Potential Biofuel Research Articles

Information and Public Knowledge of the Potential of Alternative Energies

The objective of this research project is to study the economic development model of the Angolan economy in order to analyze the adoption of an alternative strategy capable of leveraging the economy, based essentially on alternative energies, and therefore, to demonstrate and prove the need to diversify Angola’s economic model, highlighting the benefits of a diversified versus a non-diversified economy with respect to sustainability. The first stage of the design of this empirical study involved establishing a focus group in order to construct and adjust a data collection instrument in the form of a questionnaire to be applied to a broader set of managers and informed professionals with a critical view of the country’s future and the models and alternatives to economic development and diversification of the economy on a sustainable basis. Energy plays a fundamental role in Angola’s economic and social development. Excessive dependency on the oil sector and inefficient production due to high costs, combined with changes in global environmental and energy policies, make it essential to reflect on the evolution of the country’s energy sector, equating a different economic development model, the diversification of the economy, and the exploration of other sources of energy, such as biofuels. Renewable energies emerge as a safe, healthy, environmentally friendly and economically viable energy alternative that could bring the Angolan economy closer to that of developed countries. Biofuels have become popular and have begun to be seen as a valid alternative to fossil fuels because they have lower production costs and they cause less impact on nature. Furthermore, since they are biodegradable, they can be commercialized at a lower cost from renewable sources. According to the respondents, the research results show that the best energy alternatives to reduce oil dependency are solar energy, biodiesel, hydraulic energy, and bioethanol. An assessment of the attractiveness and potential of biofuels show that the best alternative is bioethanol, followed by biodiesel.

Climate change mitigation of drop-in biofuels for deep-sea shipping under a prospective life-cycle assessment

The shipping sector is seeking options to reduce its emissions of greenhouse gases (GHGs) and achieve ambitious climate change mitigation goals. Unlike short-sea shipping that can rely on electrification of coastal vessels, drop-in biofuels are among the most promising options for deep-sea shipping decarbonization. However, environmental sustainability analyses of marine biofuels are limited, and usually do not include the influence of future changes in the background energy system nor the climatic effects of near-term climate forcers (NTCFs). In our study, we assess the climate change mitigation potential of various marine biofuels produced from forest residues in Norway (a country with ambitious plans for emission reduction from shipping) using a prospective life-cycle assessment (LCA) where the projected trends in the energy and transport sectors are integrated with improvements in the biofuel value chain for the next decades (2030–2050). Relative to fossil-based alternatives, climate mitigation potentials of biofuels range from 65% to 85% with short-term (GWP20) and to 78%–87% with long-term (GTP100) climate impacts. The inclusion of NTCFs reduces the mitigation benefits of biofuels in the short term, while it slightly increases them in the long term. The explicit modeling of technology and socio-economic changes under future policy scenarios indicates a reduction in the climate impacts of biofuels by up to 54% in 2050 when compared to the current situation. The amount of residues potentially available in Norway is sufficient to meet the present demand for liquid fuels in deep-sea shipping, thus providing yearly climate mitigation of 0.9–1.1 million tons of CO2-eq (equal to 6–7% of today's climate impacts from the entire transport sector in the country). Our analysis shows the large climate change mitigation potential of drop-in biofuels, and it provides new quantitative estimates that can help guiding a sustainability shift in the deep-sea shipping sector.

An economic–environmental–energy efficiency analysis for optimizing organic waste treatment of a livestock-orchard system: a case in the Mekong Delta, Vietnam

BackgroundEconomic benefit has been analyzed for the yield of farming products when designing a farming system, while waste treatment also generates profitable energy products for this system. The economic factor is decisive in decision-making for applying waste treatment solutions for a small-scale farming system. A household farming system in the Mekong Delta generates many kinds of organic wastes, but most of the agricultural waste resources are disposed of into the environment.MethodsThis study approaches an analysis of economic–environmental–energy (EEE) efficiency for waste treatment of an integrated livestock-orchard (LO) system on a household scale in the Mekong Delta. This novel analysis method is based on the energy content of biomass and its cost. The EEE efficiency is optimized to gain objective functions regarding energy yield efficiency, system profit, and CO2 sequestration for the treatment model. The algorithms are built for optimizing these objective functions.ResultsThe optimization results show the treatment model of pyrolysis and pelleting gain all the objective functions with high efficiency. The model is efficiently applied for the LO system that generates more than 100 kg of orchard residues and 3000 kg of pig manure. The system with a charcoal oven and pellet machine is capable to gain energy efficiency due to its potential biofuel products, such as biochars and pellet products. A treatment model of composting, pyrolysis, and pelleting gives the best performance of overall EEE efficiency.ConclusionsThis work has proven economic benefits from integrating biogas tank, charcoal oven, and pellet machine in an integrated LO system. The system contributes not only for reducing CO2 emissions but also for supplementing secondary renewable bioenergy, as well as for increasing incomes and thus supporting livelihoods for the local farming households.

Hydro-treated vegetable oil as a potential biofuel for self-ignition engines

Hydro-treating vegetable oils or animal fats is an alternative process to esterification for the production of biodiesel. Hydro-treated products are also called renewable diesel fuels. Hydro-treated vegetable oils (HVO) do not have the harmful effects of FAME biodiesel such as increased NOₓ emissions, deposit formation, storage stability problems, faster aging of the engine oil or poor cold performance. HVO are straight chain paraffinic hydrocarbons which are free of aromatic hydrocarbons, oxygen and sulphur and have a high cetane number. In the article below, the authors conduct a comprehensive analysis and evaluation of the possibility of running compression-ignition engine on the hydro-treated vegetable oil, which is a second-generation biofuel. On its basis, the information on the assessment of emissions of selected toxic components of exhaust gases and pollutants of the injection system when the engine is powered with this type of fuel, was systematized. The article ends with conclusions from the conducted analyses.

Enhanced biogas production potential analysis of rice straw: Biomass characterization, kinetics and anaerobic co-digestion investigations

Present study of the biofuel potential of rice straw (RS) waste biomass materials. The average activation energy of rice straw was determined from KAS, FWO and Starink are 84.11, 89.62 and 84.52 kJ/mol, respectively. The characterized rice straw biomass has been tested for biogas potential under co-digestion mode of rice straw and cow dung in ratio 1/2. The maximum 339 ml/g Vs of biogas has been recorded in 35 days with CH4 concentration of 58.3%. The rest being CO2 as well as H2S has been found in trace amounts with observed 85% total solids and 74% volatile solids, present in rice straw.

Integrated Cascade Process for the Catalytic Conversion of 5-Hydroxymethylfurfural to Furanic and TetrahydrofuranicDiethers as Potential Biofuels.

The depletion of fossil resources is driving the research towards alternative renewable ones. Under this perspective, 5‐hydroxymethylfurfural (HMF) represents a key molecule deriving from biomass characterized by remarkable potential as platform chemical. In this work, for the first time, the hydrogenation of HMF in ethanol was selectively addressed towards 2,5‐bis(hydroxymethyl)furan (BHMF) or 2,5‐bis(hydroxymethyl)tetrahydrofuran (BHMTHF) by properly tuning the reaction conditions in the presence of the same commercial catalyst (Ru/C), reaching the highest yields of 80 and 93 mol%, respectively. These diols represent not only interesting monomers but strategic precursors for two scarcely investigated ethoxylated biofuels, 2,5‐bis(ethoxymethyl)furan (BEMF) and 2,5‐bis(ethoxymethyl)tetrahydrofuran (BEMTHF). Therefore, the etherification with ethanol of pure BHMF and BHMTHF and of crude BHMF, as obtained from hydrogenation step, substrates scarcely investigated in the literature, was performed with several commercial heterogeneous acid catalysts. Among them, the zeolite HZSM‐5 (Si/Al=25) was the most promising system, achieving the highest BEMF yield of 74 mol%. In particular, for the first time, the synthesis of the fully hydrogenated diether BEMTHF was thoroughly studied, and a novel cascade process for the tailored conversion of HMF to the diethyl ethers BEMF and BEMTHF was proposed.

Agronomic performance of camelina genotypes selected for seed yield and quality characteristics in eastern China

Camelina [Camelina sativa (L.) Crantz] has gained extensive attention in Europe and North America as a potential dietary oil and biofuel feedstock. It is a relatively new crop in Asia (e.g., China, Korea). There is great potential for the cropping of camelina in eastern China on marginal lands where the climatic conditions (e.g., cooler temperature) may be suitable for cultivating this crop. However, little has been done to evaluate its agronomic performance in eastern China. To address this, a three-year (2019–2021) field study was conducted to evaluate the effect of fall and spring seeding dates on seed yield and quality of sixteen spring camelina genotypes across the three different growing environments in eastern China and to select potentially high-yielding genotypes for fall or spring seeding with the suitable seeding dates for each growing environment. The study showed that fall seeding camelina between late Oct. and the third week of Nov. in eastern China, including Anyang, Qingdao, and Yangzhou, produced a sustainable and satisfactory seed and oil yield (mean across genotypes, locations, and years: 2372 and 921 kg ha−1, respectively). While spring seeding between mid- and the end of April at Qingdao showed a lower productive performance (mean seed and oil yield across genotypes: 1081 and 373 kg ha−1, respectively), it still provides an alternative option for the production of high-quality edible oil compared to other oilseed crops such as soybean [Glycine max (L.) Merr.]. Although the strong genotype × environment interactions showed, among the tested camelina genotypes, fall seeding camelina accessions of CamK9, CamC2, and CamC4 at the suitable seeding dates showed a consistently greater mean seed yield (range: 1648–3170 kg ha−1) and oil yield (747–1368 kg ha−1) in all test locations compared to other genotypes. At the suitable fall seeding dates, mean seed oil content and yield across the tested genotypes and locations were 43.5% (range: 39.0–48.9%) and 856 kg ha−1 (range: 161–1489 ha−1), respectively, with the highest mean oil content of 45.9% determined at Yangzhou (range: 43.6–48.9%) and the highest mean seed yield of 2539 kg ha−1 at Qingdao (range: 1365–3501 kg ha−1). The camelina genotypes indicated would be good candidates for large-scale cropping in eastern China and other parts of the world with similar climatic conditions.

Thermochemical Characterization of African Oil Bean Husk for Potential Biofuel Production

Thermochemical Characterization of African Oil Bean Husk for Potential Biofuel Production

Genome-Scale Metabolic Model-Based Reactome-Phenome Map of Synechocystis sp. PCC 6803, A Potential Biofuel Producer

Genome-Scale Metabolic Model-Based Reactome-Phenome Map of Synechocystis sp. PCC 6803, A Potential Biofuel Producer

Combined Effect of Compression Ratio and Fuel Injection Pressure on CI Engine Equipped with CRDi System Using Prosopis juliflora Methyl Ester/Diesel Blends

The exhaustion of worldwide oil reserves has created an incipient need to find hopeful alternative fuels for the future. Substantial research has been done in this direction, and all studies by researchers have provided results that proved the growing potential of biofuel as a popular alternative in the CI engine. The current investigation explores the biofuel potential derived from the wasteland tree Prosopis juliflora (Karuvalam tree seeds). Experimentation was done using a monocylinder 4-stroke water-cooled six holes CRDi CI engine with electrical loading. The experiment was conducted at three proportions (10%, 20%, and 30% volume basis) of Prosopis juliflora Oil Methyl Ester (PJOME) with diesel using 3 parametric CRs (16, 17.5, and 19) along with three different fuel injection pressure (FIP) (400, 500, and 600 bar). The impact of CR and FIP on fuel utilization BTE, cylinder pressure, net heat release, and exhaust particulates was scrutinized and characterized. The test results demonstrated that increasing the compression ratio from 16 to 19 enhanced the in-cylinder pressure, net heat release (NHR), and BTE for all the (PJOME/Diesel) combinations. With an augmentation in the compression ratio from 16 to 19, carbon monoxide and unburnt hydrocarbon discharge diminished, but the nitrogen oxide discharges augmented. FIP also had an impact of increasing the pressures on the in-cylinder, NHR, brake thermal efficiency, and nitrogen oxide and reducing the emissions of smoke, CO, and UBHC. The current research shows that the use of B20 and CR16 and FIP 600 bar as a combination improved BTE by 33.21%, BSFC by 0.25 kg/kw-hr, cylinder pressure at the maximum to reach 69.28 bar, net heat release of 79.14 J/deg, and exhaust emissions such as UHC at 55 ppm, CO at 0.25%, smoke at 34.33%, and NOx at 2401 ppm. Finally, the BTE and NOx were slightly higher, and the UHC, CO, and smoke values were diminutive compared to other blends.

Cultivation of microalgae in adjusted wastewater to enhance biofuel production and reduce environmental impact: Pyrolysis performances and life cycle assessment

The interest in microalgae as a renewable and sustainable feedstock for biofuels production has inspired a new focus in biorefinery. Current innovations in microalgae technology include the use of wastewater as the cultivation medium towards nutrients recovery, renewable energy generation, as well as wastewater treatment. Though recent studies have favoured the competitiveness of such an approach, how to maintain a high-quality microalgae-derived biofuel production in real wastewater with fluctuations in nutrient contents is still a challenge. This study investigated a strategy of adjusting the nutrient composition of the feeding wastewater (i.e. anaerobic digestion effluent) for microalgae cultivation (Desmodesmus sp.) and biofuel production. The addition of an appropriate amount of nutrients, including magnesium, iron and phosphorus, significantly enhanced the microalgal biomass production (0.78 g L−1) compared with the original wastewater (0.35 g L−1) and the standard BG11 microalgae cultivation medium (0.54 g L−1). In terms of the potential biofuel quality, the use of adjusted wastewater led to a higher content of valuable products (aliphatic hydrocarbon and fatty acids were accounted for 23.98% and 42.33% of the whole biomass, respectively) along with a reduction in potentially toxic substances (nitrogen-containing compounds and polycyclic aromatic hydrocarbons were accounted for 7.96% and 7.09% of the whole biomass, respectively) compared with the other cultivation groups. Moreover, the lower optimal temperature of pyrolysis engendered by the adjusted wastewater was significant for reduction of process energy consumption, which in turn led to overall lowered environmental impacts (838.52 mPET2000, applying life cycle assessment) than did the original wastewater (1165.67 mPET2000) and standard cultivation medium (1347.63 mPET2000). This study demonstrated that the adjustment of wastewater can act as a potential approach for the improvement in the quality of microalgal biofuel production, with consequent reduced environmental impacts.

Adoption of biofuels for marine shipping decarbonization: A long‐term price and scalability assessment

AbstractThis study assessed the long‐term annual biofuel production capacity potential and price in the United States and shed light on the prospect of biofuel adoption for marine propulsion. A linear programming model was developed to assist the projections and provide insightful analyses. The projected long‐term (2040) maximum annual capacity of biofuels in the United States is 245 million metric tons (Mt) or 65 billion gallons of heavy fuel oil gallon equivalent (HFOGE) when based on the median feedstock availability. Between 2022 (near‐term) and 2040, the potential biofuel capacity increases by over 40%, attributed to increased feedstock availability. At a price range up to $500/t, biodiesel is the main product, and the annual capacity (12 Mt) is limited to feedstock availability constraints. Biodiesel and corn ethanol are the main biofuels at a price range up to $750/t. At a higher price point (above $750/t), the biofuel types and annual capacities increase substantially (218 Mt per year). Biofuels above this price include gasoline‐, jet‐, and diesel‐range blendstocks, as well as bio‐methanol, bio‐propane, and biogas. This study concludes that the US domestic feedstock availability coupled with advanced conversion technologies can produce substantial amounts of biofuels to achieve a critical mass and be impactful as alternative marine fuels. There is also a need to improve the biofuel price for marine shipping adoption. Policies and economic incentives that provide temporary financial support would help facilitate maritime biofuel adoption. © 2022 Alliance for Sustainable Energy, LLC. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd.

A kinetic model of heterotrophic and mixotrophic cultivation of the potential biofuel organism microalgae Chlorella sorokiniana

Better microalgal growth performance under heterotrophic and mixotrophic conditions can advance production of environmentally sustainable, lipid-based third-generation biofuels. In this study, an unstructured kinetic growth model was developed by extending a Haldane-based model to account and predict the enhancing and/or inhibitory effects of substrate (i.e. initial glucose concentration, nitrogen concentration, and light intensity) on the growth and lipid accumulation rates of the microalgae Chlorella sorokiniana during its heterotrophic and mixotrophic cultivation. The model considered a nitrogen-deprived phase of cultivation during which lipid synthesis and accumulation rates increase. Model-derived estimations for glucose and nitrogen consumption, cell growth, and lipid production under heterotrophic and mixotrophic conditions, respectively, were validated and in good agreement with experimental measurements, with R2 correlation values ranging from 0.83 to 0.99. Sensitivity analysis showed that the reaction rate constant of nitrogen consumption (KNX) has a “significant effect” on both lipid production and nitrogen consumption, suggesting that rapid depletion of nitrogen is favorable to increase lipid content instead of cell growth. The rate of cell growth declined on the 4th day during heterotrophic cultivation but remained constant after the 4th day during mixotrophic cultivation under initial glucose concentrations of 2.29, 4.32, and 6.19 g L−1. Our model further confirmed experimental observations that the best growth performance and highest lipid production are obtained under mixotrophic conditions compared to heterotrophic conditions.

Economic optimization for a dual‐feedstock lignocellulosic‐based sustainable biofuel supply chain considering greenhouse gas emission and soil carbon stock

AbstractEnvironmental factors, including greenhouse gas (GHG) emissions and soil organic carbon (SOC), should be considered when building a sustainable biofuel supply chain. This work developed a three‐step optimization approach integrating a geographical information system‐based mixed‐integer linear programming model to economically optimize the biofuel supply chain on the premise of meeting certain GHG emission criteria. The biomass supply grid cell was considered first, based on a maximum level of GHG emissions, prior to economic optimization. The optimization simultaneously considered dual‐feedstock sourcing, selection between distributed and centralized configurations, and the impact of maintaining SOC balance in agricultural soil on biomass availability. The applicability of the modeling approach was demonstrated through a case study that optimized a dual‐feedstock renewable jet fuel supply chain via a gasification‐Fischer–Tropsch (gasification‐FT) conversion pathway in 2050 under three biomass availability scenarios. The case study results show that the differences in procurement costs and GHG emissions between energy crops and agricultural residues have a large impact on the layout of the supply chain. The supply‐chain configuration tends to be more centralized with large‐scale biorefineries when a supply region has an intensive and centralized distribution of biomass resources. The cost‐supply curves demonstrated the technical potential of biofuels that could be obtained at a certain level of cost. Additionally, sensitivity analysis shows that the GHG emission credit from producing extra electricity during the gasification‐FT process will be significantly reduced with a rising share of renewable electricity generation in the future. © 2022 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd.

Engineering E. coli to synthesize butanol.

Biobutanol is gaining much attention as a potential biofuel due to its superior properties over ethanol. Butanol has been naturally produced via acetone-butanol-ethanol (ABE) fermentation by many Clostridium species, which are not very user-friendly bacteria. Therefore, to improve butanol titers and yield, various butanol synthesis pathways have been engineered in Escherichia coli, a much more robust and convenient host than Clostridium species. This review mainly focuses on the biosynthesis of n-butanol in engineered E. coli with an emphasis on efficient enzymes for butanol production in E. coli, butanol competing pathways, and genome engineering of E. coli for butanol production. In addition, the use of alternate strategies for butanol biosynthesis/enhancement, alternate substrates for the low cost of butanol production, and genetic improvement for butanol tolerance in E. coli have also been discussed.

Secondary organic aerosol formation from photooxidation of γ-butyro and γ-valero-lactone: A combined experimental and theoretical study

The formation of secondary organic aerosol (SOA) generated by OH-photooxidation of γ-butyrolactone (GBL) and γ-valerolactone (GVL) in the presence of OH, NO, H2O vapour and aerosol seeds ((NH4)2SO4 and CaCl2) has been investigated for the first time. Experiments were conducted in a smog chamber at 298 K and atmospheric pressure. Lactone's decay was followed by gas chromatography with a mass spectrometric detector (GC-MS), and the temporal evolution of the SOA was monitored using a fast mobility particle sizer (FMPS). The SOA yield increases slightly when the initial GVL concentration increases. On the other hand, SOA formation is minor for GBL, and it rises slightly at low concentrations. In the case of GVL, the organic aerosol formation can be tentatively expressed by a one-product gas/particle partitioning absorption model. The particle number concentration, mass and yield decrease in the presence of NO but increase at higher relative humidity (RH) and seed surface area within the studied range. Acetic acid and succinic anhydride for GVL, and succinic anhydride for GBL were experimentally identified as oxidation products both in gas and particle phase using thermal desorption followed by GC-MS. Moreover, the theoretical studies carried out to complement the experimental results indicate that H-abstraction at the carbon site adjacent to the heterocyclic oxygen is the predominant pathway, being even more favourable when H2O was added. Also, under atmospheric conditions, the opening of the ring of the corresponding oxy-radicals and their subsequent fragmentation could be the possible explanation for the formation of detected products and the higher yield of SOA in the presence of H2O and absence of NO. Considering these results, the formation of SOA from the use of both lactones as potential biofuels is few significative, although SOA generation may be enhancement by particle-phase heterogeneous reactions catalyzed by humidity and the acidity of seed aerosols present in real atmosphere.

Indirect Effects Negate Global Climate Change Mitigation Potential of Substituting Gasoline With Corn Ethanol as a Transportation Fuel in the USA

Concerns over climate change have led to the promotion of biofuels for transport, particularly biodiesel from oilseed crops and ethanol from sugar and starch crops. However, additional concerns arose on whether the climate change mitigation potential of biofuels is negated by the associated direct land requirements (dLUC) for growing biofuel feedstocks, or by the indirect land requirements (iLUC) that compensate for the diversion of crops from food/feed into fuel, both cases potentially leading to emissions of greenhouse gases. We investigated official data over the last 20-year period to estimate the magnitude of the effects ethanol production in the USA has had on land use domestically and abroad. The data analyzed shows that, over the period, the use of corn for ethanol increased by 118 Mt per year. According to our model, most of it came from the displacement of other uses of corn, mainly feed, which was compensated for by increased feed production elsewhere. Results indicate a relatively low dLUC but a significant iLUC effect, mainly due to the compensation for the foregone feed production as a result of diverting corn into ethanol production. Meeting the renewable-energy target of 15 billion gallons of corn ethanol more than negates the climate benefits from avoided use of gasoline (by 18.0 Mt CO2-eq.), suggesting that promoting corn ethanol for global climate change mitigation may be counter-productive as, despite decreasing domestic emissions, global emissions increase. We suggest that the policy be revised accordingly.

Monoraphidium sp. IBASU-A 574 (Selenastraceae, Chlorophyta) – перспективний продуцент біомаси для біоенергетики

he present studies were carried out to evaluate a potential biofuel application of the native strain Monoraphidium sp. IBASU-A 574 (Selenastraceae, Chlorophyta) adapted to the temperate zone climatic conditions. This strain was isolated from a small freshwater lake situated in Kyiv-city (Ukraine) by the reached culture method for obtaining desired strains of different species with high growth rate. It was identified based on its morphological characterization under light microscopy and 18S rRNA sequence analysis. Its culture’s growth, kinetic characteristics (specific growth rate and productivity) and biological peculiarities of the investigated strain were studied in comparison with the well-known biomass producer Chlorella vulgaris Beijer. CALU 157 under the same autotrophic cultivating conditions with using the modified Tamiya medium. It was established an active growth of Monoraphidium sp. IBASU-A 574 which was practically equal to the well-known producer and characterized by following parameters: a maximum cell density of 248 ∙ 10-6 cells ∙ mL-1, the specific growth rate of 1.4 days-1 and productivity of 72.5 ∙ 10-6 cells ∙ mL-1 ∙ days-1. The results of gas-liquid chromatography analysis showed that a fatty acid profile of this microalga included a complex of palmitic (C16: 0), oleic (C18: 1), linoleic (C18: 2) and linolenic (C18: 3) major fatty acids with suitable proportion for developing biodiesel feedstocks. Moreover, there was considerable variation in formation of its fatty acid composition depending on the stage of growth, that confirmed the necessity for such studies to determine both optimal time for growing algae and gaing maximum yield of target products. Thus, Monoraphidium sp. IBASU-A 574 was found to be the promising producer of biomass for bioenergetic industry due to obtained data of its growth characteristics and suitable fatty acid profile of lipids.

A novel analysis of n-butanol–gasoline blends impact on spark ignition engine characteristics and lubricant oil degradation

ABSTRACT Butanol emerges as a potential biofuel for energizing modern automobiles. Its impact on engine performance and emission characteristics was investigated by many researchers. However, a research gap exists for its effect on lubricating oil deterioration. Therefore, n-butanol–gasoline blends were prepared with 6% and 12% by volume of alcohol (B6 and B12) and compared with pure gasoline (B0) in terms of engine performance, emissions, and lube oil condition. The engine performance along with exhaust gas temperature increased with an increasing ratio of butanol in the fuel blend. CO and HC emissions were the lowest in the case of B12 followed by B6 and B0. Furthermore, lubricating oil properties were determined to monitor its deterioration rate. The kinematic viscosity at 100°C and flash point temperature showed a minimum reduction in the case of B12, i.e., 22% and 16%, respectively, as compared to fresh oil. The highest concentration of wear elements in lube oil was detected for B12 fuel, which included Al (11 × 10−6), Fe (27 × 10−6), Cr (4 × 10−6), and Cu (13 × 10−6). Similarly, the additive counts for Ca, Mg, and Zn were found to be 1665 × 10−6, 7.3 × 10−6, and 730 × 10−6, respectively, in lubricating oil for B12. Therefore, advanced lubricating oil should be developed for alternative fuels to improve its lifecycle.

Strategy for the cultivation of Chlorella vulgaris with high biomass production and biofuel potential in wastewater from the oil industry

This work aimed to provide a biochemical characterisation of Chlorella vulgaris biomass cultivated with daily supplementation of produced water. The simultaneous phytoremediation and production of biomolecules and bioproducts of commercial interest were analysed and discussed. Cultures were grown in laboratory scale photobioreactors for 26 days in 1.5 L of BG11 medium, with daily supplementation of 50 mL of non-autoclaved produced water (TPW) or distilled water (TDW). Biomass production differed among the control (3.86 g L−1), TPW (1.69 g L−1), and TDW (1.82 g L−1). The TPW-treated culture showed a high concentration of carbohydrates (40.19 %) with a bioethanol production of 18.22 mL 100 g−1 of biomass. The content of carotenoids (2.4μg mL −1), protein (22.83 %), and lipids (21.53 %) were also determined. The lipid composition consisted mostly of palmitoleic (5.42 mg g−1), γ-linolenic (3.02 mg g−1), and linolelaidic (1.94 mg g−1) acids, which gave the oil the ideal properties for quality biodiesel. In addition, the high phytoremediation efficiency of heavy metals such as copper (70.00 %), manganese (76.89 %), and molybdenum (97.82 %), as well as total petroleum hydrocarbons (48.59 %), were also detected. Therefore, TPW can be a promising alternative for phytoremediation of chemical compounds, while utilising effluent from the oil industry to produce a high content of valuable biomass, biomolecules, and biofuels.