Algal Biofuel Research Articles

Algal Biofuels: Unveiling the Potential of Seaweed in Renewable Energy Production

This study examines the numerous pre-processing techniques used to convert biomass into greater sustainable biofuels and commodities, highlighting the boom in productivity and the supply of a greater uniform, dry, and suitable feedstock. by using addressing the demanding situations associated with biomass size, layout, moisture content, and variability, this study delves into mechanical procedures, drying, torrefaction, palletization, hydrolysis, hydrothermal, and microwave-primarily based strategies as possible solutions. It explores the utilization of various biomass types, which include wood, woody biomass, herbaceous streams, and agricultural streams, and assesses their impact on bioenergy production and environmental sustainability. The study also considers the position of algae, specially microalgae, in offering bioactive materials with substantial health advantages and their ability in overcoming land-use concerns associated with traditional biomass. moreover, the paper evaluates the environmental affects and sustainability of biomass usage, advocating for microalgae as a promising feedstock for 1/3-technology biofuels. The research is grounded in the context of the increasing need to reduce reliance on fossil fuels due to urbanization and population enlargement, which make contributions to environmental degradation.

Evaluation of Performance of a CI Engine Fueled With Biodiesel Produced from Unused Algae

Abundant availability and easy culture process of algae make it a better resource than other vegetable crops for biodiesel production. The oil (with 21% FFA content) extracted from the unused, mixed culture of algae in this experiment was used to produce biodiesel by an' acid esterification followed by alkaline esterification' procedure. After confirming the properties of the biodiesel to be within the limit of ASTM standard, three biodiesel blends (B10, B20 and B30) were used in an internal combustion engine (Four stroke single cylinder VCR engine) and the performance of the engine was observed at different engine loads (0%, 20%, 40%, 80%, 100%, 120%). The little higher brake specific fuel consumption (0.22kg/KWh, 0.25 kg/KWh, 0.26kg/KWh and 0.21kg/KWh respectively for B10, B20, B30 and petro-diesel at overload condition), lower brake power (3.41 kW, 3.37 kW, 3.25 kW, 3.39 kW for diesel, B10, B20 and B30 respectively for B10, B20, B30 and petro-diesel) and mechanical efficiency (63.34, 51.43%, 52.06% and 51.43% for petro-diesel, B10, B20 and B30 respectively) for biodiesel blends took place which might be the results of lower calorific value (40800 kJ/kg), higher density (875.27kg/m3) and viscosity (3.14 mm2/s) of the algal biodiesel than diesel.

Effect of compression ratio and injection timing on the performance of microalgae‐based biodiesel blend

AbstractThe manuscript addressed experimental work related to microalgae‐based biodiesel blend B20, that is, 20% algae biodiesel and 80% diesel, as an alternative fuel as a possible source to power diesel engines. The physiochemical characteristics of this B20 blend were almost in line with diesel fuel as per American Society for Testing and Material standards. Coupled experimentation related to variations in compression ratio (CR) 17, 19, and 21 and fuel injection timing (IT) of 21°, 23°, and 25° before top dead center (bTDC) with load variations noted on diesel engines. We observed that, at full load, CR21 and 23° bTDC fuel IT, the brake thermal efficiency parameters rose significantly, whereas brake‐specific fuel consumption, and combusted flue gas temperatures also plummeted. The CO, HC, and smoke opacity emission for the B20 blend at CR21 and FIT23 has decreased by 30.52%, 33.33%, and 32.96%, respectively. At full load conditions, NOx emission for B20 biodiesel at CR21 was increased compared with the standard setting and compared with diesel it was increased by 6.46%.

Experimental Studies to Reduce Usage of Fossil Fuels and Improve Green Fuels by Adopting Hydrogen–Ammonia–Biodiesel as Trinary Fuel for RCCI Engine

Experimental Studies to Reduce Usage of Fossil Fuels and Improve Green Fuels by Adopting Hydrogen–Ammonia–Biodiesel as Trinary Fuel for RCCI Engine

Biodiesel from Dunaliella salina Microalgae Using Base Catalyzed Transesterification – An Assessment through GC/MS, FTIR and NMR Studies

Algal biofuels are a promising renewable feedstock to produce energy that can supplement future energy demands greatly. The present study aims to utilize Dunaliella salina, a hypersaline, unicellular greenish-orange micro-algae, to produce bio-oil. F/2 nutrient media and trace metal and vitamin solution under carbon-dioxide-rich conditions were used to cultivate the microalgae. Ultrasonic extraction method at 60 Hz for 90 min isolated 650 mL of bio-oil. A single-stage based-catalyzed transesterification process with methanol and sodium hydroxide yielded 380 mL of Pure Dunaliella salina biodiesel at % an extraction efficiency of 87%. The Phytochemical screening on the cultivated Dunaliella sp. was performed to understand its feasibility to be used as a fuel for IC engines. Furthermore, the obtained biodiesel was characterized using Fourier Transform Infrared Spectrometer (FTIR), Gas Chromatography Mass Spectrometer (GCMS), and Nuclear Magnetic Resonance (NMR) spectral analysis.

Progress of Algaculture technology as Biofuel

As the problem of climate change becomes more and more serious, improving the carbon emission situation will be an effective way to solve various climate problems. Algal biofuels can build a complete carbon cycle and reduce carbon emissions. In this paper, the conditions required for microalgae cultivation and how diverse factors play a role in the growth rate and yield of microalgae were reviewed. And show how different factors like pH value, illumination, temperature, medium of culture, and nutrients in the medium affect the content of different substances in the final microalgae to help breed the matching microalgae. Macroscopically, this paper introduces both open raceway ponds and photobioreactors as microalgae cultivation systems and their respective characteristics. Microalgae will produce higher lipid content and hydrogen production capacity in different acid-base environments, respectively, and provide a nitrogen-deficient environment to further increase lipid production. The two-stage hybrid system combining an open raceway pond and photobioreactor has more obvious advantages in terms of growth rate and yield.

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

Investigation of Dynamic Viscosity and Calorific Value of Algae Biodiesel Blend with n-Butanol Additive

The transport sector primarily utilizes diesel fuel, which is a prominent energy source for various industries and applications. However, due to population growth, the increasing demand for diesel fuel leads to its depletion. This topic attracts many researchers looking for a solution through fuel alternatives, including the fuel properties of algae oil and its compatibility with diesel engines when combined with diesel fuel. To further understand the related topic, the study aims to explore the fuel properties, focusing on the viscosity and calorific value of Biodiesel Algae oil (BD) with n-butanol (nB). The Alge oil was prepared on the lab scale before blending to produce 4 different mixtures of Biodiesel. The results indicate that the blend 93BD7nB, which contained 93% of Algae biodiesel and 7% of n-butanol, obtained 0.168 Pa/s, which is in the required range in the standard limit ASTM D6751 whereas the calorific values for all samples above the standard limit EN 14214 indicate a good efficiency. In conclusion, this fuel blend exhibits promising potential for future utilization in diesel engine operations and provides an alternative solution for energy depletion.

Maximizing efficiency and environmental benefits of an algae biodiesel-hydrogen dual fuel engine through operational parameter optimization using response surface methodology

The utilization of clean and renewable fuels has become increasingly significant in the power generation and transportation sectors. Dual-fuel engines that employ hydrogen and algal biodiesel are potential alternatives. This study investigated the impact of pilot fuel injection pressures and engine loads on the performance and emissions of an algal biodiesel-hydrogen dual-fuel engine. The engine was optimized using response surface methodology under various operating conditions. The highest brake thermal efficiency (28.71 %) was obtained at 240 bar pilot fuel injection pressure and 100 % engine load, significantly reducing carbon monoxide and hydrocarbon emissions. The optimum parameters were identified using response surface methodology at 67.63 % engine load and 245.48 bar pilot fuel injection pressure, with a high model fit (R2) range of 88.89 %–99.59 % and composite desirability of 96.1 %. The potential for optimizing algal biodiesel-hydrogen dual-fuel engines to achieve greater efficiency and environmental benefits is highlighted in this work, as is the relevance of applying response surface methods to optimize engine performance.

Flocculation with intermittent dosing for enhanced microalgae harvesting

One of the bottlenecks to the industrialization of algal biofuel is the high cost of harvesting. Flocculation is an efficient technique for algae harvesting, but flocculant consumption results in additional expenses. To lower the overall cost of algae harvesting, it is essential to explore approaches to reduce flocculant usage. In this study, a novel flocculant dosing strategy of intermittent dosing was investigated for enhanced algae harvesting efficiency, with comparisons to traditional one-time dosing, continuous dosing and dual dosing. The impacts of critical operational parameters were examined, and the mechanism was investigated based on floc analysis. The results demonstrated that intermittent dosing can significantly enhance harvesting efficiency. At the optimal operational conditions of 5 s dosing interval, 10 mg/L min−1 dosing speed and 5 min stirring time, the algae harvesting efficiency increased from 71.1 % to 91.3 % compared to one-time dosing when 15 mg/L CPAM was used as a flocculant. According to floc analysis, intermittent dosing tended to form larger and loosely connected flocs, while traditional one-time dosing tended to produce smaller and denser flocs. The different floc growth mechanisms can help to explain how intermittent dosing improved algae flocculation. In addition, intermittent dosing resulted in a higher removal efficiency of dissolved extracellular organic matter and improved algae recultivation. Finally, the cost estimation was performed, and the operational cost was lowered from 32.65 USD ton−1 algae for one-time dosing to 20.64 USD ton−1 algae for intermittent dosing. Through the investigation of this study, the technical, mechanical and economic feasibility of intermittent dosing for enhanced algae harvesting were established.

Simultaneous production of bio-crude bio-oil via hydrothermal liquefaction and carotenoids via supercritical extraction from Nannochloropsis oceanica and recycling effluent to establish circular processes

Commercial production of microalgae biofuel is not economically feasible since it cannot compete with the price of fossil fuels. Algal biofuel could be cost-effective if high-value co-products are produced from microalgal biomass before it is converted into biofuel. Thus, this research aims to demonstrate a circular biorefinery process of producing bio-crude bio-oil as well as high-value products like carotenoids from a marine microalga Nannochloropsis oceanica. The microalga was cultivated in raceway ponds over the years with the highest biomass productivity of 30–40 g m−2 day−1 recorded in October and November of 2021, but it reduced in extremely high summer temperatures and low temperatures in winter of Delhi NCR, India. The annual average biomass productivity of 19.13 g m−2 day−1 was recorded, which is equivalent to 69825 kg ha−1 year−1. The algal biomass was processed for high-value carotenoids using a green process, i.e. supercritical carbon dioxide extraction. Carotenoid yield of 252 μg/g of biomass was obtained after optimizing temperature and pressure in the supercritical extraction process. The spent biomass after carotenoid extraction was used to produce bio-crude bio-oil using hydrothermal liquefaction. There was no significant difference between bio-crude oil yield and properties after carotenoid extraction and direct biomass use. A bioeconomic methodology for closing the circular loop involving recycling the effluent generated during hydrothermal liquefaction to re-cultivate the microalgae is demonstrated. This study highlights the potential of green technology, circular bioeconomy, and biorefinery practices in developing sustainable and environmentally friendly solutions for the chemical and energy sectors.

Prediction of RCCI combustion fueled with CNG and algal biodiesel to sustain efficient diesel engines using machine learning techniques

This study used microalgae biodiesel as a high-reactive fuel directly injected along with various Compressed Natural Gas (CNG) energy shares (10, 20, 30, and 40%) as low-reactive fuel injected into the intake system. The experiments are performed in a single-cylinder, water-cooled, 1500 rpm, 3.5 kW power Compression Ignition (CI) engine under various loading conditions to examine the effects of CNG energy share on performance and emissions in Reactivity Controlled Compression Ignition (RCCI) combustion mode. The study found that the 30%CNG share decreased Nitrogen oxides (NOx) and smoke by 25 and 31%, as well as an increase in thermal efficiency of 4.35% in comparison to traditional biodiesel combustion. Finally, two machine learning (ML) models, namely the Gradient Boosting Regressor (GBR) and LASSO (Least Absolute Shrinkage and Selection Operator) Regression, were developed for predicting the dependent variables individually from the independent variables. Both the LASSO and GBR models achieved high accuracy with R2 values of 0.98–0.99 and relatively low Root Mean Square Error (RMSE) values.

Catalytic cracking of a model bio-petroleum compound (sugar di-ketals) using beta zeolite as catalyst

Conversion of biomass (BM) to fuel is a promising solution to reduce the carbon footprint. By modifying BM by ketalization, a stable, neutral liquid we call bio-petroleum (BP) is obtained. In this study, a representative compound of BP, DX (1,2:3,5-di-O-isopropylidene-α-D-xylofuranose) was co-processed with n-hexane(nC6) into biofuel. In the search for a process to deoxygenate the DX and avoid over-cracking, to optimize gas and coke yields using a beta catalyst in a fluidized bed catalytic cracking (FCC) unit at a process temperature of 540 °C, we explored mixing 10–70 wt% DX in nC6, with catalyst/feed ratios from 3 to 6 and feed injection time of 30 versus 60 s. DX was fully converting under all conditions tested, while nC6 conversion decreased, reaching zero conversion when DX > 50 wt%. Coke yield varied from 3 to 9 wt%. The mixture containing a low amount of DX provided hydrocarbons without oxygenates. The mixture of 50% DX in nC6 only gave 2.7 wt% of oxygenates such as furans and ketones. Hence, the results confirmed the strong potential of beta catalysts to produce biofuel, superior to ZSM-5 and Y zeolites. Furthermore, the results of the variations of processing parameters added insights about the bio-petroleum conversion steps, contributing to further catalyst and process development.

The combined effect of hydrogen enrichment and exhaust gas recirculation on the combustion stability, performance and emissions of CI engine energized by algae biodiesel

The scarcity of fossil fuels, the rising cost of liquid fuels, and the wide pollution footprint of conventional fuels all motivate scientists to seek out new approaches. This experimental study aims to explore the performance and emissions of compression ignition (CI) engines by introducing hydrogen into a biodiesel blend derived from algae. According to this study, the superior thermal properties of hydrogen associated with algal biodiesel have a significant impact on the performance and emissions of dual-fuel engines. The effect of hydrogen substitution rates of 10.4, 21.6, 32.4, 43.2, and 54 g per hour (g/h) on pure algae biodiesel was investigated. In comparison to diesel, the algae biodiesel reduces unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions by 4.1% and 8.82%, respectively, while nitrogen oxide (NOx) emissions increase by 18%. Diesel was found to have increased brake thermal efficiency (BTE) and decreased brake specific energy consumption (BSEC) compared to biodiesel. With the addition of pure biodiesel, the 43.2 g/h H2 substitution rate produces a maximum thermal efficiency of 1.92% and a 9.5% decrease in brake-specific energy consumption compared to diesel at maximum load. Compared to diesel, the emission attributes of UHC, CO, and smoke opacity decreased by about 45%, 48%, and 41%, respectively. However, NOx emissions increase by about 36% compared to diesel due to the higher flame temperature and carbon-free fuel of hydrogen and oxygenated biodiesel. The induction of 15% exhaust gas with B100 + 43.2 g/h H2 reduces NOx by about 31% in comparison to B100 + 43.2 g/h H2 without exhaust gas recirculation (EGR). This is primarily attributable to the high oxygen dilution and specific heat capacity of burned gases, which result in a decrease in peak cycle temperature. Compared to diesel, B100 + 43.2 g/h H2 increased the cylinder pressure and heat release rate by about 1.86 and 4.29%, respectively. As a result of its high energy density, hydrogen improves overall energy utilization and engine performance. Hydrogen's rapid flame speed and wide flammability range contribute to the efficient and complete combustion of the algae fueling the CI engine. As well as showing outstanding performance, dual fuel CI engines have the potential to significantly contribute to lowering emissions. Finally, it was determined that using algae biodiesel and exhaust gas recirculation with hydrogen substitution in diesel engines can significantly reduce emissions while increasing efficiency.

Assessment of Performance and Emission Characteristics using Algae Biodiesel in an Additive Fuelled LHR Engine

Automobiles use compression-ignition (CI) engines because they have more pulling power, are more dependable and use less fuel than spark-ignition (SI) engines. Both CI and SI engines use petroleum-based oils, contributing to environmental pollution like acid rain, ozone depletion and climate change. The cost of petroleum-based fuel is increasing daily due to demographic growth and the development of manufacturing industries. There are four phases to the experiments. The first stage involves mixing diesel with 20% of ALME, the outcomes showed that engine operation and combustion are comparable to conventional diesel fuel. In the second stage, an LHR engine tests 20% of ALME and the results showed that BTE of LHR engine had significantly increased. In comparison, NOx increases in LHR-operated CI engine, CO, HC and smoke emissions are significantly lower than with a conventional engine. The third stage looks at how NA interacts with biodiesel to affect conventional engine’s combustion, emission and engine performance. The prepared algae biodiesel is blended with NA in various ratios of 500ppm, 1000ppm, 1500ppm and 2000ppm. At 1000ppm concentration, NOx emission from conventional and LHR engines has been effectively minimized under load conditions. Concerning diesel fuel, emissions like CO, HC and smoke are significantly reduced for all loads. In the fourth stage, tests on the LHR engine are carried out using the SBME with NA in various proportions. When compared to base fuel, it has been found that NOx emission has decreased significantly at 1000ppm compared to conventional engines and other emissions have decreased.

Optimization of the pilot fuel injection and engine load for an algae biodiesel - hydrogen run dual fuel diesel engine using response surface methodology

The main objective of the study is to enhance the performance and emissions of hydrogen and biodiesel dual-fuel engines by optimizing injection timing and engine load using response surface methodology. The pilot fuel considered for this study is Algae biodiesel. A mono-cylinder water-cooled diesel engine is tested for three different pilot fuel injection timings (23° BTDC, 26° BTDC, and 29° BTDC) and five different engine loads (20%, 40%, 60%, 80%, and 100%). For a dual fuel operation, a maximum brake thermal efficiency of 28.21% and an 85% replacement of liquid charge was achieved at pilot fuel injection timing of 26° BTDC and 100% load based on the experimental results. For the same setting of injection timing of 26° BTDC, the emissions of CO and HC were significantly reduced by 12.12% and 36.13%, respectively, at the 80% load setting. While response surface optimum was found at 72.81% load and 25.73° BTDC Injection timing. At this optimal operating parameter setting, a significant reduction of CO, HC, and NOx emissions by 20.98%, 29.15%, and 1.91%, respectively, was obtained while maintaining a comparable brake thermal efficiency of 25.06% and a replacement of liquid charge by 72.15%, respectively. Thus, a biodiesel-hydrogen dual-fuel diesel engine is one of the green solutions for power generation.

Implications of CO2 Sourcing on the Life-Cycle Greenhouse Gas Emissions and Costs of Algae Biofuels.

Production of algal biomass and its conversion to biofuels are important technological platforms within the larger umbrella of CO2 capture and utilization. This analysis incorporates a life-cycle assessment (LCA) with respect to global warming potential and techno-economic assessment (TEA) of algae biofuels, focusing on the sourcing and delivery of CO2. This analysis evolves past work in this area to include high-purity biogenic CO2, industrial fossil fuel use, fossil power plants, and direct air capture, and uses a Sherwood plot approach to estimate the CO2 capture energy penalty. We also show that allocation or displacement facilitates a more intuitive distinction between biogenic and fossil sources of carbon. Thus, the LCA better reflects the influence of coproduct handling strategies as compared to previous works. The TEA is also strongly influenced by the CO2 concentration in the flue gas. Currently, when CO2 is sourced from large-point sources, the price of biofuels ($4.5-6.5/GGE) may become comparable to fossil diesel. However, as DAC systems become more economical, they may deliver competitive CO2 sources for biofuels in 2050 with a total cost of <$7/GGE. Based on the net emissions and costs, algae biofuels with CO2 sourced from biogenic sources are consistent with a decarbonized economy as of now, with substantial potential for DAC with decreasing costs.

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.

Advancement of Abiotic Stresses for Microalgal Lipid Production and Its Bioprospecting into Sustainable Biofuels

The world is currently facing global energy crises and escalating environmental pollution, which are caused by the extensive exploitation of conventional energy sources. The limited availability of conventional energy sources has opened the door to the search for alternative energy sources. In this regard, microalgae have emerged as a promising substitute for conventional energy sources due to their high photosynthetic rate, high carbohydrate and lipid content, efficient CO2 fixation capacity, and ability to thrive in adverse environments. The research and development of microalgal-based biofuel as a clean and sustainable alternative energy source has been ongoing for many years, but it has not yet been widely adopted commercially. However, it is currently gaining greater attention due to the integrated biorefinery concept. This study provides an in-depth review of recent advances in microalgae cultivation techniques and explores methods for increasing lipid production by manipulating environmental factors. Furthermore, our discussions have covered high lipid content microalgal species, harvesting methods, biorefinery concepts, process optimizing software tools, and the accumulation of triglycerides in lipid droplets. The study additionally explores the influence of abiotic stresses on the response of biosynthetic genes involved in lipid synthesis and metabolism. In conclusion, algae-based biofuels offer a viable alternative to traditional fuels for meeting the growing demand for energy.