Challenges in microalgal biofuel production: A perspective on techno economic feasibility under biorefinery stratagem

Subhash, G. Venkata; Rajvanshi, Meghna; Kumar, Gaurav; Sagaram, Uma Shankar; Prasad, Vandana; Govindachary, Sridharan; Dasgupta, Santanu

doi:10.1016/j.biortech.2021.126155

Cited by 74 publications

(24 citation statements)

References 114 publications

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“…It has been advocated recently that the sustainability and commercial feasibility of the microalgae-mediated technologies come only from multiproduct utilization, i.e , through a biorefinery approach ( Mehariya et al., 2021 ). Although means for producing microalgae biomass at low costs, utilizing wastewater and CO 2 -rich flue gas have been worked out, the high cost of downstream processing creates a net negative energy balance making the process unfeasible for commodity applications such as that of animal feed, agrochemicals and industrial chemicals (fuels) ( Subhash et al., 2022 ). With newer findings on the potential of microalgae biomass and its metabolites for agricultural applications, it is imperative to identify sustainable biomass utilization routes for commercial feasibility.…”

Section: Microalgae Based Bio Refineries and Circular Economy For Sus...mentioning

confidence: 99%

Microalgae as next generation plant growth additives: Functions, applications, challenges and circular bioeconomy based solutions

2023

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Sustainable agriculture practices involve the application of environment-friendly plant growth promoters and additives that do not negatively impact the health of the ecosystem. Stringent regulatory frameworks restricting the use of synthetic agrochemicals and the increase in demand for organically grown crops have paved the way for the development of novel bio-based plant growth promoters. In this context, microalgae biomass and derived agrochemicals offer novel sources of plant growth promotors that enhance crop productivity and impart disease resistance. These beneficial effects could be attributed to the presence of wide range of biomolecules such as soluble amino acid (AA), micronutrients, polysaccharides, phytohormones and other signaling molecules in microalgae biomass. In addition, their phototrophic nature, high photosynthetic efficiency, and wide environmental adaptability make them an attractive source of biostimulants, biofertilizers and biopesticides. The present review aims to describe the various plant growth promoting metabolites produced by microalgae and their effects on plant growth and productivity. Further, the effects elicited by microalgae biostimulants with respect to different modes of applications such as seed treatments, foliar spray and soil/root drenching is reviewed in detail. In addition, the ability of microalgae metabolites to impart tolerance against various abiotic and biotic stressors along with the mechanism of action is discussed in this paper. Although the use of microalgae based biofertilizers and biostimulants is gaining popularity, the high nutrient and water requirements and energy intensive downstream processes makes microalgae based technology commercially unsustainable. Addressing this challenge, we propose a circular economy model of microalgae mediated bioremediation coupled with biorefinery approaches of generating high value metabolites along with biofertilizer applications. We discuss and review new trends in enhancing the sustainability of microalgae biomass production by co-cultivation of algae with hydroponics and utilization of agriculture effluents.

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Section: Microalgae Based Bio Refineries and Circular Economy For Sus...mentioning

confidence: 99%

Microalgae as next generation plant growth additives: Functions, applications, challenges and circular bioeconomy based solutions

2023

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“…While the scope of this present work is focused on experimental process optimization, further techno-economic analyses are required to continue this optimization work at scale. Previous work in that area suggest that anaerobic vs. aerobic conditions and cultivation technologies have a significant impact on microalgae economics, and that emissions also would need to be considered [52][53][54].…”

Section: Optimization Verificationmentioning

confidence: 99%

Adding Value to Wastewater Bioremediation by Lipid Extraction from Oedogonium intermedium

et al. 2023

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Macroalgae bioremediation is a potential way to deal with the escalating problem of arsenic contamination. The results of this study demonstrate that the arsenic content in wastewater treated by Oedogonium intermedium decreases by 32% from 1.13 ± 0.01 to 0.77 ± 0.03 ppb. Then, supercritical carbon dioxide (SC‐CO2) extraction was employed to isolate lipids from O. intermedium. Response surface methodology based on the Box‐Behnken design was carried out to optimize the SC‐CO2 extraction conditions of pressure (200–400 bar), temperature (30–50 °C), and extraction time (30–90 min). The optimal conditions from the model are predicted as 301.95 bar, 41.3 °C, and 30.53 min with 3.24 % lipid yield, 61.30 % PUFA ratio, and 0.106 µg g−1 of arsenic content, respectively.

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“…Microalgal biomass has attracted considerable attention in recent years as the carbon fixation rate of microalgae is 10–50 folds higher than that of biomass grown on land . Outdoor cultivation of microalgal biomass is essential to practically realize its mass production . Carbon accumulation in microalgae can be achieved autotrophically; the microalgal growth rate is proportional to the amount of solar radiation .…”

Section: Introductionmentioning

confidence: 99%

“…Outdoor cultivation has a high potential for contamination with other microbes (bacteria/fungi) . These microbes compete with microalgae for nutrients, leading to a decrease in microalgae yield . Extremophilic unicellular red algae such as Galdieria sulphuraria (G.…”

Section: Introductionmentioning

confidence: 99%

Strategic Use of Extremophilic Microalgae as a Carbon Source in the Thermo-Chemical Process

Choi

Kwon

Lee

et al. 2023

ACS Sustainable Chem. Eng.

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Microalgal biomass has a high CO2 fixation and growth rate when using CO2 as a carbon source. Moreover, biomass can also be employed as a carbon resource to produce biofuels and chemicals. As the growth rate of extremophilic microalgae remains unaffected by harsh conditions, the present study proposes that these microalgae (such as Galdieria sulphuraria) are a rapidly growing carbon resource for syngas production. Hence, two different experiments were performed as part of this study: (1) cultivation of G. sulphuraria under outdoor conditions and (2) conversion of G. sulphuraria into syngas. The productivity of G. sulphuraria under mixotrophic condition (0.82 g L–1 d–1) was about 1.6 faster than a widely cultivated Chlorella sp. HS2. Moreover, G. sulphuraria was converted into syngas using CO2 as a co-feedstock. The simultaneous reduction of CO2 and the oxidation of volatile matter (VM) from the thermolysis of G. sulphuraria promoted syngas formation. The chemical reaction was influenced by the molecular size of the VMs. In the presence of the Ni catalyst, low-molecular-weight VMs were formed owing to chemical bond scissions. Syngas formation under CO2 doubled compared with that under inert conditions. The findings suggest that G. sulphuraria is a feasible carbon source for CO2 fixation and chemical production.

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Challenges in microalgal biofuel production: A perspective on techno economic feasibility under biorefinery stratagem

Cited by 74 publications

References 114 publications

Microalgae as next generation plant growth additives: Functions, applications, challenges and circular bioeconomy based solutions

Microalgae as next generation plant growth additives: Functions, applications, challenges and circular bioeconomy based solutions

Adding Value to Wastewater Bioremediation by Lipid Extraction from Oedogonium intermedium

Strategic Use of Extremophilic Microalgae as a Carbon Source in the Thermo-Chemical Process

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