/ton, which is well below the market price of 1,5-PDO. The most important process parameters include biomass loading for biomass fractionation, enzyme loading for enzymatic hydrolysis and fermentation, and overall achievable yields from C5 sugars to 1,5-PDO.

Valorisation of textile waste by fungal solid state fermentation: An example of circular waste-based biorefinery

This study investigated the feasibility of using textile waste as feedstock for cellulase production through solid state fermentation. Aspergillus niger CKB was selected with the highest cellulase activity (0.43±0.01 FPUg−1) after 7days of cultivation on pure cotton. Material modification techniques including autoclaving, alkali pretreatment and milling were applied on six types of textiles with various cotton/polyester blending ratios. The results indicated that using autoclaved textile blending cotton/polyester of 80/20 led to the highest cellulase activity (1.18±0.05FPUg−1) with CMCase, β-glucosidase and avicelase activities of 12.19±0.56Ug−1, 1731±4.98Ug−1 and 2.58±0.07Ug−1, respectively. The fungal cellulase was then extracted and applied to textile waste hydrolysis, in which a sugar recovery yield of 70.2% was obtained. The present study demonstrates a novel circular textile waste-based biorefinery strategy with recovery of glucose and polyester as value-added products.

Convenient Product Distribution for a Lignocellulosic Biorefinery: Optimization through Sustainable Indexes

The current approach for technological projects must fulfill sustainability indexes. In this work, we use a multiobjective optimization framework to analyze the convenient product distribution in a lignocellulosic biorefinery, considering economic, environmental, and safety indexes. Corn cob was selected as feedstock due to the high annual volume produced as residue of maize crop. Products selection was based on the existing demand and economic value; bioethanol, lactic acid, succinic acid, xylitol, and lignosulfonates were chosen. Through the multiobjective optimization strategy an efficient solution with an Economic Potential Index of 0.16 is achieved, generating an annual utility of nearly 70 kUSD when bioethanol and xylitol production is favored over succinic acid and lactic acid. This tool can be applied with different feedstocks and products in a biorefinery scheme, with kinetic and yield data for corresponding processes.

A comprehensive review on the implementation of the biorefinery concept in biodiesel production plants

Biodiesel is a promising alternative to petroleum diesel and its production from various generations of feedstocks by using different technologies has been constantly growing globally. However, in spite of such large scale of production, serious considerations should be taken into account to ensure the long-term sustainability of biodiesel production. This issue becomes more of concern given the fact that some generations of feedstocks used for biodiesel production are in clear conflict with food security. The concept of biorefinery has been at the center of attention with an aim to address these challenges by promoting an integral use of biomass to allow the production of multiple products along with biodiesel. Such implementation has been extensively studied over the last years and is expected to lead to economic, environmental, and social advantages over individual processes. The current review first presented an overview on biodiesel, its different feedstocks, and production technologies. Subsequently, the biorefinery concept and its correct implementation was technically discussed. Biodiesel production under the biorefinery scheme was also presented. Finally, techno-economic analysis of biodiesel production under the biorefinery concept by considering palm oil-based biorefinery as case study was investigated.

Development of a citrus peel-based biorefinery strategy for the production of succinic acid

A preliminary study has been performed for the valorization of citrus peel waste (CPW) through the biorefinery platform aiming to produce succinic acid. Following extraction of essential oils and pectin, different conditions of dilute acid hydrolysis were evaluated based on estimation of the sugars liberated and subsequent fermentation of hydrolyzates for production of succinic acid by Actinobacillus succinogenes. The most suitable pretreatment conditions involved 116 °C for 10 min using 5% (w/v) of dry raw material (drm). Thus, a total sugar (ts) yield of 0.21 gts gdrm−1 and a succinic acid (sa) yield via microbial fermentations of 0.77 gsa gtsc−1 was achieved, while the use of lower solid contents resulted in higher sugar yields. The residues from dilute acid hydrolysis were applied for subsequent enzyme hydrolysis using commercial enzymes and the most suitable combination of enzyme units included 30 IU cellulases and 25 BGL β-glucosidases achieving a yield of 0.58 gts gdrm−1. Moreover, elemental analysis in hydrolyzates obtained from dilute acid hydrolysis and a combination of acid and enzyme hydrolysis indicated that during the combined treatment, high concentrations of Mg2+ and Ca2+ ions are liberated as compared to dilute acid hydrolysis, while the concentration of hydroxymethylfurfural was 0.038 g L−1 demonstrating low formation of inhibitors. The hydrolyzate generated through the combined pretreatment proposed was applied as feedstock for the production of succinic acid achieving a yield of 0.70 gsa gtsc−1. However, although the combined hydrolysis approach could approximately double the sugars released in the hydrolyzate, the economic analysis performed confirmed that the use of the enzymatic treatment could not be competitive. The developed bioprocess constitutes a valuable alternative to the application of energy intensive chemical technologies for succinic acid production.

Antioxidant and antimicrobial activities of extracts obtained from the refining of autohydrolysis liquors of vine shoots

Abstract Vine shoots, considered a residue from winery operations, possess valuable antioxidant and antimicrobial activities that can be potentially obtained under the scheme of biorefinery. In this framework, we evaluated the autohydrolysis of vine shoots combined with a further stage of extraction with ethyl acetate as viable valorization process. The extraction yield ranged from 0.95 to 3.80 g extract/100 g vine shoots. Moderately high temperature (215 °C) was required for the maximum recovery of phenolics, flavonoids and antioxidant activities. The major phenolic compounds identified were derived from lignin: vanillin, acetovanillone, guaiacylacetone, syringaldehyde and acetosyringone. The ethyl acetate extract from the liquors obtained at 200 °C was assayed for antimicrobial activity against Gram positive and negative bacteria showing values of MIC and MBC in the range of 5–20 mg/mL. This work showed that the antioxidant extracts could be used as cheap source of natural compounds, with potential applications in the food and pharmaceutical industries.

Lignin Hydrogenolysis: Improving Lignin Disassembly through Formaldehyde Stabilization.

Lignocellulosic biomass is available in large quantities and constitutes an attractive feedstock for the sustainable production of bulk and fine chemicals. Although methods have been established for the conversion of its cellulosic fractions, valorization of lignin has proven to be challenging. The difficulty in disassembling lignin originates from its heterogeneous structure and its propensity to undergo skeletal rearrangements and condensation reactions during biorefinery fractionation or biomass pretreatment processes. A strategy for hindering the generation of these resistive interunit linkages during biomass pretreatment has now been devised using formaldehyde as a stabilizing agent. The developed method when combined with Ru/C‐catalyzed hydrogenolysis allows for efficient disassembly of all three biomass fractions: (cellulose, hemicellulose, and lignin) and suggests that lignin upgrading can be integrated into prevailing biorefinery schemes.

Recent developments in Agave performance as a drought‐tolerant biofuel feedstock: agronomics, characterization, and biorefining

AbstractIn recent years, Agave has shown its potential as a bioenergy feedstock with a higher land productivity (up to 42 ton/ha year) than traditional feedstocks. Other features are its adaptation mechanism to high temperatures and its resistance to drought. The agronomics of Agave in Mexico are discussed, including total land planted, inputs required, and the harvesting and transport costs. Heating values, mineral concentration, and carbohydrate and lignin content show the potential of the Agave species to compete with current bioenergy crops. Currently, the pre‐treatment of Agave is the most widely studied stage in biofuels and value‐added products, which include technologies capable of reducing its recalcitrance while removing xylan and/or lignin and reducing cellulose crystallinity, among other effects, to increase the overall yield in saccharification and fermentation, which will be discussed as well. In addition to spirits and fibers from industrial interests, different liquid (ethanol and n‐butanol) and gaseous (methane and hydrogen) biofuels, including certain value‐added products (enzymes, lactic acid, and succinic acid), can be obtained from Agave in high yields. The main objective of this review is to address the recent advances in the utilization of Agave as a bioenergy feedstock for biofuels and value‐added products within a sustainable biorefinery scheme. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd

A biorefinery scheme to fractionate bamboo into high-grade dissolving pulp and ethanol

BackgroundBamboo is a highly abundant source of biomass which is underutilized despite having a chemical composition and fiber structure similar as wood. The main challenge for the industrial processing of bamboo is the high level of silica, which forms water-insoluble precipitates negetively affecting the process systems. A cost-competitive and eco-friendly scheme for the production of high-purity dissolving grade pulp from bamboo not only requires a process for silica removal, but also needs to fully utilize all of the materials dissolved in the process which includes lignin, and cellulosic and hemicellulosic sugars as well as the silica. Many investigations have been carried out to resolve the silica issue, but none of them has led to a commercial process. In this work, alkaline pretreatment of bamboo was conducted to extract silica prior to pulping process. The silica-free substrate was used to produce high-grade dissolving pulp. The dissolved silica, lignin, hemicellulosic sugars, and degraded cellulose in the spent liquors obtained from alkaline pretreatment and pulping process were recovered for providing high-value bio-based chemicals and fuel.ResultsAn integrated process which combines dissolving pulp production with the recovery of excellent sustainable biofuel and biochemical feedstocks is presented in this work. Pretreatment at 95 °C with 12% NaOH charge for 150 min extracted all the silica and about 30% of the hemicellulose from bamboo. After kraft pulping, xylanase treatment and cold caustic extraction, pulp with hemicellulose content of about 3.5% was obtained. This pulp, after bleaching, provided a cellulose acetate grade dissolving pulp with α-cellulose content higher than 97% and hemicellulose content less than 2%. The amount of silica and lignin that could be recovered from the process corresponded to 95 and 77.86% of the two components in the original chips, respectively. Enzymatic hydrolysis and fermentation of the concentrated and detoxified sugar mixture liquor showed that an ethanol recovery of 0.46 g/g sugar was achieved with 93.2% of hydrolyzed sugars being consumed. A mass balance of the overall process showed that 76.59 g of solids was recovered from 100 g (o.d.) of green bamboo.ConclusionsThe present work proposes an integrated biorefinery process that contains alkaline pre-extraction, kraft pulping, enzyme treatment and cold caustic extraction for the production of high-grade dissolving pulp and recovery of silica, lignin, and hemicellulose from bamboo. This process could alleviate the silica-associated challenges and provide feedstocks for bio-based products, thereby allowing the improvement and expansion of bamboo utilization in industrial processes.

Current research and perspectives on microalgae-derived biodiesel

ABSTRACTBiofuels have gained much attention in the recent years. Microalgae hold tremendous potential for production of biofuels as a suitable alternative to conventional fossil fuels. However, in order to ensure sustainability of the biofuel production from microalgae, many issues needs to be considered. Large-scale production of such biofuels is often limited by high cost of production, various environmental concerns including water footprint, and low yield. The algal biorefinery strategy, which can integrate several different conversion technologies to produce biofuels, holds potential for reducing the overall production cost. This paper is a review on various aspects associated with algal cultivation, lipid extraction and biodiesel production. Different factors reported to affect the process of algal cultivation and advancements in transesterification process and product recovery are summarized here. A brief on biorefinery approach is also discussed.