Raw Feedstock Research Articles

Waste to Energy: Solid Fuel Production from Biogas Plant Digestate and Sewage Sludge by Torrefaction-Process Kinetics, Fuel Properties, and Energy Balance

Sustainable solutions are needed to manage increased energy demand and waste generation. Renewable energy production from abundant sewage sludge (SS) and digestate (D) from biogas is feasible. Concerns about feedstock contamination (heavy metals, pharmaceuticals, antibiotics, and antibiotic-resistant bacteria) in SS and D limits the use (e.g., agricultural) of these carbon-rich resources. Low temperature thermal conversion that results in carbonized solid fuel (CSF) has been proposed as sustainable waste utilization. The aim of the research was to investigate the feasibility of CSF production from SS and D via torrefaction. The CSF was produced at 200~300 °C (interval of 20 °C) for 20~60 min (interval 20 min). The torrefaction kinetics and CSF fuel properties were determined. Next, the differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) of SS and D torrefaction were used to build models of energy demand for torrefaction. Finally, the evaluation of the energy balance of CSF production from SS and D was completed. The results showed that torrefaction improved the D-derived CSF’s higher heating value (HHV) up to 11% (p < 0.05), whereas no significant HHV changes for SS were observed. The torrefied D had the highest HHV of 20 MJ∙kg−1 under 300 °C and 30 min, (the curve fitted value from the measured time periods) compared to HHV = 18 MJ∙kg−1 for unprocessed D. The torrefied SS had the highest HHV = 14.8 MJ∙kg−1 under 200 °C and 20 min, compared to HHV 14.6 MJ∙kg−1 for raw SS. An unwanted result of the torrefaction was an increase in ash content in CSF, up to 40% and 22% for SS and D, respectively. The developed model showed that the torrefaction of dry SS and D could be energetically self-sufficient. Generating CSF with the highest HHV requires raw feedstock containing ~15.4 and 45.9 MJ∙kg−1 for SS and D, respectively (assuming that part of feedstock is a source of energy for the process). The results suggest that there is a potential to convert biogas D to CSF to provide renewable fuel for, e.g., plants currently fed/co-fed with municipal solid waste.

Physical and Combustion Indices of Thermally Treated Cornhusk and Sawdust Briquettes for Heating Applications in Nigeria

ABSTRACT This study focuses on the physical and combustion indices of briquettes produced from thermally treated cornhusk (CH) and sawdust (SD) through torrefaction. The raw and torrefied feedstocks were combined at different blending ratios and then preconditioned with 10% moisture content. The highest value of density, shatter index, and compressive strength was obtained at 90/10 (CH/SD) ratio. The calorific value and fixed carbon of the torrefied briquettes increased between 37.56–42.42% and 42.90–49.75% over the raw briquettes while the volatile matter decreased by 26.88–38.57%. Moreover, the combustion indices show the briquettes from these feedstock blends are suitable to replace coal. Briquettes from torrefied cornhusk and sawdust could serve as an alternative fuel for domestic and industrial heating applications in Nigeria.

Monosaccharides and carbon nanosphere obtained by acidic concentrated LiBr treatment of raw crop residues via optimizing the synthesis process

The by-product from acidic concentrated LiBr hydrolyzed (ALBH) crop residues, as ALBH biochar, showed great potential as adsorbent for removing heavy metal pollution. By optimizing the treatment conditions, this study indicated that 22.44% of cellulose was hydrolyzed to glucose, and the residues showed 86.96 mg/g of adsorption capacity to Cr(VI) after T6 treatment of elephant grass. With T3 treatment (5% solid ratio, 0.5 M HCl, at 140 °C for 150 min), the residues from treated elephant grass got 100 mg/g adsorption capability to Cr(VI). Meanwhile, the carbon sphere with uniform, dispersive and in diameter of ~100 nm was formed via the further dehydration and condensation reaction of saccharides. Among the raw feedstocks, the relative high content of cellulose (40.30%) caused elephant grass as the optimal option for carbon spheres production.

CO2 effects on catalytic pyrolysis of yard trimming over concrete waste

Syngas itself can be directly combusted as fuel and adopted as a versatile raw feedstock in many chemical industries. Nonetheless, the fossil-based resources are mainly being converted into syngas via the thermo-chemical process with substantial emissions of anthropogenic CO2, which is one of main factors deteriorating the usefulness of syngas. Thus, it is desirable to obtain syngas through sustainable conversion techniques and a carbon neutral feedstock. To achieve the noted grand challenges, suppressing CO2 formation during the synthesis of syngas by transforming CO2 into a combustible matter (CO2-to-fuel) is of great importance since it offers a precautious measure for fortifying energy security in the most countries and abating catastrophic consequences arising from global warming. To this end, this study was aimed to introduce a sustainable conversion of syngas through pyrolysis of municipal solid waste (MSW). Specifically, pyrolysis of yard trimming was investigated as a case study because it is one of the main MSW components. To offer an environmentally benign platform for producing syngas, CO2 was fed during pyrolysis of yard trimming, and the functional effectiveness of CO2 was mainly scrutinized. All experimental observations offered that reduction of CO2 and simultaneous oxidation of volatile pyrolysates coming from yard trimming thermolysis were achieved, which resulted in the enhanced formation of CO. In addition, catalytic pyrolysis was examined to expedite reaction rates using a concrete waste because the demolition waste is one of main inorganic MSW components. The effectiveness of CO2 was remarkably enhanced from catalytic pyrolysis over concrete. Conclusively, this study suggested that both the organic/inorganic MSW components could be valorized through the concept of waste-to-energy in conjunction with CO2-to-fuel.

A comprehensive investigation of hydrothermal carbonization: Energy potential of hydrochar derived from Virginia mallow

In this study, the effects of temperature, residence time and biomass to water ratio on hydrothermal carbonization of Virginia mallow were conducted. The main goal of this research was to investigate hydrochars derived from Virginia mallow in order to assess their fuel properties. Proximate, ultimate and high heating value analyses were used to establish the chemical energy content of raw biomass and hydrochars. TGA, SEM, BET and FTIR were performed to discuss the combustion characteristics and changes in the surface of the material. Temperature was found to be the main factor influencing the conversion of Virginia mallow during the HTC process. It was confirmed by the properties of hydrochar derived at 220 °C for 5 min which was as carbonaceous (51.8% carbon content) and reactive as that obtained at 200 °C for 60 min (52.5% carbon content). A sample pretreated at 200 °C for 90 min had the highest fixed carbon value (16.29%) when compared to raw feedstock (5.63%). In the resulting reduction of mass found in the hydrochar, an increase in the energy densification ratio as well as better combustion stability were also observed. Detailed analysis of the Results confirmed that the HTC is a promising method for producing energy-dense solid biofuel.

The Effect of Different Khaya Senegalensis Raw Feedstock Particle Sizes On Solid Fuel Pellet Quality

In recent years, the usage and demand for biomass pellet has been increasing due to the need of substitution for non-renewable energy source. Therefore, high quality solid fuel is in need to cater this demand. Pellet qualities such as durability, calorific value and density are different depending on the type of material, size of particle and the density of the feedstock. In this study, the durability, calorific value and unit density of Khaya Senegalensis pellet was investigated. This was done to identify the optimum particle size to obtain the best qualities of pellet possible. The ground biomass material was separated into 0.15 mm, 0.50 mm and 1.00 mm particle sizes, pelletized and ultimately the pellet durability, calorific value and unit density were tested in this study. It was found that 0.15 mm particle size resulted in the highest pellet durability, and density value. 1.00 mm particle size pellet has the highest calorific value. As a conclusion, different raw biomass feedstock particle size will affect the durability, density and calorific value of pellet.

Role of raw feedstock and biochar amendments on sorption-desorption and leaching potential of three 3H- and 14C-labelled pesticides in soils

The pesticide behavior in soils can be easily affected by biochar addition. However, studies on the effects of raw feedstock and biochar are scarce. The objective of this study was to evaluate the effect of amending soils from three Midwestern U.S. states, with biochar produced from soybean residues, sugarcane bagasse, and wood chips (grape) as well as raw feedstock on the sorption–desorption and leaching potential of the pesticides aminocyclopyrachlor, metolachlor, and imidacloprid. Soil was amended at 10% (w w−1), and sorption–desorption studies were performed using the batch equilibration method. Following the determination of the sorption coefficient (Koc) values, the groundwater ubiquity score (GUS) indices for these pesticides were calculated. The highest pesticide sorption in all unamended soils followed the order imidacloprid (Kd = 0.79–1.66 L Kg−1) > metolachlor (Kd = 0.54–0.61 L Kg−1) > aminocyclopyrachlor (Kd = 0.12–0.23 L Kg−1). Biochar has the potential to decrease metolachlor and imidacloprid availability in soil through increased sorption, while the availability of aminocyclopyrachlor differed between the use of raw feedstock and biochar. Biochar derived from wood chips had the highest impact on pesticide behavior. We confirmed that aminocyclopyrachlor, metolachlor, and imidacloprid would leach easily in the three unamended soils, as illustrated by the GUS index.

Enhanced Hydrogen Generation from Empty Fruit Bunches by Charcoal Addition into a Downdraft Gasifier

AbstractHydrogen production by co‐gasification of empty fruit bunches of palm oil could be enhanced by adding charcoal. Physiochemical characterization of raw feedstocks was performed to determine their exergy potentiality. The raw feedstocks, gasified charcoal, and the end product of produced gas were analyzed by different techniques. Gasification experiments were performed using a pilot‐scale downdraft gasifier. The heating value, composition of product gas, yield of hydrogen, and exergy efficiency were used to verify the improvement of hydrogen production during the co‐gasification process. Charcoal with empty fruit bunches of palm oil leads to a much higher yield of hydrogen than lower charcoal ratios or solely empty fruit bunches. This enhanced hydrogen fuel can contribute to future energy demand.

Comprehensive evaluation of hydro-liquefaction characteristics of lignocellulosic subcomponents

This study investigated the hydro-liquefaction behaviors of cellulose, xylan and lignin in ethanol at various temperatures. The interactions between the reaction medium and individual biomass component under different temperatures were evaluated using the Monte Carlo method. The simulation results indicated that the compatibility from cellulose and xylan system was superior to that of lignin with the elevated temperature. The liquefaction characteristics of cellulose and xylan were highly affected by temperature variation due to the existence of active chemical region and functional groups in the structures. In comparison, the reaction behavior of lignin-containing complicated polyaromatic structure was slightly dependent on the elevated temperature. The variation trend of chemical structures from solid residues was highly related to the nature of the raw feedstock. The properties of bio-oil derived from liquefaction of single biomass composition were also associated with the inherent composition of each biomass subcomponent.

Preparation and corrosion resistance of nonstoichiometric lanthanum zirconate coatings

Lanthanum zirconate is a promising thermal barrier coating material owing to its excellent thermophysical properties and La plays the key role in its corrosion resistance. Here, an amorphous precursor is used as raw feedstock material so as to synthesize lanthanum zirconate coatings with tailorable composition by atmospheric plasma spray (APS). Three lanthanum zirconate coatings of La1.7Zr2.3O7.15, La2.0Zr2.0O7.0 and La2.3Zr1.7O6.85 are fabricated. Furthermore, the corrosion resistance of the as-sprayed coatings against CaO-MgO-Al2O3-SiO2 at 1250℃ is investigated. The increased La content promotes the formation of a sealing layer of the crystalline Ca2La8(SiO4)6O2 apatite, which slows down the penetration of molten CaO-MgO-Al2O3-SiO2. Therefore, the infiltration rate of the La2.3Zr1.7O6.85 coating decreased up to 42.6 % compared with the other two coatings. This work develops a feasible preparation strategy to control the La composition for the improved corrosion resistance, which is expected to guide the future coating design and synthesis for the materials with big composition changes during the APS process.

Investigation of cottonseed oil biodiesel with ethanol as an additive on fuel properties, engine performance, combustion and emission characteristics of a diesel engine

In last few years in automobile sector there is a emerging need of an alternative fuel because of depletion of the stock of fossil fuels in all over the world. Bio-diesel in this regard contested a strong alternative to the conventional fuels. Bio-diesel contains 9-10% higher oxygen and higher cetane number which allows its good combustion in the combustion chambers of the engine. But poor hot flow and cold flow properties of biodiesel restricts their applications in the field of automotives. So the blends of biodiesel in percentage with diesel and ethanol as an properties enhancer additives are used in the biodiesel/diesel blend. Reduced viscosity, higher calorific value, improved flash and fire point and enhanced cold flow properties of the blends with ethanol as an additive, enhanced the combustion and reduced harmful emissions from the engine. Experimental work presented in this paper is by considering cottonseed biodiesel as raw feedstock blended with diesel and 5% ethanol. Properties were investigated experimentally as per IS 1448 standards. Trials were conducted on the single cylinder diesel. Results show that there are significant improvements in the properties of the blend, performance, combustion and reduced harmful emission from the engine. Experimental investigation reported that ethanol as an additives in the blends of cotton-seed biodiesel with diesel reduces kinematic viscosity by 7%, cold flow properties by 9% to 10% . But on the other hand but density of the blend is increased by 3% and higher heating value is decreased by 9%.

The effect of the lipid extraction method used in biodiesel production on the integrated recovery of biodiesel and biogas from Nannochloropsis gaditana, Isochrysis galbana and Arthrospira platensis

The integrated production of biodiesel and biogas has been explored by using N. gaditana, I. galbana and A. platensis as substrate. Three fatty acid ethyl ester (FAEE) production approaches were assessed, namely an indirect process with previously extracted lipids (IPPEL), an indirect process with extracted lipids as free fatty acids (IPELFFA) and a direct process (DP) without a previous lipid extraction stage. Besides de FAEE production, these approaches are considered as pre-treatments of the microbial biomasses evaluated in this study with the objective of increasing the methane yield during the anaerobic digestion. Biogas yields of the residues generated under the three FAEE production methodologies were compared to the biogas yield of the raw feedstock. In all cases, the biodiesel and biogas yields were higher after the FAEE production process from the previously extracted lipids as free fatty acids (IPELFFA). Therefore, this constitutes an interesting and promising route in the joint production of biodiesel and biogas.

Nonoxidative methane activation, coupling, and conversion to ethane, ethylene, and hydrogen over Fe/HZSM‐5, Mo/HZSM‐5, and Fe–Mo/HZSM‐5 catalysts in packed bed reactor

A high abundance of methane and its relatively low price make it an attractive raw feedstock for the production of ethylene, which is in the consumer demand in recent years. Direct catalytic nonoxidative conversion is interesting, because it could be utilized on natural gas well sites. Monometallic and bimetallic Fe and Mo catalysts were prepared for the purpose of the coupling to ethane and ethene. Three supported materials were synthesized with the following loading of metal: 2.5-wt% Fe, 5.0-wt% Fe, and 2.5-wt% Mo on HZSM-5. Process' chemical reactions were also catalyzed with a constant 2.5-wt% Mo/HZSM-5, which had different amounts of Fe, namely, 0.5, 1.0, and 2.5 wt%. Fourier transform infrared (FTIR), N2 adsorption/desorption, NH3 temperature-programmed desorption (TPD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were applied for characterization. Coke, accumulated on spent solids, was determined by thermogravimetric analysis (TGA). Activity was evaluated in quartz-packed bed reactor. All surfaces suffered from deactivation due to carbon formation. The addition of Fe to Mo increased CH4 reacted. The highest selectivity for alkenes was achieved over 1.0-wt% Fe to 2.5-wt% Mo/HZSM-5. At the peak of performance, the C-based reactivity was 52% for olefins and 2% for alkanes. Stability was accomplished over 2.5-wt% Fe/HZSM-5, where the rate of C2 synthesis was comparatively stable for 20 hours of the time on stream. The selective C-basis yield for C2H4 and C2H6 was 36% and 23%, respectively. The lowest measured quantity of (carbonaceous) by-products was deposited on 2.5-wt% Fe/HZSM-5 after 26 hours. Propylene was detected very limitedly.

Effect of Torrefaction on Steam Gasification of Biomass in Dual Fluidized Bed Reactor—a Process Simulation Study

In this study, a steam gasification with a dual fluidized bed reactor is constructed using a commercial process simulator and validated by experimental data to investigate the behaviors of raw and torrefied spruce wood during the conversion process. Effects of torrefaction, gasification temperature, and steam-to-biomass ratio on the performance of spruce gasification are examined. Main gasification indicators including product gas composition and heating value as well as cold gas efficiency are investigated. Simulation results show that both the H2 and CO2 contents in the product gas are reduced with increasing the gasification temperature or decreasing the steam-to-biomass ratio. On the other hand, the CO content shows an opposite trend. In addition, increasing the gasification temperature or decreasing the steam-to-biomass ratio enhances the heating value of the product gas but reduces the cold gas efficiency. Compared with the raw feedstock, the torrefied spruce offers lower H2 but higher CO content in the product gas at the same gasification condition. Nevertheless, gasification of the torrefied spruce always results in higher cold gas heating value and efficiency than that of the raw spruce. The increased values are up to 0.46 MJ/Nm3 for the heating value and 5.96% for the efficiency.

Metal sulfide-based process analysis for hydrogen generation from hydrogen sulfide conversion

Fossil fuel power plants often generate sulfur species such as hydrogen sulfide or sulfur dioxide due to the sulfur content of the raw feedstocks. To combat the associated environmental, processing, and corrosion issues, facilities commonly utilize a Claus process to convert hydrogen sulfide (H2S) to elemental sulfur. Unfortunately, the potential for H2 production from H2S is lost in the Claus process. In this study, two chemical looping process configurations utilizing metal sulfides as chemical intermediates for sulfur recovery are investigated: (1) sulfur recovery (SR) system for sulfur production; (2) sulfur and hydrogen (H2) recovery (SHR) system for sulfur and H2 and production utilizing staged H2 separation. Since, H2 yield and sulfur recovery in a single thermal decomposition reactor is limited by low H2S equilibrium conversion, a staged H2 separation approach is used to increase H2S conversion to H2 using the SHR system. Steady-state simulations and optimization of process conditions are conducted in Aspen Plus (v10) simulation software for the chemical looping process configurations and the Claus process. An energy and exergy analysis are done for the Claus and chemical looping processes to demonstrate the relative contribution to exergy destruction from different unit operations as well as overall exergy and energy efficiency. The two chemical looping process configurations are compared against the conventional Claus process for similar sulfur recovery in a 629 MWe integrated gasification combined cycle power plant. The SHR system is found to be the most efficient option due to a 97.11% exergy efficiency with 99.31% H2 recovery. The overall energy and exergy efficiencies of this chemical looping system are 14.74% and 21.54% points higher than the Claus process, respectively, suggesting more efficient use of total input energy.

Effect of Tio2 Nanoparticles In Spirulina Biodiesel-Diesel Blends at Various Injection Strategies: Performance, Combustion and Emission characteristics

Since so many years all the automobile engines are running by using the fossil fuels. Day by day the usage is increasing. So, by using the fossil fuels it reaching the last stage and finally it leads to the depletion. So, the fossil fuels are the responsible for air pollution, global warming, and the gradually increasing of global climate. So, the algae biofuels are considered to be the most renewable source of energy and also it is eco-friendly. Microalgae considered to be the potential source which can produce biofuel from algae. Nitrates, phosphates, and carbon dioxide which were produced from atmosphere are consider to be growing environment for algae. Spirulina is a blue-green algae. Autotrophic and alkallophyletic are the two attributes of spirulina. For spirulina lesser amount of sunlight is needed than the homes. pH is the important ingredient in the culture medium. After the transesterification process about 87.75% of biodiesel yield was obtained at optimum level conditions. By comparing of both spirulina bio-oil and chlorella bio-oil the parameters like viscosity and density of chlorella were very equally to the conventional diesel fuel. By the above reasons spirulina is strongly considered to be a potential raw material or feedstock for the biodiesel production to be used in diesel engines. For this investigation to measure the engine performance parameters like exhaust temperature, brake specific fuel consumption and emission parameters like hydrocarbons, carbon dioxide, nitrogen oxides, oxygen, carbon monoxides and smoke are measured by changing the injection timings like retard 23 degree, retard 21 degree and retard 19 degree. Finally B20 is the blend taken and this blend is mixed with 75 ppm of Titanium dioxide as a nanoparticle experiment was conducted on four stroke, twin cylinder diesel engineused.

Catalytic synthesis of biodiesel from waste cooking oil and corn oil over zirconia-based metal oxide nanocatalysts

In the present study, ZrO2–SrO2 and ZrO2–CuO mixed oxides with different molar ratios were synthesized via Pechini sol–gel and co-precipitation methods and their catalytic activities were examined for biodiesel production from cheap raw feedstocks. The molar ratio of the prepared mixed oxide nanocatalysts were optimized through examining the effect of different molar rations in the catalytic transesterification of waste cooking oil (WCO) and corn oil. The structural and compositional characterization of as-prepared nanocatalysts were performed using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) techniques. According to the experimental results, the optimal catalytic performance of the prepared ZrO2–SrO2 and ZrO2–CuO mixed oxides was observed at Zr/Sr and Zr/Cu molar ratios = 2/1, temperature = 120 °C, methanol/oil molar ratio = 10/1 and reaction time = 3 h. The results indicated that the new prepared zirconia-based binary mixed oxides are suitable catalysts to produce biodiesel from waste cooking oils (WCOs) and corn oil, applicable to diesel engines.

High-rate anaerobic treatment of digestate using fixed film reactors

The effluent stream of the anaerobic digestion processes, the digestate, accommodates high residual organic content that needs to be further treated before discharge. Anaerobic treatment of digestate would not only reduce the residual organic compounds in digestate but also has a potential to capture the associated biogas. High-rate anaerobic reactor configurations can treat the waste streams using lower hydraulic retention times which requires less footprint opposed to the conventional completely stirred tank reactors. This study investigated the high-rate anaerobic treatment performance and the associated biogas capture from the digestate of a manure mixture composed of 90% laying hen and 10% cattle manures in fixed-film reactors. The results indicated that it was possible to reduce total chemical oxygen demand content of the digestate by 57–62% in 1.3–1.4 days of hydraulic retention time. The corresponding biogas yields obtained were in the range of 0.395–0.430 Lbiogas/g VSadded which were found to be comparable to many raw feedstocks. Moreover, significant total phosphorus reduction (36–47%) and greenhouse gas capture (over 14.5–18.1 tCO2e/d per m3 digestate) were also recorded in the anaerobic fixed-film reactors.

Achievements and misses of the Indian national policy on biofuels 2009

The National Policy on Biofuels (NPB) 2009 was adopted on 24th December 2009 in India to ensure the minimum availability of biofuels at any given time to meet the demand. NPB 2009 laid down the vision, goals and strategy to biofuel development while proposing a framework of technological, financial and enabling mechanisms. The NPB 2009 undertook reforms and aimed to increase the biodiesel blending percentage in diesel and bioethanol blending percentage in petrol to 20% each by 2017. It promoted inclusive growth, development and contributed to energy security and climate change mitigation. The lack of assured supply of raw material feedstock for biofuel production has been the major slippage of NPB 2009. NPB 2018 was adopted on 16th May 2018 and built on the foundation laid upon by NPB 2009. The paper focuses on the importance of NPB 2009, its achievements and misses and touches upon NPB 2018.

Cellulose Dissolution and Biomass Pretreatment Using Quaternary Ammonium Ionic Liquids Prepared from H-, G-, and S-Type Lignin-Derived Benzaldehydes and Dimethyl Carbonate

The synthesis of novel benzyl alkylammonium ionic liquids (IL) from starting materials derived from grass, softwood, and hardwood lignin was performed using batch reactor systems followed by facile methyl carbonate ion exchange chemistry. Approximately 90% yields of the ILs were achieved over three synthetic steps, and all novel materials were fully characterized by 1H and 13C nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. The structure–activity relationships of the lignin-derived ILs were evaluated for their ability to dissolve microcrystalline cellulose and convert switchgrass to fermentable sugars (glucose and xylose). All ILs tested, including a 1:1:1 mixture of ILs prepared from vanillin, syringaldehyde, and p-anisaldehyde yielded 52–71% of the glucose and 50–71% of the xylose from the total amount of glucan and xylan available in the raw feedstock. These data compared well to the yields obtained from switchgrass pretreatment with the IL, 1-ethyl-3-methyl imidazolium a...