Advanced Biofuels Research Articles

Characterization of soot emitted from the atmospheric combustion of diethyl ether-diesel blends

In accordance with the European commission’s renewable energy proposal for 2030, advanced biofuels should be blended at a minimum of 3.6 % with conventional fuels used for powering internal combustion engines. Ethers, which may be produced using modern production methods from sustainable sources like biomass, may be crucial in this regard in the future. This study demonstrates the impact of diethyl ether as a blend component (mixed with diesel) on the characteristics of the soot generated from the diethyl ether-atmospheric diesel's combustion. The soot used in this work came from a smoke point lamp that burned a mixture of diesel and diethyl ether as per ASTM D1322 standard. Diethyl ether (DEE) and diesel (D) were combined in the following blends: DEE5D (5 % diethyl ether and 95 % diesel v/v), and DEE20D (20 % diethyl ether and 80 % diesel v/v). The obtained soot was characterized in detail using the following: elemental analyzer, X-Ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), RAMAN spectroscopy, thermogravimetric analysis (TGA), and proton nuclear magnetic resonance (1H NMR) spectroscopy. According to the results from XRD and Raman spectroscopy, the soot nanostructure is influenced by the amount of diethyl ether present in the mixture, which raises the reactivity. The results of the elemental analyzer and 1H NMR matched those of the TGA's soot reactivity (oxidations). The results from the SEM and TEM tests, however, were not enoughto support the experimental findings.

Eco-friendly strategy for the joint valorization of invasive macroalgae and fast-growing wood to produce advanced biofuels

A novel sustainable scheme to jointly valorize Sargassum muticum (Sm) and Paulownia wood (PW) was proposed in this work, employing the advanced environmentally friendly microwave-assisted autohydrolysis (MA) as pretreatment. Sm is an invasive macroalga that has been drastically spread in the Atlantic coast of Europe, causing environmental damage. Conversely, Paulownia elongata x fortunei is a fast-growing biomass with a high biomass production and potential for biofuels production. Thus, the concomitant valorization of both biomasses may lead to benefits related to environmental protection and bioeconomy. A sequential approach was proposed: first stage of glucose production from Sm (treated by MA and enzymatic hydrolysis to obtain a glucose-rich liquor), and second stage with MA-pretreated PW followed by saccharification and fermentation, employing in this process the glucose rich solution obtained from algae, to obtain simultaneously second and third generation bioethanol. These approaches enabled to add the ethanol production from both biomasses, leading to up to 45.2 g ethanol/L (70% ethanol yield), boosting ethanol titers compared to using only one biomass (up to 27.8 g/L) and confirming the benefits of combining MA-processed biomass. Furthermore, up to 87% of the energy may be recovered, reflecting a suitable approach within an integrated strategy.

Plating the hot potato: how to make intermediate bioenergy carriers an accelerator to a climate-neutral Europe

BackgroundWith sustainable bioenergy in the European energy mix, intermediate bioenergy carriers (IBC) become of growing importance, as they can ensure a more efficient utilisation of biomass feedstocks from agricultural and forest residues. A high potential for market uptake is foreseen for fast pyrolysis bio-oil (FPBO), one of several IBCs. While facing the chicken and egg problem in market entry, the aim of this study was the development of adequate strategies to support market implementation. The case study findings and methodological approach can provide policymakers, industry, and a broader audience with a vision for addressing similar challenges in market adoption of innovations in the bioeconomy and beyond. Therefore, we tested a new PESTEL + I approach and its practical applicability to an IBC value chain.ResultsWith an adopted PESTEL method, we analysed a promising value chain in which FPBO is produced from sawdust in Sweden and Finland, transported to the Netherlands and upgraded and marketed as a marine biofuel. Our results show that the market uptake of IBCs such as FPBO and subsequently produced biofuels is above all driven by the European Renewable Energy Directive II (RED II). In Annex IX Part A, sawdust is listed as a feedstock for advanced biofuels, which can be double counted towards the 14% renewable energy share goal in the transport sector in 2030. To support the use of advanced biofuels in the maritime and aviation sector, the proposal for revision of RED II 2021 contains a new multiplier (1.2x) for fuels delivered to these sectors, while all other multipliers are deleted. These legal European obligations and implementation into national law of member states create strong incentives for many downstream market actors to use advanced biofuel. However, technological challenges for FPBO use still hamper fast market introduction.ConclusionsOvercoming technology challenges and the creation of long-term validity of guidelines and regulatory framework will create stable market conditions, investment security and finally stimulate long-term offtake agreements between feedstock providers, technology developers and downstream customers. The approach and findings can provide a vision to overcome similar challenges in other bioeconomy innovations’ market uptake and beyond.

Characterization of β-glucosidases from Meridianimaribacter sp. CL38

The production of second-generation biofuel requires a huge amount of freshwater. It is estimated that at least three gal of freshwater is used to produce one gal of biofuel. The replacement of freshwater with seawater serves as a potential alternative in biofuel generation. Therefore, salt-tolerant enzymes play an important role in saccharification and fermentation process. Halophilic β-glucosidase is one of the key enzymes for the process. In this study, the β-glucosidase of halophile Meridianimaribacter sp. CL38 isolated from mangrove soil was characterized. Strain CL38 achieved maximum production of β-glucosidase at 12th hour of growth. The β-glucosidase showed highest activity at 2% (w/v) NaCl while highly stable at salt concentration ranging from 1-2% (w/v) (more than 96% of relative activity). Its β-glucosidase activity remained active in the presence of 5mM Mn2+, Mg2+, Ca2+ ions, and 1% (v/v) Tween-20 and Tween-80. The draft genome sequence of strain CL38 was retrieved from GenBank database and submitted to dbCAN meta server for CAZymes annotation. Strain CL38 harbors 44 GHs and GH3 are annotated as β-glucosidases. The β-glucosidases of Meridianimaribacter flavus (99.61%) and Mesoflavibacter sabulilitoris (97.44%) showed the closest identity with Bgl3a and Bgl3b protein sequences from strain CL38, respectively. Glycoside hydrolase family 3 domain was identified in both enzymes via InterPro scan server. The presence of signal peptides indicated that both enzymes were secreted extracellularly. Five motifs were identified in Bgl3a and Bgl3b, with the active site (nucleophile) found at Asp296 and Asp297, respectively. Collectively, these β-glucosidases could be potentially used in the biofuel production, in particular the lignocellulosic biomass pretreatment process. This is the first attempt to characterize the β-glucosidase in genus Meridianimaribacter as so far none of the lignocellulolytic enzymes from this genus were characterized.

Life cycle assessment of a marine biorefinery producing protein, bioactives and polymeric packaging material

Abstract Purpose Algal research has been dominated by the use of marine biomass (mainly microalgae) as feedstock in the production of second-generation biofuels, albeit with limited economic success. A promising alternative strategy is the valorisation of seaweed (macroalgae), with the cascaded extraction of its high-value components, as well as lower-value components further downstream, under the ‘biorefinery concept’. The goal of this study was to assess the environmental performance of one such marine biorefinery situated in the UK. Methods Attributional life cycle assessment (LCA) was conducted on a hypothetical marine biorefinery coproducing fucoidan, laminarin, protein and alginate/cellulose packaging material (target product), from cultivated Saccharina latissima. The functional unit was the production of 1 kg of packaging material. A total of 6 scenarios were modelled, varying in coproduct management methodology (system expansion, mass allocation or economic allocation) and applied energy mix (standard or green energy). Sensitivity analysis was also conducted, evaluating the systems response to changes in allocation methodology; product market value; biomass composition and transport mode and distance. LCA calculations were performed using OpenLCA (version 1.10.3) software, with background processes modelled using the imported Ecoinvent 3.6 database. Environmental impacts were quantified under ReCiPe methodology at the midpoint level, from the ‘Heirarchist’ (H) perspective. Results and discussion The overall global warming impacts ranged from 1.2 to 4.52 kg CO2 eq/kg biopolymer, with the application of economic allocation; 3.58 to 7.06 kg CO2eq/kg with mass allocation and 14.19 to 41.52 kg CO2eq/kg with system expansion — the lower limit representing the instance where green electricity is used and the upper where standard electricity is employed. While implementing the green energy mix resulted in a 67% reduction in global warming impacts, it also incurred a 2–9 fold increase in overall impacts in the categories of terrestrial acidification, human non-carcinogenic toxicity, land-use and terrestrial ecotoxicity. Economic allocation resulted in burden shifting most favourable to the packaging material pathway. Conclusions This study demonstrates that the road to environmental optimisation in marine biorefineries is fraught with trade-offs. From the perspective of LCA — and by extension, the eco-design process that LCA is used to inform — when evaluating such product systems, it serves to strike a balance between performance across a broad spectrum of environmental impact categories, along with having consideration for the nature of energy systems incorporated and LCA methodological elements. Graphical Abstract

Admissibility Grid to Support the Decision for the Preferential Routing of Portuguese Endogenous Waste Biomass for the Production of Biogas, Advanced Biofuels, Electricity and Heat

A methodology was developed to assess the allocation of different types of endogenous waste biomass to eight technologies for producing electricity, heat, biogas and advanced biofuels. It was based on the identification of key physicochemical parameters for each conversion process and the definition of limit values for each parameter, applied to two different matrices of waste biomass. This enabled the creation of one Admissibility Grid with target values per type of waste biomass and conversion technology, applicable to a decision process in the routing to energy production. The construction of the grid was based on the evaluation of 24 types of waste biomass, corresponding to 48 sets of samples tested, for which a detailed physicochemical characterization and an admissibility assessment were made. The samples were collected from Municipal Solid Waste treatment facilities, sewage sludges, agro-industrial companies, poultry farms, and pulp and paper industries. The conversion technologies and energy products considered were (trans)esterification to fatty acid methyl esters, anaerobic digestion to methane, fermentation to bioethanol, dark fermentation to biohydrogen, combustion to electricity and heat, gasification to syngas, and pyrolysis and hydrothermal liquefaction to bio-oils. The validation of the Admissibility Grid was based on the determination of conversion rates and product yields over 23 case studies that were selected according to the best combinations of waste biomass type versus technological solution and energy product.

Unpacking the legal conundrum of nature-based soil remediation and sustainable biofuels production in the European Union

The fight against soil contamination and the development of sustainable fuels constitute major environmental and climate change objectives under the European Green Deal. At the same time, the uptake of nature-based solutions is increasingly advocated in the European Union as viable techniques to enhance soil ecosystem services while addressing the soil vs. food vs. energy conundrum to achieve the UN Sustainable Development Goals and the European Green Deal objectives. This contribution deals with unlocking the potential of phytoremediation both a soil remediation technique and a source of sustainable feedstock for advanced biofuels. Phytoremediation consists of the use of plants and their associated microbes to extract, volatilize, stabilize, or degrade soil pollutants. Furthermore, phytoremediation's by-products may be used to develop advanced, low indirect land use change biofuels thus contributing to the EU's climate change mitigation objectives.The value chain entailed in the deployment of phytoremediation techniques and recovery of phytoremediation's output materials for biofuels production faces an array of legal and policy roadblocks in the European Union. Importantly, such barriers relate both to material legal obstacles, policy fragmentation and lack of a holistic approach towards complex processes. This contribution aims to provide a comprehensive overview of such legal and policy roadblocks with a view to champion the embedding of phytoremediation in the existing EU legal framework also in relation to the development of low-Indirect Land Use Change biofuels.

Learning through interdisciplinary dialogue: Methodological approaches for bridging epistemological divides

Scientific innovations for sustainable development often make huge promises about overcoming climate change, or promote technological innovations that have potential development implications. However, the social outcomes of such interventions are often considered superficially; thus potentially reinforcing injustices or producing unforeseen, undesirable outcomes. Increasingly, projects claim to have an interdisciplinary dimension, but processes of interdisciplinary dialogue can be difficult to maintain. This means that researchers have to be prepared to engage in potentially extensive, transformative dialogue and be willing to learn from the disciplinary knowledge of the other. This can be methodologically challenging both for natural and social scientists. This paper reports meta-research exploring the methodological processes and learning experiences of academics involved in research on the implementation of second-generation biofuel technology. Through interdisciplinary meetings, workshops, reflections and interviews we built up sustainable relationships and bridged epistemological divides. Our approach to interdisciplinary dialogue offers insights into the methodological challenges of interdisciplinary work. We used the framework of transformative learning theory to identify key aspects of the interdisciplinary process and reflected on the need for sustained and open opportunities for dialogue in order to find genuine ways to communicate across disciplines. We explicitly revealed and considered our taken-for-granted assumptions to identify what we understood by key terms and processes, including ‘sustainable’, ‘development’, ‘methodology’, ‘truth’, ‘marginal land’ and ‘outputs’. We found these encounters created opportunities to influence the trajectory of each other’s research and thinking, with the ideal of social and environmental justice prominent in all our discussions. It was through ongoing learning and dialogue that we found that the multifaceted challenges of sustainable development research can become more open, more critical and more able to reveal appropriate solutions and promote relevant ongoing scientific research. This interplay between disciplines is an innovative way to influence decision-making directly.

Determination of the Effect of the Addition of Second-Generation Biodiesel BBuE to Diesel Fuel on Selected Parameters of “B” Fuels

Progressive and increasingly noticeable climate change is forcing the search for new energy sources to reduce greenhouse gas emissions, especially carbon dioxide. One way to reduce greenhouse gas emissions is by gradually replacing fossil fuels with biofuels. The authors of this work addressed the production of second-generation biofuel. The purpose of this study was to produce second-generation biodiesel from babassu palm oil (BBuE) and first-generation biodiesel from rapeseed oil (RME), to study their properties, and to determine the effect of the addition of these biodiesels to diesel fuel on selected properties of “B” fuels that affect the fuel–air mixture formation process and the combustion process. Biodiesel from babassu oil was produced because it is non-edible and has a different composition than canola oil. Then, fuels were prepared that were mixtures of diesel oil and biodiesel containing from 10 to 40% (v/v) BBuE or RME (B10, B20, B30, and B40).Tests were conducted on selected physicochemical properties of the obtained fuels. “B” fuels prepared with BBuE and DF were shown to have more favorable fuel properties than those obtained from RME and DF. Fuels that are blends of BBuE and DF have slightly higher heating values, higher cetane number values, a more favorable distillation curve, lower dynamic viscosity values as a function of temperature, and marginally lower flash point values compared to the corresponding blends of RME and DF. Esters with shorter molecules have been shown to have more favorable fuel properties.

Agricultural biomass feedstock for biofuels production in Ukraine

Ukraine has a large potential of biomass available for the production of solid, gaseous and liquid biofuels. According to 2021 data, the bioenergy potential is about 25 Mtoe, of which 49% is agricultural residues and 30% is energy crops (in case of growing on 2 mln ha). Of the agriresidues, only sunflower husk is now widely used for energy, while the potential of straw, corn stalks and sunflower stalks is practically untapped for this purpose. For Ukraine, one of the promising directions is priority use of corn stalks for the production of energy and solid biofuels such as briquettes and pellets. Another prospective area is growing energy crops. Ukraine has 3-4 mln ha of unused (marginal) agricultural land, which can be engaged for growing energy crops such as willow, poplar, miscanthus (for solid biofuels) and corn silage for biogas. Growing energy crops as biomass feedstock and its further use for the production of heat and power becomes competitive in light of growing prices of natural gas and issues with providing security of its supply. An important but less-developed sector of Ukraine’s bioenergy is motor biofuels. Having such a big potential of agribiomass, the country could produce bioethanol and biodiesel including the advanced biofuels from lignocellulosic feedstock. It is necessary to create favourable conditions for the development of domestic production of motor biofuels. This may include a reduction in the excise tax, the abolition of compulsory tax bill for the full rate of excise duty when transporting bioethanol, the introduction of an export duty on rapeseed, and some other measures.

Enhanced ethanol production using hydrophobic resin detoxified Pine forest litter hydrolysate and integrated fermentation process development supplementing molasses.

Globally escalating ethanol demand necessitates the use of hybrid technologies integrating first- and second-generation biofuel feedstocks for achieving the futuristic targets of gasoline replacement with bioethanol. In present study, an optimized two-step sequential pre-treatment (first dilute alkali, then dilute acid) of Pine forest litter (PFL) was developed. Furthermore, the saccharification of pre-treated PFL was optimized through Response Surface Methodology using Box-Behnken Design, wherein 0.558g/g of reducing sugar was released under the optimized conditions (12.5% w/v of biomass loading, 10 FPU/g of PFL enzyme loading, 0.15% v/v Tween-80 and 48h incubation time). Moreover, during hydrolysate fermentation using Saccharomyces cerevisiae NCIM 3288 strain, 22.51 ± 1.02g/L ethanol was produced. Remarkably, hydrophobic resin (XAD-4) treatment of PFL hydrolysate, significantly removed inhibitors (Furfural, 5-hydroxymethylfurfural and phenolics) and increased ethanol production to 27.38 ± 1.18g/L. Furthermore, during fermentation of molasses supplemented PFL hydrolysate (total initial sugar: 100 ± 3.27g/L), a maximum of 46.02 ± 2.08g/L ethanol was produced with 0.482g/g yield and 1.92g/l/h productivity. These findings indicated that the integration of molasses to lignocellulosic hydrolysate, would be a promising hybrid technology for industrial ethanol production within existing bio-refinery infrastructure.

PROSPECTS FOR THE PRODUCTION OF ADVANCED BIOFUELS IN UKRAINE

Perspective directions for the development of motor biofuels market in Ukraine are considered. It is shown that Ukraine has a significant potential for the production of liquid biofuels for the transport sector. Today, it is mainly biodiesel and bioethanol of the first generation, since the technologies for obtaining advanced biofuels from lignocellulosic feedstocks are not yet sufficiently developed in the country. However, as these technologies improve, one of directions for the development of motor biofuels market will be the expansion of production opportunities for second generation (advanced) biofuels with a significant share of their export to EU countries. Directive (EU) 2018/2001 on renewable energy sources (RED II) limits the share of 1st generation biofuels in achieving the goals for the consumption of renewable energy in transport. The share of such biofuels in a certain EU country can be no more than 1 % higher than the share of these biofuels in the gross final energy consumption of road and rail transport of that country in 2020, but no more than 7 %. For Ukraine, this means that the share of 1st generation biofuels in the final energy consumption in transport in 2030 cannot exceed 1.85 %, since in 2020 this indicator was 0.85 %. A possible option for solving this problem is to coordinate with the European Commission the issue of increasing the quota of 1st generation biofuels for Ukraine to 7 % in 2030, which is equivalent to the consumption of 503 ktoe/y. In the future, it seems appropriate to develop the production of advanced bioethanol from byproducts of grain corn cultivation as well as advanced biodiesel from oilseed energy crops grown on unused agricultural land. According to RED II, such biodiesel is not subject to restrictions on biofuels produced from food or feed crops. Production and consumption of biomethane is also a promising direction for the introduction of renewable energy in transport. It is shown that the total potential of biogas production in Ukraine is currently 8.16 Mtoe/y, of which a quarter can be allocated for the transport needs. By 2050, the production potential of biogas as a motor fuel may increase to 4.7 Mtoe/y, mainly due to the use of cover crops as feedstock to obtain biogas. Bibl. 21, Tab. 4.

Geospatial environmental techno-economic assessment of pretreatment technologies for bioethanol production

Second-generation biofuels, starting from lignocellulosic biomass, are considered as a renewable alternative for fossil fuels with lower environmental impact and potentially higher supply and energy security. The economic and environmental performance of second-generation bioethanol production from corn stover in the European Union (EU) is studied, starting in Belgium as base case. A comparative environmental techno-economic assessment has been conducted, with process simulations in Aspen Plus and corn stover availability data in thirteen EU countries to calculate minimum ethanol selling prices (MESP) and Greenhouse gas emissions (GHGe). In this analysis, the emphasis is on the comparison of different pretreatment technologies, namely (i) dilute acid, (ii) alkaline, (iii) steam explosion and (iv) liquid hot water. Dilute acid showed the best economic and environmental performance for the base case scenario. Within the EU, Hungary and Romania presented the lowest MESP for the steam explosion model at 0.39 and 0.43 EUR/L respectively. Poland showed the lowest GHGe, at 0.46 kg CO2eq/L for the alkaline model, mainly due to the avoided product allocation on electricity and its high carbon intensity in the electricity generation sector. The second lowest GHGe were obtained in France for the dilute acid model and are attributed to its low agricultural emissions intensity. This study identifies a location-dependence of the economic and environmental performance of pretreatment technologies, which can be extrapolated from the EU to other large regions around the world and should be taken into consideration by decision-makers.

Integrated hydropyrolysis and vapor-phase hydrodeoxygenation process with Pd/Al2O3 for production of advanced oxygen-containing biofuels from cellulosic wastes

This study focuses on developing advanced oxygen-containing biofuels with high furan, cyclic ketone, and ethanol content from holocellulose and cellulosic wastes. To achieve this, we employed an integrated process that combined hydropyrolysis and vapor-phase hydrodeoxygenation using Pd/Al2O3 as a catalyst. In the first stage, the non-catalytic hydropyrolysis of hemicellulose resulted in furfural and acetic acid fractions that were effectively converted into furans, cyclic ketones, and ethanol in the second-stage reactor over Pd/Al2O3 under 0.3 MPa H2. We found that a hydropyrolysis temperature of 440 °C in the first stage reactor resulted in the highest yield of oxygen-containing biofuels (171.1 mg/g) with 89.2% hemicellulose conversion. However, increasing the hydrodeoxygenation temperature in the second stage reactor reduced the yield of oxygen-containing biofuels, and at 400 °C, excess deoxygenation led to hydrocarbon production. The Pd/Al2O3 catalyst demonstrated high stability during the vapor-phase hydrodeoxygenation of primary furfural and acetic acid intermediates, with only 2.1% coke formation after three reaction cycles. This scalable process enables the conversion of various cellulosic wastes into advanced oxygen-containing biofuels, with considerable total yields. Our findings suggest that this integrated process holds great promise for converting biomass waste into advanced oxygen-containing biofuels.

Non-destructive analytical strategies based on NIR spectroscopy for monitoring the quality of biodiesel/diesel blends in terms of the authentication of second-generation biodiesel feedstock using DD-SIMCA and quantification of the biodiesel content using iSPA-PLS

Considering relevant environmental, economic, and social factors, the discussion on the use of second-generation biofuels has gained prominence in recent years, especially supported by the Sustainable Development Goals (SDGs) and the Paris COP21 climate change agreement. One of the policies implemented by different countries has been the mandatory blend of biodiesel in commercial petrodiesel. Thus, this work proposes the use of NIR spectroscopy to monitor the quality of biodiesel/diesel blends. The analytical strategies involve the authentication of second-generation biodiesel feedstock using Data-Driven Soft Independent Modeling of Class Analogy (DD-SIMCA) and the quantification of biodiesel content regardless of the biodiesel feedstock using the Successive Projections Algorithm for interval selection in Partial Least Squares (iSPA-PLS). To avoid dilution of the samples with organic solvents, two spectral regions (881–1651 and 1911–2203 nm) were investigated. As a result, the spectral range of 1911–2203 nm achieved the best results for both the qualitative and quantitative analysis. Accordingly, the authentication efficiencies for DD-SIMCA were 97.6% and 99.2% for jatropha and beef tallow biodiesel/diesel blends using multiplicative scattering correction (MSC) and Savitzky-Golay smoothing (with a second-order polynomial and a 15-point window) coupled with the first derivative (SGD) as pre-processing algorithms, respectively. Furthermore, a relative error of prediction of only 2.85% was obtained for the biodiesel content quantification using SGD/iSPA-PLS. Hence, the proposed analytical methodology provides valuable support to governments and regulatory bodies in overseeing the quality of this product, ensuring that consumers are safeguarded against economic repercussions resulting from improper or fraudulent blending. Moreover, it aligns with the principles of Green Analytical Chemistry and contributes to the SDG 7 (affordable and clean energy) and SDG 13 (climate action).

Bioinformatics approaches in upgrading microalgal oil for advanced biofuel production through hybrid ORF protein construction

Bioinformatics approaches in upgrading microalgal oil for advanced biofuel production through hybrid ORF protein construction

Hydrogen-Free Deoxygenation of Oleic Acid and Industrial Vegetable Oil Waste on CuNiAl Catalysts for Biofuel Production

The pyrolysis of vegetable oil waste is an alternative way to convert biomass into high-quality second-generation biofuels, with social, economic and environmental sustainability. The present work deals with the pyrolysis of oleic acid as a model compound and an industrial vegetable oil residue on CuNiAl mixed oxide catalysts, derived from layered double hydroxides. Reactions of the oils pre-adsorbed on the catalysts (catalyst:oil mass ratio of 5:1) were performed at 550 °C on a micro-pyrolysis system and the analyses of volatile products were carried out online using GC/MS. Copper addition to NiAl catalysts increased the cracking of oleic acid. Increasing copper content also decreased the formation of aromatics and coke precursors, as well as oxygenated compounds. The CuNiAl catalyst with a Cu/Ni ratio of 0.4 showed strong catalytic activity in the conversion of an industrial vegetable oil residue with a high volume of free fatty acids produced. Compared to the non-catalytic reaction, the catalyst reduced the content of oxygenates and increased the content of hydrocarbons, particularly in the gasoline range (C5–C9). The CuNiAl oxide catalyst was able to convert vegetable oil residues into hydrocarbons in the range of gasoline, kerosene and diesel, and also linear alkylbenzenes as chemical precursors for surfactant production.

Pretreatment and Bioconversion for Valorization of Residues of Non-Edible Oilseeds

Biodiesel production currently follows a first-generation model using edible oils as raw materials. Such a production model is unsustainable, considering that it is limited by the high cost of edible oils, competes with the food sector, and is linked to deforestation and other environmental threats. Changing the raw material base to non-edible oils provides an opportunity to increase the sustainability of the biodiesel industry and to avoid conflicts with food production. Processing non-edible oilseeds for extracting the oil to be used for producing biodiesel generates large amounts of residues, such as de-oiled cakes, seed husks, and fruit shells and pods as well as plant stems and leaves resulting from pruning and other agronomy practices. Most of those residues are currently disposed of by burning or used in a suboptimal way. Bioconversion following the sugar platform route, anaerobic digestion, or enzyme production provides means for upgrading them to advanced biofuels and high-added value products. Bioconversion of plant biomass, including oilseed residues, requires pretreatment to enhance their susceptibility to enzymes and microorganisms. This review provides an outlook on bioconversion approaches applicable to different residues of oilseed-bearing plant species. Recent reports on the pretreatment of non-edible oilseed residues for enhancing their bioconversion through either the sugar platform route or anaerobic digestion are critically discussed. This review is based on an exhaustive Web of Science search performed in January–May 2023.

Biofuel technologies: Lessons learned and pathways to decarbonization

AbstractThis Opinion highlights several successful cases of biofuel technologies recently described by the IEA Bioenergy Intertask Report on Lessons Learned. The report discussed the potential of biofuels to contribute to a significant market supply, thus replacing fossil fuels and mitigating global warming, and it underscores the challenges in expanding biofuel production and replicating successful models between countries and regions. Based on the lessons learned from conventional, established technologies, the authors analyzed policies, feedstocks, products, technologies, economics, environmental concerns, social aspects, scalability, and ease of implementation and replication in different countries or regions. There are blending mandates in place around the world to foster the use of biofuels. Dependence on the availability and price fluctuations of crop feedstocks may limit biofuel production in certain circumstances. Legal restrictions on using food crops as feedstocks present obstacles to scaling up production. Temporary constraints related to feedstock costs and availability, as evidenced by changes and postponements of biofuel blending mandates in various countries (particularly during the COVID‐19 pandemic) also pose challenges. Technological hurdles exist for advanced biofuels that implicate premium pricing. Still, 2G ethanol from sugarcane meets very strict feedstock requirements with a carbon footprint so low that only electric vehicles charged in Norway could have life‐cycle GHG emissions at the same level as a 2G ethanol‐fueled combustion engine car. The authors evaluate whether and how much electrification could contribute to advance the decarbonization efforts in different countries. Drawing from these observations, the authors express their viewpoints to assist researchers and policymakers in the energy sector in formulating viable approaches to combat the climate crisis.

Nanozymatic Biofuel Cell-Enabled Self-Powered Sensing System for a Sensitive Immunoassay.

Self-powered sensing system (SPSS) integrating the enzymatic biofuel cell and biosensing platform has attracted tremendous interest. However, natural enzymes suffer from the intrinsic drawbacks of enzymes and enzymatic proteins. Nanozymes with enzyme-like activities are the ideal alternatives to enzymes, and it is greatly challenging to explore high-performance nanozymatic biofuel cell for SPSS. Herein, the advanced nanozymatic biofuel cell-enabled SPSS is developed for the sensitive detection of the prostate-specific antigen (PSA), where Ir single atoms supported by nitrogen-doped carbon and Au nanozymes serve as the cathode and anode, respectively. Based on the excellent electrochemical activity and stability, the resultant nanozymatic biofuel cell exhibits a higher power output and open-circuit potential than the Pt/C-based counterpart, which is beneficial for the application of SPSS. As a proof of concept, the nanozymatic biofuel cell-enabled SPSS shows a wide detection range of 0.2-500 ng mL-1 with a detection limit of 62 pg mL-1 for PSA, which provides new insight into broadening the application scenarios of nanozymes.