Biomass as Renewable Energy: Worldwide Research Trends

Harnessing the potential of agriculture biomass: reuse, transformation and applications in energy and environment

Biomass, an organic matter, has gained worldwide attention due to the overconsumption of fossil fuels. Biomass has emerged as a new alternative resource with implications for efficient energy production, environmental benefits and socio-economic impacts. According to the World Bioenergy Association, biomass has accounted for 14% of the energy supply in 2016 and is expected to provide 44% of the energy demand by 2030. This literary endeavour comprises insights into past developments, including biomass types, characterization methods and conversion technologies. This review article aims to facilitate a deeper understanding of agriculture biomass utilization and its significance in achieving sustainable development goals by analysing the latest research findings. Moreover, the emerging role of biosensors in optimizing biomass utilization and monitoring environmental impacts has been documented. The scope embraces the vast realm of bioenergy production, environmental mitigation and the generation of valuable by-products. In conclusion, portraying biomass conversion technologies as the transition towards cleaner, renewable energy, the potential benefits and challenges extend beyond energy production, encompassing effective agricultural residue management and the creation of valuable by-products. This review will guide the researchers and stakeholders towards a deeper understanding of the transformative potential embedded in biomass conversion processes for a sustainable and cleaner energy future.

Health risks connected with energy disposal of pandemic waste

Enormous amount of protective masks was consumed in connection with the COVID-19 pandemic and they still burden the environment. Therefore, it is necessary to look for possibilities of their disposal in an ecologically acceptable way. This article focuses on particulate matter produced concerning the energy disposal of pandemic FFP2 masks. These masks were processed into small pieces, added to spruce and beech wood (in the weight proportion 5 % and 10 % of FFP2 masks) and formed into pellets. The concentration of particulate matter formed during their combustion was measured by the gravimetric method. The inorganic elements were detected from filters with captured particulate matter by an energy-dispersive X-ray fluorescence spectrometer and verified by inductively coupled plasma-optical emission spectroscopy. It was found that higher concentrations of particulate matter were recorded predominantly with a higher mass airflow. In both airflows (40 % and 50 %), beech pellets had a higher mass concentration than spruce pellets probably caused by the presence of bark in beech wood. Based on the chemical composition, the following elements in small amounts (0-2 mg on a filter) were identified: K, S, Cl and Fe. High concentrations of harmful elements carried in particulate matter have not been detected. FFP2 masks added in a small percentage (up to 10 %) can be used in wood pellets for combustion purposes without significantly affecting the combustion process.

Engineering an All-Biobased Solvent- and Styrene-Free Curable Resin

The sustainable production of polymers and materials derived from renewable feedstocks such as biomass is vital to addressing the current climate and environmental challenges. In particular, finding a replacement for current widely used curable resins containing undesired components with both health and environmental issues, such as bisphenol-A and styrene, is of great interest and vital for a sustainable society. In this work, we disclose the preparation and fabrication of an all-biobased curable resin. The devised resin consists of a polyester component based on fumaric acid, itaconic acid, 2,5-furandicarboxylic acid, 1,4-butanediol, and reactive diluents acting as both solvents and viscosity enhancers. Importantly, the complete process was performed solvent-free, thus promoting its industrial applications. The cured biobased resin demonstrates very good thermal properties (stable up to 415 °C), the ability to resist deformation based on the high Young's modulus of ∼775 MPa, and chemical resistance based on the swelling index and gel content. We envision the disclosed biobased resin having tailorable properties suitable for industrial applications.

Optimal pretreatment of plantain peel waste valorization for biogas production: Insights into neural network modeling and kinetic analysis

This work proposed a model for the substrate treatment stage of biogas production process in an anaerobic digestion system. Adaptive neuro-fuzzy inference system (ANFIS), response surface method (RSM), and artificial neural network (ANN) were comparatively used in the simulation and modeling of the treatment process for improved biogas yield. Waste plantain peels were pretreated and used as substrate. FTIR and SEM results revealed that the pretreatment improved the substrate's desirable qualities. The amount of biogas yield was controlled by time, NaOH concentration, and temperature of the substrate pretreatment. Optimum pretreatment conditions obtained were a temperature of 102.7 °C, time of 31.7 min and NaOH concentration of 0.125 N. RSM, ANN, and ANFIS modeling techniques were proficient in simulating the biogas production, as evidenced by high R2values of 0.9281, 0.9850, and 0.9852, respectively. Furthermore, the values of the calculated error terms such as RMSE (RSM = 0.04799, ANN = 0.00969, and ANFIS = 0.00587) and HYBRID (RSM = 18.556, ANN = 0.803, and ANFIS = 0.0447) were low, indicating a satisfactory correlation between experimental and predicted values. Scrubbing of the biogas with caustic soda and activated charcoal increased the methane content to 94 %. The kinetics of the cumulative biogas yield were best fit with the Logistics and Modified Logistics models. The low C/N ratio in addition to the presence of potassium, nitrogen, and phosphorus suggested that the spent plantain peel slurry can be utilized as an agricultural fertilizer in crop production. The observations of this study therefore recommends the pre-treatment of biodigestion substrates as a key means to enhance beneficiation of methane production.

Applying feature selection and machine learning techniques to estimate the biomass higher heating value

The biomass higher heating value (HHV) is an important thermal property that determines the amount of recoverable energy from agriculture byproducts. Precise laboratory measurement or accurate prediction of the HHV is essential for designing biomass conversion equipment. The current study combines feature selection scenarios and machine learning tools to establish a general model for estimating biomass HHV. Multiple linear regression and Pearson's correlation coefficients justified that volatile matter, nitrogen, and oxygen content of biomass samples have a slight effect on the HHV and it is better to ignore them during the HHV modeling. Then, the prediction performance of random forest, multilayer and cascade feedforward neural networks, group method of data handling, and least-squares support vector regressor are compared to determine the intelligent estimator with the highest accuracy toward biomass HHV prediction. The ranking test shows that the multilayer perceptron neural network better predicts the HHV of 532 biomass samples than the other intelligent models. This model presents the outstanding absolute average relative error of 2.75% and 3.12% and regression coefficients of 0.9500 and 0.9418 in the learning and testing stages. The model performance is also superior to a recurrent neural network which was recently developed in the literature using the same databank.

Glycerol photocatalytic oxidation to higher value-added compounds via bismuth oxyhalide photocatalysts

Bismuth oxyhalides (BiOX) including BiOCl, BiOBr, and BiOI, were well synthesized using solvothermal technique and then used in the aqueous phase photooxidation of glycerol as a catalyst. The as-synthesized BiOBr could achieve the highest glycerol transformation of around 85.6% in 8 h under ultraviolet light (UV) irradiation among as-synthesized BiOXs. Moreover, the BiOBr/TiO2 heterojunction was also prepared through an ethylene glycol-assisted solvothermal process. This new BiOBr/TiO2 heterostructure exhibited excellent photocatalytic activity (97.4%) for the oxidation of glycerol compared with pure BiOBr (74%) under ultraviolet light irradiation at 6 h. This obtained behavior was confirmed by more produced OH• radicals of BiOBr/TiO2.

Development of bioenergy technologies: A scientometric analysis

Bioenergy has the potential to substitute the current demand for fossil fuels in various applications. Recovering energy from bio-based materials due to environmental considerations has been adopted as a policy objective by governments and international organizations, which led to both vast financial investment and scientific research, especially in the last two decades. So far, various feedstocks and technologies have been scrutinised by the research community, although not all of them are commercially adopted due to sustainability considerations. This study employs scientometric analysis to survey the progress of scientific development in the field of bioenergy from 1966 to 2022, using ten parameters including publication year, type of document, categories, countries, affiliations, document citations, co-authorship, author citation networks, journal citation networks, and keywords. A total of 51,905 scientific documents were collected from the Web of Science, involving more than 96,000 authors from 162 countries. The dispersion of studies followed an ascending distribution with a sharp increase in the second half of the 2000s. The evolution of keywords in terms of burst strength confirmed the advancements of technologies from primary first-generation to advanced fourth-generation bioenergies. Based on the evolution of science in this area, it is concluded that integrated sustainability assessment studies, covering technical, economical, environmental, and social aspects, are needed to bridge the gap between abundant theoretical endeavours and limited commercial use of this energy source.

Recovery of agricultural waste biomass: A path for circular bioeconomy

Circular bio-economy is a significant approach to resolving global issues elevated by environmental pollution. The generation of bioenergy and biomaterials can withstand the energy-environment connection as well as substitute petroleum-based materials as the feed stock production, thereby contributing to a cleaner and low-carbon-safe environment. Open discarding of waste is a major cause of environmental pollution in developing and under developed countries. Agricultural bio-wastes are obtained through various biological sources and industrial processing, signifying a typical renewable source of energy with ample nutrients and readily biodegradable organic substances. These waste materials are competent to decompose under aerobic and anaerobic conditions. The projected global population, urbanization, economic development, and changing production and consumption behavior result in bounteous bio-waste production. These bio-wastes mainly contain starch, cellulose, protein, hemicellulose, and lipids, which can operate as low-cost raw materials to develop new value-added products. Thus, this review discussed specifically the agricultural waste and valorization processes used to convert this waste into value-added products (biofuel, enzymes, antibiotics, ethanol and single cell protein). These value added products are used in the supply chain and enhance the overall performance of agriculture waste management, execution of circular bio-economy has attained significant importance and it explains a closed-loop system in which the potential resources remain in the loop, allowing them to be sustained into a new value.

PolyE-IL Is an Efficient and Recyclable Homogeneous Catalyst for the Synthesis of 5-Hydroxymethyl Furfural in a Green Solvent

5-Hydroxymethyl furfural (5-HMF) is a potential platform molecule with multidimensional applications and can be produced from biomass-based hexose sugars. In the present article, polyethyleneimine (PEI)-functionalized polymeric Bronsted acid ionic liquid (PolyE-IL) catalyst has been explored for fructose dehydration in the presence of isopropyl alcohol (IPA) as a green and low-boiling-point (LBP) organic solvent. The use of homogeneous PolyE-IL catalyst provides several specific advantages in terms of high yield, conversion, selectivity, ease of catalyst separation, recycle and reuse, and so forth. PEI with various Bronsted acid counterions such as H₂SO₄, H₃PO₄, TsOH, TfOH, and TFA provides the corresponding variables of PolyE-IL such as [PEI]⁺[HSO₃]^-, [PEI]⁺[H₂PO₄]^-, [PEI]⁺[CF₃CO₂]^-, [PEI]⁺[TfO]^-, and [PEI]⁺[TsO]^-, which are tested for fructose dehydration in the presence of IPA. Of the tested catalysts, only PolyE-IL with [HSO₄]^-, [CF₃CO₂]^-, [TfO]^-, and [TsO]^- counterions showed the formation of 5-HMF. [PEI]⁺[HSO₄]^- showed the maximum yield of 5-HMF (61%) and selectivity (70%) with (87%) fructose conversion. Thus, further process optimization study was conducted to obtain the maximum yield, conversion, and selectivity. The intensified process provides a maximum yield of 5-HMF of 75% with 85% fructose conversion and 90% selectivity. The catalyst recyclability study showed the consistency in 5-HMF yield (75%), conversion (85%), and selectivity (90%) for five consecutive recycle runs. However, the study of reaction kinetics showed the first-order kinetics with an activation energy of 12.4 kJ/mole by using [PEI]⁺[HSO₄]^- catalyst. Thus, the use of an easily recyclable and robust catalyst provides an efficient route for production of 5-HMF in the presence of a green solvent.

Catalytic Esterification of Levulinic Acid into the Biofuel n-Butyl Levulinate over Nanosized TiO2 Particles

Levulinic esters, synthesized by the esterification of biomass-derived levulinic acid with various alcohols, is an important chemical that plays an essential role in the fields of biomass fuel additives, organic synthesis, and high value-added products. In the present work, the catalytic esterification of levulinic acid with n-butyl alcohol was selected as a typical model reaction to investigate the catalytic performance of an inexpensive commercial catalyst, titanium oxide nanoparticles. The influences of reaction time, reaction temperature, and catalyst loading on the conversion of levulinic acid to n-butyl levulinate were systematically examined through single-factor experiments. Additionally, the optimization of the reaction conditions was further investigated by a Box-Behnken design in response to the surface methodology. The desired product, n-butyl levulinate, with a good yield (77.6%) was achieved under the optimal conditions (reaction time of 8 h, reaction temperature of 120 °C, and catalyst dosage of 8.6 wt.%) when using titanium oxide nanoparticles as catalysts. Furthermore, it was found that addition of water to the catalytic system facilitated the reaction process, to some extent. This study reveals that the nanosized TiO₂ material_, as an efficient solid acid catalyst, had good catalytic performance and stability for the esterification of levulinic acid after six consecutive uses.

Glycolaldehyde as a Bio-Based C1 Building Block for Selective N-Formylation of Secondary Amines

Biomass derived glycolaldehyde was employed as C1 building block for the N-formylation of secondary amines using air as oxidant. The reaction is atom economic, highly selective and proceeds under catalyst free conditions. This strategy can be used for the synthesis of cyclic and acyclic formylamines, including DMF. Mechanistic studies suggest a radical oxidation pathway.

Efficient removal of tar employing dolomite catalyst in gasification: Challenges and opportunities

Fossil fuels are currently the dominant source of electricity and energy production around the world. Biomass is one of the most referred renewable carbonaceous resource(s) that can be employed for the waste-to-energy concept. Syngas obtained from biomass gasification can be utilized for a variety of key industrial purposes, including internal gasification engine operation, power generation, and hydrocarbon compound production using the Fisher-Tropsch technique. However, the existence of impurities such as hydrogen sulfide, tar, and particulate matter along with other undesirable chemicals present in syngas are major disadvantages of biomass gasification. Tar is the most difficult among all the pollutants to be removed from syngas; it also causes serious problems in downstream syngas applications. For decades, studies have been performed with various catalysts to remove the tar. Dolomite has shown positive response for tar elimination and hydrogen-enriched gas production. Several studies have been carried out on dolomite for eliminating the tar from syngas. This review encompasses sources of solid waste, the mechanism of catalysis, and in-situ and ex-situ usage of dolomite in the gasification process. It addresses the key issues such as fragmentation and attrition, elutriation, and coke formation along with dolomite's usefulness in amalgamation with other catalysts, environmental consequences, and economic viability of dolomite applications. It also discusses the challenges and opportunities for tar removal using catalysts, with a specific focus on dolomite along with economic and environmental sustainability considerations.

Co-Fermentation of Microalgae Biomass and Miscanthus × giganteus Silage—Assessment of the Substrate, Biogas Production and Digestate Characteristics

The development of a sustainable bioenergy market is currently largely fueled by energy crops, whose ever-increasing production competes with the global food and feed supply. Consequently, non-food crops need to be considered as alternatives for energy biomass production. Such alternatives include microalgal biomass, as well as energy crops grown on non-agricultural land. The aim of the present study was to evaluate how co-digestion of microalgal biomass with giant miscanthus silage affects feedstock properties, the biogas production process, biogas yields, methane fractions and the digestate profile. Combining giant miscanthus silage with microbial biomass was found to produce better C/N ratios than using either substrate alone. The highest biogas and methane production rates—628.00 ± 20.05 cm3/gVS and 3045.56 ± 274.06 cm3 CH4/d—were obtained with 40% microalgae in the feedstock. In all variants, the bulk of the microbial community consisted of bacteria (EUB338) and archaea (ARC915).

Enzymatic Conversion of Different Qualities of Refined Softwood Hemicellulose Recovered from Spent Sulfite Liquor

Spent sulfite liquor (SSL) from softwood processing is rich in hemicellulose (acetyl galactoglucomannan, AcGGM), lignin, and lignin-derived compounds. We investigated the effect of sequential AcGGM purification on the enzymatic bioconversion of AcGGM. SSL was processed through three consecutive purification steps (membrane filtration, precipitation, and adsorption) to obtain AcGGM with increasing purity. Significant reduction (~99%) in lignin content and modest loss (~18%) of polysaccharides was observed during purification from the least pure preparation (UFR), obtained by membrane filtration, compared to the purest preparation (AD), obtained by adsorption. AcGGM (~14.5 kDa) was the major polysaccharide in the preparations; its enzymatic hydrolysis was assessed by reducing sugar and high-performance anion-exchange chromatography analysis. The hydrolysis of the UFR preparation with Viscozyme L or Trichoderma reesei β-mannanase TrMan5A (1 mg/mL) resulted in less than ~50% bioconversion of AcGGM. The AcGGM in the AD preparation was hydrolyzed to a higher degree (~67% with TrMan5A and 80% with Viscozyme L) and showed the highest conversion rate. This indicates that SSL contains enzyme-inhibitory compounds (e.g., lignin and lignin-derived compounds such as lignosulfonates) which were successfully removed.

Biomass Potential and Utilization in Worldwide Research Trends—A Bibliometric Analysis

Biomass, as a part of renewables, is a resource found in large quantities and is a basis for many different industries. This paper presents the most important trends and characteristics of research in biomass potential and biomass utilization on a world scale. The main objective of this work is to analyze the state of research and trends in biomass potential and biomass utilization from 1974 to 2021, including 7117 relevant documents. The methodology part comprised two main stages: obtaining data from Scopus and then exporting the data into Excel. The VOSviewer bibliometric tool was used to analyze clusters of countries and groups of keywords. Research on this topic experienced significant development after 2000; moreover, the global trend of publications marked a significant increase after 2012. China and India have shown exponential growth, followed by USA, Germany, and UK. An important trend globally is that energy topics are gaining more importance and percentage annually, especially in photovoltaics and new generations of biofuels in terms of keywords. The paper aims to provide a tool for the scientific community by introducing the current state and potential tendencies in this special field, including the various sides of biomass use.

Hydrogen-Rich Syngas and Biochar Production by Non-Catalytic Valorization of Date Palm Seeds

Pyrolysis has been demonstrated to be a highly effective thermochemical process for converting complex biomaterials into biochar and syngas rich in hydrogen. The pyrolysis of mixed date palm seeds from Saudi Arabia was conducted using a fixed-bed pyrolyzer that was custom made for the purpose. The influence of the pyrolysis temperature (200–1000 °C) on the various physicochemical parameters of the date seed biochar generated through the pyrolysis process and the hydrogen-rich syngas was investigated. Proximate and ultimate analyses indicated a high carbon content in the lignocellulosic constituents such as cellulose, hemicellulose, and lignin. Using energy-dispersive X-ray (EDX) analysis, it was discovered that the elemental composition of biochar changes with the pyrolysis temperature. The date seeds pyrolyzed at 800 °C were found to have the maximum carbon concentration, with 97.99% of the total carbon content. The analysis of the biochar indicated a high concentration of carbon, as well as magnesium and potassium. There was a potential for the production of hydrogen-rich syngas, which increased with the pyrolysis temperature. At 1000 °C, the highest hydrogen and carbon monoxide compositions of 40 mol% and 32 mol%, respectively, were obtained. The kinetic data of the date seed pyrolysis were fitted using linearized model-free methods, such as Friedman, Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS), as well as non-linear methods such as Vyazovkin and advanced Vyazovkin. The activation energies obtained from Friedman, FWO, and KAS varied in the range of 30–75 kJ/mol, 30–65 kJ/mol, and 30–40 kJ/mol, respectively, while those of Vyazovkin and advanced Vyazovkin were found in the range of 25–30 kJ/mol, and 30–70 kJ/mol, respectively. The analysis showed that the FWO and KAS models show smaller variation compared to Friedman.

Integration of Waste to Bioenergy Conversion Systems: A Critical Review

Sustainable biofuel production is the most effective way to mitigate greenhouse gas emissions associated with fossil fuels while preserving food security and land use. In addition to producing bioenergy, waste biorefineries can be incorporated into the waste management system to solve the future challenges of waste disposal. Biomass waste, on the other hand, is regarded as a low-quality biorefinery feedstock with a wide range of compositions and seasonal variability. In light of these factors, biomass waste presents limitations on the conversion technologies available for value addition, and therefore more research is needed to enhance the profitability of waste biorefineries. Perhaps, to keep waste biorefineries economically and environmentally sustainable, bioprocesses need to be integrated to process a wide range of biomass resources and yield a diverse range of bioenergy products. To achieve optimal integration, the classification of biomass wastes to match the available bioprocesses is vital, as it minimizes unnecessary processes that may increase the production costs of the biorefinery. Based on biomass classification, this study discusses the suitability of the commonly used waste-to-energy conversion methods and the creation of integrated biorefineries. In this study, the integration of waste biorefineries is discussed through the integration of feedstocks, processes, platforms, and the symbiosis of wastes and byproducts. This review seeks to conceptualize a framework for identifying and integrating waste-to-energy technologies for the varioussets of biomass wastes.

Recent Developments in Lignocellulosic Biofuels, a Renewable Source of Bioenergy

Biofuel consists of non-fossil fuel derived from the organic biomass of renewable resources, including plants, animals, microorganisms, and waste. Energy derived from biofuel is known as bioenergy. The reserve of fossil fuels is now limited and continuing to decrease, while at the same time demand for energy is increasing. In order to overcome this scarcity, it is vital for human beings to transfer their dependency on fossil fuels to alternative types of fuel, including biofuels, which are effective methods of fulfilling present and future demands. The current review therefore focusses on second-generation lignocellulosic biofuels obtained from non-edible plant biomass (i.e., cellulose, lignin, hemi-celluloses, non-food material) in a more sustainable manner. The conversion of lignocellulosic feedstock is an important step during biofuel production. It is, however, important to note that, as a result of various technical restrictions, biofuel production is not presently cost efficient, thus leading to the need for improvement in the methods employed. There remain a number of challenges for the process of biofuel production, including cost effectiveness and the limitations of various technologies employed. This leads to a vital need for ongoing and enhanced research and development, to ensure market level availability of lignocellulosic biofuel.

Multifaceted Analysis of the Use of Catalytic Additives for Combustion with Hemp Pellets in a Low-Power Boiler

This paper presents the results of a multifaceted analysis of the application of catalytic additives to hemp pellets’ combustion in a low-power boiler. The research concerns the effects of five catalytic additives applied inside the boiler’s combustion chamber—based on TiO2, MnO2, Cu(NO3)2 × 3H2O, H2PtCl6 solution, and 99.5% pure urea solution—on the quality of hemp pellets’ combustion process. For this purpose, technical and elemental analyses of the used fuel were performed. The chemical composition of exhaust gases (NOx, CO, SO2, and PM content) was also examined using an exhaust gas analyzer and a dust meter. The highest reductions in emissions of individual pollutants were for CO (−113%; combustion with Ad3), NOx (−66%; combustion with Ad 4), SO2 (−48%; combustion with Ad3), and PM (−78%; combustion with Ad1). The study also determined the amount of avoided costs due to the use of catalytic additives, as well as the annual prevented CO2 emissions to the atmosphere. Due to rising fuel and energy prices, this study could be helpful for biomass boiler owners who would like to burn locally available raw materials and increase the combustion process’ efficiency.

Enrichment of the hydrogenotrophic methanogens for, in-situ biogas up-gradation by recirculation of gases and supply of hydrogen in methanogenic reactor

During in situ biogas up-gradation by supplying hydrogen from an external source and enrichment of hydrogenotrophic methanogens, high pressure of H₂ negatively affects hydrolytic and fermentative activities. To overcome this problem, the present study aimed to enrich the hydrogenotrophic methanogens by optimization of various parameters associated with gas recirculation along-with hydrogen supply from the external source. Due to recirculation of gases and supplied hydrogen, methane generation was two-fold higher in the optimal condition than in conventional anaerobic digestion, with the highest methane content of 99%. Additionally, the hydrogenotrophic methanogens were enriched, with a decrease in acetoclastic methanogens and an increase in Bathyarchaeia population, which utilizes H₂ and CO₂ to produce acetate and lactate as end products. The study concludes that recirculation increases methane production by converting H₂ and CO₂ into methane and enhances the degradation of organic matter left over undigested in the hydrolytic reactor.

Valorization of rubberwood sawdust and sewage sludge by pyrolysis and co-pyrolysis using agitated bed reactor for producing biofuel or value-added products

This study investigated experimentally pyrolysis of rubberwood sawdust (RWS), sewage sludge (SS), and their blends (25:75, 50:50, and 75:25 by weight) in an agitated bed pyrolysis reactor. The yields and characteristics of liquid product and biochar were determined for pyrolysis at 450, 500, and 550 °C and were affected both by temperature and feedstock type. The liquid and biochar yields were in the ranges 27.30-52.42 and 21.43-49.66 (wt%). Pyrolysis of RWS at 550 °C provided the highest liquid yield, while SS gave a high biochar yield. Co-pyrolysis of SS with RWS improved yield and quality of liquid and biochar products. The liquid product had 57.54-70.70 wt% of water and a low hydrocarbon content. The higher heating value (HHV) of water-free liquid product was 14.73-22.45 MJ/kg. The major compounds of liquid product included acetic acid, 2-propanone, 1-hydroxy, and phenols according to GC-MS. The biochar from RWS had a high carbon content (83.37 wt%) and a high HHV (33.57 MJ/kg), while SS biochar was mainly ash (67.62 wt%) with low carbon content. The SS biochar also had high contents of Si, Ca, Fe, K, and Mg as determined by XRF. Co-pyrolysis of SS with RWS improved the biochar by increasing its carbon content and reducing ash and inorganic elements. The surface of RWS biochar was more porous, while SS biochar had the larger specific surface according to SEM and BET. Based on these results, co-pyrolysis of 75:25 feedstock mix is recommended for further studies on applications of liquid product and biochar.

A critical review on biogas production from edible and non-edible oil cakes

The circular economy is at the core of sustainable development. The generation of biogas from the massive quantity of agricultural waste biomass is one of the critical drivers of the circular economy. Biogas has enormous renewable energy potential and has multitudes of applications in today's energy-intensive society. Oil cakes, a known Agri-waste, are the by-product of oil processing, and are rich in nutrients. The edible oil cakes mostly have been used as a cattle feed; however, non-edible oil cakes do not find many applications. Their production is continuously escalating as non-edible oils are increasingly used in biodiesel production. Recently, there is a lot of emphasis on biogas production from these oil cakes. This paper reviews in detail biogas production from both edible and non-edible oil cakes. Chemical composition and various other applications of the cakes are also reviewed in brief. The survey illustrates that multiple parameters such as inoculum sources, co-digestion and reactor design affect the biogas production. All those factors, along with biogas upgrading and the economy of the process, are reviewed. Finally, future research opportunities are suggested to improve the viability of the biogas production from oil cakes.

Performance of a Gasifier Reactor Prototype without a Blower Using Palm Oil Waste

The usage of palm oil empty fruit bunches (EFBs) in the gasification process adds value to the empty bunches as a renewable energy source. In this study, we design and manufacture a new updraft type of gasifier reactor without a blower so that it does not require electric power in its operation, but uses power from engine suction. Our test results compare the use of biomass waste in conjunction with diesel fuel to run a diesel power plant for 20 min at a load of 10,000 W: diesel with coconut shell charcoal (350 mL), diesel with acacia wood charcoal (380 mL), and diesel with EFB charcoal (400 mL). The test shows that the highest efficient and the most optimal biomass in the gasification process is coconut shell charcoal, because coconut shell charcoal has a dense structure and, at the time of the experiment, the coconut shell charcoal was filled 15 cm below the gas outlet pipe hole. From the standpoint of the economic value of the gasifier reactor that is proposed in this study, the result with the lowest cost is that of diesel with EFB charcoal, because, in this experiment, EFBs were the biomass that was not purchased. The additional use of empty fruit bunches of charcoal is able to save 50% diesel usage.

The current status, challenges and prospects of using biomass energy in Ethiopia

Despite enormous challenges in accessing sustainable energy supplies and advanced energy technologies, Ethiopia has one of the world's fastest growing economies. The development of renewable energy technology and the building of a green legacy in the country are being prioritized. The total installed capacity for electricity generation in Ethiopia is 4324.3 MW as on October, 2018. Renewable energy accounts for 96.5% of total generation; however, despite the county's enormous biomass energy potential, only 0.58% of power is generated using biomass. Ethiopia has surplus woody biomass, crop residue and animal dung resources which comprise about 141.8 million metric tons of biomass availability per year. At present the exploited potential is about 71.9 million metric tons per year. This review paper provides an in-depth assessment of Ethiopia's biomass energy availability, potential, challenges, and prospects. The findings show that, despite Ethiopia's vast biomass resource potential, the current use of modern energy from biomass is still limited. As a result, this study supports the use of biomass-based alternative energy sources without having a negative impact on the socioeconomic system or jeopardizing food security or the environment. This finding also shows the challenges, opportunities and possible solutions to tackle the problem to expand alternative energy sources. The most effective techniques for producing and utilizing alternate energy sources were also explored. Moreover, some perspectives are given based on the challenges of using efficient energy production and sustainable uses of biomass energy in Ethiopia as it could be also implemented in other developing countries. We believe that the information in this review will shed light on the current and future prospects of biomass energy deployment in Ethiopia.

Strategies to improve solid state anaerobic bioconversion of lignocellulosic biomass: an overview

Solid state anaerobic digestion (SSAD) of lignocellulosic biomass may be attractive solution for its valorisation. Compared to liquid state anaerobic digestion (LSAD), SSAD can handle higher organic loading rates (OLR), requires a less water and smaller reactor volume. It may require lower energy demand for heating or mixing and has higher volumetric methane productivity. Besides numerous benefits of SSAD processes and progress in system design, there are still obstacles, which need to be overcome for its successful implementations. This review aims to compile the recent trends in enhancing the bioconversion of agricultural stubbles in SSAD. Several pretreatment procedures used to breaking lignin and cellulose complex, method to overcome carbon to nitrogen ratio imbalance, use of carbon-based conducting materials to enhance Volatile Fatty Acids (VFA) conversion and additives for achieving nutrient balance will be discussed in this review. Leachate recirculation and its impacts on SSAD of agricultural stubbles are also discussed.

Agricultural Residue Management for Sustainable Power Generation: The Poland Case Study

The European Union has set targets for renewable energy utilization. Poland is a member of the EU, and its authorities support an increase in renewable energy use. The background of this study is based on the role of renewable energy sources in improving energy security and mitigation of climate change. Agricultural waste is of a significant role in bioenergy. However, there is a lack of integrated methodology for the measurement of its potential. The possibility of developing an integrated evaluation methodology for renewable energy potential and its spatial distribution was assumed as the hypothesis. The novelty of this study is the integration of two renewable energy sources: crop residues and animal husbandry waste (for biogas). To determine agricultural waste energy potential, we took into account straw requirements for stock-raising and soil conservation. The total energy potential of agricultural waste was estimated at 279.94 PJ. It can cover up to 15% of national power generation. The spatial distribution of the agricultural residue energy potential was examined. This information can be used to predict appropriate locations for biomass-based power generation facilities. The potential reduction in carbon dioxide emissions ranges from 25.7 to 33.5 Mt per year.

Selecting a Biomass Pelleting Processing Depot Using a Data Driven Decision-Making Approach

Bioenergy is one of the potential solutions to satisfy the extensive demand for energy and reduce fossil fuel dependency. For biomass to be an efficient source of bioenergy, it must be converted to a usable form, one of which is pellets. This study compares three commonly used methods to produce pellets in a biomass depot and presents a framework to select the most effective and economic pelleting processes. The comparison is performed using a data driven decision-making method called the Preference Index Selection Method (PSI). We considered three main pelletization technologies and compared four of their most critical attributes. The three popular biomass pellet processing methods used for this study are the conventional pelleting process (CPP), the high moisture pelleting process (HMPP), and the ammonia fiber expansion (AFEX). These processes were evaluated from both economic and environmental perspectives. We used the state of Mississippi as a testing ground for our analyses. The results obtained through the PSI method were validated with the Grey relational analysis (GRA) method. The results revealed that of the three available pelleting processes, the conventional pelleting process and the high moisture pelleting process were the most economic and environmentally friendly.

Importance of Agriculture in Creating Energy Security—A Case Study of Poland

Analyses of statistical data were made and their results discussed in this article to identify the level of Poland’s energy security and to determine the role of agriculture in ensuring it. It has been demonstrated that coal continues to be the staple resource for the generation of energy in Poland. The current demands and requirements concerning the reduced consumption of non-renewable resources and Poland’s obligations towards the European Union regarding the production of energy from renewable resources—all these considerations contribute to the promotion of a skillful development of energy crop farming, which, in Poland, is likely to be very successful. Agriculture plays an important role in ensuring Poland’s energy security, and this branch of farming can grow dynamically provided adequate legal regulations and promotion are in place. The chief resource for renewable energy generation is biomass. Straw and biogas production in agricultural biogas plants are two solutions whose full energy production potential still awaits to be tapped.

Investigation on the performance and emissions profile of CI engine using cashew nut shell pyro oil–toluene–diesel blends

Abstract

This article examines the prospects of using toluene added cashew nut shell pyro oil–diesel blends as alternative fuels in CI engine. Effects of adding fixed proportion (by vol.) of toluene (TU) to various cashew nut shell pyro oil (CPO)–diesel (D) blends on the performance and exhaust emission characteristics of a direct injection, single cylinder, water cooled, naturally-aspirated, constant speed run, 4-stroke CI engine were investigated under varied brake power conditions. Tested fuels were neat diesel, CPOT5 (5% CPO + 5% TU + 90% D), CPOT10 (10% CPO + 5% TU + 85% D) and CPOT15 (15% CPO + 5% TU + 80% D). CPO was extracted through a lab-scale fast pyrolysis apparatus. Fuel samples were prepared and characterized according to ASTM standards. Owing to the features like low sensitivity, impressive anti pinging, etc., presence of toluene in an optimal CPO-diesel blend was expected to promote the engine characteristics. Set of experiments were conducted for each fuel mixture and the respective in-cylinder pressure, fuel consumption, exhaust emission levels, temperatures were recorded. At the rated power output condition, CPOT5 fuel had shown 1.67% increased brake thermal efficiency, 5% reduced brake specific fuel consumption, almost 3% reduced exhaust gas temperatures as well as reduced the exhaust emissions such as HC (from 91 to 87 ppm), CO (from 0.1 to 0.08%), NOx (from 458 to 426 ppm), smoke levels (from 72 to 69 BSN). CPOT5 showed improved combustion characteristics like reduced ignition delays and combustion durations, increased rates of cylinder pressure rise and heat release. However, overall attained improvements in the engine parameters were found to be not up to the mark which makes the chances of using CPOT5 as best alternative to diesel feeble.

Article highlights

Effects of alkali, autoclaving, and Fe+ autoclaving pretreatment on anaerobic digestion performance of coking sludge from the perspective of sludge extracts and methane production

Pretreatment of activated sludge is an important step in increasing the reaction speed during anaerobic digestion by accelerating the hydrolysis process. It is necessary not only to analyze the changes in the general properties of the sludge before and after pretreatment but also to further analyze and evaluate the sludge structure and extracellular polymeric substances (EPS). In this study, the changes in coking sludge extracts after pretreatments with alkali, autoclaving, and Fe+ autoclaving were analyzed and compared using EPS heat extraction method. Moreover, the methane production potential of the pretreated coking sludge was investigated via biochemical methane potential (BMP) test. The results showed that after alkali, autoclaving, and Fe+ autoclaving, the concentration of protein and polysaccharide in the bound sludge extract accounted for approximately 40% and 28%, 62% and 51%, and 66% and 83% of the total protein and polysaccharide extracted from the sludge, respectively. In the experiment without pretreatment, there is no phenomenon of gas production from coking sludge. According to the BMP test results, Fe+ autoclaving pretreatment showed the highest methane production of 257 mL/gVSS. This study revealed that the analysis of sludge extracts was necessary in assessing the effects of anaerobic digestion pretreatment and methanogenic potential. Moreover, coking sludge showed higher methanogenic potential after Fe+ autoclaving pretreatment.

Economic Evaluation, Use of Renewable Energy, and Sustainable Urban Development Mamminasata Metropolitan, Indonesia

The acceleration of the development of the Metropolitan Mamminasata area has an impact on the socio-economic dynamics of the community and the use of excess energy resources. The purpose of this study was to analyze (1) economic growth and energy security work as determinants of urban development for Metropolitan Mamminasata, (2) the effect of economic growth, energy consumption, availability of transportation infrastructure, and renewable energy on the quality of the environment and the sustainability of the Metropolitan Mamminasata system, and (3) renewable energy management strategies and sustainable urban development for Metropolitan Mamminasata. An explanatory sequential approach was used. Data were obtained through observation, surveys, and documentation. The results showed that renewable energy which has the potential to used, in the Mamminasata Metropolitan urban area to support economic growth and increase urban productivity, namely water energy, wind energy, and biomass energy. Furthermore, it takes the effectiveness and efficiency of energy users toward improving environmental quality. Economic growth, energy consumption savings, the availability of transportation infrastructure, and renewable energy have a significant effect on environmental quality, with a determination coefficient of 82.3%, and the sustainability of the Metropolitan Mamminasata system, with a determination coefficient of 75.7%. Use of renewable energy in the management of urban development will require support from government policies, as well as community and business participation. This study recommends a renewable energy management strategy as an important part of supporting the sustainability of urban development in Metropolitan Mamminasata, Indonesia.

Graphite-type activated carbon from coconut shell: a natural source for eco-friendly non-volatile storage devices

Carbon from biomass as an active material for supercapacitor electrodes has attracted much interest due to its environmental soundness, abundance, and porous nature. In this context, activated carbon prepared from coconut shells via a simple activation process (water or steam as activation agents) was used as an active material in electrodes for eco-friendly supercapacitors. X-ray diffraction (XRD), Raman spectroscopy, conductivity, scanning electron microscopy (SEM), N₂ sorption and thermogravimetry coupled to mass spectrometry (TGA-MS) studies revealed that activated carbon produced by this approach exhibit a graphitic phase, a high surface area, and large pore volume. The energy storage properties of activated carbon electrodes correlate with the morphological and structural properties of the precursor material. In particular, electrodes made of activated carbon exhibiting the largest Brunauer-Emmett-Teller (BET) surface area, i.e. 1998 m² g^-1, showed specific capacitance of 132.3 F g^-1 in aqueous electrolyte (1.5 M H₂SO₄), using expanded graphite sheets as current collector substrates. Remarkably, this sample in a configuration with ionic liquid (1-methyl-1-propy-pyrrolizinium bis(fluorosulfonyl)mide) (MPPyFSI) as electrolyte and a polyethylene separator displayed an outstanding storage capability and energy-power handling capability of 219.4 F g^-1 with a specific energy of 92.1 W h kg^-1 and power density of 2046.9 W kg^-1 at 1 A g^-1 and maintains ultra-high values at 30 A g^-1 indicating the ability for a broad potential of energy and power related applications. To the best of our knowledge, these values are the highest ever reported for ionic liquid-based supercapacitors with activated carbon obtained from the biomass of coconut shells.

Investigation of Buckwheat Hulls as Additives in the Production of Solid Biomass Fuel from Straw

The aim of this study was to further increase the amount of straw that can be used to produce solid biofuels, as currently only about 130–140 thousand of the 3 million tonnes of straw collected annually in Lithuania are used for solid biofuel production. Therefore, the use of buckwheat hulls as an additive in solid biofuel production was investigated. Mixtures of wheat straw and buckwheat hulls were used for this research, with an increase in buckwheat hulls from 25% to 75% of the total weight of the mixture. Results of the analysis of the chemical composition, moisture, ash, and volatile matter content of the mixtures, as well as their ash properties, were compared with the corresponding results obtained with pure buckwheat hulls, wheat straw, and wood chips. It is observed an increase in all ash melting temperatures by increasing the portion of buckwheat hulls in the mixture. Additionally, the ash shrinkage starting temperature was shown to increase as the total content of buckwheat hulls also increased in the mixture. This increase ranged from 90 °C to 210 °C. Furthermore, the Cl concentration in fuel mixtures and the corrosion risk of equipment are accordingly reduced by using buckwheat hulls, as an addition that does not contain Cl.

Removal of Siloxanes from Model Biogas by Means of Deep Eutectic Solvents in Absorption Process

The paper presents the screening of 20 deep eutectic solvents (DESs) composed of tetrapropylammonium bromide (TPABr) and glycols in various molar ratios, and 6 conventional solvents as absorbents for removal of siloxanes from model biogas stream. The screening was achieved using the conductor-like screening model for real solvents (COSMO-RS) based on the comparison of siloxane solubility in DESs. For the DES which was characterized by the highest solubility of siloxanes, studies of physicochemical properties, i.e., viscosity, density, and melting point, were performed. DES composed of tetrapropylammonium bromide (TPABr) and tetraethylene glycol (TEG) in a 1:3 molar ratio was used as an absorbent in experimental studies in which several parameters were optimized, i.e., the temperature, absorbent volume, and model biogas flow rate. The mechanism of siloxanes removal was evaluated by means of an experimental FT-IR analysis as well as by theoretical studies based on σ-profile and σ-potential. On the basis of the obtained results, it can be concluded that TPABr:TEG (1:3) is a very effective absorption solvent for the removal of siloxanes from model biogas, and the main driving force of the absorption process is the formation of the hydrogen bonds between DES and siloxanes.

Distributed Generation: A Review on Current Energy Status, Grid-Interconnected PQ Issues, and Implementation Constraints of DG in Malaysia

Electric supply is listed as one of the basic amenities of sustainable development in Malaysia. Under this key contributing factor, the sustainable development goal aims to ensure universal access to an affordable, clean, and reliable energy service. To support the generation capacity in years to come, distributed generation is conceptualized through stages upon its implementation in the power system network. However, the rapid establishment growth of distributed generation technology in Malaysia will invoke power quality problems in the current power system network. In order to prevent this, the current government is committed to embark on the development of renewable technologies with the assurance of maintaining the quality of power delivered to consumers. Therefore, this research paper will focus on the review of the energy prospect of both fossil fuel and renewable energy generation in Malaysia and other countries, followed by power quality issues and compensation device under a high renewable penetration distribution network. The issues and challenges of distributed generation are presented, with a comprehensive discussion and insightful recommendation on future work of the distributed generation. In accordance with the addressed highlights in this paper, it would serve as the criterion on upcoming revolution of distributed generation integrated along with the traditional network in Malaysia.

The role of biorefinering research in the development of a modern bioeconomy

The current economy system is based in an intensive consumption of fossil fuels in a way that severely compromise future of the planet due to the severe consequences in climate change. In this scenario, the development of flexible and integrated biorefineries to produce biofuels and bioproducts from renewable biomass sources represent a key tool to perform the transition from a petroleum-based economy to a novel bioeconomy that looks for a more efficient and sustainable global development. This article analyses: the significance of biomass sources (such as agricultural and woody crops and residues, agro-food and wood processing industries residues and urban wastes) as feedstocks in the biorefinery, the most relevant biorefinering process technologies of the biochemical and thermochemical conversion pathways that are nowadays under development, and the need of further research and innovation effort to eventually achieve the commercialization and application in the market of the different biorefinery products.

Waste valorization and resource conservation in rice processing industries-an analytical study from Pakistan

The study aims to analyze and enhance the eco-efficiency of rice processing in Pakistan while focusing on pollution prevention, waste management, and valorization opportunities. Three rice mills were selected, and physical and chemical properties of their wastewater and solid waste were analyzed. It is depicted that rice husk has the highest share in the solid waste stream and possesses a significant renewable energy potential with a calorific value of 16 MJ/kg and a much lower energy cost of about 0.4 USD/MJ as compared to diesel and furnace oil, i.e., 36.8 and 26.2 USD/MJ, respectively. Recovery of commercially valuable by-products from the effluent of parboiling process is also investigated, and about 0.25 kg of starch/L from wastewater has been effectively reclaimed by wet milling method. The effluent water is also analyzed using Streeter-Phelps model which confirmed that value of contaminants in the wastewater of two of the selected rice mills exceeds the dilution capacity of the receiving body, with dissolved oxygen values at critical level as 0.54 mg/L and -20.7 mg/L respectively. Water pinch analysis and water cascade analysis (WCA) have also been employed to monitor and manage the water footprints. While the concentration composite curve depicted that about 0.8 ton/h of freshwater is saved by an application of smart water integration and pinch point was determined as 1814 ppm. While the WCA confirms that a total water demand of 45.3 kg/s at the third purity level has been reduced to 28.0 kg/s at the lowest purity level.

Avocado-Derived Biomass as a Source of Bioenergy and Bioproducts

The avocado (Persea americana Mill.) is a tree native to Mexico and Guatemala. Avocado consumption, fresh or in the form of processed products, is growing everywhere and it has caused a large number of countries to invest heavily in avocado production. The industrialization of avocado gives as a result a huge amount of waste, not only the peel and stone but also that waste generated by the pruning practices and oil extraction. These biomasses could be converted into raw materials to obtain different types of co-products, but this implies changes in the use of these resources, the design of efficient production systems, and integration to take full advantage of them, e.g., by developing biorefinery models. Therefore, this review firstly gives a snapshot of those residues generated in the avocado industry and provides their chemical composition. Secondly, this review presents updated information about the valorization ways of avocado-derived biomass to obtain bioenergy, biofuels, and other marketable products (starch, protein, phenolic compounds, and biosorbents, among others) using a single process or integrated processes within a biorefinery context. Green technologies to obtain these products are also covered, e.g., based on the application of microwaves, ultrasound, supercritical fluids, etc. As a conclusion, there is a variety of ways to valorize avocado waste in single processes, but it would be promising to develop biorefinery schemes. This would enable the avocado sector to move towards the zero-waste principle.

Sustainable Production of Monoraphidium Microalgae Biomass as a Source of Bioenergy

Microalgae are a renewable source of unconventional biomass with potential application in the production of various biofuels. The production of carbon-neutral fuels is necessary for protecting the environment. This work determined the possibility of producing biomass of microalgae belonging to Monoraphidium genus using saline wastewater resulting from proecological salmon farming in the recirculating aquaculture system. The tests were carried out in tubular photobioreactors using LED light. As a part of the analyses, the growth and productivity of microalgal biomass, cell density in culture, and lipid concentration and ash content in biomass were determined. In addition, the concentration of selected phosphorus and nitrogen forms present in wastewater corresponding to the degree of their use by microalgae as a nutrient substrate was determined. The biomass concentration estimated in the tests was 3.79 g·L−1, while the maximum biomass productivity was 0.46 g·L−1·d−1. The cells’ optical density in culture measured at 680 nm was 0.648. The lipid content in biomass was 18.53% (dry basis), and the ash content was 32.34%. It was found that microalgae of the genus Monoraphidium effectively used the nitrogen as well as phosphorus forms present in the wastewater for their growth. The total nitrogen content in the sewage decreased by 82.62%, and total phosphorus content by over 99%. The analysis of the individual forms of nitrogen showed that N-NO3 was reduced by 85.37% and N-NO2 by 78.43%, while orthophosphate (V) dissolved in water was reduced by 99%. However, the content of N-NH4 in wastewater from the beginning till the end of the experiment remained <0.05 mg·L−1.

Production of Cellulosic Ethanol from Enzymatically Hydrolysed Wheat Straws

The aim of this study is to find the optimal pretreatment conditions and hydrolysis in order to obtain a high yield of bioethanol from wheat straw. The pretreatments were performed with different concentrations of sulphuric acid 1, 2 and 3% (v/v), and were followed by an enzymatic hydrolysis that was performed by varying the solid-to-liquid ratio (1/20, 1/25 and 1/30 g/mL) and the enzyme dose (30/30 µL/g, 60/60 µL/g and 90/90 µL/g Viscozyme® L/Celluclast® 1.5 L). This mix of enzymes was used for the first time in the hydrolysis process of wheat straws which was previously pretreated with dilute sulfuric acid. Scanning electron microscopy indicated significant differences in the structural composition of the samples because of the pretreatment with H2SO4 at different concentrations, and ATR-FTIR analysis highlighted the changes in the chemical composition in the pretreated wheat straw as compared to the untreated one. HPLC-RID was used to identify and quantify the carbohydrates content resulted from enzymatic hydrolysis to evaluate the potential of using wheat straws as a raw material for production of cellulosic ethanol in Romania. The highest degradation of lignocellulosic material was obtained in the case of pretreatment with 3% H2SO4 (v/v), a solid-to-liquid ratio of 1/30 and an enzyme dose of 90/90 µL/g. Simultaneous saccharification and fermentation were performed using Saccharomyces cerevisiae yeast, and for monitoring the fermentation process a BlueSens equipment was used provided with ethanol, O2 and CO2 cap sensors mounted on the fermentation flasks. The highest concentration of bioethanol was obtained after 48 h of fermentation and it reached 1.20% (v/v).

Experimental investigation of the adsorption and desorption of cellulase enzymes on zeolite-β for enzyme recycling applications

The recyclability of cellulase enzymes using zeolite and polyethylene glycol (PEG) was investigated. The cellulase enzymes from cellulose hydrolysate suspensions were adsorbed onto zeolite-β under typical working conditions (pH 5). PEG having a molecular weight of 200 Da and 20 kDa was used as an eluent to desorb the cellulase enzymes from zeolite-β. Adsorption and desorption profiles of cellulase enzymes were studied by varying pH, PEG concentration, and salt concentration. Maximum binding capacity, q_m of the zeolite decreased by increasing the pH, or by introducing PEG. At pH 5, the q_m of the zeolite was determined to be 121 × 10^-3 g/g. About 24%, 51% and 75% of the adsorbed enzyme can be recovered using 1 M NaCl, PEG 200 and PEG 20000, respectively. The specific activity of the recovered enzyme increased by 57% due to the presence of residual PEG.

Zapote Seed (Pouteria mammosa L.) Valorization for Thermal Energy Generation in Tropical Climates

According to the Law for the Use of Renewable Energies and the Financing of Energy Transition, Mexico’s goal for 2024 is to generate 35% of its energy from non-fossil sources. Each year, up to 2630 tons of residual biomass from the zapote industry are dismissed without sustainable use. The main purposes of this study were to determine the elemental chemical analysis of the zapote seed and its energy parameters to further evaluate its suitability as a solid biofuel in boilers for the generation of thermal energy in a tropical climate. Additionally, energy, economic, and environmental assessments of the installation were carried out. The results obtained show that zapote seed has a higher heating value (18.342 MJ/kg), which makes it appealing for power generation. The Yucatan Peninsula is the main zapote-producing region, with an annual production of 11,084 tons. If the stone of this fruit were used as biofuel, 7860.87 MWh could be generated and a CO2 saving of 1996.66 tons could be obtained. Additionally, replacing a 200 kW liquefied petroleum gas (LPG) boiler with a biomass boiler using zapote seed as a biofuel would result in a reduction of 60,960.00 kg/year of CO2 emissions. Furthermore, an annual saving of $7819.79 would be obtained, which means a saving of 53.19% relative to the old LPG installation. These results pave the way toward the utilization of zapote seed as a solid biofuel and contribute to achieving Mexico’s energy goal for 2024 while promoting sustainability in universities.

Organic Carbonate Production Utilizing Crude Glycerol Derived as By-Product of Biodiesel Production: A Review

As a promising alternative renewable liquid fuel, biodiesel production has increased and eventually led to an increase in the production of its by-product, crude glycerol. The vast generation of glycerol has surpassed the market demand. Hence, the crude glycerol produced should be utilized effectively to increase the viability of biodiesel production. One of them is through crude glycerol upgrading, which is not economical. A good deal of attention has been dedicated to research for alternative material and chemicals derived from sustainable biomass resources. It will be more valuable if the crude glycerol is converted into glycerol derivatives, and so, increase the economic possibility of the biodiesel production. Studies showed that glycerol carbonate plays an important role, as a building block, in synthesizing the glycerol oligomers at milder conditions under microwave irradiation. This review presents a brief outline of the physio-chemical, thermodynamic, toxicological, production methods, reactivity, and application of organic carbonates derived from glycerol with a major focus on glycerol carbonate and dimethyl carbonate (DMC), as a green chemical, for application in the chemical and biotechnical field. Research gaps and further improvements have also been discussed.