Lower Heating Value Research Articles

Investigating the sustainable energy generation potential of an invasive weed: Lantana camara.

Lantana camara, one of the world's top ten most invasive species, was initially cultivated for ornamental use. However, it spread uncontrollably across the fallow areas and agricultural lands, threatening approximately 44% of Indian forests. Its invasion disrupts ecosystems by suppressing nearby plant growth through allelopathy and poses toxicity risks to grazing ruminants. It significantly increases forest fire risk by adding large amounts of combustible biomass, particularly dried L. camara. Despite efforts to control it using mechanical, chemical, and biocontrol methods, the results have been largely unsatisfactory, with associated costs estimated at $18,000 per square kilometre. Considering these challenges, recent research explored the potential of L. camara as a bioenergy resource. TheL. camarabriquettes exhibit a heating value of approximately 20MJ/kg with a low sulphur (0.5%), nitrogen (1%), and ash content (2%), making them suitable for decentralised energy production. Furthermore, bioethanol production fromL. camarahydrolysate has shown promising results, yielding 0.33g/g withPichia stipitisand0.47g/g with Saccharomyces cerevisiae, which is comparable to other lignocellulosic feedstocks. Additionally, the gasification of L. camara using a downdraft gasifier produced syngas with a lower heating value (LHV) of 6.4MJ/Nm3. These findings demonstrate that using L. camara for bioenergy production presents a dual solution, addressing the growing demand for renewable energy and managing invasive species. This review aims to critically evaluate the potential and challenges associated with the different energy production pathways for L. camara, highlighting its role in sustainable energy generation.

Insights into the influence of anions on the syngas production behavior of bio-wastes during molten salt thermal treatment

Thermal treatment of bio-wastes in molten nitrate at low temperatures has emerged as an efficient approach for producing syngas. Molten salt facilitates the thermal conversion of bio-wastes due to its superior heat transfer and catalytic properties. To enhance the depolymerisation of macromolecules in bio-wastes for the production of high-quality syngas, molten NaNO3-NaNO2 with varying anion ratios was employed in this study, and the effects of these anions on bio-wastes with diverse properties were thoroughly investigated. The results indicated that NO3− tended to be significantly involved in the cleavage of carbonyl groups and C–C/CC bonds, which dominated the high CO2 production. NO2− tended to be significantly involved in the cleavage of ether and C–C/CC bonds, which dominated the high CO production. The elevated NO2− ratio in molten salt significantly facilitated the depolymerisation of bio-wastes, increasing the yield of combustible gases (CO, CH4, H2) while decreasing CO2 yield in the syngas. This resulted in a notable enhancement of the lower heating value (LHV) of syngas, reaching up to 11.55 MJ/Nm3. This behavior also led to the formation of substantial quantities of nitro-phenols and amines containing nitro/nitroso groups in the tar. The nitrosation reaction of NO2− with bio-wastes was the primary factor in this process and took precedence over the nitrification of NO3−. This study elucidated the reaction pathways of NO3−/NO2− with bio-wastes and their contributions to the production of high-quality syngas at low temperature.

Exploring Nigeria’s waste-to-energy potential: a sustainable solution for electricity generation

Abstract This research explored the potential of waste-to-energy (WtE) technology as a sustainable solution to Nigeria’s energy deficit and waste management challenges. Various WtE technologies were reviewed, including incineration, anaerobic digestion, gasification, and pyrolysis, highlighting their applicability and benefits for Nigeria. The potential energy yield from different waste streams, combined with economic viability, environmental benefits, and social impacts, demonstrates the importance of WtE technology for the country. The lower heating value of municipal solid waste and agricultural residue significantly affects energy yield. The incineration of 27.36 million tons of organic waste annually while using relevant technology with energy recovery could generate between 14.52 and 23.08 TWh of electricity per annum. The inclusion of paper and textiles increases the potential yield to 18.69 and 29.71 TWh per year. The potential power generation from agricultural residues is estimated at 80.3 GW. However, Nigeria must address technical, economic, and policy challenges to realize this potential. This can be achieved by developing a robust regulatory framework, fostering public–private partnerships, enhancing local capacity, engaging communities, and investing in research and development. The implementation of WtE projects will facilitate sustainable waste management, improve energy security, create jobs, and promote environmental stewardship.

Effect of isobutanol/gasoline blends on the performance and emissions of an Otto engine-powered vehicle operating on a driving cycle

Abstract This study experimentally investigates the performance and emissions of a typical vehicle in the Latin American automobile sector–specifically; a 1.6 L spark ignition engine with port fuel injection (PFI) was used. The tests were performed using a Mustang MD150 chassis dynamometer under transient running conditions following the worldwide harmonised light test cycle (WLTC). Commercial gasoline (containing 10 vol. % ethanol; E10) was blended with 10, 20, and 30 vol. % of isobutanol. Results reveal that despite the reduction in the fuel lower heating value (LHV), adding the isobutanol B20 blend can improve the fuel economy by up to 6%. Similarly, when the alcohol content in the blend increased, the CO and HC emissions decreased by 10.5 and 10.2%, respectively. Furthermore, the B30 blend resulted in the lowest emissions but had the highest fuel consumption. Notably, these results were achieved without any adjustments to engine key components. Thus, the effects of isobutanol were consistent with the increase in octane and oxygenation of fuel blends.

Optimizing process parameters and materials for the conversion of plastic waste into hydrogen

Abstract This study has investigated hydrogen production from waste plastics using pyrolysis, steam methane reforming, and water-gas-shift reactions modelled via Aspen Plus. After evaluating multiple alternatives, polypropylene (PP) was selected as the feedstock. The research has been focused on how reformer temperature, steam-to-fuel ratio (S/F), reformer pressure, and pyrolysis temperature impact syngas composition, heating values, syngas (H2/CO) ratios, and yields of hydrogen (H2), methane (CH4), and carbon dioxide (CO2). Key findings have indicated that raising reformer temperatures to around 1000°C maximizes hydrogen production in syngas, reaching peak levels of 2360 Nm3/Ton and 2525 Nm3/Ton for reformer temperature and steam-to-fuel ratio (S/F) ratios, respectively, via processes like steam methane reforming and the water-gas-shift reaction. Moreover, other parameters like steam-to-fuel (S/F) ratio and reformer pressure have produced the highest amount of hydrogen at 0.25 and 1 atm, respectively. Optimizing reformer temperature and steam-to-fuel ratio (S/F) have been selected as key in hydrogen production, with peak lower heating values (LHV) of 1.15 MJ/kg for temperature and 1.035 MJ/kg for S/F ratios, highlighting the importance of balancing these parameters for efficiency. Additionally, syngas' hydrogen (H2) composition increased with pyrolysis temperature, peaking at 8.5% at 700°C. Finally, this research has provided valuable insights into optimizing process parameters for sustainable hydrogen production. Moreover, the simulation process has provided cost-effective adjustments and informed decision-making for sustainable and scalable technologies, benefiting researchers, investors, engineers, and policymakers involved in innovative hydrogen generation.

Experimentally Investigating the Potential of Iso-Stoichiometric GEM Blends as a Drop-in Replacement for E50 in SI Engines

Background: Research on alternative fuels for internal combustion engines is crucial due to climate change and energy security concerns. Ethanol-blended gasoline has been a popular alternative fuel, but biomass limitations restrict its widespread use. Methanol offers a solution as it can be produced from non-food sources, extending ethanol's availability. Objective: This study explores a ternary fuel blend consisting of gasoline, ethanol, and methanol as an alternative to binary gasoline-ethanol blend. The objective is to investigate if the isostoichiometric ternary blend offers equivalent fuel properties to E50 (Ethanol 50%, Gasoline 50% (v/v)) gasohol while potentially enhancing engine performance, reducing emissions, and improving combustion characteristics. Methods: A single-cylinder, four-stroke, port fuel injection spark ignition engine was used. The engine was tested with three fuels: pure gasoline, E50 blend, and an equivalent iso-stoichiometric GEM blends. Engine tests were conducted at constant load with varying engine speeds. Performance, emission, and combustion parameters were experimentally measured and compared across all fuels. Results: E50 and its equivalent blends improved brake thermal efficiency but increased brake specific fuel consumption compared to gasoline. It significantly reduced unburned hydrocarbon and carbon monoxide emissions but slightly increased nitrogen oxide emissions. Conclusion: Formulated E50 equivalent blends have identical air to fuel ratio, lower heating values as conventional binary E50 gasoline-ethanol blends. The study suggests that iso-stoichiometric GEM blends have the potential to be a viable alternative drop-in fuel for E50 in internal combustion engines. The future advancements in GEM blends, particularly in optimizing ratios, could lead to patentable inventions.

Challenges in the Valorization of Green Waste in the Central European Region: Case Study of Warsaw

Expanding green areas in cities results in growth in green waste generation. This study presents the findings of an investigation into green waste from selective collection in a large Central European city (Warsaw, Poland), which can be identified as a valuable biomass resource. The research objective was to identify the properties of garden waste from single-family housing to determine valorization opportunities, emphasizing the utilization of GW as a source of energy. The research yielded several findings, including a notable degree of variability in fuel properties, including moisture content (CV = 30%), lower heating value (CV = 14.3%), and ash content (CV = 62.7/56.2%). The moisture content suggests composting, while the fertilizing properties indicate suitability for anaerobic digestion. The instability of the fuel properties, coupled with the elevated levels of chlorine, sulfur, and moisture, constrains the use of garden waste in thermal processes and alternative fuel production. Pyrolysis could be a viable approach for green waste feedstock, offering value-added products depending on the processing conditions and pre-treatment. Nevertheless, implementing a selective collection system is a critical condition for the optimal utilization of bio-waste, facilitating the quality and property control of green and food waste. This is essential for their effective processing, including energy recovery, thereby contributing to the efficient valorization of biomass.

Thermodynamic investigation of biomass-steam gasification in converter vaporisation flue for synthesis gas production

Biomass gasification for hydrogen production is a highly promising technology for energy conversion and utilisation. This paper proposed a novel technology for the injection of biomass and steam into the flue of a converter vaporisation to produce hydrogen-rich syngas. The feasibility of hydrogen generation through gasification between biomass, steam, and carbon dioxide in the high-temperature flue gas was investigated based on the thermodynamic principle of Gibbs free energy minimisation. The influence of gasification parameters on the composition of syngas was also explored. The results indicate that in the gasification process, biomass and steam injected into the converter vaporisation flue can effectively inhibit the generation of by-products such as tar. As the steam volume increases, the volume fraction of hydrogen in the product also increases, while the concentration of carbon monoxide decreases. By adjusting the steam-to-biomass ratio, syngas with a hydrogen content exceeding 20% can be produced. At a reaction temperature of 1200 °C, with a steam addition of 5%, a biomass addition of 8 g/L, and a [Formula: see text] ratio of 3, the gas products are composed of 25% hydrogen and 67% carbon dioxide. The process has the potential to achieve a hydrogen yield of up to 90%, a syngas yield of 94%, and a CO2 conversion rate of 70%. Additionally, the lower heating value of the syngas is measured at 11.24 MJ/Nm3. The research results have confirmed the viability of the new technology, thus establishing a theoretical foundation for the industrial implementation of injecting biomass and steam into the converter vaporisation flue to produce hydrogen-rich syngas.

Experimental evaluation of municipal solid waste air-gasification in a pilot-scale reciprocating moving-grate furnace

The increasing volume of municipal solid waste (MSW) worldwide presents significant environmental challenges, necessitating the development of efficient waste-to-energy (WtE) solutions. Among various thermochemical methods, gasification offers a promising approach for converting MSW into syngas, which can be utilized for energy generation. This study investigates the gasification characteristics of MSW in a pilot-scale reciprocating moving-grate furnace, focusing on the effect of key operating parameters such as equivalence ratio (ER), gasification temperature, and gasifying agent-staged ratio on gasification characteristics.Seven experimental schemes were tested with varying lower heating values (LHV) of MSW (ranging from 6.98 to 15.1 MJ/kg) and throughputs (ranging from 0.77 to 1.67 tons per day) to assess the adaptability and stability of the moving-grate system under different conditions. The results indicate that an ER between 0.6 and 0.7, a gasification temperature of 760 °C, and a gasifying agent-staged ratio of 7:3 are optimal for achieving a maximum energy conversion efficiency of 71.6 %. It was observed that the LHV of syngas decreases when the gasification temperature exceeds 850 °C due to increased oxidation of light hydrocarbons. Moreover, the study highlights the influence of grate moving speed on residence time and reaction completeness, which are critical for optimizing syngas yield and quality.The findings demonstrate that while the maximum energy conversion efficiency of the moving-grate system is lower than other reactor types, its lower capital and operating costs, due to the lack of dedicated feedstock pretreatment, make it a viable option for small-scale and pilot-scale applications. This study provides valuable insights into optimizing MSW gasification processes and underscores the potential of the moving-grate furnace for adaptable and cost-effective WtE applications. The novelty of this work lies in the comprehensive evaluation of the moving-grate gasification process under varied operating conditions, providing a foundation for future research on improving efficiency and reducing environmental impact in large-scale MSW management.

Combination of integrated machine learning model frameworks and infrared spectroscopy towards fast and interpretable characterization of model pyrolysis oil

Model pyrolysis oil (bio-oil) is a promising bio-fuel with complex and unstable contents, making its fast characterization an essential demand in industrial production. This study proposed an integrated machine learning framework to predict elemental composition, low heating value, and unsaturated concentration from infrared spectra, achieving fast and interpretable characterization of bio-oil. In the integrated framework, a peak loading-based strategy was used to dimensionally reduce the spectral data. Bayesian optimized random forest (RF) and extreme gradient boosting (XGBoost) models were used to predict bio-oil properties from dimensionally reduced spectral data. Ensemble learning was used to combine RF and XGBoost models together for better predicting performance. Results showed that the proposed characterization method achieved an average accuracy of 99.53 %, a low RMSE value of 0.726, and an R2 of 0.98. The Shapley value analysis revealed that the vibration of NH2 stretch (1594 cm−1), C-H stretch (2868 cm−1), and C-N stretch in the aromatic ring (1229 cm−1) have a significant contribution to the characterization results. The working mechanism of the proposed characterization method was interpreted by the internal relationship among spectral peak location/height, functional group species/amount, and the predicted characteristics. The results are hoped to serve quality control in production of bio-oil.

Experimental study on co-gasification of cellulose and high-density polyethylene with CO2

Co-gasification of biomass and waste plastic with CO2 presents an effective strategy for integrating biomass conversion, waste utilization and carbon recycling. In this study, the co-gasification of cellulose and high-density polyethylene with CO2 was investigated experimentally. The effects of mixing ratio and temperature on co-gasification characteristics, including gas yield, product gas composition, lower heating value of syngas and gasification efficiency, were comprehensively evaluated. Additionally, the interaction between cellulose and high-density polyethylene was analyzed. The results suggested that increasing the polyethylene content in feedstock resulted in decreased yields of H2 and CO, increased CH4 yield, increased lower heating value of syngas and reduced gasification efficiency. The interaction between cellulose and high-density polyethylene enhanced the gas yield, with the most significant effect at 40 % polyethylene content. In the range of 900 °C–1000 °C, increasing the temperature resulted in increased gas yield, reduced lower heating value of syngas and increased gasification efficiency. The positive interaction between cellulose and high-density polyethylene on gas yield was more significant at higher temperatures. This work shed light on reaction characteristics for co-gasification of biomass and high-density polyethylene with CO2, laying the foundation for the design and application of this technology.

Effect of Feedstock Blends and Equivalence Ratio on the Thermal Arc Plasma Assisted Co-Gasification of Biomass and Plastic using Air-Blown Downdraft Reactor

Plastic waste is known to cause an emerging environmental pollution, posing risks to both terrestrial and aquatic ecosystems. Co-gasification method is an alternative way to reduce municipal solid waste and plastic waste by converting it into useful gas fuel energy. The present study used empty fruit bunch biomass (EFB), plastic waste of low-density polyethylene (LDPE) and Polyethylene terephthalate (PET) as a feedstock for thermochemical conversion process into syngas fuel energy via plasma co-gasification method. The effect of multiple feedstocks mixture between biomass and plastic and equivalence ratio on the compositions of produced syngas, high heating value (HHV), lower heating value (LHV), cold gas efficiency (CGE) and carbon conversion efficiency (CCE) were critically investigated. A reactor of air-blown downdraft arrangement was used in these experiments. The gasifying agent flow rate of air was set at the frequency range of 10 to 22Hz to achieve equivalence ratio between 0.15 to 0.30. The blending ratio (BR) between biomass and plastic (EFB:Plastic) were set as E90:P10, E80:P20 and E70:P30. The results indicate that H2 and CO composition is typically decrease as ER increase for the mixture of EFB and LDPE. In contrast, the composition of H2 and CO is generally increase as ER increases. However, the maximum value of H2 and CO is dominated by the mixture of EFB and LDPE at any blending ratio and lower ER condition. This is due to the higher element of H, C and O in the raw material of EFB and LDPE compared to PET. This study is crucial in understanding the synergistic effect of co-gasification assisted with plasma reaction between biomass and plastic waste.

Production and characterization of two-step condensation bio-oil from pyrolysis

The goal of this project is to investigate the potential of fuel production directly from slow pyrolysis of straw pellets without further refining. A two-step condensation was used to separate liquids from the volatiles. The thermal process chosen is slow pyrolysis at 500°C to couple the fuel production with carbon capture by maximizing the char production alongside bio-oils collection. Condensation parameters were tuned to improve the pyrolysis oil quality. To assess the oil quality some requirements on marine fuels, bio-oils and boiler fuels were taken as reference. Three condensation conditions were inspected: the best pyrolysis overall process was repeated three times for a total of five pyrolysis processes (lately referred to as runs). As expected, the bio-oil characteristic changed with the condensation temperature. As a result of lowering the bio-oil condensation temperature, the bio-oil results less viscous, less dense, with lower heating value and with higher water content. The final bio-oil produced was almost compliant to ISO 8217:2017 for residual marine fuels K 380, apart from water content and acid number, while it was almost compliant for the standard EN 16900:2017 for industrial boilers fuels, apart for the kinematic viscosity. It was assessed that the char is produced with an average yield of 27 w% on dry basis, while bio-oil has a yield between 5 and 10 w%. It is possible to recover an average of 72 % of the total energy contained in the straw in the valuable products, gas, char and bio-oil. The carbon captured with charcoal was around 49 w% of the total present in straw. The pyrolysis experiments were performed using an innovative semi-batch, packed-bed reactor with gas re-circulation and a new two-fraction condensation appliance that is DTU patented. The innovation is both in the reactor, where the gas is directly heated and flushed back into the pyrolyser, and in the condensation section, where the bio-oil is separated from the water fraction during the pyrolysis. The company Stiesdal SkyClean A/S showed interest in further development and scale up of this pyrolysis and condensation system.

Unlocking the techno-economic potential of biomass gasification for power generation: Comparative analysis across diverse plant capacities

This research aims to evaluate the techno-economic viability and commercial potential of biomass gasification across different capacities. Sensitivity analysis was conducted based on an established downdraft gasifier model using Aspen Plus. Results underscored the significant impact of gasification temperature and equivalence ratio (ER) on syngas composition, low heating value (LHV), and cold gas efficiency (CGE). Among the feedstocks tested, coconut shell emerged as a feasible feedstock, yielding syngas with an LHV of 8.93 MJ/Nm3 and achieving a CGE of up to 71.12 %. Optimal gasification temperatures ranged between 750 °C to 1,000 °C, with peak ER falling within 0.1 to 0.3. Economic analysis revealed that smaller-scale operations like Plant A resulted in a negative net present value of − US$0.63 million, indicating unfavorable investments. The internal rate of return notably increased from 9.53 % for Plant B compared to −2.56 % for Plant A (20 kW). Plant D, with larger capacity of 20 MW, showed an impressive payback period of less than two years (1.69 years). Medium to large-scale plants such as Plant C (2 MW) and Plant D demonstrated greater economic resilience, with Plant D achieving a significantly lower levelized cost of electricity of US$ 0.19/kWh compared to Plant A at US$ 0.86/kWh. It was noted that the impact of capital costs, operating expenses, and revenue variations is less pronounced at larger scales. The findings from this study shed light on the feasibility of biomass gasification for power generation as a viable option, thereby unlocking the potential for its large-scale commercialization.

Impact of Thickness of Pd/Cu Membrane on Performance of Biogas Dry Reforming Membrane Reactor Utilizing Ni/Cr Catalyst

The present study pays attention to biogas dry reforming for the purpose of producing H2. It is known that biogas contains approximately 40 vol% CO2, causing a decrease in the efficiency of power generation due to its lower heating value compared to natural gas, i.e., CH4. We suggest a hybrid system composed of a biogas dry reforming membrane reactor and a high-temperature fuel cell, i.e., a solid oxide fuel cell (SOFC). Since biogas dry reforming is an endothermic reaction, we adopt a membrane reactor, controlled by providing a non-equilibrium state via H2 separation from the reaction site. The purpose of the present study is to understand the effect of the thickness of the Pd/Cu membrane on the performance of the biogas dry reforming membrane reactor with a Pd/Cu membrane as well as a Ni/Cr catalyst. The impact of the reaction temperature, the molar ratio of CH4:CO2 and the differential pressure between the reaction chamber and the sweep chamber on the performance of the biogas dry reforming membrane reactor with the Pd/Cu membrane as well as the Ni/Cr catalyst was investigated by changing the thickness of the Pd/Cu membrane. It was revealed that we can obtain the highest concentration of H2, of 122,711 ppmV, for CH4:CO2 = 1:1 at a reaction temperature of 600 °C and a differential pressure of 0 MPa and using a Pd/Cu membrane with a thickness of 40 μm. Under these conditions, it can be concluded that the differential pressure of 0 MPa provides benefits for practical applications, especially since no power for H2 separation is necessary. Therefore, the thermal efficiency is improved, and additional equipment, e.g., a pump, is not necessary for practical applications.

A surrogate fuel emulating the physical and chemical properties of aviation biofuels

AbstractThe development of aviation biofuels is a key strategy for reducing carbon emissions in the aviation industry. This study aimed to establish a surrogate model for aviation biofuels using a hybrid approach that combined explicit equations with an artificial neural network (ANN). The low heating value was calculated using an explicit equation, whereas the ANN predicted changes in density, viscosity, surface tension with temperature, and the distillation curve of the surrogate model. An optimization algorithm was then employed to identify suitable substitutes, which consisted of 11.44% n‐decane, 43.43% n‐dodecane, 43.11% n‐tetradecane, and 2.02% methylcyclohexane. The maximum error between the physical properties of the surrogate components and the measured biofuels did not exceed 7%. The ignition delay time of the substitute components matched that of real aviation biofuels at an equivalence ratio of 1.0 and a pressure of 10 bar.

MSW-TO-RDF CONVERSION FOR CEMENT PLANT IN INDONESIA THROUGH PILOT PROJECT AND MODELING

Aiming for sustainable MSW and cement industry practices, this study assessed the conversion of municipal solid waste (MSW) to refuse-derived fuel (RDF) in four major Indonesian areas. Physical and chemical properties, particle size distribution, and MSW fraction analysis were performed to characterize the MSW before utilizing the MSW for the pilot project. In the pilot project, MSW was shredded and separated to produce RDF and low-grade RDF. RDF produced was quantified, and the output was analyzed to determine the RDF quality. RDF modeling was set based on the pilot project outcome, where the potential quantity, analysis, and feasibility were evaluated. The analysis revealed a need for better MSW processing due to a low heating value (LHV) of 5.4 MJ/kg and high moisture content (MC) of 52-57%. Combustible materials were found to be crucial for RDF quality. A pilot processing 1,000 Mg of MSW resulted in RDF with an LHV of 8.7 MJ/kg and MC of 47% and low-grade RDF with an LHV of 3.0 MJ/kg and MC of 61%, highlighting the importance of drying phase to meet quality standards. The modeling incorporated a two-step drying process, including hot gas utilization at the cement plant. 13 RDF units processing 6,500 MSW Mg/day were needed to produce 3100 Mg/day of RDF (equal to 50% fuel substitution), which could significantly reduce CO2 emissions and MSW by 45% in Jakarta and its neighboring cities, marking an effort for eco-friendlier cement manufacturing.

Transforming Wine By-Products into Energy: Evaluating Grape Pomace and Distillation Stillage for Biomass Pellet Production

The by-products of the wine industry represent a global production of 10.5 to 13.1 million tons of wine pomace annually. This study examines the chemical composition and energy potential of wine pomace and distillation stillage, evaluating their suitability for pellet production within ENplus® standards. Proximate analysis, elemental analysis, and calorimetric analysis were conducted on samples of the two by-products collected in a local Distillery in Portugal. The results reveal that wine pomace has a higher volatile matter content (62.695%) than distillation stillage, which, however, has lower ash content (3.762%) and higher fixed carbon (31.813%). Calorimetric analyses show that distillation stillage has a superior low heating value compared to wine pomace, with values exceeding 19 MJ/kg. Both by-products, however, exceed ENplus® limits for ash (≤0.70), nitrogen (≤0.3), and sulfur (≤0.04) content, presenting challenges for use as high-quality fuel pellets. Combining these biomasses with other materials could reduce the pollutant content of the pellet and improve efficiency. This study highlights the need for pre-treatment strategies to lower ash content and enhance combustion. Policy support for sustainable practices is essential to optimize the use of wine pomace and distillation stillage as renewable energy sources.

Bench-Scale Gasification of Olive Cake in a Bubbling Fluidized Bed Reactor

The gasification of olive cake is a promising method for converting this material into valuable energy. This work offers interesting results about the effect of equivalence ratio and temperature on the composition and quality of the produced gas obtained during olive cake gasification in a fluidized bed plant with air as a gasification agent. Additionally, the efficiency of the gasification process was evaluated. The results show that, for a specific temperature, an equivalence ratio of 0.3 showed a higher cold gas efficiency. For example, at 850 °C and an equivalence ratio of 0.1, the cold gas efficiency was 22.7%; however, at the same temperature but at an equivalence ratio of 0.3, the cold gas efficiency was increased to 61.2%. In addition, for a constant equivalence ratio, by increasing the operating temperature, there was no significant increase in the lower heating value of the exit gas, and the gas flow was practically constant with temperature, but it varied substantially with the equivalence ratio, reaching values in the range of 3.44–14.89 NL/min (825.6–3573.6 NL/kg feed). Finally, the production of CO, H2, and CH4 is estimated to be higher for tests conducted with an equivalence ratio of 0.3.

Production of high calorific value hydrogen-rich combustible gas by supercritical water gasification of straw assisted by machine learning

This article reveals the basic laws of straw supercritical water gasification (SCWG) and provides basic experimental data for the effective utilization of straw. The paper studied the impact of three operational conditions on the production of high-calorific value hydrogen-rich combustible gases through SCWG of straw within a quartz tube reactor. The findings reveal that elevated reaction temperatures, extended residence times, and reduced feedstock concentrations favor the SCWG of straw. When combustible gas contains carbon dioxide, the maximum low heating value (LHV) of the gas is 21 MJ/Nm3. Upon removing carbon dioxide, the LHV of the gas reached 38 MJ/Nm3. Subsequently, a machine learning (ML) model was developed to forecast gas yield and LHV during the SCWG process. The results demonstrate that the model exhibits robust generalization capabilities. ML can be extensively applied to forecast biomass SCWG processes across various operational conditions.