Liquid Biofuels Research Articles

Assessment of liquid biofuel potential from energy crops within the sustainable water–land–energy–carbon nexus

With the rapid development of biofuels, doubts about their sustainability have also been raised.

Energy-Saving and Sustainable Separation of Bioalcohols by Adsorption on Bone Char

The separation of ethanol, propanol, and butanol from aqueous solutions was studied using adsorption on bone char. Adsorption kinetics and thermodynamic parameters of this separation method were studied at different conditions of pH and temperature. Results showed that the maximum adsorption capacities of these bioalcohols were obtained at pH 6 and 20°C. An exothermic separation was identified, which can be mainly associated to hydrophobic interactions between bone char surface and bioalcohols. Binary adsorption studies were also performed using mixtures of these bioalcohols. An antagonistic adsorption was observed for all bioalcohols where the ethanol and propanol separation was significantly affected by butanol. A model based on an artificial neural network was proposed to correlate both single and binary adsorption isotherms of these bioalcohols with bone char. It was concluded that the bone char could be an interesting adsorbent for the sustainable separation and recovery of bioalcohols from fermentation broths, which are actually considered emerging liquid biofuels and relevant industrial chemicals.

Combustion characteristics of compression ignition engine fuelled with rapeseed oil–diesel fuel–n-butanol blends

Liquid biofuels for compression ignition engines are often based on vegetable oils. In order to be used in compression ignition engine the vegetable oils have to be processed because of their high viscosity or it is also possible to use vegetable oils in fuel blends. In order to decrease the viscosity of the fuel blends containing crude vegetable oil the alcohol-based fuel admixtures can be used. The paper describes the effect of rapeseed oil–diesel fuel–n-butanol blends on combustion characteristics and solid particles production of turbocharged compression ignition engine. The 10% and 20% concentrations of n-butanol in the fuel blend were measured and analysed. The engine Zetor 1204, located in tractor Zetor Forterra 8641 with the power of 60kW and direct injection was used for the measurement. The engine was loaded through power take off shaft of the tractor using mobile dynamometer MAHA ZW500. The measurement was carried out in stabilized conditions at 20%, 60% and 100% engine load. The engine speed was kept at 1950 rpm. Tested fuel blends showed lower production of solid particles than diesel fuel and lower peak cylinder pressure and with increasing concentration of n-butanol in the fuel blend the ignition delay was prolonged and premixed phase of combustion was increased.

World market of liquid biofuels: trends, policy and challenges

This paper aimed at studying the current state of development of liquid biofuels’ world market. The authors considered the theoretical bases of liquid biofuels production, their types, disadvantages and advantages. The world experience of introducing stimulation mechanisms of development and their influence on the sectors’ growth is analyzed. In this study’s frame, there is outlined the world leaders in the production of liquid biofuels. The findings represent the peculiarities of state regulation in implementing mandates for creating transport fuels with bioliquids. The current state of investment in the production of liquid biofuels was investigated. The obtained results contribute to the prospects for promoting world production of liquid biofuels to achieve the Paris Agreement’s goals by 2030 under the sustainable development scenario.

Microwave-assisted pyrolysis and distillation of cooking oils for liquid bio-fuel production

The goals of this study are to produce and to characterize bio-oil from pyrolysis and distillation of liquid samples in a microwave reactor. Waste cooking oil (WCO) and fresh cooking oil (FCO) were employed as the feedstocks. A 900 W microwave reactor was modified and filled with 300 g of charcoal. It was used for both pyrolysis and distillation experiments. The pyrolysis experiments were performed at various feed flow rates and temperatures ranging from 0.051 kg/h to 0.306 kg/h and 400 °C–550 °C, respectively. The sample was introduced continuously into the microwave reactor for 60 min. Nitrogen gas was also supplied to ensure pyrolysis condition. The bio-oil product was then distilled to obtain fuel fractions. The results showed that the products yield and bio-oils composition were strongly influenced by pyrolysis temperature and type of cooking oils, while there was almost no influence of feed flow rate under the investigated condition. The bio-oil contained 90−100 wt.% aliphatic hydrocarbons and the rest were aromatic hydrocarbons. The bio-oil produced from WCO contained more than 50 wt.% green-diesel (C10-C15) which was comparable to that from FCO. The green-diesel fraction showed good fuel properties agreement to that of fossil diesels. Overall, microwave-assisted pyrolysis and distillation processes are potential ways to convert problematic WCO into useful liquid bio-fuel and green-diesel fuel.

Аналіз напрямків та перспектив використання агробіомаси для виробництва енергії в Україні

Purpose of the study is to assess the current and prospective energy potential of agribiomass (agricultural residues and energy crops) in Ukraine, to determine its main components and the most effective areas of their use. Methods. The assessment of the current potential of agribiomass is performed using official statistics on crop production in Ukraine. Based on these data, the total amount of crop residues formed and their share available for energy needs is determined. When assessing the potential of energy crops, it is assumed that they are grown on 2 million hectares of unused agricultural land, the total area of which is up to 4 million hectares in Ukraine. The study of the prospective potential of biomass is performed for 2050, based on key growth factors, such as increasing yield of crops, especially cereals; doubling the area under energy crops and increasing their yields, etc. Results of the assessment show that according to 2018 data, the total bioenergy potential in Ukraine is more than 23 Mtoe (the economic potential). Its largest components are agricultural residues (44%) and energy crops (32%). Expert estimates suggest that by 2050, the biomass potential could increase to more than 47.5 Mtoe/yr, in other words almost to double. Forecasting the structure and directions of use of biomass potential by 2050 shows that about 20 Mtoe of biomass/biofuels of the following types will be consumed for energy: wood biomass, primary and secondary agricultural residues, energy crops, biogas/biomethane from different types of raw materials, liquid biofuels (biodiesel, bioethanol). Conclusions. Areas of use of biomass/biofuels include the production of heat and electricity from solid biofuels, obtaining of biogas and biomethane, as well as the production of motor biofuels (biomethane, biodiesel, bioethanol). In the near future, it is considered necessary to develop a long-term strategy for the development of bioenergy in Ukraine, taking into account results of the study. In turn, the basic figures of the bioenergy development strategy can be used for the elaboration of the updated Energy Strategy of Ukraine until 2050.

Ethanol Production Potential of Sweet Sorghum in North and Central Ukraine

Background: Sweet sorghum (Sorghum saccharatum (L.) Moench) is a unique crop with great potential to serve both the food and energy industries. It is due to the possibility of (bio)ethanol production both from the juice and biomass of this crop. The sorghum stems juice contains sugar in the levels similar to that of sugarcane. Besides, low cultivation requirements for the sweet sorghum make this crop even more attractive for sugar and ethanol production. In terms of technology, sweet sorghum is seen as a transitional feedstock for the first to the second generation bioethanol production. However, effective technological development of the plant cultivation and processing in the Northern and Central Ukraine is restrained by the lack of a collection of sweet sorghum genotypes and adapted varieties for its large-scale cultivation. Additionally, no evaluations of potential (bio)ethanol productivity have been performed for this region, which is important for efficient implementation of novel biofuel-producing technologies and for successful development of a green economy. Objective: This research was aimed to create a pool of sweet sorghum genotypes with the involvement of worldwide germplasm, analyze their morphology and breed high-yielding plant lines for the efficient production of liquid biofuels for second-generation bioenergy. Based on that, we also aimed to explore the prospects regarding the efficiency of sweet sorghum cultivation for (bio)ethanol production in the Northern and Central Ukraine. Methods and Materials: A valuable gene pool of S. saccharatum (L.) Moench (41 samples) was created; in particular, high-performance genotypes were created for cultivation under the soil-climatic conditions of Ukraine. The bio-morphological features and the yield potential of the plants were determined and the biochemical composition of the phyto-raw materials was determined in different periods of vegetation, in particular, during the technical ripeness of the above-ground mass of plants. The more productive forms and varieties of sugar sorghum in terms of yield, dry matter content, sugar, and energy value of biomass during flowering and waxy ripeness are highlighted. The technological properties of plant biomass for the production of alternative liquid fuels (in particular, bioethanol) have been analyzed. Importantly, optimal cultivation conditions have been elaborated for the newly created sweet sorghum genotypes, and their productivity has also been evaluated. Moreover, for the first time, a detailed study on potential ethanol yield has been conducted. Results: Sweet sorghum has considerable potential in Ukraine as a new sugar-producing energy crop. The germplasm collection of this crop has been created (41 accessions), including introduced and acclimated genotypes and newly bred lines and varieties. The biological performance of sorghum in Ukraine and plant morphology have been analyzed. The most promising genotypes were used for breeding of new high-productive sweet sorghum varieties. The potential (bio)ethanol yield for different sugar feedstocks (juice, grain bagasse) can reach up to 11423 L/ha in total from juice, grain and bagasse. Conclusion: The estimated values of ethanol productivity are comparable to the results of other similar investigations. In conclusion, a high performance of sweet sorghum in Ukraine can be suggested.

A study on different parameters affecting the saccharification rate of Typha orientalis pretreated with Ionic Liquids (ILs) and microwave irradiation for bioethanol production by using response surface methodology

This study investigates the saccharification rate of Typha orientalis pretreated with Ionic liquids 4-(3-Methyl−1-imidazolio) − 1-butanesulfonic acid hydrogen sulfate [BSO3HMIM] [HSO4], combined with microwave irradiation for liquid biofuel production. Methods of full factorial experimental design was used to explore the factors affecting the conversion rate of fibers into fermentable sugar. The results from Plackett-Burman Design (PBD) shows that efficiency on the saccharification rate of Typha orientalis was in the order of microwave power > solvent volume > catalyst > reaction time. From the results obtained, optimum parameter was determined by Central Composite Design (CCD) where the highest saccharification rate attained was 52.9%.

Advantages and Disadvantages of the Production and Using of Liquid Biofuels

This article is devoted to the study of the possibilities of using liquid biofuels to mitigate environmental pollution and stabilize the economy in countries where there is a shortage of natural resources that are energy carriers. To this end, the authors considered the positive and negative aspects of using biofuels as a mixture, including bioethanol or biodiesel. In addition, the article includes an analysis of the situation in Russia regarding the orientation towards replacing traditional fuels.

Recent innovations for reviving the ABE fermentation for production of butanol as a drop-in liquid biofuel

Butanol is a key microbial product that provides a route from renewable carbohydrate resources to a "drop-in" liquid biofuel, broadening its market in the near future. The acceptable performance of butanol as a neat or a blended fuel in different engines both from the technical and environmental points of view has attracted a wide range of research for reviving the old acetone-butanol-ethanol (ABE) fermentation. In this review, recent findings on fuel characteristics of butanol, different generations of substrate for large scale butanol production, and alternative process designs for upstream, mainstream, and downstream operations have been critically reviewed and discussed. In the upstream, studies devoted to designing and optimization of pretreatments based on prerequisites of butanol production, e.g., maximizing cellulose and hemicellulose recovery and minimizing lignin degradation, are presented. In the mainstream, different microbial systems and process integrations developed for facilitating ABE production (e.g., in-situ butanol removal) are scrutinized. Finally, innovations in ABE recovery and purification as "Achilles Heel" of butanol production processes which directly controls the energy return on investment (EROI), are reviewed and discussed.

Synthesis of high-titer alka(e)nes in Yarrowia lipolytica is enabled by a discovered mechanism

Alka(e)nes are ideal fuel components for aviation, long-distance transport, and shipping. They are typically derived from fossil fuels and accounting for 24% of difficult-to-eliminate greenhouse gas emissions. The synthesis of alka(e)nes in Yarrowia lipolytica from CO2-neutral feedstocks represents an attractive alternative. Here we report that the high-titer synthesis of alka(e)nes in Yarrowia lipolytica harboring a fatty acid photodecarboxylase (CvFAP) is enabled by a discovered pathway. We find that acyl-CoAs, rather than free fatty acids (FFAs), are the preferred substrate for CvFAP. This finding allows us to debottleneck the pathway and optimize fermentation conditions so that we are able to redirect 89% of acyl-CoAs from the synthesis of neutral lipids to alka(e)nes and reach titers of 1.47 g/L from glucose. Two other CO2-derived substrates, wheat straw and acetate, are also demonstrated to be effective in producing alka(e)nes. Overall, our technology could advance net-zero emissions by providing CO2-neutral and energy-dense liquid biofuels.

Biofuel from Rice Husk Pyrolysis: Effect of Temperature to Pyrolysis Oil and Its Kinetic Study

e husk is counted as an agricultural waste that results in environmental problems during its handling. In this work, rice husk was used as raw material for producing liquid biofuel (pyrolysis oil) via pyrolysis. The pyrolysis reaction was carried out at temperatures of 450, 500, and 550°C for 1 hour. The pyrolysis oil was collected and weighted for every 10 minutes. The results showed that the increase in pyrolysis temperature caused the yield of pyrolysis oil to increase. The properties in the term of heating value also increased while viscosity and density of pyrolysis oil decreased. These properties were almost similar to diesel oil with a slightly lower heating value. The proposed model using the single reaction model and two stages model were fit to represent the mechanism of rice husk pyrolysis reaction in this study. However, the results of two stages model gave a lower error than those of the single reaction model. Furthermore, the rate of pyrolysis reaction at various temperatures could be determined using the kinetic data obtained from the developed model. This information would be useful for designing the pyrolysis reactor especially for producing biofuel (pyrolysis oil) from the rice husk.

Modelling the interaction between policies and international trade flows for liquid biofuels: an agent-based modelling approach

World biofuel production and trade have grown exponentially in the last decade. Nevertheless, the interaction between the markets for oilseeds (food/feed/bioenergy) and liquid vegetable oil-based biofuels is overwhelmingly complex and thus not well understood. In this study, we developed a spatially explicit agent-based model to provide insights into the effect of farmers' behaviour on trade flows and biodiesel production and to shed light on the influence of import tariffs for both palm oil and biodiesel on system behaviour. This new approach enables us to assess different types of rational economic behaviour for the adoption of crops by farmers. Results show that model outcomes can vary substantially based on the assumptions made concerning the behaviour of farmers. Moreover, we found that biodiesel trade and production are more sensitive to a change in the EU-28's biodiesel import tariff than to a change in the EU-28's palm oil import tariff. Overall, our results show that social processes, actors' heterogeneity, and institutions play an important role in the behaviour of the system.

Food Security in the Context of Liquid Biofuels Production

A crucial factor that determines the development of production and consumption markets for biofuels is the choice of raw materials that can ensure the highest possible production efficiency, the lowest cost and the smallest emission of harmful substances to the atmosphere during all production stages. Considerations underlying the development of biofuel production have been discussed as well as the theoretical mechanisms linking the generation of biofuels to the level of production and the variability of prices of agricultural raw products. The aim of this study has been to identify the scale at which energy raw materials originating from agriculture are used for liquid biofuels production and to explore their impact on food security. The study used public statistical data (OECD-FAO and IndexMundi). The time span of the analysis was from 2005 to 2018. First-generation biofuels based on food raw materials (cereal grains, root crops, sugarcane and vegetable oils) are becoming increasingly competitive with food production recent years have been a period of the dynamic growth in production of liquid biofuels. In 2018, the global production of these substances reached 167.9 billion litres (bioethanol and biodiesel together), consuming 16.1% of maize grain, 1.7% of wheat grain, 3.3% of grain of other feed grains and 13.5% of vegetable oil.

(Invited) Increasing Biogas to Liquid Fuel Yield By Solid Oxide Co-Electrolysis of Biogas CO2 Fraction

OxEon Energy, LLC (OxEon) plans to demonstrate production of liquid hydrocarbon fuels using both the methane and CO2 generated in a food waste digester operated by the Environmental Products & Technologies Corporation (EPT). The EPT food waste digester in Burley Idaho sells produced biogas into a natural gas pipeline after separating and venting the bio-CO2. This project will convert the bio-methane to synthesis gas (syngas, as CO & H2) using a non-thermal plasma catalyzed autothermal reformer. To achieve high bio-carbon utilization, an OxEon high temperature solid oxide co-electrolysis (HTCE) system will electrochemically generate additional syngas from the bio-CO2 combined with steam raised by cooling the Fischer Tropsch (FT) reactor. Syngas from the reformed methane and co-electrolyzed CO2, will be converted to liquid fuels using an OxEon developed FT reactor. Each of the technology components have been field tested independently and will be combined for the first time in this project. The project outcome will be an engineering scale demonstration of liquid hydrocarbon bio-fuel production achieving > 50% conversion to liquids of the biogenic carbon in both CH4 & CO2 produced by an anaerobic digester.Each of the three technology elements of the integrated engineering test incorporates numerous innovations. The plasma reactor is designed to be fuel flexible, sulfur tolerant, and economically scalable to small, distributed bio-gas resources. It is also very efficient using a low power non- thermal plasma. High temperature solid oxide electrolysis has demonstrated efficiency at the thermodynamic limit as shown by analysis and testing at DOE and NASA laboratories, and is unique in its ability to co-electrolyze steam and CO2 directly to syngas. The HTCE stacks use innovations proven for the NASA Mars 2020 project which required exceptional ruggedness and effective high temperature seals. The FT reactor enables economical fabrication of smaller size synthetic fuel plants designed to match the scale of distributed renewable biomass resources. This is achieved with large diameter standard piping combined with a novel internal thermal management structure.The status of the technology elements and the planned engineering demonstration will be presented.This work is supported by the Bioenergy Technologies Office of the US Department of Energy.

Low-temperature catalytic conversion of alkaline sewage sludge bio-oil to biodiesel: Product characteristics and reaction mechanisms

Sewage sludge is a promising biomass alternative for the production of liquid biofuels. In this study, bio-oil derived from the fast pyrolysis of domestic sewage sludge was upgraded in a micro Robinson–Mahoneyreactor at 4 MPa and 260 °C, and in the presence of hybridized Ni/HZSM-5 catalyst and ethanol. Fourier transform infrared and gas chromatography-mass spectrometry analyses were used to identify the functional groups and chemical components of raw and upgraded sewage sludge bio-oil. Results showed that catalytic upgrading reduced the relative content of acids, aldehydes, phenols, ketones, and nitrogenated compounds in the pyrolytic bio-oil. Thus, the main components of the upgraded bio-oil product included esters (48.59%), alkanes (10.12%), aromatics (9.38%), and alkenes (5.08%). Water and nitriles in the raw pyrolytic bio-oil together with in-situ-produced carbon oxides helped in the esterification of raw bio-oil. Reaction mechanisms such as nitrile hydrolysis, hydrogenation, and esterification were proposed to elucidate the conversion of the non-acidic pyrolytic bio-oil into ester-dominating upgraded bio-oil. Overall, upgrading sewage sludge pyrolytic oil is crucial to produce high-quality diesel-range biofuel.

PERFORMANCE AND EMISSION CHARACTERISTIC ANALYSIS OF CUCURBITA PEPO L. AND TECTONA GRANDIS SEED OIL BIODIESEL BLENDS IN CI ENGINE WITH ADDITIVE

ABSTRACT Biodiesel is produced from the refined/edible type oils using methanol and an alkaline catalyst which is one of the environmentally friendly alternative liquid biofuels that has proven itself commercially, with international standards all around the world. In present investigation, mixture of two biodiesels in equal weight ratio namely Cucurbita pepo.L (pumpkin) and Tectona grandis (teak) seed oil was used for the synthesis of biodiesel with 5-ml Diethyl ether as additive. Performance test was made with the biodiesel blend using water-cooled, constant speed, CI engine, and emission characteristics were analyzed using a five-gas analyzer. It was observed that there was 35.5% increment in Brake Thermal efficiency and 25.8% reduction in Brake Specific Fuel consumption at maximum load for 200-ml pumpkin and teak biodiesel blend mixed to the diesel with additive. For this blend, it was observed at maximum load, the emission of Carbon monoxide reduced by 26.67% of diesel; Carbon di-oxide reduced by 12.96% and Nitrous oxide reduced by 26.57%. The emission gets increased in over load condition. Unburned Hydro Carbon emission and smoke opacity increased by 67.16 and 9.84%. The combustion characteristics of blended biodiesel with additive closely followed the diesel fuel operation. Hence, this blend was used as fuel in CI engine without engine modification.

Why does the European Union produce biofuels? Examining consistency and plausibility in prevailing narratives with quantitative storytelling

This paper seeks to clarify the confusion created by the simultaneous use of non-equivalent policy discourses about biofuels within the EU and addresses the inconsistency between long-term goals and short-term targets. To this purpose, a novel approach, quantitative storytelling, is employed to examine the plausibility of current policy narratives. It confronts quantitative data on the production and use of biofuels at member-state (the Netherlands) and EU level against the official storytelling. Our analysis shows that in the Netherlands the actual production and use of biofuels are motivated by economic incentives and trade opportunities rather than the original policy justifications and hitting biofuel targets has become a justification in itself (the phenomenon of displacement). At EU level, the vast majority of the current (inadequate) supply of liquid biofuels still consists in first-generation biofuels, which are to be phased out. Advanced and food-waste-based biofuels are unlikely to fill the void any time soon. The analysis shows incoherence among the narratives underlying the justification of policies and those used for their implementation. It is concluded that the quality of the biofuels policy debate could be improved by acknowledging the existence and influence of untold stories and hidden justification narratives.

Environmental sustainability of biofuels: a review.

Biofuels are being promoted as a low-carbon alternative to fossil fuels as they could help to reduce greenhouse gas (GHG) emissions and the related climate change impact from transport. However, there are also concerns that their wider deployment could lead to unintended environmental consequences. Numerous life cycle assessment (LCA) studies have considered the climate change and other environmental impacts of biofuels. However, their findings are often conflicting, with a wide variation in the estimates. Thus, the aim of this paper is to review and analyse the latest available evidence to provide a greater clarity and understanding of the environmental impacts of different liquid biofuels. It is evident from the review that the outcomes of LCA studies are highly situational and dependent on many factors, including the type of feedstock, production routes, data variations and methodological choices. Despite this, the existing evidence suggests that, if no land-use change (LUC) is involved, first-generation biofuels can—on average—have lower GHG emissions than fossil fuels, but the reductions for most feedstocks are insufficient to meet the GHG savings required by the EU Renewable Energy Directive (RED). However, second-generation biofuels have, in general, a greater potential to reduce the emissions, provided there is no LUC. Third-generation biofuels do not represent a feasible option at present state of development as their GHG emissions are higher than those from fossil fuels. As also discussed in the paper, several studies show that reductions in GHG emissions from biofuels are achieved at the expense of other impacts, such as acidification, eutrophication, water footprint and biodiversity loss. The paper also investigates the key methodological aspects and sources of uncertainty in the LCA of biofuels and provides recommendations to address these issues.

Balanced Xylan Acetylation is the Key Regulator of Plant Growth and Development, and Cell Wall Structure and for Industrial Utilization.

Xylan is the most abundant hemicellulose, constitutes about 25–35% of the dry biomass of woody and lignified tissues, and occurs up to 50% in some cereal grains. The accurate degree and position of xylan acetylation is necessary for xylan function and for plant growth and development. The post synthetic acetylation of cell wall xylan, mainly regulated by Reduced Wall Acetylation (RWA), Trichome Birefringence-Like (TBL), and Altered Xyloglucan 9 (AXY9) genes, is essential for effective bonding of xylan with cellulose. Recent studies have proven that not only xylan acetylation but also its deacetylation is vital for various plant functions. Thus, the present review focuses on the latest advances in understanding xylan acetylation and deacetylation and explores their effects on plant growth and development. Baseline knowledge about precise regulation of xylan acetylation and deacetylation is pivotal to developing plant biomass better suited for second-generation liquid biofuel production.