Search

The paper drying process has the highest level of energy consumption in the pulp and paper production process. Analysis and optimization of the energy system during the paper drying process is critical for improving the energy efficiency of the entire paper mill. In the existing model for the paper drying process, the solution requires accurate boundary conditions such as the air temperature and humidity of the pocket area and the cylinder surface temperature, which are very difficult to obtain in the papermaking process. This can result in significant deviations between the model solution and the actual production process. This paper focuses on the single-tier dryer cylinder-based paper drying process that has been widely used with high-speed papermaking machines in recent years. A mathematical model is proposed based on real-time data. The verification via industrial production demonstrates that the proposed model is reliable for the paper drying process. Based on the simulation results, two optimization operations have been proposed. The energy consumption decreases from 1.51 t steam/t paper to 1.44 t steam/t paper, 4.6% of the steam and 1.26 × 106 RMB can be saved for a medium-scale paper mill with the annual production capacity of 105 t paper.

The Swedish pulp and paper industry (PPI) must increase energy efficiency to remain competitive on the global market, which has experienced entries from countries with cheaper energy and raw material supplies. Interactions among variables for energy use, production, energy management, electricity price and firm characteristics (FC), in different types of mills, i.e., pulp, paper and integrated mills, in Sweden from 2006 to 2015 indicate that correlations among the studied variables were different in different types of mills. This difference between types of mills seemed to originate partly from varying accessibility to production residue that could be used for energy. For all types of mills, variation of electricity prices did not correlate significantly with energy efficiency during the study period. The studied FC were firm's age, number of employees, number of companies in company group, net sales and profit for the year. Energy efficiency was more affected by the variables characterizing energy and production compared to the variables representing FC. This study also suggested presence of possible discrepancies between FC that were perceived as barriers to energy management towards energy efficiency, according to previous studies, and what was shown by the data combining variables representing energy use, production and FC.

In this paper an original and exhaustive mathematical modelling of air impingement drying systems for the production of tissue paper in the Yankee-hoods configurations is reported, which offers the possibility to optimize its energy performance. The model takes into account many detailed operative parameters of the overall drying process with the aim to execute its energy and mass balance and to evaluate its energy performances. The validity of the mathematical model has been assessed by comparison with actual data from an existing tissue paper mill. Finally, the energy performances of two different layouts of the air system have been evaluated and compared. Changing the operative parameters of the drying process, such as air jet temperature and speed and moisture content of the extraction air, it is possible to obtain the same paper production with an energy saving of about 4.5%. In average, the layout with two parallel air circuits assure an energy saving of about 1% with respect to the layout with a single air circuit.

In order to explore hydrothermal carbonization (HTC) behavior of municipal solid wastes (MSW), four typical components, waste textile, wood, paper and food, were employed to perform HTC and co-HTC process. The experiments were conducted at 240 ○C and 90 min with a 1:12 solid/liquid ratio, where blending ratios of 1:3, 1:1 and 3:1 with waste textile were investigated. As expected, the increase of fixed carbon and carbon content improved the fuel potential of hydrochar. The synergistic index (SI) analysis clearly indicated that significant synergistic effects occurred during co-HTC process. Specifically, all the SI values of hydrochar yield from co-HTC of waste textile with wood and paper were negative, while all SI values of hydrochar yield for waste textile with food were positive. Particularly, the SI values of fuel ratio for all hydrochars were positive which suggested co-HTC could promote to enhance the coalification degree of hydrochars. However, the undesirable increment of O content for hydrochars (derived from 75%waste textile-25% waste food and 50%waste textile-50% waste food) decreased the high heating value. The combustion behavior and nth-order kinetic model analysis showed that hydrochars derived from co-HTC rendered a more stable and lasting combustion profile.

Production of transportation fuels from biorefineries via biomass gasification has been suggested as a way of introducing renewable alternatives in the transportation system with an aim to reduce greenhouse gas emissions to the atmosphere. By co-locating gasification-based processes within heat demanding industries, excess heat from the gasification process can replace fossil or renewable fuels. The objective of this study was to compare the heat integration potential of four different gasification-based biorefinery concepts with a chemical pulp and paper mill. The results showed that the choice of end product which was either methanol, Fischer-Tropsch crude, synthetic natural gas or electricity, can have significant impact on the heat integration potential with a pulp and paper mill and that the heat saving measures implemented in the mill in connection to integration of a gasification process can increase the biomass resource efficiency by up to 3%-points. Heat saving measures can reduce the necessary biomass input to the biorefinery by 50% if the sizing constraint is to replace the bark boiler with excess heat from the biorefinery. A large integrated gasification process with excess steam utilisation in a condensing turbine was beneficial only if grid electricity is produced at below 30% electrical efficiency.

This paper presents a comparison between four gasification-based biorefineries integrated with a pulp and paper mill. It is a continuation of 'Transportation fuel production from gasified biomass integrated with a pulp and paper mill - Part A: Heat integration and system performance'. Synthesis into methanol, Fischer-Tropsch crude or synthetic natural gas, or electricity generation in a gas turbine combined cycle, were evaluated. The concepts were assessed in terms of GHG (greenhouse gas) emissions and economic performance. Net annual profits were positive for all biofuel cases for an annuity factor of 0.1 in the year 2030; however, the results are sensitive to biofuel selling prices and CO2,eq charge. Additionally, GHG emissions from grid electricity are highly influential on the results since all biofuel processes require external power. Credits for stored CO2 might be necessary for processes to be competitive, i.e. storage of separated CO2 from the syngas conditioning has an important role to play. Without CO2 storage, the gas turbine case is better than, or equal to, biofuels regarding GHG emissions. Efficiency measures at the host mill prior to heat integration of a gasification process are beneficial from the perspective of GHG emissions, while having a negative impact on the economy.

Paper mill sludge (PMS) can be efficiently utilized to produce fuels and chemicals. However, wastewater is usually generated during the de-ashing step of the PMS for fibrous materials recovery. Per process requirements, the wastewater stream must be treated which results in an increase in the overall process production cost. Therefore, this research aims at reusing the wastewater produced during the de-ashing step as a substitute for freshwater addition during the conversion of PMS into ethanol. The advantages of this approach include reducing the amount of wastewater produced and enhancing the overall efficiency of the process. It will contribute to the circular economy of zero waste discharges. The results showed that 30% of the process wastewater can be recycled without affecting the enzymatic hydrolysis and ethanol fermentation. Hence, the amount of wastewater that needs to be treated is reduced by 30% resulting in a cost reduction of 22.5%. The results also showed that wastewater recycling minimized the energy demands in the distillation and evaporation units by 1206 kJ/kg. The energy reduction is due to the increase of metals and total soluble solids in the broth stream after fermentation. This process configuration enhanced the process economy, saved energy and managed waste streams.

In this study, through orthogonal experiments design, the influences of ultrasonic pretreatment (frequency, power and treatment time) on co-pyrolysis and catalytic pyrolysis of municipal solid waste and paper mill sludge were explored. The differential thermogravimetry curves became steeper and the peak values were larger after pretreatment, which made the pyrolysis reaction rapidly and the volatile separated out timely. However, the change of pyrolysis characteristics was not obvious after adding MgO. The catalytic effect of MgO increased with the increase of sludge ratio. After pretreatment, the average activation energy of the samples had an overall increasing trend, but the change was small. MgO had a decreasing effect on activation energy, and with the increasing proportion of sludge the degree of reduction became significant. In addition, high ultrasonic frequency had a negative effect on reducing activation energy.

The waste biomass has immense opportunities and plenty of potentials to be an efficient source of renewable energy. Initially, native unripe coconut husk (NCH) was used as raw material for fluidized bed gasification. Then NCH was treated with paper and pulp waste water to impregnate metals present in it for getting enhanced H2 yield in fuel gas. Humidified air was used as gasifying medium, which served the purpose of introducing water vapour to take part in the gasification process. Then after, gasification medium was retrofitted with CO2, which enhanced both the higher heating value (HHV), and CO and H2 content in the fuel gas. This research serves the dual benefit of energy generation and waste minimization. HHV of unripe coconut husk was investigated and found to be 20.95 MJ/kg. H2 yield and HHV from impregnated coconut husk (ICH) were obtained as 55.55 vol % and 5.24 MJ/Nm3, respectively at HER 0.1 and gasification temperature of 850 °C in case of fluidized bed gasification. The GC-MS analysis of fuel oil obtained from ICH gasification was done to get the information about high yield of fuel gas as promise product of fluidized bed gasification.

Long term annual electricity consumption forecasting is very important for country's energy planning. These forecasts are influenced by several factors (political, technological, social, environmental and economic), and brings with itself a high uncertainty degree in its results and difficulties in the evaluation of such factors over them. A methodology that eases to take into account these factors aiming improve the results and help understanding the electricity consumption annual trajectory till the forecast horizon is, therefore, very much useful and desired. So, we propose a modelling structure using the bottom-up approach to cope with these matters and to evaluate the trajectory of long term annual electricity consumption of a sector of the Brazilian industry up to 2050 considering energy efficiency (EE) scenarios. It is important to emphasize that Brazil is a developing country, and to build a bottom-up approach was a challenge, mainly due to the fact that this model is data intensive. In particular, this modelling was applied in the pulp and paper sector. The main goal was to consider technological diffusion scenarios in EE measures, and show the energy savings achieved. The results point an energy savings in the order of 25% when an actual scenario is considered.

In hot and dry climatic zones, direct evaporative cooling (DEC) system is used as an economical and efficient alternative to traditional air conditioning systems. The present paper concerns comprehensive experimental investigations and analysis of heat and mass transfer characteristics and thermal performance parameters of a bee-hive construction of corrugated-cellulose papers as a new cooling pad material. The performance parameters used to evaluate the effectiveness of the cooling pad materials are the outlet air temperature and relative humidity, pressure drop, humidifier effectiveness, rate of the evaporated water, sensible cooling capacity, specific cooling capacity (SCC), coefficient of performance (COP), specific water consumption (SWC), and Nusselt and Sherwood numbers. The cooling pad performance was investigated for a wide range of air and water temperatures and flow rates and pad thicknesses. The results show the enhancements of heat and mass transfer coefficients and the performance parameters with rising air temperature and water flow rate to humidifier. High values of the performance parameters (hc = 45 W/m2 oC and hm = 0.23 m/s, e h u m = 0.85 and COP = 170) are obtained compared to the traditional pad materials. Experimental correlations for the evaporative cooler performance parameters in terms of air and water temperatures and flow rates pad thicknesses are presented.

Power generation by variable renewable energy (VRE) is expected to expand for decarbonization, although it is difficult to ensure stabilization of the energy demand due to fluctuations in the power output from VRE. To accelerate VRE implementation, wind-powered thermal energy systems (WTth-ES), which can provide dispatchable power using wind–thermal energy converter (WECth) and thermal energy storage (TES), have been proposed. In this study, we are tackling the installation of VRE, i.e., wind energy, by TES with WECth compared with wind turbine (WTp) in paper mills to demonstrate the applicability of TES in an industrial sector. Conventional and alternative energy systems in paper mills with TES were mathematically modeled and simulated to analyze the transmittable power output and the greenhouse gas (GHG) emissions by life cycle assessment. With the installation of TES and wind energy, transmittable power could be increased with GHG emissions reduction. However, their excess installation or unbalanced combination resulted in an increase in GHG emissions and a decrease in transmittable power. By comparing the cases, the combination of paper mill, TES, and WECth could convert thermal energy efficiently and mitigate fossil fuel consumption for multiple production of paper and power from the paper mill.

The aim of this paper is to develop a novel method for the retrofit of Heat Exchanger Networks based on Bridge Retrofit analysis. The method identifies Retrofit Bridges that correspond to energy saving modifications using two new proposed tools: The Heat Surplus-Deficit Table and the Modified Energy Transfer Diagram. These tools both allow the identification and quantification of Retrofit Bridges. These tools have been developed following conventional Pinch Analysis tools such as the Composite Curve and Grand Composite Curve. The connection between the conventional Heat Exchanger Network synthesis tools and the proposed retrofit tools is established to improve understanding of the method and relate it to what is currently used in both literature and industry. The method is demonstrated with a simple illustrative example and a more detail paper mill case study. The paper mill incorporates a paper machine and paper recycling plant and is co-located with a Kraft pulp mill in New Zealand. Results from the retrofit method suggest a retrofit design that will achieve an annualised profit of NZD 570,000/y (USD 414,000/y) with a payback of 2.4 y.

This paper investigates the performance and emission analyses of a turbo-charged diesel engine fuelled with pre-mixed and post-mixed hybrid biodiesel blends at varying load condition thereby maintaining injection timing, injection pressure and speed constant at 230bTDC, 220 bar and 1500 RPM. The experimental result depicted that post-mixed biodiesel blends (POBD 20) showed higher brake specific energy consumption and exhaust gas temperature by 4.6% and 2.02% than that of diesel while brake thermal efficiency was reduced by 5.68%. However, engine overall performance of post-mixed biodiesel blends (POBD 20) was found to be comparable with diesel and other prepared test fuel blends. Similarly, comparing exhaust emissions, oxides of nitrogen and carbon dioxide were on its higher side by 2.64% and 2.43% than normal diesel fuel. On the contrary, carbon monoxide, hydrocarbon and smoke opacity for POBD 20 were found to be 36.87%, 51.5% and 23.2% lower than conventional diesel fuel. From the above study, it is finally concluded that POBD 20 blend may be used as an alternative optional fuel that can substitute present diesel fuel without much engine modification and exhaust related problems.

The co-gasification of coal and dried sewage sludge (DSS) was conducted using a two-stage gasifier consisting of a fluidized bed gasifier and a tar-cracking reactor. In this study, the effect of the blending ratio of coal and DSS was investigated. Producer gases that were obtained from the tar-cracking reactor filled with active carbon contained high levels of hydrogen (maximum H2: 27.7 vol%) and low tar contents (minimum tar: 0 mg/Nm3). Upon gasification of the coal/DSS blends, the hydrogen content decreased and tar content increased with increasing DSS. Blends with coal/DSS ratios of 70/30 and 50/50 showed a synergetic effect on tar reduction, which could be attributed to the high ash content of the DSS. The gasification of the 70% DSS blend increased the condensed tar yield by only 0.1 wt%, compared to coal gasification. Lastly, a hot filter filled with Fe-impregnated active carbon was applied to completely remove tar from producer gas, which led to the production of a tar-free and hydrogen-rich gas (30 vol%). Furthermore, the Fe-impregnated active carbon reduced the H2S content to 229 ppmv. In summary, it was possible to produce a clean gas from coal and DSS blends in the UOS gasification process.

The energy consumption of an ammonia process plays an important role in the industrial energy consumption. For an ammonia synthesis process using pure oxygen gasification, the energy consumption of cryogenic air separation occupies a large proportion. The purity of the oxygen product from the air separation unit is mostly 99.6% in an ammonia process with pure oxygen gasification. The energy consumption of air separation will decrease significantly, if the purity of the oxygen product is reduced properly, which will lead to the decrease of the energy consumption of the total ammonia process, as the nitrogen element is needed for ammonia synthesis. However, the operating costs of the subsequent units will increase because of the increase of the syngas flow rate. So, there is an optimal oxygen purity that can minimize the energy consumption of the whole ammonia synthesis process. According to temperature, purification technology can be divided into cold and hot technologies. In this work, two different process models for ammonia production from coal with different purification technologies are developed to determine the process energy consumption with different inlet oxygen purity. In the process of ammonia production from coal with cold purification, the reduction of oxygen purity leads to the increase of energy consumption of oxygen compressor, methanol regeneration and refrigeration, and the decrease of nitrogen compressor power consumption. In the process with hot purification, the reduction of oxygen purity leads to the increase of energy consumption of oxygen compressor, preheating and MDEA regeneration, and the decrease of nitrogen compressor power consumption. The relationships between the eight kinds of energy consumption and oxygen purity are linear. Combined with the relationship between oxygen purity and the energy consumption of the air separation unit, the optimal oxygen purity which minimizes the process energy consumption is obtained. In the ammonia production process with cold purification, the optimal oxygen purity is 95%, which can save 10.3% of the energy consumption of the air separation compared with the current process using the 99.6% purity oxygen. While in the ammonia production process with hot purification, the optimal oxygen purity is 96%, which can save 8.4% of the energy consumption of the air separation.

The co-combustion of raw and torrefied biomasses is recognised as environmental friendly energy conversion. Co-combustion of hard coal with raw biomass has been widely investigated in the literature. In contrast, co-combustion with torrefied biomass has been not particularly investigated. This paper shows the investigations of co-combustion of raw, torrefied biomass and biodegradable waste in bubbling fluidized bed combustor. Two kind of biomass sources (i.e. willow (Salix viminalis), olive oil residue) and waste wood from furniture manufacturing were analysed in terms of fuel feeding rate, CO, SO 2 and NO x emission and ash behavior. The part of a raw biomass was torrefied using a rotary kiln reactor. Hence, the combustion performance of raw and torrefied biomass was compared. The impact of torrefaction on the emission of CO, SO 2 and NO x depends on biomass type. In the case of willow the decrease of SO 2 emission was obtained when the raw biomass was substituted by the torrefied biomass. Additionally, ash fusibility from the raw and torrefied biomass was analysed. It was noticed that co-combustion of torrefied biomass caused increase of ash initial deformation temperature (IDT) comparing to co-combustion with a raw biomass.

The main objective of the research was to develop a method of biomass grindability determination (Biomass Grindability Index), which would allow for a clear classification of different types of solid biofuels in terms of their milling properties. The objective of the research included also the assessment of the possibility of adaptation of the existing coal grindability determination methods for evaluation of biomass milling. In the course of research, the biomass grindability determination method was modified to obtain the highest possible reliability of the developed index. The scope of laboratory tests being focused on influence of circumferential speed of test mill beaters, particle size distribution of sample, test time, mass and volume of sample. The results of laboratory and industrial tests have shown that the grindability index based on mean particle sizes of feed and product is unreliable. Grindability of different types of biomass, comminuted in beater mills, can be clearly determined by the index expressed as the ratio of energy consumption during the test to the amount of specified product size fraction. During the study laboratory test results obtained for proposed grindability index were compared to other grindability indices determined for utilized in research types of biomass.

In this work, the liquefaction of coal and biomass with direct liquefaction strategy was explored. The point of liquefaction is both to utilize a greater amount of the current coal and biomass assets all the more productively and to create an alternative liquid fuel to oil. Along these lines, the procedure parameters must be resolved to expand the liquefaction efficiency. In addition, it is proposed to do the liquefaction efficiency, particularly in the reactant conditions, to expand the measure of oil. Process parameters were controlled by utilizing Factorial Experimental Design technique in the liquefaction procedures. The solid/liquid ratio was changed as 1/2-1/4, the catalyst concentration was 2–6%, the temperature was 375–400 °C and the duration was 30–90 min. Starting nitrogen pressure was set at 30 bar, stirring speed was 400 rpm, coal/biomass proportion was settled at 1/1. Tetralin as a solvent and MoO3 as catalyst were utilized. Toward the finish of the liquefaction procedure, the total conversions were computed in view of the acquired non-reactive solid (char). As indicated by the outcomes obtained, the most total conversion (81.9%) was acquired at a solid/liquid proportion of 1/2, a catalyst concentration of 2%, a reaction time of 90 min and a reaction temperature of 400 °C. In light of total conversions and elective liquid fuel (oil) in the given conditions, the solid/liquid ratio should be taken as 1/2, the catalyst concentration is 2%, the reaction time is 30–90 min and the reaction temperature is 400 °C. The lowest reaction time found, in this study, is the innovative solution for reducing co-liquefaction cost preferred.

Biodiesel appears as a replenishable and sustainable energy source and can be used a direct replacement to petro-diesel without any major transformations in ongoing diesel engines. This work concentrates on production of Calophyllum Inophyllum biodiesel (CIB) and preparing 10% blend (CIB10) sample to investigate the effects of varying the injection strategies and exhaust gas recirculation (EGR) in common-rail direct injection engine. The experimental results shows that 10% of pilot fuel and 90% main injection strategy (B10@P10-M90) is superior among all others injection strategies with respect to pure diesel. B10@P10-M90 fuel injection strategy produces the maximum efficiency of 35.8% and lowest fuel consumption of 0.25 kg/kWh compared to all the injection strategies. The carbon monoxide (CO) and hydrocarbon (HC) emissions are also found to be quite low compared to all the other test samples including pure diesel. However B10@P10-M90 results in higher average oxides of nitrogen (NOx) emission which is 18.9% higher in contrast to conventional diesel at full load condition. With the implementation of 10% and 20% EGR with B10@P10-M90, the average NOx emissions decreased by 14.4% and 27.6% respectively compared to B10@P10-M90 without any EGR without significant loss in the performance of the existing diesel engine.

Two sugarcane biofuels and mineral diesel fuel are tested under full load conditions, under the same values of performance and under the European Transient Cycle on an engine test bench, without any modifications to the ECU. The target is to compare engine performance and emissions. At full load, engine performance varies due to the variation in LHV. Under the same values of performance, the sugarcane biodiesel-LS9 provides the lowest THC emissions. The higher CN and exhaust gas recirculation of the sugarcane biodiesel-LS9 and the higher H/C ratio of the sugarcane diesel-farnesane compared to the diesel S50 provide a NOx reduction. Neither the increment in bsfc nor the increment of %EGR for the sugarcane biodiesel-LS9 deteriorate the combustion, so its CO emissions are lower. The sugarcane biodiesel-LS9 leads to the lowest NOx and PM specific emissions under transient operation, followed by the sugarcane diesel-farnesane. The THC and CO specific emissions are higher for the biofuels in comparison to the diesel S50. The main reason for these results is the impact of the properties of the biofuels on the ECU response However, both biofuels produce less harmful emissions at idle conditions, which supports their usage to reduce exhaust emissions in urban areas.

Brazil has a well-developed forest sector and is the largest producer of charcoal in the world in addition to being one of the main producers of wood. A big part of this production is destined to the steel industry. However, approximately 30 wt% of all wood energy is transformed into charcoal, and the other 70 wt% consisting of condensable and non-condensable gases (NCG) emitted in the atmosphere generating pollution and energy waste. With the purpose of altering this scenario, the present project, undertaken in laboratory scale from muffle furnace, saught as its main objective to carbonize species of Eucalyptus urograndis. Charcoal physical-chemical characterization, bio-oil and (NCG) produced by the process have also been done. In parallel, the performance of some operational variables (heating rate and final carbonization temperature) have been analyzed which affect the process of charcoal production through experimental design. The average income in charcoal, bio-oil and NCG has reached values of approximately 32.6, 40.1 and 27.3 wt% respectively. To obtain a quality charcoal as in the quantitative point of view (yield), as to the qualitative point of view (performance in fixed carbon and low friability), it must operate at a lower heating rate and milder final carbonization temperatures.

This study presents the energy and exergy-based performances of a solar dryer integrated with packed bed (TES) as thermal energy storage medium. As a sample application, drying kinetics of orange slices was determined. The aim of this study is to evaluate the thermal storage potential of the packed bed by focusing on energy consumption and exergy-sustainability indicators. Experiments were repeated twice a day (sunshine hours and off-sunshine hours). The results indicated that solar dryer integrated with packed bed reduced the moisture content of orange slices from 93.5% to 10.28% (at the first experiment) and 10.76% (at the second experiment), respectively. Total useful energy consumption for both the two status were detected as 89.892 MJ and 88.11 MJ, respectively. The exergy efficiency for the drying system during the sunshine hours ranged from 50.18 to 66.58%.The exergy efficiency of the drying process, in case of using the stored thermal energy, also changed between 54.71 and 68.37%. Moreover, a mathematical model was developed to predict the change of the moisture ratio of orange slices during time. According to the results of the model, Modified Henderson and Pabis Model presented the optimum parameters for determining the drying kinetics of orange slices.

The main purpose of this study was the optimization of torrefaction conditions for biochar cofiring with new Taguchi indicators. However, the combustion characteristics of biochar cofiring in different furnaces and reactors are distinct. Examining optimal torrefaction conditions using the Taguchi method based on maximum energy or mass yields is paradoxical. Accordingly, three indicators, that is S index, proximate-based index (PA index), and elemental-based index (EB index), were proposed for solid fuel combustion. To study the combustion behavior of biochar torrefied under optimal conditions, a single pellet combustor was employed to record the characteristic time and gas emission at various reaction regions. Furthermore, the effects of ambient temperature and biomass blending ratio (BBR) on combustion behavior were investigated in the single pellet combustion experiment. When the temperature was increased to 600 °C, the ignition delay time ranged from 8 to 29 s, whereas at 800 °C, the fuels were ignited within 4 s of each other. The total combustion times were shortened as the reaction rate increased. The total combustion time of Australian coal, raw Miscanthus, 50% blended biochar (S index), 50% blended biochar (PB index), and 50% blended biochar (EB index) were shortened by 19.3%, 18.9%, 14.2%, 12.9%, and 13.5%, respectively.

The increasing cost of fossil fuels as well as increasing environmental pollution has attracted research in alternative fuels and additives for improving the performance and reducing emissions of diesel engines without costly engine modifications. In the present article, an exhaustive analysis of the performance and emissions of oxygenated ternary fuel blends is done through modeling and experimental investigation to determine the optimal blending ratio of additives for reduced emissions. The Nitromethane-n-butanol–diesel blend is termed as bio-oxygenated fuel. Baseline data were generated by using diesel and a blend of 20% (v/v) n-butanol with diesel (B20). Ternary blends of Nitromethane (NM) and B20 containing 1–3% NM by volume were prepared and experiments were conducted. It was observed that 1% of Nitromethane by volume (NM1B20) gives best results for emission reduction. The overall effect of this ternary blend was reduction in smoke and nitrogen oxides (NOx) by 61.85% and 8.07%, respectively, as compared to diesel. Moreover, the performance of ternary blend was also found to be better than the base fuels. It was thus concluded that Nitromethane-n-butanol–diesel blends can be highly effective alternatives in reducing emissions in diesel engines with a little improvement in the overall performance characteristics.

One prevailing issue for assessing the performance of hydrothermal liquefaction is understanding the role of the extraction solvent used for product separation. This study evaluated the extraction agent's impact on the hydrothermal liquefaction products and energy efficiency. Three representative solvents (acetone, dichloromethane, and toluene) were chosen with three representative high-carbohydrate, protein, and ash content feedstocks (Chlorella sp., Nannochloropsis sp., and Enteromorpha pr., respectively). Extraction of the oil using dichloromethane led to the highest biocrude oil yield (dry biomass) for Chlorella sp. (48.8%), toluene for Nannochloropsis sp. (23.3%), and acetone for Enteromorpha pr. (9.8%). The solvent selection led to a maximum variation of 20.4% for all oil yields. Dichloromethane produced high energy recovery values (maximum: 67.1%) and low energy consumption ratios (minimum: 0.06) regardless of the feedstock chemical composition. Dichloromethane also led to consistently high net energy values and high fossil energy ratios amongst all feedstocks. We speculate that the solvent polarity, chemical structure, hydrogen bonding, and dipole-dipole interactions influenced output parameters by the selective isolation and extraction of the chemical compounds in the biocrude oil. This study suggested that the extraction solvent selection should be carefully considered and normalized for the reporting of hydrothermal liquefaction yields and energy efficiency values.

In this study, the utilization of textile fibres as energy feedstock in the form of biochar was investigated depending on the fibre type. The biochars were produced from waste natural and synthetic fibres and its blends. For this purpose, different types of textile fibres (cotton, viscose, polyester, acrylic) and their blends (cotton/polyester, acrylic/wool, acrylic/polyester, acrylic/viscose) were torrefied at temperatures between 300 and 400 degrees C. The effects of torrefaction temperature and fibre type on biochar yield and biochar properties (fuel properties, morphological and structural properties and combustion characteristics) were investigated. The results showed that the temperature had a significant effect on biochar yield whereas the fibre type was the only significant factor on energy densification ratio and biochar properties. The torrefaction of tested fibres and blends resulted in an energy-intensive solid fuel, having a negligible amount of ash and sulphur. Although torrefied acrylic based textile fibres had similar H/C and O/C ratios to bituminous coal, it was concluded that high nitrogen contents will limit their usage as fuel. Overally, this study showed that torrefaction of cotton and cotton/polyester textile wastes is a promising process for the production of a solid fuel, which can be used as a substitute fuel in coal/waste co-firing systems. (C) 2018 Elsevier Ltd. All rights reserved.

To achieve reductions in CO2 emissions, replacing fossil fuels with biomass in thermal power generation is becoming increasingly prevalent. In general, the fuel nature and combustion characteristics of biomass are distinct from those of fossil fuels. Biomass is typically subjected to torrefaction to improve its grindability, hydrophobicity, and heating value (HV). However, the pretreatment process is accompanied by fuel property alteration and an energy penalty. This is strongly associated with the operating envelope and combustion stability of biochar cofiring with coal. Therefore, in this study, the Taguchi method was used to calculate the optimal torrefaction parameters for maximum energy yield and HV. Thermogravimetric and fuel characteristic analyses were performed to examine the pyrolysis features and combustion behavior of the studied fuels. In addition, a blend of 50% Miscanthus biochar and 50% Australia coal was produced and pressed into pellets. The pellets were placed into a free-drop furnace to observe their combustion behavior. The results demonstrated that the ignition temperature and burnout temperature of the blended fuels could be effectively reduced, and that their fuel conversion rates and combustion characteristic index could be enhanced. The results can be applied to coal cofiring in large-scale boilers in the future.

In this study, municipal solid waste was gasified with switchgrass, i.e., co-gasification, using a commercial-scale downdraft gasifier to produce power. The experiments were performed using a commercial-scale 100 kg/h downdraft gasifier at co-gasification ratios of 0, 20 and 40%. The hot and cold gas efficiencies, syngas compositions, heating value and yield, gasifier temperatures and tar content were measured and analyzed. The results indicate that co-gasification of up to 40% MSW performed satisfactorily. The heating values of syngas were 6.2, 6.5 and 6.7 MJ/Nm3 for co-gasification ratios of 0, 20 and 40%, respectively. The cold and hot gas efficiencies were 60.1, 51.1 and 60.0% and 65.0, 55.2 and 64.4% for co-gasification ratios of 0, 20 and 40%, respectively.

The targets for renewable energy set by the European Union have resulted in a surge in consumption of wood pellets, and the demand is expected to further increase the next decade. We use economic modelling to assess the impact on global wood-based product markets of gradually increasing wood pellets consumption within the EU. Comparing a scenario wherein consumption is determined exclusively by market forces with one where EU consumption is set to double between 2015 and 2030, we characterize the deviation from the unregulated market equilibrium that would attain. Our results highlight the necessity of assessing market impacts over time, with a sufficient geographical disaggregation. An increased EU demand for wood pellets would, apart from increased EU production, results in increased imports. The main sources are projected to be Russia, Canada, and, particularly, the USA. The results indicate synergies and competition between wood-based products and wood pellets. In general sawmilling stand to gain from increased wood pellets' consumption, while the opposite holds for wood-based panels and most paper grades. Due to the feedstock mix used in production of wood pellets and wood-based products, effects vary over time and among different EU members, as well as between EU and other regions.

Facing the global issues of dwindling oil reserves and global warming, the search for alternative green energy source has become a priority. Microalgal biofuels has been regarded as a potential sustainable energy source, due to the high oil yield per area of land, ease of culturing microalgae, zero net carbon emission and reduced competition for arable land. In this paper, five different lipid extraction methods were studied using dry biomass of the microalga Chlamydomonas sp. Folch et al. method gave the highest oil yield of 26.27 wt%. The extracted microalgal oil underwent transesterification process using immobilised lipases. The highest conversion achieved was 72.09% in the following optimized conditions: 0.100 g of immobilised enzymes and solvent to methanol volume ratio of 1:1 with tert-butanol as the organic solvent.

Primary energy sources have limited deposits and their exploitation has a negative impact on the environment. Biofuels production is an efficient and profitable method of environmentally-friendly energy production in terms of economic reasons. In recent years use of renewable energy sources (RES) in the Polish energy balance can be noticed. The main sector in which can be observed a dynamic growth is the biomass market, with the solid biofuel market in particular. The aim of this research was to perform an economic and energy analysis of briquettes and pellets production. The obtained results of economic analyzes have shown that the individual production of solid biofuels from digestate is more profitable than using sawdust as a substrate. The costs of producing solid biofuels from solid fraction of digested pulp, as well as their calorific value, make the discussed substrate to be used to produce energy. The calorific value of the solid biofuel produced from the digested pulp solid fraction (DSF) can be compared to the calorific value of biofuel generated from sawdust. The digested pulp can be considered as an alternative to the sawdust in the production of solid biofuels.

One sustainable use of sewage sludge (SS) is to use it as fuel in existing coal-fired plants. Towards this end, this study evaluated thermal characteristics and co-combustion efficiency of dried SS samples from six wastewater treatment plants with different sludge treatment units. Fuel quality of SS based on proximate and ultimate analyses and calorific value, and ash composition by XRF analysis were investigated. Then the SS samples were co-combusted in a laboratory batch reactor in mixtures with coal (3%, 5%, 10%, 20% and 30%). Results showed that samples had good calorific values (between 1931 and 3852 cal/g). Furthermore, the type of sludge stabilization processes had an important effect on thermal characteristics of samples and the point where the sludge addition started to intrude the combustion efficiency. Among all stabilization methods, lime stabilization was observed to affect the thermal characteristics the most. Sludge treated with anaerobic stabilization had lower calorific values than the ones stabilized aerobically. The results from co-combustion experiments showed that as the percentage of SS in the mixture increased from 5% to 30%, the combustion efficiency decreased gradually from 99.5% to 97.5%. Furthermore, according to XRF analysis result, fouling and slagging indices of samples were higher than the limit values.

Herein, we report on a combined process that incorporates hydrothermal liquefaction (HTL) and supercritical water gasification (SCWG) to improve energy recovered from algal biomass. Eight algal biomasses, including four microalgae and four macroalgae with a large difference in biochemical compositions, were screened for this dual process. The algal biomass feedstocks significantly affected the carbon and energy distribution in the product fractions (crude bio-oil, solid, gas, and water-soluble products). 62.50–71.34% energy of microalgae and 6.03–41.06% energy of macroalgae could be recovered as crude bio-oil. 11.86–21.55% carbon of the microalgae and 8.01–15.82% carbon of the macroalgae was distributed in the HTL process water in form of water soluble products after the HTL process. 14.3–33.7% energy of microalgae and 30.18–36.34% energy of macroalgae was retained in the HTL process water. SCWG could convert the organics in the HTL process water into fuel gases consisting mainly of H2 and CH4. 54–91% carbon of the HTL process water was transformed into the fuel gases, which correspond 5.53–18.30% energy of the algal biomass. Thus, this work shows that the integration of HTL and SCWG could improve energy recovery from algal biomass relative to the HTL process alone.

Non-centrifuged sugar (NCS) is produced through the evaporation of water from sugarcane juice, using the thermal energy released from the combustion of sugarcane bagasse. The energy efficiency of the process varies significantly according to the technology implemented in evaporation and combustion operations. Therefore, energy optimization usage becomes essential for the improvement of the equipment, as well as the appropriate development of the manufacturing process. The aim of this study was to evaluate seven groups of technologies related to bagasse combustion and heat exchange systems, used in the production of NCS. The evaluation was performed based on five parameters: overall thermal efficiency (η), energy consumption (MJ)/NCS (kg), O2, CO2 and CO emission indices at the exit of the process, flue gases/NCS (kg/kg), and air-fuel ratio (AFR). Each group of technologies evaluated had a significant effect on the parameters considered. However, the best results were shown by the technologies where steam was used in closed systems, obtaining an overall thermal efficiency of 63.63 ± 5.17%, with a significant decrease in fuel consumption and lower gas emissions.

Lignite is one of common applied fossil fuels worldwide, and solid wastes like biomass as well as sewage sludge are promising alternatives of fossil fuels. The isothermal combustion performances of lignite/solid wastes (eucalyptus bark and sewage sludge) briquettes between 500 °C and 800 °C in a bench-scale fixed bed furnace were examined based on a macro-thermogravimetric analysis approach. Compared with untreated samples, the average combustion rates of lignite and sewage sludge with the microwave treatment decreased, while those for treated eucalyptus bark increased. The drying, devolatilization and char combustion processes overlapped in the isothermal combustion for all samples. The treated lignite had a high aromatic hydrocarbon, while both the treated sewage sludge and eucalyptus bark had high hydroxyl and methyl group (CH3). After the microwave pretreatment, the fuel rank of lignite was prompted, while that for eucalyptus bark and sewage sludge degraded. Through the microwave pretreatment, the activation energies of lignite, sewage sludge, and eucalyptus bark grew from 15.45 to 21.20 kJ mol−1, 18.23–20.77 kJ mol−1, and 13.27–14.22 kJ mol−1. The study can provide some basic data for the energy utilization of lignite and solid wastes.

Chemical looping combustion (CLC) is regarded as the most promising technology for CO2 capture to mitigate greenhouse gas effect. In this work, a technical and economic performance of CH4-feed CLC power plant by means of utilizing promising nickel-, copper-, and ilmenite-based oxygen carriers is studied. Nickel-based CLC power plant has the highest net power efficiency of 50.14%, followed by 48.02% for ilmenite-based case and 45.59% for copper-based case. By contrast nickel-based case has a specific CO2 emission of 1.44 kg/MW h, which is dramatically lower than the referenced NGCC with CCS system (40.10 kg/MW h). The economic analyse reveal nickel-based case is most economic-benefits due to the lowest cost of electricity (COE) of 71.66€/MW h, approximately 0.32 €/MW h and 13.06 €/MW h COE reduction benefits have been increased in comparison with ilmenite-based and copper-based case, respectively. The natural gas price has an important influence on COE, as approximately 49.73%, 48.60% and 56.30% of COE enhancement is expected with the natural gas price ranging in 4–8 €/GJ for nickel-based, copper-based, and ilmenite-based case, respectively. Finally a comparison between NGCC and CLC-related power system in terms of economic performance further demonstrates the feasibility of the latter system.

In this work, 138 datapoints, including elemental composition and ultimate analysis of various types of sewage sludge, and the hydrothermal carbonization reaction conditions, are used to develop a prediction model for the nitrogen content of the hydrochar. The results suggested that a two-layer feedforward neural network with five (05) neurons in the hidden layer can accurately predict the nitrogen content of the hydrochar based on the reaction temperature and the contents of nitrogen, carbon, volatiles and fixed carbon in the feedstock. Over 100 runs, the R2 and RMSE are in [87.547–99.097%] and [0.243–1.431] wt.% (db), respectively. Moreover, a statistical and regression analysis revealed that the sewage sludge-N is the main contributor to the hydrochar-N. Mostly, 40–70% of sewage sludge-N goes to hydrochar-N. The results are consistent with previous experimental reports, and this model can be used to predict the sewage sludge-derived hydrochar-N.

Microbial fuel cell (MFC) technology allows renewable energy production from the decomposition of organic matter present in wastewater. This technology, however, poses challenges that hinder scaling up of its usage in practical implementation. Also, resource recovery from the available waste sources is attracting attention due to the immense amount of valuable nutrients present in the wastewater. Herein, the present study focuses on investigating high-performance anodes, that is, using a stainless-steel brush (SSB) and carbon brush (CB) to accommodate the MFC in terms of energy production, leading to transformation into a microbial nutrient recovery system (MNRS) for nutrients’ recovery from wastewater. The present novel SSB anode system generated a stable voltage of ∼0.4V and a maximum power density of ∼400 mW/m2 whereas CB anode system produced the voltage and maximum power density of ∼0.5 V and ∼800 mW/m2, respectively. Besides, using the MNRS process, recovery of nutrients in terms of PO43− (80–83.4% for CB-MNRS and 60–69.5% for SSB-MNRS when using feed PO43− concentration of 10–20 ppm) and NH4+ (63–80.64% for the CB-MNRS and 52–70% for the SSB-MNRS when using feed NH4+ with a concentration of 10–20 ppm) was achieved.

The production of biogas for combined heat and power generation represents a common method in Germany. An alternative is the purification of biogas to biomethane and injection into the natural gas grid to decouple gas production from usage in terms of space and time. The concept of pressurized two-stage anaerobic digestion integrates biogas production, upgrading and pressure boosting within one process. The increasing solubility of CO 2 in process liquid at high pressures results in high methane contents in gaseous phase and in drop of pH. To investigate the effects of high initial pressures (10, 20, 30 bar) and dissolved CO 2 on pH-value, production kinetics and specific methane yields, pressurized batch methane reactors were built up. Additionally, a method for indirect measuring of pH-value was determined. The results of the experiment showed a decrease in pH from 7 to 6.31 (10 bar) and 6.25 (30 bar). Furthermore, neither a significant influence of initial pressures on the pressure increase nor on the degradation of organics and the specific methane yields was observed. However, the results show that anaerobic digestion at high pressures up to 30 bar might be a promising alternative to post purification and pressure boosting applications.

Effect of wastewater characteristics on bioenergy recovery in sewage treatment by anaerobic membrane bioreactor (AnMBR) was investigated. Based on COD removal, sludge concentration change and COD mass balance, nonionic surfactant or operation at 20–25 °C had no effect on the energy recovery with COD conversion of 72–79%. The anaerobic microbes can cope with the characteristic by releasing more SMP/EPS or changing its community structure. Compared with Control (6.99 × 10 7 kJ/d, HRT 12 h), with suspended solid or operation at 15 °C and 10 °C, the captured energy was only 5.90 × 10 7 kJ/d, 6.0 × 10 7 kJ/d and 3.10 × 10 7 kJ/d, respectively while the energy in dissolved methane was 1.08 × 10 7 kJ/d, 0.98 × 10 7 kJ/d and 1.26 × 10 7 kJ/d. Hence, the recovery efficiency was decreased by 15.6%, 14.2% and 55.7%. The recovery also decreased by 26% (5.17 × 10 7 kJ/d) in the presence of anionic surfactant. The toxicity of anionic surfactant to the anaerobic microbes and lower growth rate of microorganism at psychrophilic temperatures were responsible to the decrease of bioenergy recovery efficiency. SS accumulation will finally increase the loading rate of sludge and decrease the bioenergy recovery from the long-term view.

The present study evaluates a sugarcane biorefinery producing ethanol through juice fermentation and methanol via gasification of sugarcane lignocellulosic residues and liquid fuel synthesis. Two technologies of gasification named entrained flow and circulating fluidized bed are compared. Flowsheet modeling and thermo-economic analysis methods are applied, followed by a multi-objective optimization based on a genetic algorithm. The optimum Ethanol–Methanol biorefinery design options are compared with other previously studied sugarcane biorefineries. The results show that the biorefinery's energy efficiency increases significantly with the integration of a methanol production plant in a conventional ethanol distillery. The configuration using an entrained flow gasifier presents lower conversion efficiency than the one using a circulating fluidized bed gasifier. However, for the entrained flow gasifier configuration, the size of the methanol production process could be bigger since more heat is available for the ethanol process favouring the integration with the ethanol plant. Higher energy efficiency due to increase of methanol production leads to a higher total investment for both gasification technologies. The cost analysis shows that the calculated methanol production cost is 30% higher than its current market price. Environmental incentives for biofuels could change this scenario but are not in the scope of this study.

Co-hydrotreating of microalgae (M) and UEO (used engine oil) was examined for the direct production of gasoline and diesel fuels or blending components. The addition of the noble metal catalysts promoted the cracking and in situ hydrogenation of liquid products (oils) and was beneficial for the production of liquid products. Using Pt/C as the catalyst, the effects of temperature (350–450 °C), time (2–6 h), UEO/M mass ratio (6/0–0/6), catalyst loading (1–60 wt.%), and initial H2 pressure (0.1–8 MPa) on the yield and quality of the liquid products were studied. A synergistic effect existed during the co-hydrotreating of the UEO and microalgae, which not only favored the production of liquid products but also promoted in situ denitrogenation and deoxygenation. Co-hydrotreating produced an upgraded oil with fuel properties (e.g., density, calorific value) comparable to traditional liquid transportation fuels derived from fossil fuel. The S content (45 ppm) of the upgraded oil produced at 450 °C is even below the minimum requirement of China IV diesel (50 ppm). Examination of the composition of the upgraded oils showed the formation of dominant light aliphatic and aromatic hydrocarbons that could also be used as a chemical feedstock.

This paper is aimed at performing an environmental evaluation regarding biofuel production. The process combines four sections: biomass fast pyrolysis to bio-oil with two phases, oil-phase upgrading by hydrotreating, using H2 obtained by steam reforming, and a new process to produce Fischer-Tropsch biofuels from supercritical water reforming of the aqueous phase. This phase can be valorised in the latter process entirely so natural gas is reformed to H2 (case-study 1), or partially so a fraction of this aqueous phase is reformed (case-study 2), or all this phase is reformed to H2 (case-study 3). The two former can include CO2 storage and aqueous phase concentrations were 15, 25 and 35 wt% organic compounds. At 25 wt%, the global warming potential is 11 g CO2-eq/MJ-biofuel for the case 2 with CO2 storage, while it was 11.3, 12.6, 27.7 and 34 g CO2-eq/MJ-biofuel for the cases 3, 2 without CO2 storage, 1 with and without CO2 storage, respectively. Thus, the case-study 2 with CO2 storage gives the minimum global warming potential, allowing significant reductions with respect to the use of fossil fuels. For the other categories, the case-study1 presents the lowest impacts. Similar trends are found at 15 and 35 wt%.

During the operation of industrial gasifier, the concentrations of CO2 and H2O in gasification media vary with the change of stages, causing the gasification process being affected accordingly. Therefore, dividing the gasification process into different stages to study the effect of multi-stage switching atmosphere is significant. The conversion rate, reaction characteristics and reaction process for the gasification of Xiaolongtan (XLT) coal char in different atmospheres (CO2/H2O/N2) switching in the early, middle and late reaction stages were investigated using thermo-gravimetric analysis (TGA). The results indicated that the average reaction rate of coal char with H2O was approximately 3 times that of CO2. Increasing H2O concentration improved the reaction and conversion rate of coal char, which was the most obvious in the early stage. With the H2O concentration increasing from 0 to 95%, the increment of conversion rate in the early, middle, and late stages were 7.13%, 4.40%, and 3.92%, respectively. Thus, considering the problem of H2O corrosion in practical production, the H2O concentration could be appropriately increased in the early stage to improve efficiency. Compared with the random pore model, the shrinking core model fitted the gasification process of coal char better in a highly reactive 95% H2O/5% N2 atmosphere.

Automotive engines are encouraged to utilize biofuels to lower the net CO2 and to enhance the usage of renewable energy. With well-proven biodiesel engine characteristics, a comprehensive study about the impact of biodiesel on the fuel filter is lacking in the literature. Hence the current study investigates the comparative impact of higher blends of biodiesel and diesel on the fuel filter. Here, the authors have conducted both experimental and simulation studies on the fuel filter with diesel, two biodiesel fuels namely karanja, and waste cooking oil. Filter blocking tendency (FBT) was measured for the test fuels following ASTM D2068 . Also, a comparative tensile strength analysis of an automotive filter media was examined. The test results reveal that FBT increases exponentially with an increase in biodiesel blend concentration with a maximum FBT value of 30 for karanja biodiesel. Further, the tensile strength of the filter media reduces significantly with soaking in biodiesel compared to fossil diesel. Filter pressure drop measurement results with biodiesel were observed to be 35% higher than diesel. Consequently, effective countermeasures such as fuel preheating, varying the filtration area and ethanol blending are proposed to reduce the filter pressure drop with biodiesel. Filter pressure drop with karanja can be reduced similar to diesel fuel by increasing the fuel temperature by 16 °C or enhancing the filtration area by 35%. Karanja blended with 20% ethanol was also observed to have lowered the pressure drop. The present study concludes that neat biodiesel operation affects the filtration process and the filter media of the conventional fuel filter significantly.

In the ethanol production process from sugarcane molasses, the distillation process is a high-energy demand stage. The distillation energy efficiency is strongly associated with the alcoholic fermentation performance in the process. The final ethanol concentration in the alcoholic wines has a direct impact on consumption of thermal energy in ethanol separation. In this paper, ethanol production with a H-SBMF (Hybrid-Simple Batch Membrane Fermenter) using PDMS (polydimethylsiloxane) pervaporation membrane was modelled and simulated, in order to determine its influence on energy consumption in distillation. Steam in distillation and electrical energy needs in permeate recovery were mainly influenced by membrane adaptation. The H-SBMF achieved a higher ethanol production in the range of 10–13% compared to the conventional batch fermenter, and an increase in productivity of 150%. The distillation system consisted of two sets of columns: the ethanol recovery column and the rectification column. The permeate recovery system (i.e. vacuum and compression) was regarded in order to evaluate the electrical energy requirement, and the thermal energy demand was evaluated. A decrease in steam consumption was evidenced by the adaptation of the membrane to the fermenter. Higher energy efficiencies were achieved in distillation with larger membrane areas, achieving almost 17% steam reduction.

This paper presents an in-depth exergy analysis of the ethanol fermentation process with various forms of fungus Mucor indicus under aerobic and anaerobic conditions to select the most productive and sustainable conditions. Various carbon sources including fructose, glucose, and sucrose as well as the whole and inverted sugar beet and sugarcanes molasses were used during the fermentation. The rational and process exergetic efficiencies were found to be in the range of 65.21%–88.54% and 0.00%–44.31%, respectively. Overall, the exergy-based parameter based on the process outputs could provide useful information about the sustainability and productivity of the fermentation process compared to the rational analysis. More specifically, the inverted sugar beet molasses with MF (mostly filamentous) form of M. indicus under anaerobic cultivation was shown to be the best option for industrial production phase with respect to the productivity and sustainability issues. The results obtained confirmed that the process yield alone cannot perfectly reflect the exact sustainability parameters of the renewable ethanol production systems. Finally, the developed exergetic framework could help engineers to couple biochemical and physical concepts more robustly for achieving the most cost-effective and eco-friendly pathways for bioethanol production.

Turpentine, a mixture of terpenes obtained as a product from oleoresin distillation or as a side product from paper industry, can contribute to the production of oxygenated fuels from renewable sources with properties different from normal alcohols or typical esters. In the present work, the product of turpentine oxyfunctionalization (oxyturpentine), which is composed mainly of nopol, α-terpineol and α-pinene, is evaluated as diesel fuel component blended at 20% vol., by measuring the performance and emissions of a Euro 6 engine under a standard driving cycle. The results show a reduction in particulate number, particulate matter and nitrogen oxides (the tightest emissions from diesel engines), while carbon monoxide and hydrocarbon emissions were increased. The emissions were influenced by the fuel properties and the changes in equivalence ratio and the EGR in the engine (derived from the fuel properties). These results show a high potential of oxyturpentine to be used as component of diesel fuel.

Regarding the supply of fossil fuels, greenhouse gasses emission, global warming, and increasing fuel price; there is a need to find alternative energy resources, which are renewable, environmentally sustainable, and economically viable. Agro-industrial biomass such as sugarcane bagasse, rice and wheat straw, corn stover, and switchgrass, named as lignocellulosic biomass (LCB) which is inexpensive, abundant, renewable, and provides a unique natural resource for large-scale and cost-effective bio-energy production. During the production of biofuels, pretreatment is a necessary step due to the recalcitrant structure of LCB. Various pretreatment methods were employed with a different mechanism of action, feasibility, and practicability to produce high yield biofuels. Since many years ago, the development of an effective pretreatment method has been challenging due to the existence of barriers and obstacles. Besides, each pretreatment method has its advantage and disadvantage, which should be investigated to obtain a higher yield of bioethanol. In this paper, the recent findings regarding the application of various pretreatment techniques such as chemical, physical and biological methods for bioethanol production from LCBs have been reviewed. The limitations of the mentioned methods based on the existing barriers were explained, and the future recommendations were discussed.