Algal Biofuel Production Research Articles

Advancements and Prospects in Algal Biofuel Production: A Comprehensive Review

Advancements and Prospects in Algal Biofuel Production: A Comprehensive Review

Current Scenario and Global Perspective of Sustainable Algal Biofuel Production.

Industrialization and globalization have increased the demand for petroleum products that has increased a load on natural energy resources. The escalating fossil fuel utilization has resulted in surpassing the Earth's capacity to absorb greenhouse gases, necessitating the exploration of sustainable bioenergy alternatives to mitigate emissions. Biofuels, derived from algae, offer promising solutions to alleviate fossil fuel dependency. Algae, often regarded as third-generation biofuels, present numerous advantages owing to their high biomass production rates. While algae have been utilized for their bioactive compounds, their capability as biomass for the production of biofuel has gained traction among researchers. Various biofuels such as bio-hydrogen, bio-methane, bio-ethanol, bio-oil, and bio-butanol can be derived from algae through diverse processes like fermentation, photolysis, pyrolysis, and transesterification. Despite the enormous commercial potential of algae-derived biofuels, challenges such as high cultivation costs persist. However, leveraging the utilization of algae byproducts could improve economic viability of biofuel production. Moreover, algae derived biofuels offer environmental sustainability, cost-effectiveness, and waste reduction benefits, promising novel opportunities for a more sustainable energy future.

Algal Biofuels: A Comprehensive Review and Analysis

The depletion of fossil fuels and increased atmospheric CO2 levels have precipitated a global energy and environmental crisis. The cultivation of microalgae offers a viable remedy by utilizing solar energy and assimilating CO2 for biofuel production via photosynthesis. Microalgae demonstrate rapid growth in diverse environments, rendering them a dependable biomass source for large-scale biofuel generation. Furthermore, their biofuel production can be tailored through the manipulation of growth conditions or genetic engineering. This review aims to highlight the variety of biofuels produced from microalgae and the methodologies to optimize their yield. This review also explores the economic implications of algal biofuel production in both open ponds and closed photobioreactors. Various strategies for the photo-production of biohydrogen utilizing the hydrogenase enzyme from green algae are investigated. Additionally, certain microalgae species are recognized for their potential as biodiesel sources due to their high lipid content. The lipid profiles of leading oil-producing algal strains under optimal conditions are assessed. This review further examines the potential of microalgae in synthesizing petroleum-based chemicals and in generating bioethanol and biogas from algal biomass.

Integrating direct air capture with algal biofuel production to reduce cost, energy, and GHG emissions

We investigate the potential to reduce costs and greenhouse gas emissions of the utilization of direct air capture of CO2 (DAC) for the production of algal biofuel. We examine four integrated designs for a DAC system comprised of solid amine monolith adsorbents delivering CO2 at the required level for algae cultivation with a photobioreactor (PBR)-based fuel production facility. We show that the integration of DAC with this biofuel production facility provides cost and greenhouse gas emissions benefits. Heat integration decreases operating expenses by reducing energy demand for heating requirements. Mass integration, utilizing flue gas CO2 as a carbon source for the PBRs, decreases the DAC system scale, resulting in both capital and operating cost savings. The most advantageous option depends on the interplay of heat and mass integration while matching the diurnal rhythm of algal growth with the inherently steady pace and energy requirements of the DAC system and fuel production. For these technologies, the DAC-PBR mass and energy integration provides an 18 % cost reduction and a 50 % reduction in greenhouse gas emissions for the current state of the technology.

Algal biomass based bio-refineries: Concurrent pre-treatment strategies and perspectives for sustainable feedstock

The quest for viable and scalable biofuel sources has been at the forefront of scientific innovation for the past three decades. Due to its rich chemical constituents, microalgal biomass has emerged as a pivotal sustainable and scalable feedstock for biorefineries. This comprehensive review critically analyzes the different types of microalgae feedstock, concurrent extraction technologies, bio-pre-treatment procedures, and the key chemical and physical parameters influencing lipid formation and algal biofuel production. We propose a novel approach of photo-initiated culturing of algal biomass using photobioreactors (PBRs) to address the limitations of concurrent space and time-related constraints. The innovative photo bio-refinery strategy presented herein aims to enhance sustainability factors while minimizing emissions, catering to the needs of futuristic non-electric vehicles. A comparative quality analysis of microalgae-derived biofuel against conventional fossil fuels and other biofuels is conducted, considering chemical, environmental, economic, and social perspectives. Furthermore, we elucidate the efficacy of bio-pre-treatment strategies such as dehydration, hydrothermal liquefaction, pyrolysis, and gasification in optimizing biofuel production. The proposed photo biorefineries exhibit the potential to yield a diverse range of value-added products, including biodiesel, biogases, bio-fertilizers, bio-pesticides, bio-alcohols, dyes, proteins, carotenoids, and drug vitals. This review provides a comprehensive framework for the development of sustainable and efficient microalgae-based biorefineries, paving the way for a greener and more economically viable future in the biofuel industry.

Green Synthesis and Characterization of CaO Nanoparticles using Hen Eggshells and its Impact on Biomass Concentration, Chlorophyll-a and Lipid Content of Chlorella sp.

Biodegradable wastes e.g. the outer cover of a boiled hen egg generally haphazardly discarded by humans in different locations of the country and generates problems for the local creatures. Although different researchers reported different methods to utilize the waste through the nanotechnological approach. Here, green synthesis of calcium oxide (CaO) nanoparticles from the hen eggshells was carried out and characterized them by using X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray (EDX) analysis, Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectrophotometer (UV). Further application of the synthesized nanoparticles was done on Chlorella sp. to investigate the impact on algal growth, lipid and chlorophylls. Synthesized CaO nanoparticles were applied in different concentration (0, 10, 20 and 30 mg L–1) and readings were monitored for 20 days. The highest biomass concentration 242.56 mg L–1 was achieved for the nanoparticle concentration of 20 mg L–1 and the lipid content increased up to 35.71% in 20 mg L–1. These results pave the way for enhanced algal biofuel production.

The phycosphere and its role in algal biofuel production

Oleaginous microalgae have become a focus for large-scale biofuel production due to their ability to accumulate large quantities of lipids. However, production is currently limited by cost and predation. At present, algal biofuel cultivation is optimized through starvation, supplementing media with nutrients, or genetic engineering; these methods can often be costly with little to no increase in lipid production or the culture’s defense. Investigating the phycosphere of algal-bacterial interactions may overcome these current barriers to large-scale production. The phycosphere of algal-bacterial interactions have formed over millions of years through mutualistic and symbiotic relationships and can provide a more direct source of nutrients compared to adding the nutrients in bulk. The most promising of these interactions include the production of phytohormones and quorum signaling compounds that alter the behaviors of the consortia. Phytohormones can improve algal growth rates, lipid production, and stress resistance. Quorum signaling could create consortia capable of warding off invaders—such as rotifers—while self-regulating and altering behavior based on population density. Mechanisms within the algal phycosphere present many opportunities for the development of novel engineering strategies to further improve algal lipid production and operational costs. This review outlines previous preliminary phycosphere research as well as posing possible opportunities to be pursued in future biofuel production.

Self-flocculation behaviour of cellulose-based bioflocculant synthesized from sewage water grown Chlorella sorokiniana and Scenedesmus abundans.

The global energy crisis has spurred a shift from conventional to clean and sustainable energy sources. Biomass derived from microalgae is emerging as an alternative energy source with diverse applications. Despite the numerous advantages of microalgae, large-scale biomass harvesting is not economical and convenient. Self-flocculation is considered an effective phenomenon facilitated by extracting the flocculating substances from microalgae that assist aggregation of algal cells into flocs. A novel cellulose-based bioflocculant has been synthesized from sewage water grown Chlorella sorokiniana and Scenedesmus abundans for harvesting application. The produced bioflocculant amounted to 38.5% and 19.38% of the dry weight of S. abundans and C. sorokiniana, respectively. Analysis via FTIR, XRD, and FESEM-EDX revealed the presence of cellulose hydroxyapatite (HA) in algae-derived cellulose. Harvesting efficiencies of 95.3% and 89.16% were attained for S. abundans and C. sorokiniana, respectively, at a dosage of 0.5g/L. Furthermore, the bioflocculant was recovered, enabling its reuse with recovery efficiencies of 52% and 10% for S. abundans and C. sorokiniana, respectively. This simple and efficient approach has the potential to replace other harvesting methods, thereby contributing to the economic algal biofuel production.

Potential of algal oil production from secondary treated sewage: a study using Chlorella vulgaris and synthetic wastewater

ABSTRACTTo assess the potential of using the secondary treated wastewater for the production of algal biofuel, batch experiments were carried out in photobioreactors using indigenous Chlorella vulgaris isolated from the natural freshwater body. Secondary treated wastewater with partial nitrification was simulated using various proportions of NO3-N and NH4-N while keeping the total nitrogen the same. Experiments with similar concentrations of nitrate without the NH4-N were used for comparison. In the presence of only NO3-N in the concentration range of 9–37 mg/L, the growth and fatty acid methyl ester (FAME) production was similar to the literature reports. When NH4-N was present along with NO3-N, the biomass growth was adversely affected, indicating an impact on the metabolic activity. For the same initial concentrations of nitrate in the culture, the maximum biomass concentration was reduced by 50–60% in the presence of NH4-N. The FAME profile changed significantly and a new FAME was identified, suggesting an impact on the lipid synthesis pathway. Comparison and analysis with the help of existing literature indicated that the adverse effect due to NH4-N was a function of pH. The growth, biomass yield, and FAME production were unaffected by a wide range of phosphorus concentrations. Maximum fatty acid methyl ester (FAME) suitable for biodiesel production (fatty acid carbon chain length C16 to C18) was 381.01 mg/L (224.58 mg/g of dry biomass), produced at NO3-N concentration of 18.5 mg/L and initial nitrogen loading per unit biomass of 0.37 g NO3-N/g of dry biomass.

Multi-objective optimization of algal biofuel production integrating resource recirculation and quality considerations

Multi-objective optimization of algal biofuel production integrating resource recirculation and quality considerations

Global Life Cycle and Techno-Economic Assessment of Algal-Based Biofuels.

Techno-economic analyses (TEAs) and life cycle assessments (LCAs) of algal biofuels often focus on locations in suboptimal latitudes for algal cultivation, which can under-represent the sustainability potential of the technology. This study identifies the optimal global productivity potential, environmental impacts, and economic viability of algal biofuels by using validated biophysical and sustainability modeling. The biophysical model simulates growth rates of Scenedesmus obliquusbased on temperature, photoinhibition, and respiration effects at 6685 global locations. Region-specific labor costs, construction factors, and tax rates allow for spatially resolved TEA, while the LCA includes regional impacts of electricity, hydrogen, and nutrient markets across ten environmental categories. The analysis identifies optimal locations for algal biofuel production in terms of environmental impacts and economic viability which are shown to follow biomass yields. Modeling results highlight the global variability of productivity with maximum yields ranging between 24.8 and 27.5 g m-2 d-1 in equatorial regions. Environmental impact results show favorable locations tracked with low-carbon electricity grids, with the well-to-wheels global warming potential (GWP) ranging from 31 to 45 g CO2eq MJ-1 in South America and Central Africa. When including direct land use change impacts, the GWP ranged between 44 and 55 g CO2eq MJ-1 in these high-productivity regions. Low-carbon electricity also favors air quality and eutrophication impacts. The TEA shows that minimum algal fuel prices of $1.89-$2.15 per liter of gasoline-equivalent are possible in southeast Asia and Venezuela. This discussion focuses on the challenges and opportunities to reduce fuel prices and the environmental impacts of algal biofuels in various global regions.

Nanotechnology for improved production of algal biofuels: a review

Nanotechnology for improved production of algal biofuels: a review

Biocoagulation of Dried Algae Chlorella sp. and Pellets of Aspergillus Niger in Decontamination Process of Wastewater, as a Presumed Source of Biofuel.

The removal of microalgae represents a problematic part of the water decontamination process, in which most techniques are expensive and non-ecological. In the paper, we focus on the synergistic relationship between microscopic filamentous fungi and algal culture. In the process of decontamination of a model sample containing ammonium ions, efficient biocoagulation, resp. co-pelletization of dried algae Chlorella sp. and Aspergillus niger sensu stricto are shown. The microscopic filamentous fungus species A. niger was added to a culture of an algal suspension of Chlorella sp., where the adhesion of the algal cells to the fungi subsequently occurred due to the electrostatic effect of the interaction, while the flocculation activity was approximately 70 to 80%. The algal cells adhered to the surface of the A. niger pellets, making them easily removable from the solution. The ability of filamentous fungi to capture organisms represents a great potential for the biological isolation of microalgae (biocoagulation) from production solutions because microalgae are considered to be a promising renewable source of oil and fermentables for bioenergy. This form of algae removal, or its harvesting, also represents a great low-cost method for collecting algae not only as a way of removing unnecessary material but also for the purpose of producing biofuels. Algae are a robust bioabsorbent for absorbing lipids from the environment, which after treatment can be used as a component of biodiesel. Chemical analyses also presented potential ecological innovation in the area of biofuel production. Energy-efficient and eco-friendly harvesting techniques are crucial to improving the economic viability of algal biofuel production.

Fuzzy set scoring methodology for multi-objective sustainability assessment of algal biofuel pathways

This work implements a multi-objective scoring methodology based on fuzzy set theory to evaluate and compare the sustainability metrics of microalgal biorefining concepts. Fuzzy membership functions are developed for three key metrics: minimum fuel selling price, global warming potential, and net energy ratio. Membership functions yield satisfaction scores ( λ ) between 0 and 1 for each objective; achieving λ = 1 indicates a sustainability metric has fully met its target, while λ = 0 is unacceptable for the standards of that metric. The individual λ are combined into an overall satisfaction score, λ o , also ranging from 0 to 1, which is used here to simplify the comparison of sustainability metrics. In addition to baseline biorefining conditions, uncertainties across the algal biofuel production system are assessed through a Monte Carlo analysis of λ o . A case study is developed to compare Combined Algal Processing (a biochemical conversion pathway) against hydrothermal liquefaction (a thermochemical conversion pathway). Baseline results show that lipids are always heavily favored for fuel production, but no practical cultivation operations would be able to achieve such lipid-heavy biomass. The Monte Carlo analysis reveals that current algal fuel conversion technologies cannot simultaneously satisfy all key sustainability objectives. If biomass productivity is doubled and the feedstock is high in lipids, hydrothermal liquefaction can achieve a mean λ o = 0.53 ± 0.12 , still well below a desirable λ o of 1. Combined Algal Processing struggles to achieve high satisfaction scores even in optimistic scenarios and requires a high-lipid feedstock to achieve a mean λ o = 0.10 ± 0.03 . Hydrothermal liquefaction can be integrated downstream of Combined Algal Processing to increase fuel yield and optimistically can achieve a mean λ o = 0.48 ± 0.07 . A combination of system improvements, including biomass productivity, feed composition, fuel yield, and implementation of co-product pathways must work together to satisfy all the relevant sustainability metrics for algal biofuels. The scoring methodology developed here can be readily applied to other microalgal biorefinery concepts and, more broadly, to sustainable fuel development and production. • Holistic evaluation of algal based biofuel systems. • Sustainability assessed through economic and environmental metrics. • Fuzzy set scoring system is applied to holistically assess algae fuel pathways. • Overall satisfaction of sustainability targets depends on algae composition. • Thermochemical pathway outscores biochemical pathway when biofuels are sole product.

Managing weather- and market price-related financial risks in algal biofuel production

Large-scale algae production has garnered interest due to its potential as a biofuel feedstock. Previous research assessing the profitability of algae products has been mostly based on values averaged over time, but algae production and resulting financial returns exhibit significant variability due to weather and fluctuations in selling prices for algae-based products. In other sectors, producers often reduce weather- and market price-related financial risk with financial instruments such as insurance, but little research has been performed on the design of insurance products to protect algae producers. This study develops a novel index-based insurance instrument that pays-out during unfavorable weather and market conditions, then explores the instrument's effectiveness, combined with a cash reserve, in reducing revenue stream variability for an algae producer. Results indicate that a biophysically based index-insurance product tailored to the specific financial risks in algae production can reduce variability in net revenues and can do so at a lower cost than relying solely on cash reserves, the most common financial risk management tool. Assessing the performance of index-insurance in algae production is particularly timely given the passage of the 2018 Farm Bill, which newly opens opportunities for the USDA to provide crop insurance to algae producers.

Waste utilization and biodiesel production from Desmodesmus maximus grown in swine wastewater using waste eggshells as a catalyst

Desmodesmus maximus is a potential candidate for algal biofuel production. It was cultivated for lipid enhancement in four different types of wastewater used as algal growth media. After growing Desmodesmus maximus for period of 10 days in four different types of waste water, it was found that swine wastewater collected from Swine Research Center of Oklahoma state university was the best media because of the faster biomass yield and lipid content in the algal biomass. The specific growth rate of algal strain grown in swine waste water was found to be 0.88 µ/d with doubling time T2 of 1.3 h which shows the better quantity of algal biomass. Algal lipids comprised 72.3 % (dry weight %) of the biomass. In our study wastewater was used as a nutrient source for biofuel production while remediating the waste. Calcined waste eggshells doped with lanthanum and switchgrass biochar were used to catalyze the conversion of algal lipid to biodiesel. Our study found that Biochar doped 950 degree Celsius CaO provided the optimal catalyst. The physicochemical characteristics of wastewater were analyzed and it was found that swine wastewater contains all the vital macro and micronutrients required for the optimal growth of this microalgae. The catalyst synthesized from waste eggshells was characterized by FTIR-ATR, SEM-EDX techniques and N2 physisorption by Brunauer–Emmett–Teller (BET) theory. The resulting produced biodiesel was analyzed by 1H NMR, 13C NMR, GC-MS techniques. Conversion to biodiesel was 99 % efficient with the optimized catalyst. The catalyst was subjected to 10 runs of transesterification to study reusability. After 10 runs the reused catalyst still provided 77 % conversion efficiency. The result obtained shows that Desmodesmus maximus grown in swine wastewater yields a very good quality and quantity of biodiesel. The waste eggshells and switchgrass can be utilized as renewable heterogeneous catalysts because of their highly porous nature and a more specific surface area that acts as a catalyst in the transesterification reaction of biodiesel.

Predicting Drying Curves in Algal Biorefineries using Gaussian Process Autoregressive Models

In algal biofuel production, drying of the microalgal biomass is considered the most energy-intensive process. To save on operating costs, optimal control of the drying process should be guided by accurate mathematical models of the biomass parameters, particularly its moisture content. In this paper, we propose the use of Gaussian process autoregressive models (GPAR) for long-range moisture content prediction in the vacuum drying of algal biofuels. Our experiments involve the drying of Chlorococcum infusionum, wherein the measured variables are temperature, pressure, and moisture ratio. By computing the root mean squared error (RMSE) on test data, we demonstrate the superiority of GPAR to other models, namely Neural Networks, Support Vector Machines, Random Forest, Gradient Boosting, and Autoregressive Models for the same task. Through automatic relevance determination kernels, GPAR also found that the most significant predictors are the pressure readings. In the future, GPAR can potentially be used for the predictive control of the drying process, leading to more efficient biorefinery operations.

A review on the current status and post-pandemic prospects of third-generation biofuels

The rapid increase in fossil fuel depletion, environmental degradations, and industrialization have encouraged the need and production of sustainable fuel alternatives. This has led to the increase in interest in biofuels, especially third-generation biofuels produced from microalgae since they do not compete with food and land supplies. However, the global share for these biofuels has been inadequate recently, especially due to the ongoing global pandemic. Therefore, this paper offers a review of the state-of-the-art study of the production field of third-generation biofuel from microalgae. The current review aims to focus on the different aspects of algal biofuel production that requires further attention to produce it at a large scale. It was found that several strategies during the life cycle of algal biofuel production can significantly increase its quality and yield while reducing cost, energy, and other related attributes. This paper also focuses on the challenges for large-scale production of third-generation biofuels pre and post COVID-19 to better understand the barriers. The high cost of this fuel’s production and sale tends to be the major reason behind the lack of large-scale production, hence, inadequacy to meet the global need. Third-generation biofuel has so much to offer including many integrated applications and advanced uses in the future fuel industry. Therefore, it is important to cope with the ongoing circumstances and emphasize the future of algal biofuel as a sustainable source.

Accelerated sunlight-driven conversion of industrial flue gas into biofuels by microfluidic high-throughput screening towards improving photosynthesis in microalgae under fluctuating light

Sunlight-driven microalgal conversion of CO2 is a promising carbon neutral strategy for the sustainable production of various value-added products. However, its real-world application is challenging due to the irregularity of sunlight which reduces photosynthetic efficiency. Here, we report that microdroplet-based screening of photosynthesis-augmented microalgae mutant under fluctuating light accelerates mass production of CO2-derived algal biofuel in natural sunlight. Random insertional Chlamydomonas reinhardtii mutants were cultivated in single-layered microdroplet photobioreactors to be effectively applied to light conditions mimicking natural sunlight without self-shading. High-density microdroplets containing fast-growing mutants were efficiently selected at the single-droplet level by a centrifugation-assisted droplet sorting platform for high-throughput screening. Consequently, we isolated a mutant exhibiting cell growth 1.85-fold that of the wild-type even under continuous and rapid alteration in light intensity, which can serve as a cell stressor. After whole-genome resequencing, we found disruption in the SNF2 gene encoding ATP-dependent chromatin remodeling complexes, which reveal its importance for the regulation of chlorophyll biosynthesis and accumulation of reactive oxygen species under fluctuating light. After a 1.6 ton-scale field culture utilizing natural sunlight and industrial CO2, the mutant showed increased biomass productivity, CO2 fixation rate, and calorific value, a crucial parameter of fuel performance, by 34.38%, 45.07%, and 16.82%, respectively. Our results indicate that improving photosynthesis of microalgae in fluctuating light environments elucidates the mechanisms responsible for enhancing the sunlight utilization, allowing industrial-scale biological CO2 conversion.

Enabling Production of Algal Biofuels by Techno-Economic Optimization of Co-Product Suites

Recent techno-economic analysis (TEA) has underscored that for algal biofuels to be cost competitive with petroleum fuels, co-products are necessary to offset the cost of fuel production. The co-product suite must scale with fuel production while also maximizing value from the non-fuel precursor components. The co-product suite also depends on algal biomass composition, which is highly dynamic and depends on environmental conditions during cultivation. Intentional shifts in composition during cultivation are often associated with reduced biomass productivity, which can increase feedstock production costs for the algae-based biorefinery. The optimal algae-based biorefinery configuration is thus a function of many factors. We have found that comprehensive TEA, which requires the construction of process models with detailed mass and energy balances, along with a complete accounting of capital and operating expenditures for a commercial-scale production facility, provides invaluable insight into the viability of a proposed biorefinery configuration. This insight is reflected in improved viability for one biorefining approach that we have developed over the last 10 years, namely, the Combined Algal Processing (CAP) approach. This approach fractionates algal biomass into carbohydrate-, lipid-, and protein-rich fractions, and tailors upgrading chemistry to the composition of each fraction. In particular, transitioning from valorization of only the lipids to a co-product suite from multiple components of high-carbohydrate algal biomass can reduce the minimum fuel selling price (MFSP) from more than $8/gallon of gasoline equivalent (GGE) to $2.50/GGE. This paper summarizes that progress and discusses several surprising implications in this optimization approach.