Carbon Conversion Research Articles

Temperature-Pressure Swing Process for Reactive Carbon Capture and Conversion to Methanol: Techno-Economic Analysis and Life Cycle Assessment.

A model was developed to conduct techno-economic analysis (TEA) and life cycle assessment (LCA) for reactive carbon capture (RCC) and conversion of carbon dioxide (CO2) to methanol. This RCC process is compared to a baseline commercialized flue gas CO2 hydrogenation process. An ASPEN model was combined with existing TEA and LCA models into a larger TEA/LCA framework in Python. From preliminary experimental data, the model found a levelized cost of $0.79/kg methanol for the baseline process and $0.99/kg for the RCC process. The cradle-to-gate carbon intensity of the baseline process was 0.50 kg-CO2e/kg-methanol, compared to 0.55 kg-CO2e/kg-methanol for the RCC process. However, water consumption for RCC (10.21 kg-H2O/kg-methanol) is greatly reduced compared to the baseline (12.89 kg-H2O/kg-methanol). Future improvements in hydrogen electrolysis costs will benefit the RCC. A target H2/methanol mass ratio of 0.26 was developed for RCC laboratory experiments to reduce methanol cost below the baseline. If a ratio of 0.24 can be achieved, a levelized cost of $0.76/kg methanol is projected, with a carbon intensity of 0.42 kg-CO2e/kg-methanol.

Dynamics of the Boundary Layer in Pulsed CO2 Electrolysis

AbstractElectrochemical reduction of CO2 poses a vast potential to contribute to a defossilized industry. Despite tremendous developments within the field, mass transport limitations, carbonate salt formation, and electrode degradation mechanisms still hamper the process performance. One promising approach to tweak CO2 electrolysis beyond today's limitations is pulsed electrolysis with potential cycling between an operating and a regeneration mode. Here, we rigorously model the boundary layer at a silver electrode in pulsed operation to get profound insights into the dynamic reorganization of the electrode microenvironment. In our simulation, pulsed electrolysis leads to a significant improvement of up to six times higher CO current density and 20 times higher cathodic energy efficiency when pulsing between −1.85 and −1.05 V vs SHE compared to constant potential operation. We found that elevated reactant availability in pulsed electrolysis originates from alternating replenishment of CO2 by diffusion and not from pH‐induced carbonate and bicarbonate conversion. Moreover, pulsed electrolysis substantially promotes carbonate removal from the electrode by up to 83 % compared to constant potential operation, thus reducing the risk of salt formation. Therefore, this model lays the groundwork for an accurate simulation of the dynamic boundary layer modulation, which can provide insights into manifold electrochemical conversions.

Dynamics of the Boundary Layer in Pulsed CO2 Electrolysis.

Electrochemical reduction of CO2 poses a vast potential to contribute to a defossilized industry. Despite tremendous developments within the field, mass transport limitations, carbonate salt formation, and electrode degradation mechanisms still hamper the process performance. One promising approach to tweak CO2 electrolysis beyond today's limitations is pulsed electrolysis with potential cycling between an operating and a regeneration mode. Here, we rigorously model the boundary layer at a silver electrode in pulsed operation to get profound insights into the dynamic reorganization of the electrode microenvironment. In our simulation, pulsed electrolysis leads to a significant improvement of up to six times higher CO current density and 20 times higher cathodic energy efficiency when pulsing between -1.85 and -1.05 V vs SHE compared to constant potential operation. We found that elevated reactant availability in pulsed electrolysis originates from alternating replenishment of CO2 by diffusion and not from pH-induced carbonate and bicarbonate conversion. Moreover, pulsed electrolysis substantially promotes carbonate removal from the electrode by up to 83 % compared to constant potential operation, thus reducing the risk of salt formation. Therefore, this model lays the groundwork for an accurate simulation of the dynamic boundary layer modulation, which can provide insights into manifold electrochemical conversions.

Fe–Ni composite oxygen carrier for chemical looping gasification with diverse fuels to produce syngas

Coal-based chemical looping gasification (CCLG) has been proposed as an emergent type of coal gasification technology that produces high-quality syngas by using lattice oxygen from oxygen carrier instead of molecular oxygen. In this paper, the Fe–Ni composite oxygen carrier was synthetized using sol-gel method and the gasification performance of the prepared sample was analyzed by a fixed-bed reactor. The results indicated that the Fe–Ni composite oxygen carrier presented a high carbon conversion of fuel and syngas selectivity during the CCLG process. Additionally, the cycle stability test showed that the carbon conversion of fuel and syngas selectivity did not change significantly with the increase of cyclic frequency. To further study the influence of volatiles released from coal on the gasification performance of oxygen carrier, the interactions between the oxygen carrier samples and char obtained at different pyrolysis temperatures were investigated by a fixed-bed reactor and TG-MS, respectively. The results suggested that the gas products (H2, CO, CO2 and CH4) yields of char-oxygen carrier were significantly lower than those of coal-oxygen carrier. Besides, the pyrolysis temperature for preparing char had a great effect on the carbon conversion of fuel and syngas selectivity due to the distinction of volatiles released from solid fuel.

Experimental study on thermal conversion characteristics of char in a pressurized O2/CO2/H2O atmosphere

Pressurized oxy-fuel combustion represents an advanced coal-fired power generation technology advantageous for CO2 capture and system efficiency enhancement. This study employed a pressurized tube furnace experimental system to investigate the thermal conversion characteristics of char in a pressurized O2/CO2/H2O atmosphere. The carbon conversion under varying pressures (0.1–1.3 MPa), atmospheres, and residence times were analyzed. The physical and chemical structural evolutions of char, which are directly related to its reactivity, were elucidated using nitrogen adsorption, XPS, Raman, and FTIR analysis. The findings indicate that both pressurization and increasing O2/CO2 enhanced char conversion. Transitioning from kinetic to diffusion control in the O2/CO2/H2O atmosphere necessitated high pressure. The influence of CO2 on the physical and chemical structure of char under pressurized conditions was found to be less significant compared to that of O2 and H2O. Furthermore, pressurization and elevated O2 ratios were observed to reduce the microporous structure's contribution to the specific surface area of the char. Pressurization also increased the degree of graphitization of the char. Elevated O2/CO2 concentrations facilitated the breakdown of C–C structures, the melting of large aromatic rings, and the reduction in the degree of graphitization, particularly under higher pressures. In the O2/CO2/H2O pressurized atmosphere, more oxygen-containing functional groups were formed within the char structure, with the C–OH structure forming initially, followed by the O–CO structure.

Temperature-Driven Activated Sludge Bacterial Community Assembly and Carbon Transformation Potential: A Case Study of Industrial Plants in the Yangtze River Delta.

Temperature plays a critical role in the efficiency and stability of industrial wastewater treatment plants (WWTPs). This study focuses on the effects of temperature on activated sludge (AS) communities within the A2O process of 19 industrial WWTPs in the Yangtze River Delta, a key industrial region in China. The investigation aims to understand how temperature influences AS community composition, functional assembly, and carbon transformation processes, including CO2 emission potential. Our findings reveal that increased operating temperatures lead to a decrease in alpha diversity, simplifying community structure and increasing modularity. Dominant species become more prevalent, with significant decreases in the relative abundance of Chloroflexi and Actinobacteria, and increases in Bacteroidetes and Firmicutes. Moreover, higher temperatures enhance the overall carbon conversion potential of AS, particularly boosting CO2 absorption in anaerobic conditions as the potential for CO2 emission during glycolysis and TCA cycles grows and diminishes, respectively. The study highlights that temperature is a major factor affecting microbial community characteristics and CO2 fluxes, with more pronounced effects observed in anaerobic sludge. This study provides valuable insights for maintaining stable A2O system operations, understanding carbon footprints, and improving COD removal efficiency in industrial WWTPs.

Green iron and syngas production via continuous solar-driven agricultural waste biomass gasification combined with iron(III) oxide reduction

The production of renewable synthetic fuels and chemicals from solar energy and agricultural waste biomass is considered. Solar thermochemical conversion processes offer a promising pathway to a sustainable fuel economy and green chemical industry. This study investigates the continuous solar-driven gasification of agricultural biomass (betel nut waste) combined with iron oxide (Fe2O3) reduction to produce carbon-neutral syngas and green metallic iron in a single process. A thermodynamic analysis of the system was initially conducted to predict the distribution of equilibrium products. Then, on-sun continuous processing was experimentally carried out under different operating conditions, including betel/Fe2O3 molar ratios (0.56–1.5) and temperatures (900–1200 °C) to evaluate the process feasibility and reliability. As a result, solar gasification of betel nut waste combined with Fe2O3 reduction performed exceptionally well with continuous reactant particles feeding, demonstrating a feasible pathway for producing green iron and high-quality syngas. The maximum syngas yield reached 63.3 mmol/gdry_betel, approaching its theoretical value, and high-purity Fe was simultaneously produced. The process demonstrated high efficiency, with maximum carbon conversion approaching 98 %, energy upgrade factor up to 1.26, and solar-to-fuel energy conversion efficiency up to 14.4 %, highlighting remarkable conversion performance of biomass and solar energy to chemicals.

Engineering Lewis-Acid Defects on ZnO Quantum Dots by Trace Transition-Metal Single Atoms for High Glycerol-to-Glycerol Carbonate Conversion.

Efficient conversion of biomass wastes into valuable chemicals has been regarded as a sustainable approach for green and circular economy. Herein, a highly efficient catalytic conversion of glycerol (Gly) into glycerol carbonate (GlyC) by carbonylation with the commercially available urea is presented using low-cost transition metal single atoms supported on zinc oxide quantum dots (M1-ZnO QDs) as a catalyst without using any solvent. A facile one-step wet chemical synthesis allows various types of metal single atoms to simultaneously dope and introduce Lewis-acid defects in the ZnO QD structure. It is found that doping with a trace amount of isolated metal atoms greatly boosts the catalytic activity with Gly conversion of 90.7%, GlyC selectivity of 100.0%, and GlyC yield of 90.6%. Congruential results from both Density Functional Theory (DFT)and in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (in situ DRIFTS) studies reveal that the superior catalytic performance can be attributed to the enriched Lewis acid sites that endow optimal adsorption, formation of the intermediate for coupling between urea and Gly, and desorption of GlyC. Moreover, the tiny size of ZnO QDs efficiently promotes the accessibility of these active sites to the reactants.

Synergistic co-steam gasification of biomass and refuse-derived fuel: A path to enhanced gasification performance

The co-steam gasification of biomass (straw) and Refuse-Derived Fuel (RDF) presents a promising pathway for sustainable waste management and renewable energy production, with significant implications for environmental protection. This study investigates the co-gasification of straw and RDF to optimize syngas production and minimize undesired by-products. The optimization of the S/M ratio and gasification temperature is crucial for efficient RDF gasification. The optimal S/M ratio and temperature balance syngas yield, quality (LHV), and process efficiency (carbon conversion efficiency and cold gas efficiency), while minimizing environmental hazards from solid residues. The carbon conversion efficiency of co-gasification of RDF increased by 12.7 % at the S/M 0 f 0.75 and gasification temperature of 800°C, a significant improvement compared to the efficiencies observed for the separate gasification of straw and RDF. Additionally, the gas yield and the cold gas efficiency were increased by 14.43 % and 26.42 % compared to the separate gasification processes, respectively. These results demonstrate the synergistic effects of co-gasifying straw and RDF, enhancing gasification performance and reducing tar formation. The study underscores the potential of co-steam gasification of straw and RDF as a technologically viable and environmentally friendly approach to waste-to-energy conversion, emphasizing the importance of operational optimization for achieving superior energy recovery, resource efficiency, and reduced environmental impact.

Distribution Characteristics and Source Analysis of Carbonaceous Aerosols Before and After the Spring Festival in the Guanzhong Plain

The spatio-temporal variation characteristics and potential sources of carbonaceous aerosols in the Guanzhong Plain during the Spring Festival in 2023 were analyzed using inverse distance weighting spatial interpolation （IDW）, secondary organic carbon （SOC） estimation, and potential source contribution factor analysis （PSCF）, with the OC and EC in the PM2.5 of five cities： Xi'an, Baoji, Xianyang, Weinan, and Tongchuan as the research objects. The results showed that in terms of time distribution, ρ（OC） was as follows： after the Spring Festival [（18.6 ±11.0） μg·m-3] &gt; during the Spring Festival [（16.2 ±15.1） μg·m-3] &gt; before the Spring Festival [（10.0 ±8.3） μg·m-3], and ρ（EC） was as follows： after the Spring Festival [（2.2 ±1.2） μg·m-3] &gt; during the Spring Festival [（1.7 ±1.5） μg·m-3] &gt; before the Spring Festival [（1.4 ±1.1） μg·m-3], which indicated that OC and EC concentrations were the most severe after the Spring Festival. In terms of spatial distribution, ρ（OC） was as follows： Xianyang [（21.4 ±17.3） μg·m-3] &gt; Baoji [（15.8 ±12.8） μg·m-3] &gt; Xi'an [（13.6 ±11.3） μg·m-3] &gt; Weinan [（11.6 ±9.1） μg·m-3] &gt; Tongchuan [（10.0 ±8.3） μg·m-3], and ρ（EC） was as follows： Xianyang [（2.1 ±1.4） μg·m-3] &gt; Weinan [（1.8 ±1.4） μg·m-3] &gt; Xi'an [（1.8 ±1.2） μg·m-3] &gt; Tongchuan [（1.6 ±1.4） μg·m-3] &gt; Baoji [（1.2 ±0.9） μg·m-3]. Overall, Xianyang had the most severe PM2.5 and carbon aerosol pollution, whereas Tongchuan had the least pollution. IDW results showed that the high-value center of OC and EC concentration [ρ（OC） &gt; 27.3 μg·m-3, ρ（EC） &gt; 2.9 μg·m-3] was in the middle of the plain, the low-value center of OC and EC concentration [ρ（OC） <7.0 μg·m-3, ρ（EC） < 1.0 μg·m-3] was in the northern plain, and the distribution of OC was higher in the west and lower in the east, whereas the distribution of EC was higher in the east and lower in the west. The proportion of SOC in OC was as follows： after the Spring Festival （51.7%） &gt; during the Spring Festival （41.1%） &gt; before the Spring Festival （36.8%）. The SOC/OC values of each city and the contribution rate of SOC of each city to the Guanzhong Plain indicated that Tongchuan, Baoji, and Xianyang were greatly affected by the secondary conversion of organic carbon. The correlation of OC and EC before, during, and after the Spring Festival （r = 0.85, r = 0.98, and r = 0.94, respectively） indicated a high degree of homology between them. Carbonaceous aerosols had a certain correlation with humidity and wind speed before and during the Spring Festival but had a weak correlation with meteorological factors after the Spring Festival. Carbonaceous aerosols generally were strongly correlated with CO and NO2, and the correlation was strongest after the Spring Festival, whereas the correlation with SO2 was strongest during the Spring Festival. The potential source areas of carbonaceous aerosols in the five cities were mainly concentrated in the local and surrounding areas of southern Gansu, northern Shaanxi, and southern Shaanxi. They were also affected by long-distance transportation from the northwest before the Spring Festival.

Metal-organic framework-derived base catalyst for conversion of dimethyl carbonate to glycerol carbonate

Glycerol carbonate (GLC) offers a range of benefits including biodegradability, versatility, and its potential for carbon capture and utilization. Base catalysts play a crucial role for GLC synthesis by facilitating the activation of reactants, enhancing nucleophilicity, accelerating reaction kinetics, and enabling catalyst regeneration. In this study, metal–organic framework (MOF) derived hybrid structure, CaO-MgO@Al2O3, was developed as a base catalyst to promote transesterification of glycerol with dimethyl carbonate (DMC) to form GLC. The results show that hydrothermal plus wet-impregnation routes formed the hybrid nanostructure with homogenously dispersed Ca, Mg and Al elements. Further, the synthesized catalysts showed significantly high specific surface area and basicity (2.656 mmol g−1). High selectivity (>99 %) and high GLC yield (96.2 %; 208.9 mmol g-cat−1) were achievable. This study demonstrated the rational design concept of MOF-derived hybrid structures used in the enhancement of base catalysis for transesterification of DMC to GLC, offering an effective solution with mild reaction conditions and high conversion.

Autotrophic poly-3-hydroxybutyrate accumulation in Cupriavidus necator for sustainable bioplastic production triggered by nutrient starvation

Cupriavidus necator is a facultative chemolithoautotrophic bacterium able to convert carbon dioxide into poly-3-hydroxybutyrate. This is highly promising as the conversion process allows the production of sustainable and biodegradable plastics. Poly-3-hydroxybutyrate accumulation is known to be induced by nutrient starvation, but information regarding the optimal stress conditions controlling the process is still heterogeneous and fragmentary. This study presents a comprehensive comparison of the effects of nutrient stress conditions, namely nitrogen, hydrogen, phosphorus, oxygen, and magnesium deprivation, on poly-3-hydroxybutyrate accumulation in C. necator DSM545. Nitrogen starvation exhibited the highest poly-3-hydroxybutyrate accumulation, achieving 54% of total cell dry weight after four days of nutrient stress, and a carbon conversion efficiency of 85%. The gas consumption patterns indicated flexible physiological mechanisms underlying polymer accumulation and depolymerization. These findings provide insights into strategies for efficient carbon conversion into bioplastics, and highlight the key role of C. necator for future industrial-scale applications.

Progressive inhibition of [formula omitted] reaction in wood char packed bed by in-situ evolving [formula omitted]: Experimental insights and theoretical analysis

Previous research on Char reactions with gas phase compounds under micro-thermogravimetry systems shows that hydrogen inhibits heterogeneous char reactions. However, its impact on larger gasification systems with evolving hydrogen profiles remains largely unexplored. This study examines a macro-scale wood char bed to understand the influence of in situ evolving hydrogen on char reactions. When subjected to a specific steam flux, carbon conversion and pore morphology changes are mainly confined to the bed’s upstream, with the downstream char retaining its original characteristics. Numerical investigations reveal over 75 % of species production and consumption occurs within the initial 20 % of bed height. Fourier-transform infrared spectroscopy confirms hydrogen-induced inhibition in downstream segments, showing a shift from C–OH to C–H bonds. Particle-scale analysis indicates significantly higher rates of hydrogen diffusion and adsorption compared to H2O, impeding downstream C+H2O reactions. Increased temperature, higher reactant concentrations, or reduced residence time can overcome this inhibition, enhancing conversion rates. These findings are critical for optimizing steam-to-biomass ratios in oxy-steam gasification systems for generating hydrogen-rich syngas.

Effects of Biochar on Gaseous Carbon and Nitrogen Emissions in Paddy Fields: A Review

The paddy field is a major source of gaseous carbon and nitrogen emissions, and reducing these emissions is of great significance for mitigating greenhouse effects and non-point source pollution in farmland. Biochar, derived from agricultural waste, possesses a stable structure, large specific surface area, abundant pore structures, and surface functional groups. These characteristics could enhance soil physicochemical properties and microbial activity, thereby facilitating the dual goals of increasing crop yield and reducing emissions. Based on numerous studies, this review summarizes the effects of biochar on the emissions of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and ammonia volatilization (NH3), as well as on global warming potential (GWP) and greenhouse gas emission intensity (GHGI). It elucidates the mechanism of emission reduction by biochar amendment from the perspective of carbon and nitrogen conversion processes and soil physicochemical and biological properties. Numerous studies showed the application of 5~40 t ha−1 biochar reduced CO2, CH4, N2O, and NH3 emissions by 1.64~89.6%, 8.6~89.6%, 10~90%, and 12.27~53%, respectively. A small number of studies found that the application of 5~48 t ha−1 biochar increased CO2, CH4, N2O, and NH3 emissions by 12~37%, 19.85~176%, 13~84.23%, and 5.47~70.9%, respectively. Most scholars have found that biochar has varying degrees of emission reduction capabilities in different parts of the world. Therefore, future research directions have been suggested for utilizing biochar to reduce carbon and nitrogen emissions in paddy fields.

Transforming CO2 into Synthetic Fuels: Modeling, Simulation, and Optimization Analysis of Methanol Production from Industrial Wastes

Carbon capture and utilization (CCU) has emerged in recent years as a promising decarbonization solution for hard-to-abate industries. Compared to carbon capture and storage (CCS), CCU aims not for the storage of carbon dioxide (CO2) but for its use in the production of synthetic fuels, such as synthetic methanol (MeOH). Synthetic MeOH is produced through CO2 hydrogenation, utilizing green hydrogen (H2). Efficient use of CO2 and H2 feedstocks is essential to maximize the carbon reduction potential and energy efficiency of the process. This study performed an optimization analysis on a small-scale, containerized, and portable CO2 hydrogenation unit with a 5 kg MeOH/h production capacity goal, focusing on carbon conversion efficiency (CCE), MeOH yield, H2 consumption, and MeOH purity. The analysis was conducted using Aspen Plus V12. A single-pass model was used first to evaluate an initial reactor design. The reactor was then re-designed according to the results of the gas hourly space velocity (GHSV). The model was then expanded to include a recycling loop and the final reactor design was validated, aiming to maximize overall efficiency. The effects of the operational parameters including the reactor inlet temperature, reactor pressure, thermal fluid temperature, and condensation temperature were examined. The model was then further expanded to include the MeOH distillation process, and the effect of the distillation temperature was examined. The final product of the analysis was a fully-defined and optimized unit, achieving an 87.97% CCE and an 84.99% MeOH yield, consuming 1.11 kg H2/h for the production of 5.01 kg MeOH/h of 99.86 wt% purity. This study can provide valuable information and guidelines for designing small-scale, containerized, and portable CO2 hydrogenation units, which can serve as alternative solutions to address issues of H2 production and transportation related to large-scale installations.

Pyrolysis of high-density polyethylene: Degradation behaviors, kinetics, and product characteristics

Pyrolysis is a promising technology for converting plastic waste into valuable raw materials while offering a potential solution to the global plastic pollution crisis. In this study, the thermal pyrolysis of high-density polyethylene (HDPE) is investigated in a drop tube reactor under nearly isothermal conditions. The impact of reaction temperature and gas/volatile residence time on carbon conversion and product distribution is examined across a range of 500–900 °C and 3.6–32.2 s, respectively. Non-condensable gas products detected by online mass spectrometry are H2, CH4, C2H4, C2H6, C3H6, and C3H8. At elevated temperatures and prolonged residence time, H2 yield reaches as high as 8.6 wt% of the initial HDPE mass due to intensified cracking reactions of C2–C3 hydrocarbons and long-chain aliphatic compounds. Consequently, pyrolysis tars consist mainly of polycyclic aromatic hydrocarbons (PAHs) with 5–7 rings, accompanied by visible coke deposition within the reactor. HDPE decomposition to volatiles is an endothermic process and it is complete at a temperature between 492 °C and 525 °C, depending on the heating rate employed, from non-isothermal thermogravimetric analysis and differential scanning calorimetry (TGA-DSC) measurements. The thermal degradation of HDPE pellets follows the two-dimensional nucleation growth model for conversion levels up to 0.8 with an apparent activation energy of 259–270 kJ/mol and a pre-exponential factor of 4.83 × 1017–1.37 × 1019 min−1, determined from various isoconversional methods such as Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Starink, along with Criado's master plots. These findings provide valuable insights into optimizing process parameters and refining reactor design for pyrolysis, which can be integrated with gasification and reforming processes to enhance hydrogen production on a larger scale.

Olivine nanoparticles for Fast Atmospheric CO2 capture at Ambient Conditions

AbstractTo mitigate climate change, CO2 sequestration from the atmosphere is being considered as a method to reduce its greenhouse effect and subsequently lower the Earth's surface temperature. A promising approach is the storage of CO2 in minerals, of which Olivine is a promising candidate due to its Earth abundance and high CO2 absorption capacity, which is of the order of 50 wt.%. A bottleneck for Olivine carbonation is the slow reaction rate at ambient conditions, which previously resulted in supplying CO2 at extreme pressures and temperatures to force carbonation. In this study, nanoscale Olivine particles are fabricated, which due to their high surface‐to‐volume ratio, reach a very high carbonation conversion at a time scale of minutes at ambient conditions. The carbonation is measured by X‐ray photoelectron spectroscopy (XPS), which yielded both the presence of carbonates as well as information on the Olivine oxidation state, in agreement with electron diffraction analysis. This work forms the basis for employing Olivine nanoparticles, as fabricated by the relatively simple method of magnetron sputtering, to capture CO2 from the atmosphere at economic conditions.

Optimizing small-scale power generation: Exergetic and exergoeconomic evaluation of an integrated gasification system for sacha inchi residues

Biomass is the primary non-fossil energy source, especially in regions such as Central and South America, and holds immense potential for non-fossil energy. Utilizing waste biomass, mainly through gasification for syngas production, offers environmental advantages over direct combustion for electricity and heating. The sacha inchi seed shell (SIS), currently discarded, presents an untapped biomass resource. Hence, the significance of this work lies in assessing the gasification potential of SIS for decentralized power generation, targeting rural off-grid areas. Detailed modeling of mass, energy, and exergy flows was used to establish a self-sustaining 35 kW sacha inchi processing plant using Aspen Plus software. The best operational condition was identified at an equivalence ratio of 0.25, achieving 100 % carbon conversion efficiency and 73.5 % cold gas efficiency with a lower heating value of 6.126 MJ/kg. Exergetic analysis highlights heat exchangers and the power generator as the least efficient components (0.214 % to 27.85 %), contrasting with superior efficiencies in the gasifier, compressor, and cyclone (82.85 %, 85.5 %, and 96.13 %, respectively). Exergoeconomic assessment reveals an energy cost of 10.25 USD/GJ, notably lower than Colombian energy costs for equivalent power needs.

Circular fuel production through steam reforming of waxy crude sludge: Enhancing syngas production using transition bimetallic catalyst

Waxy crude sludge (WCS) is an ignitable and hazardous semi-solid mixture containing petroleum, water, and heavy metals. Due to its high hydrocarbon content, WCS is a promising feedstock for syngas production. The carbon and hydrogen conversions were found to depend on temperature, primarily due to endothermic reactions. Ni and Cu metals were successfully doped onto dolomite to synthesize mono-metallic and bi-metallic catalysts to enhance the steam reforming. Notably, bimetallic Ni-Cu/dolomite catalysts exhibited high H2 and CO conversions. The 5 %Ni-5 %Cu/dolomite catalyst achieved the highest conversion yield, with total CO and H2 conversions of 21.15 % and 28.93 %, respectively, resulting in a H2 to CO molar ratio of 1.36 and a lower heating value (LHV) of 5.35 MJ/m3. These findings indicate that the surface-active site of dolomite-supported Ni-Cu catalysts exhibit enhanced activity and reduced carbon deposition. The study also demonstrated that using bimetallic catalysts with inexpensive mineral supports like dolomite is a viable solution for generating syngas from waxy sludges encountered during petroleum drilling operations. Additionally, this process aligns with the principles of the circular economy, facilitating energy generation and efficient hydrogen production.

Experimental and simulation study on coal-fired power generation coupling with fluidized bed biomass gasification

Positive-pressure fluidized bed technology utilizes the pressure generated by biomass gasification to facilitate further combustion within the furnace. This technique addresses the safety risks associated with external pressure in fluidizing medium and high-temperature situations and reduces equipment investment and operating expenses. However, research on the effects of the positive-pressure process in fluidized beds on gasification coupled with coal-fired power generation systems is scarce. To fill this research gap, extensive experimentation and Aspen Plus simulation were conducted to investigate the impact of equivalence ratio (ER), gasification pressure, and gasification temperature on the gasification performance. A 660 MW coal-fired boiler model was established to reveal the coupling effect on flue gas temperature and thermal efficiency by gasification from a positive-pressure fluidized bed on the boiler, and its accuracy was proved by comparing the actual boiler design parameters. The power generation cost of the positive-pressure gasification coupled coal-fired power generation system is calculated with the established model. The results indicate that an increase in gasification pressure from 4000Pa to 8000Pa resulted in no significant change in the operating indicators of the boiler, with the tail gas temperature near 132 °C and a boiler thermal efficiency of 92.68 %. Gas yield, carbon conversion rate, and gasification efficiency were positively correlated with gasification temperature and ER. However, the heat value of combustible gas increased with the gasification temperature and decreased with an increase in ER. With the rise of the biomass gas blending ratio, the power generation cost of the unit gradually decreases. Respectively, the positive -pressure would lower the power generation costs of a 660 MW coal-fired boiler by 5.76 × 105$/year. This study demonstrates that positive-pressure fluidized bed gasification may retain high gas yields and efficiency, significantly lowering equipment investment and operating expenses, as a very efficient energy-saving and carbon-reduction technique.