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Mitigation of global warming, energy security and industrial competitiveness urge the energy-intensive pulp and paper industry (PPI) to transform energy use practices. This study investigates how the PPI has responded to the need for the energy transition in the 2000s. Finland and Sweden as forerunners of energy-efficient operation and decarbonization of the PPI are used as target countries. Understanding of changes in energy consumption is complemented using decomposition analysis (Logarithmic Mean Divisia Index Method) and the energy efficiency index approach. Analysis of companies’ investments in energy technologies is used for explaining changes in energy production. Evidence of significant development towards the more sustainable operation of the PPI was found. Energy consumption per produced unit has decreased, i.e., energy efficiency has improved. Fossil fuels have been partially replaced with bio-based alternatives. Thus, the CO2 intensity has decreased substantially. The generation of renewable electricity has increased in both countries. Examples of Finland and Sweden indicate that the PPI has great potential to contribute to CO2 emission reduction worldwide in the future as energy efficiency can be further improved, and the share of fossil fuels can be decreased increasing the use of biofuels and self-generated green electricity at least in kraft pulp mills.

By way of broadening the use of diverse sustainable bioethanol feedstocks, the potentials of Paper mulberry fruit juice (PMFJ), as a non-food, sugar-based substrate, were evaluated for fuel ethanol production. The suitability of PMFJ was proven, as maximum ethanol concentration (56.4 g/L) and yield (0.39 g/g) were achieved within half a day of the start of fermentation, corresponding to very high ethanol productivity of 4.7 g/L/hr. The established potentials were further optimally maximized through the response surface methodology (RSM). At the optimal temperature of 30 °C, yeast concentration of 0.55 g/L, and pH of 5, ethanol concentration, productivity, and yield obtained were 73.69 g/L, 4.61 g/L/hr, and 0.48 g/g, respectively. Under these ideal conditions, diverse metal salts were afterward screened for their effects on PMFJ fermentation. Based on a two-level fractional factorial design, nutrient addition had no positive impact on ethanol production. Thus, under the optimal process conditions, and without any external nutrient supplementation, bioethanol from PMFJ compared favorably with typical sugar-based energy crops, highlighting its resourcefulness as a high-value biomass resource for fuel ethanol production. Graphical Abstract

Paper sludge is a solid waste by-product abundantly produced in the paper industry and contains fine minerals and lignocellulosic biomass. In this contribution, the ex-situ catalytic fast pyrolysis of paper sludge with a high mineral content of ca. 71 wt% is reported for the first time and demonstrated in a pilot-scale unit (feeding rate of 11.3 kg h−1) using a granular Na2CO3/γ-Al2O3 catalyst (loading of 650 g) to produce a high-grade bio-oil at a fast pyrolysis temperature of 475 ± 5 °C (pre-screened using a pyroprobe) and a catalytic upgrading temperature of 500 °C. Besides, > 99 wt% minerals in the paper sludge could be recovered, including paper fillers such as CaCO3 (major) and talc. The bio-oil obtained at a carbon yield of 21 C.% has a low oxygen content of 3.2 wt%, a low total acidity number of 5.2 mg KOH g−1, low H2O content of 0.7 wt%, and a high higher heating value of 40.9 MJ kg−1. It consists of value-added bio-based chemicals such as paraffins, olefins, and low molecular weight aromatics. The results demonstrate that the use of paper sludge to recover minerals and to obtain fuels and chemicals using ex-situ catalytic pyrolysis is technically feasible at a pilot plant scale, which will be of importance for the development of future bio-based economy.

Sustainable power generation for portable electronic devices is of high interest due to increasing energy demands. Miniaturized biofuel cells are well-reported for this purpose where ubiquitous fluids, like glucose or lactate, can be leveraged. However, such biofuel cells need enzymes to complete the catalysis, leading to many prevalent issues like the longevity of enzymes, complicated immobilization, additional mediators etc. Therefore, non-enzymatic glucose biofuel cells (NEGBFCs) are gaining interest due to their cost-effectiveness, high repeatability and excellent stability. However, based on our best knowledge such glucose biofuel cells are not reported in microfluidic environment, and therefore their potential is not exploited. Realization of the functionality of such NEGBFCs in a microscale is crucial to replace them with their enzymatic counterparts. In this work, for the first time, a microfluidic non-enzymatic glucose biofuel cell (μNEGBFC) is developed on a paper-based platform using metallic catalysts. The catalysts for electrocatalytic energy generation is fabricated using electrodeposition method and their detailed physicochemical characterizations are done. The μNEGBFC is capable of producing a power density of 12.5 μW/cm2 with a stable potential of 410 mV. This green power output can be used to operate low-power micro-devices and lab-on-chip sensors in a more continual and viable manner.

The aim of the project “More Fuels from Organic Residues” (MOTOR) is to produce advanced biofuels for the transport sectors where electrification or gaseous biofuels will not generate the reduction of their carbon footprint in the short term. In MOTOR, wet lignocellulosic waste streams that do not compete with the food/feed market are used as a feedstock for a smart fermentation process. In the present study, the utilization of paper sludge as substrate for fermentation for production of fuel precursors and subsequent catalytic conversion to fuels at laboratory scale is described. The steps of the process were assessed experimentally, and based on the data generated, a conceptual process is being developed to explore the economic and sustainability aspects of the new value chain for biofuel.. Results show that solubilization of sugars from paper sludge using existing enzyme cocktails is very limited and needs improvement. On the other hand, the catalytic production of fuel from the fermentation products shows promising results in terms of type of products., Proceedings of the 30th European Biomass Conference and Exhibition, 9-12 May 2022, Online, pp. 24-27

The demand for more environmentally friendly alternative renewable fuels is growing as fossil fuel resources are depleting significantly. Consequently, bioethanol has attracted interest as a potentially viable fuel. The key steps in second-generation bioethanol production include pretreatment, saccharification, and fermentation. The present study employed simultaneous saccharification and fermentation (SSF) of cellulose through bacterial pathways to generate second-generation bioethanol utilizing corncob s and paper waste as lignocellulosic biomass. Mechanical and chemical pretreatments were applied to both biomasses. Then, two bacterial strains, Bacillus sp. and Norcadiopsis sp., hydrolysed the pretreated biomass and fermented it along with Achromobacter sp ., which was isolated and characterized from a previous study. Bioethanol production followed by 72 h of biomass hydrolysis employing Bacillus sp. and Norcadiopsis sp ., and then 72 h of fermentation using Achromobacter sp. Using solid phase micro extraction combined with GCMS the ethanol content was quantified. SSF of alkaline pretreated paper waste hydrolysed by Bacillus sp. following the fermentation by Achromobacte r sp. showed the maximum ethanol percentage of 0.734±0.154. Alkaline pretreated corncobs hydrolyzed by Norcadiopsis sp. yielded the lowest ethanol percentage of 0.155±0.154. The results of the study revealed that paper waste is the preferred feedstock for generating second-generation bioethanol. To study the possible use of ethanol-diesel blends as an alternative biofuel E2, E5, E7, and E10 blend emulsions were prepared mixing commercially available diesel with ethanol. The evaluated physico-chemical characteristics of the ethanol-diesel emulsions fulfilled the Ceypetco requirements except for the flashpoint revealing that the lower ethanol-diesel blends are a promising alternative to transport fuels. As a result, the current study suggests that second generation bioethanol could be used as a renewable energy source to help alleviate the energy crisis..

Microalgae-bacteria symbiotic association can provide many competitive advantages over the pure axenic culture of microalgae to obtain biofuel. This system significantly reduces an important technical constraint, including associated capital cost with the infrastructure required for maintaining pure microalgae culture. The current study aims to compare the symbiotic growth of Tetraselmis indica - Pseudomonas aeruginosa consortium with axenic growth of Tetraselmis indica in dairy wastewater (DWW). The extraction and optimization of chlorophyll-a were also investigated. The overall maximum chlorophyll-a recovery of 29.106 ± 0.045 mg L−1 was obtained through the sonification as extractant method with methanol as an extraction solvent. The chlorophyll-a content of consortium cultivated in DWW higher than the axenic pure microalgae culture (APMC). The maximum biomass yield of the consortium was achieved as 1454.88 mg L−1, which is much higher than APMC growth in DWW by 38.80%. On the 10th day, the consortium removed 87.49%, 83.76%, and 79.83% of chemical oxygen demand (COD), total dissolved nitrogen (TDN), and total dissolved phosphorus respectively. The higher biomass growth and wastewater nutrient removal exhibited by the symbiotic microalgae-bacteria consortium can be utilized in biofuel technology.

Generating capacities supplied by solid biomass (renewable waste) gather at the moment less than 4.5% of the total renewable power installed worldwide. Given the two folded implications of such technology development and spreading (i.e. energy production and waste management), researches regarding efficient conversion processes and improved power facilities are of great interest currently. In this context, the paper addresses the particularities of high oxygen content biofuels pyrolysis, proposing innovative solutions to overcome the issues found in experimental investigations. Based on thorough experimental research conducted on agricultural wooden biomass and poultry manure, a number of problems arise. Among them, it is highlighted the heating in the absence of oxidants, an undesirable internal process caused by the high oxygen content, which contravenes the general principles regarding pyrolysis. Furthermore, the high oxygen content is associated with great moisture percentages. The present paper reveals the challenges determined by some negative aspects emerging during the pyrolysis of high oxygen content biofuels. Several solutions are proposed to improve the efficiency of the conversion process through adequate control. For instance, it is pointed out that the temperature level at which the pyrolysis process develops plays a crucial role in the general energy balance. On this matter, investigating poultry manure pyrolysis at low temperatures, a significant decrease of the final coke product is noticed. Poultry manure pyrolysis results as a suitable and simple solution to be employed for waste treatment purposes, as its combustible effects (combustible gases and semicoke / coke) are good candidates for energy production.

In this paper, thermal degradation (TGA) and pyrolysis studies of sunflower shell biomass (SSB), eucalyptus biomass (EB), wheat straw biomass (WSB), and peanut shell biomass (PSB) were carried out using the thermogravimetric analysis and stainless steel tubular reactor. Thermal degradation of all biomass wastes was examined at a heating rate of 10 °C/min in nitrogen atmosphere between 20 and 800 °C. Experiments of pyrolysis were carried out in a tubular reactor from 300 to 700 °C with a heating rate of 10 °C/min, a particle size of 0.1–0.3 mm and nitrogen flow rate of 100 mL.min−1, which the aim to study how temperature affects liquid, solid, and gas products. The results of this work showed that three stages have been identified in the thermal decomposition of SSB, EB, WSB, and PSB wastes. The first stage occurred at 120–158 °C, the second stage, which corresponds to hemicellulose and cellulose's degradation, occurred in temperatures range from 139 to 480 °C for hemicellulose, and from 233 to 412 °C for cellulose, while the third stage occurred at 534–720 °C. It was concluded that temperature has a significant effect on product yields. The maximum of bio-oil yields of 37.55, 30.5, 46.96, and 50.05 wt% for WSB, PSB, SSB, and EB, were obtained at pyrolysis temperature of 500 °C (SSB, PSB, and WSB) and 550 °C (EB). Raw biomass, solid and liquid products obtained were characterized by elemental analysis, Fourier transformed infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), and x-ray diffraction (XRD). The analysis of solid and liquid products showed that bio-oils and bio-chars from agricultural biomass wastes could be prospective sources of renewable fuels production and value added chemical products.

In recent years renewable and cleaner fuel for diesel engines are compulsory due to depletion of fossil fuel. Various types of bio-based fuels are investigated by the researchers. Biodiesel is anticipated as potential contenders of diesel fuel. Though it is possible to utilize pure biodiesel in diesel engines, some burdens like higher density, lower cetane number and lesser calorific value hinder it from replacing conventional diesel completely. Therefore, using blends with biofuels in diesel engines has a preference. Thus, this paper reviews two different approaches on the role of nanoparticles on biofuel production and effects of nanoparticles in biodiesel–diesel fuel blends on performance, combustion analysis and emission characteristics of diesel engines. Wide range of results from previous research studies with potential and application of nanoparticles in bioethanol production, the effect of the addition of nanoparticles into diesel fuel with different biofuels ratios are collected in this review study. There are different engine performances enhancing methods surveyed. Nanoparticles can be utilized in the production of biofuels from feedstock pre-treatment to chemical reaction as catalysts. It was observed from the overall results that by adding nanoparticles, there was a significant reduction in the brake specific fuel consumption about 20% to 23% as compared with biodiesel–diesel blends with and without alcohol as additives. Besides as nanoparticles possess high thermal conductivity, the addition of nanoparticles enhanced the process of combustion and increases the brake power about 2.5% to 4%. Emission results showed that in most reviews, NO x emission is increased by up to 55%, while HC, CO and PM are decreased significantly. It was concluded from the study that a diesel engine could be effectively run and give better performance and effective regulated emissions on the application of added nanoparticles with biodiesel and their blends as fuel in a CI engine.

Recently, the demand for biodegradable, eco-friendly and sustainable alternatives has been on the increase. Although numerous biopolymers such as cellulose, starch, plants proteins and polylactic acid, etc., have been used to produce bioplastics, the outcomes need more improvement to suit different applications. This paper comprehensively maps the expanding academic territory using lignin as a reinforcement material to improve biopolymers-based materials' properties. A brief discussion on the chronological development of lignin, types, isolation, physical and chemical modifications was presented. Also, the role of lignin in biopolymeric blends such as starch, polylactic acids, plants proteins, polyhydroxy butyrate and polyamides was reviewed. Finally, the review extensively and critically discusses the current findings on lignin/biopolymers blends in various industrial applications, including wood adhesives, adsorbent for toxic heavy metal removal, production of carbon materials, dispersant medium, flame retardant and storage materials, etc., and highlighted the possible applications of lignin in biofuel, hydrocarbon, lubricant, renewable chemical, and smart materials.

Microalgae have been evaluated as promising resource for biodiesel production, but algal biofuel production is not yet commercially viable, which reflects the high energy costs linked with cultivation, harvesting, and dewatering of algae. As crude oil processing declines, microalgae biorefineries are being considered for producing bioactives such as enzymes, proteins, omega-3 oils, pigments, recombinant products, and vitamins, to offset the costs of biofuel production. We believe that producing algal bioactives through advanced manufacturing pathways, encompassing a biorefinery approach, would be effective, profitable, and economical.

Microalgae as source of renewable energy are very potential due to high biomass productivity and lipid content. The nutritious culture for microalgae cultivation, however, should be concerned to be affordable and feasible. Here, the utilization of peat swamp culture for microalgal cultivation was studied in comparison to the nutritious pure water. The effects of photoperiod and nitrogen sources on biomass were conducted as well. Compared to the commercial microalgae, the microalgae isolated from peat swamp showed excellent performance with the faster growth time of 10 days as well as higher biomass and its productivity of 1.72 g L−1 and 0.16 g L−1 d−1, respectively. Even for the commercial microalgae, the cultivation process using the peat swamp water led to increase in biomass by 17.2% and its productivity by 10% compared to that using the nutritious pure water. The proposed kinetic model with a modification to the modified Gompertz model showed an excellent prediction with the experimental data as R2 of 0.985 was obtained. The model could well envisage the initial biomass and lag phase compared to the original model. Hence, the model is deemed beneficial for the research development for implementation in high scale of microalgal cultivation.

Microbial electrosynthesis (MES) for bioelectro carbon dioxide (CO2) recycling is an interesting and sustainable opportunity to exploit off gases from industrial facilities and convert them into valuable energy sources. In the present study, a two-step process based on coupling a bioelectrochemical system (BES) and heterotrophic microalgae Auxenochlorella protothecoides is proposed to convert carbon dioxide into a biodiesel compatible oil. The MES effluent was further processed in a heterotrophic microalgae batch reactor, where the acetate previously synthesized from CO2 was converted into bio-oil in a subsequent, extraction-free step. Two MES reactors were operated in batch mode at an applied cathodic potential of 0.8 V vs. SHE (standard hydrogen electrode) for 95 days. The system reached a concentration of up to 13 g L 1 of acetate (at a maximum production rate of 0.29 g L 1 d 1). Microbial community analysis revealed the presence of Clostridium spp. in both reactors. In a second stage, the effluent from the biocathode was transferred to microalgae reactors containing A. protothecoides to assess oil production. The bio-oil content was up to 22% w/w (dry weight), sufficient to further explore the feasibility of microalgae-to-oil recovery in the future. According to our estimations, 7.59 kg CO2 can be converted into 1 kg acetate, which can be used to grow heterotrophically 1.11 kg dry algae; an overall balance of 0.03 kg bio-oil produced per kg CO2 captured was assessed. The oil obtained can be further processed to produce a biodiesel compatible with EU requirements for biofuels This research was funded by the Spanish Ministry of Science through the grant RTI2018-098360-B-I00 and the Agency for Business Competitiveness of the Government of Catalonia (ACCIO) through the DigesTake Project (COMRDI16-1-0061). E. ´ P.-V. is grateful for the Research Training grant from the University of Girona (IFUdG2018/52). S. P. is a Serra Hunter ´ Fellow (UdG-AG-575) and acknowledges the funding from the ICREA Acad`emia award. LEQUiA and Ecoaqua have been recognized as consolidated research groups by the Catalan Government with codes 2017-SGR-1552 and 2017SGR-548, respectively

In recent times, biohydrogen production from microalgal feedstock has garnered considerable research interests to sustainably replace the fossil fuels. The present work adapted an integrated approach of utilizing deoiled Scenedesmus obliquus biomass as feedstock for biohydrogen production and valorization of dark fermentation (DF) effluent via biomethanation. The microalgae was cultivated under different CO2 concentration. CO2-air sparging of 5% v/v supported maximum microalgal growth and carbohydrate production with CO2 fixation ability of 727.7 mg L−1 d−1. Thereafter, lipid present in microalgae was extracted for biodiesel production and the deoiled microalgal biomass (DMB) was subjected to different pretreatment techniques to maximize the carbohydrate recovery and biohydrogen yield. Steam heating (121 °C) in coherence with H2SO4 (0.5 N) documented highest carbohydrate recovery of 87.5%. DF of acid-thermal pretreated DMB resulted in maximum H2 yield of 97.6 mL g−1 VS which was almost 10 times higher as compared to untreated DMB (9.8 mL g−1 VS). Subsequent utilization of DF effluent in biomethanation process resulted in cumulative methane production of 1060 mL L−1. The total substrate energy recovered from integrated biofuel production system was 30%. The present study envisages a microalgal biorefinery to produce biohydrogen via DF coupled with concomitant CO2 sequestration.

In this study, the performance and emission characteristics of produced biodiesel from Dunaliella tertiolecta microalgae are investigated for the first time. To achieve reliable results, all production stages including cultivation, harvesting, oil extraction, and transesterification are executed in the current study. The cetane number and heating value of the produced biodiesel from Dunaliella tertiolecta microalgae were 54 and 40.2 MJ kg−1, respectively. The results of emission analysis showed that the use of B10 and B20 biofuels emitted less CO, HC, and NOx pollutants than diesel fuel (the average reductions of CO, HC, and NOx emissions for B10 are 9.21%, 7.32%, and 2.89%, and for B20 are 23.54%, 18.28%, and 6.97%, respectively); however, these biofuels resulted in more O2 and CO2 relative to the pure diesel fuel (the average increments of O2 and CO2 emissions for B10 are 1.55% and 1.33%, and for B20 are 3.46% and 5.43%, respectively). Also, the engine output power with B20 fuel decreased averagely 2.64%, and the BSFC increased 3.46% compared to pure diesel fuel. The results demonstrate the considerable capability of Dunaliella tertiolecta microalgae to be the source of a clean fuel.

Castor bean (Ricinus communis) can be a high-demand crop for the production of biodiesel, an alternative biofuel similar to conventional diesel. The objective of the work has been to optimize the method of obtaining biodiesel from a “green technology” process, directly splitting the seeds of three macerated castor varieties, without prior extraction of the oil with n-hexane as is traditional. Also using low-cost heterogeneous basic catalysts, friendly to the environment. It has been shown that it is feasible to obtain biodiesel as an eco-fuel from castor beans directly, without prior oil extraction with the consequent saving of n-hexane solvent and the non-use of sodium hydroxide. It is feasible to substitute methanol for ethanol (less toxic and cheaper), and as a novel aspect, the use of BaCO3 as a heterogeneous catalyst, not reported in any reference of those consulted. Yield percentages ranging between 31% and 45% were obtained, comparable to those obtained from previous oil extractions. It was concluded that of the three varieties of castor bean evaluated, the variety HG-A-1 (collected in Atotonilco el Grande, Municipality of the State of Hidalgo) classified as IBEA type, is the one that presents the best results. Keywords: Barium carbonate, Castor oil, Eco-fuel, Ethanol, Seed.

Pyrolysis of triglycerides based on biomass was used at large scale for fuels supply during the world wars. For this study, the bio-oil produced from waste fish oil pyrolysis was fractioned in a distillation column to produce a light fraction cut in the range of gasoline. This biofuel was tested in a motorcycle engine to measure its performance in terms of torque and analysing its exhaust gas composition. The emissions were assessed by exploring the combustion of a fossil gasoline without additives and with blends of bio-gasoline, BG20 and BG30 fuels, meaning 20 and 30% of bio-gasoline in fossil gasoline, respectively. Results allowed the identification of the torque and emission gases combinations for each fuel type and the determination that as the percentage of bio-gasoline in the gasoline is increased, the concentration of CO2, CH4, C2H6, C3H8 decreased in direct relation to the engine rotation. The results show that bio-gasoline can be used as an additive of fossil gasoline with gains of performance in terms of torque and lower concentration of CO2 in the emissions. The torque increased from 3.5 to 3.7 N.m and from 4.0 to 5.0 N.m at fifth gear and at 2000 and 4000 rpm, respectively.

Biodiesel production continuously increases. This also increases the production of glycerol, the main by-product of transesterification, whose surplus is not fully absorbed by the market. An interesting destination for glycerol is the production of additives for the biofuel itself, as a green and economical alternative to conventional additives. The objective of this work is to simulate the production processes of three oxygenated fuel additives from the glycerol that is generated in the biodiesel production process: solketal, glycerol tert-butyl ethers (GTBE) and glycerol ethyl ethers (GEE). The processes were simulated in Aspen HYSYS® v8.8 and the capital and production costs were estimated. Among the evaluated alternatives, solketal production showed to be the most promising, since it is simpler than those of the other products and it works with acetone, which is cheaper than tert-butanol - required for GTBE production - and is needed in lower flowrates than ethanol - required for GEE production.

A pretreatment process is a preliminary stage to alter the recalcitrant structure of lignocellulosic biomass for enhancing its digestibility. An evaluation of the energy consumption and the environmental restrictions of the pretreatment step is required to develop a feasible eco-friendly process for industrial implementation. In this study, a combined alkaline-mechanical fractionation of rice straw for fermentable sugar (FS) production was developed with the objectives of i) evaluating energy efficiency and ii) addressing the sustainability of technology. The maximum fermentable sugar production was 0.54 kg/kg rice straw with an enzymatic hydrolysis efficiency of 97.34%. Furthermore, the results indicated that the pretreatment by 5% NaOH followed by mechanical size reduction provided the highest energy efficiency of 0.35 kg of FS/kWh with 94.44% glucose recovery, which also provided the lowest waste generation of less than 0.1 kg of waste/kg FS. These experimental results suggest that the combined alkaline-mechanical fractionation could effectively increase total FS yields and could be a promising pretreatment technology for an eco-friendly and sustainable pretreatment process integrated into a biorefinery platform.

A biodiesel substitute for regular diesel is widely seen as having greater social advantages, such as decreasing greenhouse gas emissions and sustaining rural agriculture economies, than conventional diesel fuel. As a natural fuel, biodiesel has a variety of feedstocks such as vegetable oils and animal fats. A biodegradable material made from fatty acid esters such as methyl and ethyl. Oils such as palm oil, soya bean oil, sunflower oil, etc., produce the majority of today's biodiesel fuels due to their eco-friendliness and sustainability.. Transesterification of waste chicken fat oil to produce biodiesel in a 1:1 ratio, followed by testing the performance and emission characteristics of a C.I engine running on the biodiesel. There will be three distinct proportions of B10, B20, and B30 blends of biodiesel with diesel and 100 ppm of metal oxide (sio and nio) additive in order to improve fuel ignition and cold starting. When using Conventional Diesel at 180 bar, performance measures such as Brake Power (BP), Brake Specific Fuel Consumption (BSFC), and NOx, HC, and CO emission characteristics of the stated engine at 1500 rpm are analysed. The B20 Biofuel sample was shown to be the most efficient and economical compared to the other two samples, B10 and B30. Nickle oxide and silicon oxide nanoparticles in the B20 blend are particularly interesting due to their features such as improved heat transfer rate.

The increasingly severe environmental pollution and energy shortage issues have demanded the production of renewable and sustainable biofuels to replace conventional fossil fuels. Lignocellulosic (LC) biomass as an abundant feedstock for second-generation biofuel production can help overcome the shortcomings of first-generation biofuels related to the “food versus fuel” debate and feedstock availability. Embracing the “circular bioeconomy” concept, an integrated biorefinery platform of LC biomass can be performed by employing different conversion technologies to obtain multiple valuable products. This review provides an overview of the principles and applications of thermochemical processes (pyrolysis, torrefaction, hydrothermal liquefaction, and gasification) and biochemical processes (pretreatment technologies, enzyme hydrolysis, biochemical conversion processes) involved in LC biomass biorefinery for potential biofuel applications. The engineering perspective of LC biofuel production on separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), simultaneous saccharification and co-fermentation (SSCF), and consolidated bioprocessing (CBP) were also discussed.

Better and more efficient use of biomass energy is seen as a favourable option for reducing carbon emissions. Biomass pellet fuel is one of the most common and important ways of utilising biomass energy. The use of diverse biomass resources with different properties for pelletizing is a current research hotspot. This paper provides an innovative overview of co-pelletization technology for biomass pellet fuels. The chemical composition of various types of biomass is classified and the influence of different biomass matrix feedstocks and pelletizing operating parameters on pellet quality and pelletizing process is summarized. The research results indicate that the natural chemical fraction of biomass has a significant influence on the pelletizing process and fuel quality. Furthermore, co-pelletizing can be divided into biomass-biomass co-pelletizing and biomass-non-biomass co-pelletizing. Common co-pelleting combinations include: woody and herbaceous crop co-pelleting; woody or herbaceous crops with high starch and oil content (e.g. microalgae, peanut shells, etc.); mixed pelleting of different parts of the same crop (e.g. bark and leaves of the same quality); co-pelleting of biomass with solid waste (e.g. municipal sludge, waste paper, etc.). Crop types such as oil and sugar used for co-pelletizing with herbaceous and woody crops help to reduce energy consumption in the preparation of biomass pellet fuel and improve the quality of the pellets. Co-pelletization of non-biomass-based materials (domestic production waste, inorganic additives) with biomass also facilitates the pelletizing process and improves the quality of pellet fuel. It is obvious that mixing different raw materials for co-pelletizing is considered a promising way for upgrading biomass pellet and that economical, environmentally friendly and sustainable raw materials are prerequisites for co-pelletizing. Moreover, co-pelletizing seems to be a strong option for enhancing the competitiveness of biomass pellet fuel production at scale in the future.

Cassava processing wastes are suitable substrates for bioethanol production due to their high starch contents. However, these cassava wastes often contain various substances that inhibit cell growth and ethanol production. The abilities of multi-stress tolerant Saccharomyces cerevisiae LC269108 and Pichia kudriavzevii LC375240 to produce ethanol from cassava industrial wastes were evaluated. Analysis of cassava peels and pulps from two cassava starch factories showed that the cassava peels contained high cyanide (KCN) concentrations while cassava pulps contained high concentrations of sodium dodecyl benzene sulfonate (SDBS) used to improve starch extraction in the factory. Although S. cerevisiae LC269108 produced ethanol efficiently from the cassava peel, its growth and ethanol production were inhibited in the cassava pulp. On the other hand, the growth and ethanol production by P. kudriavzevii LC375240 were inhibited slightly in the cassava peel but not in the cassava pulp. Based on the intracellular pyruvate concentrations in the presence of KCN and SDBS, it was inferred that their inhibition site is on the pyruvate synthetic pathways. With a co-culture of the two strains, ethanol production from the cassava peel increased significantly but there was no significant improvement in ethanol production from the cassava pulp.

Cheese whey is the major by-product of the dairy industry, and its disposal constitutes an environmental concern. The production of cheese whey has been increasing, with 190 million tonnes per year being produced nowadays. Therefore, it is emergent to consider different routes for cheese whey utilization. The great nutritional value of cheese whey turns it into an attractive substrate for biotechnological applications. Currently, cheese whey processing includes a protein fractionating step that originates the permeate, a lactose-reach stream further used for valorisation. In the last decades, yeast fermentation has brought several advances to the search for biorefinery alternatives. From the plethora of value-added products that can be obtained from cheese whey, ethanol is the most extensively explored since it is the alternative biofuel most used worldwide. Thus, this review focuses on the different strategies for ethanol production from cheese whey using yeasts as promising biological systems, including its integration in lignocellulosic biorefineries. These valorisation routes encompass the improvement of the fermentation process as well as metabolic engineering techniques for the introduction of heterologous pathways, resorting mainly to Kluyveromyces sp. and Saccharomyces cerevisiae strains. The solutions and challenges of the several strategies will be unveiled and explored in this review., This work was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020; the Ph.D. grants SFRH/BD/130739/2017 and SFRH/BD/132717/2017 to CEC and SLB, respectively., info:eu-repo/semantics/publishedVersion

Lignocellulosic biomass is a promising renewable feedstock for the sustainable manufacturing of biofuels and bioproducts. Among emerging bioproducts, 3-hydroxypropionic acid (3-HP) is of particular...

The consumption of fuel for transportation is increasing during the last decade. Bioethanol is one of the renewable energy has a good opportunity to be applied when the lack of fossil fuel. Bioethanol is derived from the lignocellulose substance through a fermentation process. In this research, the lignocellulose came from the petai peel (Parkia speciosa). The peel was hydrolyzed using an enzyme and continuously fermented for 5 days. The aim of this research is to analyst the mass balance of the bioethanol production from petai peel (Parkia speciosa) through the enzymatic process. The enzyme used in this research are alfa amylase (10 ml) and glucoamylase (10 ml), also Saccharomyces cerevisiae used in the fermentation process. The result shows that the initial material of petai peel was 57 grams will produce bioethanol around 14 grams.

Agricultural wastes are cost-effective, renewable, and abundant. Using bioethanol from oat hulls (o.h.) could be a promising technology to produce ethylene and valuable derivatives. This process fo...

This study investigated bioethanol production from rice straw (RS) and sugarcane bagasse (SCB) which containing 72.8 and 73.2% holocellulose, 56.8 and 58.6% α-cellulose, and 14.9 and 25.1% lignin for RS and SCB, respectively. To eliminate the lignin content, different pretreatment conditions, such as hot water, dilute acid, and acid-alkali, were designed. Acid-alkali was characterized as the best pretreatment for removing ∼79 and 70% of lignin, α-cellulose increased 91.4 and 91%, and holocellulose reached 90.8 and 90% for RS and SCB, respectively. The results revealed that acid-alkali was highly efficient than other pretreatment used for both RS and SCB. After enzymatic hydrolysis of acid-alkali-treated RS and SCB with cellulase, glucose concentrations reached 45 and 42 g/l, respectively. Pichia occidentalis AS.2 was isolated and identified based on 18S rRNA sequencing as a bioethanol producer. Maximization of bioethanol production by P. occidentalis AS.2 using the resulting glucose as a carbon source from RS and SCB was studied using an experimental design. The pH, incubation period, and inoculum size were optimized using Box-Behnken designs (BBD), the final conditions for bioethanol production used 100 g/l acid-alkali-treated fibers, 10 ml cellulase enzyme at 50°C for 5 days at 75 rpm for enzymatic hydrolysis. After time consumed and adjusting the pH to 6, the mixture was inoculated with 2.5% P. occidentalis AS.2 and incubated at 35°C for 24 h at 200 rpm to increase the bioethanol yield by 1.39-fold to 23.7 and 21.4 g/l compared to initial production (17 and 15.3 g/l) between RS and SCB, respectively.

The use of biofuels in vehicles becomes more advantageous than the consumption of fossil fuels, mainly because it uses renewable sources of energy. Recently there are some concerns about biodiesel sources, and hydrotreated vegetable oils (HVO) appear as a possible advanced solution. To understand the effect that the implementation of the new and old European type-approval test cycles (NEDC e WLTP) has on the results of these fuels considering pollutant emissions and fuel consumption results, a EURO V vehicle was subject to these cycles and also to engine performance evaluation tests. For this analysis, the fuels considered were: B0 (pure diesel), B7 (7% of biodiesel), B15 (15% of biodiesel), B100 (pure biodiesel), and HVO15 (15% of HVO). The findings lead to the conclusion that completely replacing fossil fuels with biofuels is not the most cost-effective approach. No significant differences were observed considering the two homologation cycles, the oldest (NEDC) and the actual (WLTP) and the use of HVO also does not present any relevant differences concerning the fuel consumption differences to B0 (+0.58% NEDC and +0.05%WLTP), comparing well with biodiesel behavior (−1.74% NEDC and −0.69%WLTP for B7 and +1.48% NEDC and 1.89% WLTP for B15). Considering the power of the engine obtained with the fuels, the differences are almost negligible, revealing variations smaller than 2% for B7, B15, and HVO15.

Algae biomass is perceived as a prospective source of many types of biofuels, including biogas and biomethane produced in the anaerobic digestion process, ethanol from alcoholic fermentation, biodiesel synthesized from lipid reserve substances, and biohydrogen generated in photobiological transformations. Environmental and economic analyses as well as technological considerations indicate that methane fermentation integrated with bio-oil recovery is one of the most justified directions of energy use of microalgae biomass for energy purposes. A promising direction in the development of bioenergy systems based on the use of microalgae is their integration with waste and pollution neutralization technologies. The use of wastewater, another liquid waste, or flue gases can reduce the costs of biofuel production while having a measurable environmental effect.