Biofuel Production Technologies Research Articles

Prospects of graphene quantum dots preparation using lignocellulosic wastes for application in photofermentative hydrogen production

Graphene quantum dots (GQDs) are a novel carbon nanomaterial from the graphene family due to their unique physicochemical properties and diverse range of applications. However, in terms of the sustainable utility of GQDs, their synthesis methods are the main roadblock because of their high production costs and the release of toxic byproducts during the production processes. Thus, the search for sustainable and economical fabrication methods for preparing GQDs is one of the most essential areas of research for their practical applications. In this context, lignocellulosic biomass (LCB) wastes are a prime choice for the fabrication of GQDs due to their high carbon and cellulose content, which are favorable for being employed as precursors and reducing agents Additionally, LCBs are a prime source of potential bioenergy production, which is currently a key research hotspot to combat environmental pollution, global warming, and energy crises. Therefore, the present review provides feasibility for sustainable and environmentally friendly fabrication of GQDs using LCB wastes for their possible utility in cellulosic biofuel production technology improvement. Furthermore, the prospective of using these GQDs as catalysts in bioenergy production for the development of low-cost biomass-based biofuel production technology has been discussed along with the existing limitations and their sustainable recommendation.

Optimization of bio-oil production from macroalgae, caulerpa lentillifera via hydrothermal liquefaction

Abstract An environmentally friendly method of producing bio-oil through the hydrothermal liquefaction (HTL) of algae has emerged, providing a path toward renewable energy and reducing greenhouse gas emissions. Algae is currently received a lot of interest as biomass feedstock due to its long growing season in warm climate area, does not require arable land, and relatively rapid growing rate. This study aims to optimize the HTL process of macroalgae (Caulerpa lentillifera) for bio-oil production, focusing on optimizing the bio-oil yield based on three parameters (operating temperature, the loading size of catalyst sodium hydroxide (NaOH), and algae-to-water ratio) using Box Behnken Design (also generally known as Response Surface Methodology). The results showed that an ideal reaction temperature of 277 °C, a 1:10 algae-to-water ratio, and 0.88 wt% catalyst loading led to an optimal experimental bio-oil yield of 11.65 wt%. Sensitivity study also revealed that the temperature is the second most important component, after the algae-to-water ratio. The difference in the catalyst loading showed low impact on the HTL of algae. Slight improvement to the bio-oil yield under the presence of NaOH is mainly due to the alkali environment provided by NaOH. The FTIR spectrum revealed the existence of various functional groups in the bio-oil. In summary, HTL has been effective in turning Caulerpa lentillifera into useful bio-oil. Overall, this study contributes to the growing body of research on algae-based bio-oil production. The results highlighted the potential of HTL as a promising technology for sustainable biofuel production, offering a pathway towards a greener and more energy-efficient future.

Biofuel production from macrophytes

The depletion of natural resources and minerals is leading to slower economic growth in many countries. Sustainable economic development requires rational resource management and waste reduction, as disposal or incineration pollutes fertile soils, the atmosphere, and water bodies. This study aimed to develop methods for obtaining the technology of liquid biofuel (bio-oil) production by hydrothermal revitalization of the biomass of macroalgae and aquatic macrophytes. The thermal properties and caloric content of aquatic plant biomass, specifically Phragmites australis, Scirpus lacustris, Typha angustifolia L., and Sparganium erectum L., were investigated, and the optimal parameters for hydrothermal revitalization of their biomass were identified. The biomass of P. australis and S. lacustris was shown to have optimal thermal properties, having an ash content of 7.6% and 6.6%, respectively, and a maximum mass loss temperature of 351 °C and 345 °C, respectively. The production regimes for liquid biofuel (bio-oil) were established. The properties of fuel derived from P. australis biomass were evaluated, including the content of easily boiling fractions and coke residue. The magnitude of fuel yield from biomass P. australis was found to be correlated with the quality of bio-oil. Thus, obtaining biofuels from aquatic plants is one of the promising areas of plant biomass processing.

Biofuels Production: A Review on Sustainable Alternatives to Traditional Fuels and Energy Sources

With increased worldwide energy demand and carbon dioxide emissions from the use of fossil fuels, severe problems are being experienced in modern times. Energy is one of the most important resources for humankind, and its needs have been drastically increasing due to energy consumption, the rapid depletion of fossil fuels, and environmental crises. Therefore, it is important to identify and search for an alternative to fossil fuels that provides energy in a reliable, constant, and sustainable way that could use available energy sources efficiently for alternative renewable sources of fuel that are clean, non-toxic, and eco-friendly. In this way, there is a dire need to develop technologies for biofuel production with a focus on economic feasibility, sustainability, and renewability. Several technologies, such as biological and thermochemical approaches, are derived from abundant renewable biological sources, such as biomass and agricultural waste, using advanced conversion technologies for biofuel production. Biofuels are non-toxic, biodegradable, and recognized as an important sustainable greener energy source to conventional fossil fuels with lower carbon emissions, combat air pollution, empower rural communities, and increase economic growth and energy supply. The purpose of this review is to explain the basic aspects of biofuels and their sustainability criteria, with a particular focus on conversion technologies for biofuel production, challenges, and future perspectives.

Graphene and its derivatives fabrication from paddy straw for improved and sustainable application in biofuels production: New Insight

One of the most sustainable processes for producing green fuels for industrial use is biomass to biofuels production. However, the high production cost of enzymes, the low functional stability of microbes and enzymes with low sugar, and fuel production are key challenges. Nanocatalyst implementation can be a potential strategy to resolve the technical hurdles of biomass-based biofuel production. Due to its distinct physicochemical features, graphene and its derivatives have recently attracted a lot of interest in microbial interaction and microbial based biomass to biofuels production technologies. The diverse physicochemical properties of graphene have created new prospects for biomass to biofuels manufacturing technology to become more cost-effective at the pilot stage. However, sustainable fabrication methods and scale-up process optimization are still not well explored for mass application trials. Therefore, the present review is based on developing a sustainable approach towards the green synthesis of graphene and its derivatives from paddy straw waste. Furthermore, potential opportunities for low-cost synthesis approaches of graphene and its derivatives from paddy straw and their sustainable application in economical biomass to biofuel production processes using paddy straw as a substrate itself, as well as current challenges and feasible future applications, have been discussed.

Review of biofuel production technologies in biorefinery systems

Review of biofuel production technologies in biorefinery systems

Assessment of the grindability and component variation of torrefied agricultural wastes for industrial furnace application

The utilization of agricultural solid biowastes is essential for resource saving and bioenergy conversion. By this way, the demand of industrial furnace for biomass would be compensated, and the energy structure would also be greener. Among them, torrefaction is a hopeful technology for solid biofuel production. This study investigates the grinding performance of torrefied biochar to achieve the grindability and component variation analysis of torrefied agricultural wastes for fluidized bed boiler, and thus realize pulverized biochar injection for industrial application. Totally crystallinity index (CrI), average particle size distribution, energy input for grinding process, component analysis, and elemental carbon state are adopted and analyzed around Hardgrove grindability index (HGI). The values of HGI are in the range of 45–120, 45–105, 60–120, and 60–135, respectively. The results indicate that torrefaction is conducive for biochar properties upgrading, especially for a higher temperature, and thus contributes to a higher HGI, lower particle size and grinding energy input, as well as better elemental carbon state. The produced powder from torrefied biochar is highly correlated to torrefaction temperature and biochar component, and thus leads to an excellent industrial application potential. Overall, this study is conducive for the agricultural biowastes conversion and solid biofuel production.

EUROPEAN EXPERIENCE OF BIOGAS AND BIOMETHANE PRODUCTION FROM WASTE ACCORDING TO THE CIRCULAR ECONOMY PRINCIPLE IN AGRICULTURE

The article analyses the production of biogas from agricultural waste in the context of the circular economy. It is noted that waste-free biofuel production technologies can provide up to 50% of all farm incomes. The types of raw materials from which biogas production was carried out in the countries of the European Union in 2022 and their structure in different countries were investigated. It has been proven that in the structural ratio of the types of raw materials used for biogas production in the EU countries, energy crops and agricultural waste are leading. The volumes of biogas and biomethane production in the EU countries in 2021 are depicted and 16 countries are identified, which are the largest producers of biogas and biomethane relative to the total gas consumption among the countries of the European Union. A comprehensive analysis of the support and stimulation schemes for biogas and biomethane production was carried out in the context of the European Union and other European countries. The program documents in the field of energy of the European Union, which provide the reduction of consumption of fossil energy sources, the accelerated introduction of renewable energy sources (hereafter – RES) in order to reduce greenhouse gas emissions by 55% by 2030 and the achievement of climate neutrality of the European Union by 2050, have been analyzed. It was determined that biomethane will be the most promising type of biofuel in the future. The potential of biomethane production in the EU countries until 2030 according to the production technologies is presented. A number of measures are proposed for the policy of stimulating biomethane production in order to achieve the growth in biomethane production in the countries of the European Union in 2030 – 40 billion cubic meters, in 2050 – 151 billion cubic meters. Attention is focused on additional types of raw materials for the production of ecologically clean biomethane (biomass from marginal or polluted lands and seaweed), as well as the latest technologies – hydrothermal gasification of wet raw materials, including organic waste and residues. EU countries are offered to include in their national climate and energy plans measures to stimulate the development of the biomethane industry.

Solid Biofuel Production from Biomass: Technologies, Challenges, and Opportunities for Its Commercial Production in Nigeria

Producing durable and efficient solid biofuels should be an important consideration in Nigeria’s present economy due to the numerous advantages associated with it. It offers the benefit of energy generation, particularly in rural areas, and could potentially replace fossil fuels. However, the adoption and production of solid biofuels at commercial scale in Nigeria is limited by some challenges, including the lack of a developed supply chain structure, inadequate facilities, and air pollution. The present study summarizes the types of solid biofuel production technologies deployed in Nigeria as well as the biomass feedstock utilized in the production of fuel briquettes and pellets. While opportunities exist in the gasification of biomass in Nigeria, direct combustion is a readily applicable fuel conversion process that can be utilized to generate electricity from solid biofuel. The major challenges surrounding the full adoption of solid biofuel production and utilization in Nigeria are highlighted. Among others, promotion of clean energy alternatives, investments and financial incentives, sustainable renewable energy policy and energy transition plan, and legislative backing are identified as factors that could accelerate the commercial production and adoption of solid biofuel in Nigeria.

Rice Straw Waste-Based Biogas Production via Microbial Digestion: A Review.

The development of sustainable and renewable energy production is in high demand, and bioenergy production via microbial digestion of organic wastes is in prime focus. Biogas produced from the microbial digestion of organic waste is the most promising among existing biofuel options. In this context, biogas production from lignocellulosic biomass is one of the most viable and promising technologies for sustainable biofuel production. In the present review, an assessment and feasibility advancement have been presented towards the sustainable production of biogas from rice straw waste. Rice straw (RS) is abundantly available, contains a high composition of cellulose, and is found under the category of lignocellulosic waste, but it may cause severe environmental issues if not treated. Whereas, due to its high cellulose and inorganic content, lower cost, and huge availability, this waste can be effectively valorized into biogas production at a lower cost on a commercial scale. Therefore, the present review provides existing insight in this area by focusing on the operational parameter's improvement and advancement in the research for the expansion of mass-scale production at a lower cost. Thus, the presented review analyzed the processing parameters status, associated challenges, and positive endnote solutions for more sustainable viability for biogas production.

EUROPEAN REGULATORY PRACTICES AND HANDLING OF DIGESTATE IN THE CONTEXT OF AGRO-ECOLOGICAL TRANSITION OF EU COUNTRIES WITHIN THE EUROPEAN GREEN DEAL

Overcome the negative consequences of climate change and achieve climate neutrality in Europe by 2050. The author of the publication singles out waste-free biofuel production technologies as one of the most effective methods of circular economy, which turns waste into a valuable resource. The scheme of waste-free biofuel production technologies is given, due to which alternative sources of energy and organic fertilizers (digestate), are received. It is noted that scientists and practitioners, to a greater extent, pay attention to the study of biogas, and to a lesser extent to the by-product of its production – digestate. The European schemes of certification and regulation of the handling of digestate are analyzed. The volumes of digestate production from various raw materials in the countries of the European Union in 2021, as well as the volumes of raw materials required for its production, have been calculated. The largest digestate-producing countries among the countries of the European Union, which produce more than 1 million tons of digestate every year, are singled out. The main directions of the final use of digestate in the countries of the European Union are highlighted, among which the largest share is: application of raw digestate as a biofertilizer directly to the soil (67%); processing of the produced digestate before applying it to the soil (8%); applications in the «other uses» category, which include use in horticulture, soil production (for non-agricultural soils), covering solid waste landfills, etc. (8%). The average rates of applying raw digestate to the soil and the most common ways of applying it are given. The potential volume of digestate production in 2022 in the countries of the European Union is calculated and it is predicted that it can replace 5-6% of the use of mineral nitrogen fertilizers. The forecast for the production of digestate and its replacement of mineral fertilizers until 2030 and 2050 is also given. Due to the analysis of European practices of regulation and handling of digestate in the context of the agro-ecological transition of the countries of the European Union, within the European Green Course, a number of measures are proposed that should be taken by Ukraine for the implementation and harmonization of domestic legislation with European legislation in this field of activity.

Yeast-Mediated Biomass Valorization for Biofuel Production: A Literature Review

The European Union has recommended that about 10–50% of the global energy requirement should be supplemented by waste biomass resources by 2050 in order to achieve the objective of having net-zero-emission economies. This has led to intensive research being conducted on developing appropriate biofuel production technologies using advanced or integrated systems to tackle local, national, and global energy challenges using waste feedstock. Researchers have realized the potential of microbes (e.g., yeast strains) for bioenergy production. For this paper, both non-oleaginous and oleaginous yeasts were reviewed, with a specific focus being placed on their diversity in metabolism and tolerance to the various challenges that arise from the use of waste feedstock and influence bioprocessing. Gathering in-depth knowledge and information on yeast metabolism has paved the way for newer and better technologies to employ them for consolidated biorefineries to not only produce biofuels but also to cut down process expenses and decrease the risks of net carbon emissions. The rationale for using yeast strains improved by metabolic engineering and genetic manipulation that can substantially meet the challenges of alternate fuel resources is also described in this paper. This literature review presents the advantages and disadvantages of yeast-based biofuel production and highlights the advancements in technologies and how they contrast to conventional methods. Over the last decade, scientific publications have endorsed the idea of biorefineries for environmentally friendly, cost-effective, and sustainable biofuel production.

Algae–water–silica interactions in low and high ionic strength environments

The interaction between algae and solid surfaces is of direct interest for the optimization of biofuel production technologies. Silica is particularly relevant due the use of solgel matrices for enhanced growth and ease of processing, where ionic strength variation is an important consideration. Here, an inverted fluorescence experiment is used to perform measurements of the distance between a silica surface and algae in solution. At low ionic strength, the average algae–silica distance is approximately 90 nm but increases to roughly 130 nm at 1 M NaCl, contradicting the prediction based on simple electrical double layer interaction models. These findings illustrate the role of biochemical and electrostatic interactions at charged aqueous interfaces of relevance to biofuel production.

High-efficiency catalytic pyrolysis of palm kernel shells over Ni2P/nitrogen-doped activated carbon catalysts

Catalytic pyrolysis is a cost-effective technology for high-quality biofuel production. Biomass is converted to bio-oil by a thermal process in the presence of a catalyst. Catalyst development influences the reaction-pathway control to form a specific product. Here, the catalytic pyrolysis of palm kernel shells was investigated on melamine-doped activated-carbon-supported Ni2P. Different amounts of melamine (25–100 wt% support) were loaded on activated carbon by impregnation and carbonization, while the Ni2P catalyst was fabricated by the co-impregnation of nickel nitrate and ammonium hydrogen phosphate. The interaction between nitrogen-containing functional groups on the carbon surface and Ni2P caused a uniform dispersion of small-sized crystalline Ni2P particles on the activated-carbon surface, reduced from 28.91 nm to 10.85 nm, as shown by transmission electron microscopy analysis. The Ni2P/CN catalyst exhibited high oxygen removal and alkylphenol selectivity (more than 63%) in the liquid product at 350 °C under atmospheric pressure. Therefore, the Ni2P/CN catalyst described here exhibits good potential for high-selectivity catalytic pyrolysis of biomass to produce phenolic compounds, which have wide application in monomers and fuel additives.

Economic and environmental impacts of biofuels in Indian context

Carbon dioxide (CO2), one of the major greenhouse gases, is released when fossil fuels are burned. Over the past decade, there has been a significant progress in global energy recovery from biomass resources and the use of biofuels as a renewable and sustainable alternative to fossil fuels. Biofuels are considered a carbon–neutral energy source, due to the fact that the CO2 through photosynthesis is captured by the plants during their growing period. The commonly used feedstocks for the production of biofuels are sugar cane, corn and vegetable oils etc. However, in order to minimize the impact on land use, food and feed prices, and other environmental factors; advanced feedstocks such as agriculture residue, algae, aquatic biomass, and waste derived feedstock are strongly suggested. The aim of this work is to review about different available feedstock for biofuel production, generations of biofuels, and its application as automotive fuels. The study concludes with recent advancements in modern biofuel production technology, significant policy implications, challenges and the prospects of biofuel in India.

Advancing Process Intensification with High-Frequency Ultrasound: A Mini-Review of Applications in Biofuel Production and Beyond

High-frequency ultrasound (HFU) is an ultrasound technology with a frequency higher than 1000 kHz. It has become increasingly recognized as an emerging process intensification technology in various fields, such as biofuel production, carbon dioxide absorption, and wastewater treatment. HFU is seen as a potential intensifier technology for biofuel production, as its mechanisms, such as cavitational phenomena, microstreaming, and fountain formation, can benefit biofuel production. Previous research has shown that HFU can decrease the reaction time required for biofuel production, aid in lipid extraction, increase carbon dioxide absorption rates, and be effective in destroying pathogens in wastewater treatment. However, despite the potential benefits, there are limited reports on the use of HFU technology for biofuel production, which has led to uncertainties and constraints in its industrial deployment. These constraints include equipment design, economic analysis, and safety concerns, which require further in-depth analysis. Despite these limitations, previous studies have shown promising results for the incorporation of HFU into various fields due to its unique characteristics and mechanisms. This paper presents a review of the theory and application of HFU for process intensification, with a focus on its potential for biofuel production. It also provides recommendations for the further exploration of the technology to overcome industrial deployment obstacles.

Bioexcitons by Design: How Do We Get There?

Biological pigment-protein complexes (PPCs) exhibit a remarkable ability to tune the optical properties of biological excitons (bioexcitons) through specific pigment-protein interactions. While such fine-tuning allows natural systems (e.g., photosynthetic proteins) to carry out their native functions with near-optimal performance, native function itself is often suboptimal for applications such as biofuel production or quantum technology development. This perspective offers a look at near-term prospects for the rational reoptimization of PPC bioexcitons for new functions using site-directed mutagenesis. The primary focus is on the "structure-spectrum" challenge of understanding the relationships between structural features and spectroscopic properties. While recent examples demonstrate that site-directed mutagenesis can be used to tune nearly all key bioexciton parameters (e.g., site energies, interpigment couplings, and electronic-vibrational interactions), critical challenges remain before we achieve truly rational design of bioexciton properties.

In Situ Synergistic Catalysis Hydrothermal Liquefaction of Spirulina by CuO-CeO2 and Ni-Co to Improve Bio-oil Production.

Hydrothermal liquefaction (HTL) is one of the most promising technologies for biofuel production. The preparation and application of catalysts for HTL have been the research focus in recent years. In this study, a new synergistic catalytic process strategy is proposed. CuO-CeO2/γ-Al2O3 was used as an in situ hydrogen donor catalyst and Ni-Co/SAPO-34 was synthesized for hydroprocessing to improve bio-oil production process. The results of XRD and XPS demonstrated that the metal components were well supported on the catalyst. When the two catalysts were mixed, the yield of bio-oil increased from 51.00% to 64.51%, the carbon recovery rate raised from 69.53% to 88.18%, the energy recovery rate grew from 63.42% to 80.22%, and the S content is relatively reduced by 83.3%. Also, TG analysis showed that the content of light components in bio-oil increased. Moreover, the hydrocarbons and alcohols were observed to a higher proportion from the GC-MS analysis. This new method still has high catalytic activity after repeated use for five times. This study provides a new idea for preparing higher yield and superior quality bio-oil.

The Role of Copper in the Hydrogenation of Furfural and Levulinic Acid.

Currently, there is a great interest in the development of sustainable and green technologies for production of biofuels and chemicals. In this sense, much attention is being paid to lignocellulosic biomass as feedstock, as alternative to fossil-based resources, inasmuch as its fractions can be transformed into value-added chemicals. Two important platform molecules derived from lignocellulosic sugars are furfural and levulinic acid, which can be transformed into a large spectrum of chemicals, by hydrogenation, oxidation, or condensation, with applications as solvents, agrochemicals, fragrances, pharmaceuticals, among others. However, in many cases, noble metal-based catalysts, scarce and expensive, are used. Therefore, an important effort is performed to search the most abundant, readily available, and cheap transition-metal-based catalysts. Among these, copper-based catalysts have been proposed, and the present review deals with the hydrogenation of furfural and levulinic acid, with Cu-based catalysts, into several relevant chemicals: furfuryl alcohol, 2-methylfuran, and cyclopentanone from FUR, and γ-valerolactone and 2-methyltetrahydrofuran from LA. Special emphasis has been placed on catalytic processes used (gas- and liquid-phase, catalytic transfer hydrogenation), under heterogeneous catalysis. Moreover, the effect of addition of other metal to Cu-based catalysts has been considered, as well as the issue related to catalyst stability in reusing studies.

A vision of renewable thermal technologies for drying, biofuels production and industrial waste, gas or water recovery

Rapid population growth and the finite nature of fossil-fuel resources have given rise to an urgent interest in sustainable energy development. Thermal technologies include several devices and systems able to improve energy use, recycle resources and waste, and harness renewable energy sources. In particular, thermal technologies applied to renewable sources have been improving over the years in terms of performance costs have reduced, however, several challenges remain that need to be overcome. This vision article is concerned with the prevailing challenges for thermal technologies applied to renewable energy; specifically, solar drying technologies, focussing on medium and large-capacity solar drying systems, thermal devices for waste heat and gas treatment/recovery, and thermochemical technologies for the valorization of biomass to fuels. Firstly, a brief description of each technology is provided while remarking on their importance in energy transition and resource recovery scenarios. Subsequently, key challenges are identified and promising directions and areas for exploration and future research are suggested. The most common critical challenges for the further development and deployment of these technologies include improved designs and material use to decrease final costs and minimize environmental impact. In particular, managing this process within a circular economy perspective would be necessary for improved sustainability. Incorporating renewable energy sources with thermal technologies to reduce the need for fossil fuels is of major interest globally, and optimizing the combined use of mathematical, computational, and experimental tools is the most promising approach for accelerated understanding and development in this space.