Total CO2 Production Research Articles

The sustainable mitigation of in vitro ruminal biogas emissions by ensiling date palm leaves and rice straw with lactic acid bacteria and Pleurotus ostreatus for cleaner livestock production.

The sustainable utilization of date palm leaves (DPL) and rice straw (RS) as feed materials for ruminant was evaluated using an in vitro wireless gas production (GP) technique. DPL and RS were individually ensiled with lactic acid bacteria (LAB) for 45days or used as substrates for the cultivation of Pleurotus ostreatus (PO) mushroom for 35days. A total mixed ration was formulated as a control ration. In the other rations, berseem hay replaced DPL (ensiled without additives or ensiled with LAB or PO) at 25%, 50%, 75% and 100%. Ensiling with LAB did not affect the chemical composition of DPL or RS, while PO treatment reduced their fibre fraction contents. Ensiling without additives lowered (p<0.05) the asymptotic production of total gas, methane (CH4 ) and carbon dioxide (CO2 ), and the rate of CH4 and CO2 while increasing (p<0.05) the lag time of CH4 and CO2 production. Ensiling of materials with LAB and treatment with PO decreased (p<0.05) the asymptotic production of total gas, CH4 and CO2 production and decreased the rate of CH4 and CO2 production. Ensiling without additives decreased (p<0.05) total bacterial count, and increased (p<0.05) fermentation pH and total volatile fatty acids (VFA), while LAB-ensiled DPL increased (p<0.05) total VFA and propionate concentrations and decreased total protozoal count. The PO-treated DPL decreased (p<0.05) bacterial count, protozoal count and fermentation pH and increased total VFA production. Replacing berseem hay with LAB or PO-treated DPL at 25% increased GP; however, increased CH4 and CO2 production, whereas the other replacement levels decreased total gas, CH4 and CO2 production. The treatment with LAB is more recommended than the PO treatment.

Gas-heat characteristics and oxidation kinetics of coal spontaneous combustion in heating and decaying processes

To reduce the hazardous effect of coal fires, gas-heat dynamic characteristics were investigated in the closed fire zone. A temperature-programmed experiment and a C80 microcalorimeter were employed to evaluate the heating and decaying processes of coal spontaneous combustion, CO production and thermal oxidation were compared to analyze the gas-heat dynamic relationship and nonlinear dynamics. The results revealed that CO production and the heat flux exhibited obvious hysteresis in the decaying process, the oxygen concentration linearly increased with the total CO production and cumulative heat release. Moreover, the heat release in the heating process was lower than that in the decaying process under identical oxygen-poor conditions, this mechanism increasingly dominated with increasing oxygen concentration. Additionally, the total CO production exhibited a good linear relationship with the cumulative heat release during the heating process, the decaying process exhibited a nonlinear trend due to the hysteresis effect. Compared with that of the heating process, the apparent activation energy of the decaying process was lower, the coal spontaneous combustion risk was higher and reignition was more likely to occur. These research results are great practical significance for inhibiting coal fire hazards and guiding fire area unsealing in the closed fire zone.

MOFs-derived self-sacrificing template strategy to double-shelled metal oxides nanocages as hierarchical interfacial catalyst for suppressing smoke and toxic gases releases of epoxy resin

• Hierarchical interfacial catalysts (Co3O4/Co3O4; Co3O4/NiCo2O4 DSNCs) are designed. • Efficient removal of smoke and toxic gases are obtained after their low additions. • Flame retardancy comparison with reported works strongly affirms their superiorities. • Satisfactory promotions in mechanical property are acquired. The emission of considerable smoke and toxic gases has been the notorious stumbling block on the extended usage of epoxy resin (EP), which often causes serious fire casualties in real fire. Hence, metal organic frameworks (MOFs)-derived self‐sacrificing template strategy is adopted, to prepare metal oxides double-shelled nanocages (Co 3 O 4 /Co 3 O 4 and Co 3 O 4 /NiCo 2 O 4 DSNCs) as hierarchical interfacial catalysts for suppressing the releases of smoke and toxic gases. With the addition of 2.0 wt% Co 3 O 4 /Co 3 O 4 DSNCs, the peak smoke production rate (PSPR), total smoke production (TSP), peak CO production rate (PCOP) and total CO production (TCOP) are reduced by 15.8%, 46.9%, 36.2% and 49.1%, separately. When 2.0 wt% Co 3 O 4 /NiCo 2 O 4 DSNCs is incorporated, the PSPR, TSP, PCOP and TCOP are markedly decreased by 40.8%, 55.5%, 46.6% and 48.5%, respectively. These results strongly corroborate the efficacy of DSNCs in suppressing the emission of smoke and toxic CO gas. Additionally, the values of peak heat release rate are reduced by 15.9% and 28.4%, reflecting the inhibited heat release. Flame retardancy comparison with reported works corroborates the prominent merit of DSNCs in inhibiting the smoke release. The clear evidence for suppressed toxic CO and NO gases releases is also acquired from TG-IR test. Profiting from the well-formed nanoflake-polymer interfaces, the mechanical performance is obviously improved. In short, these designed DSNCs possess great efficacy in smoke as well as toxic gases removal and mechanical enhancement of EP. This investigation may provide useful inspirations for designing MOFs-derived hierarchical interfacial catalysts, towards impairing the fire toxicity of polymer.

A Minimally Invasive and Highly Effective Extracorporeal CO2 Removal Device Combined With a Continuous Renal Replacement Therapy.

Extracorporeal carbon dioxide removal is used to treat patients suffering from acute respiratory failure. However, the procedure is hampered by the high blood flow required to achieve a significant CO2 clearance. We aimed to develop an ultralow blood flow device to effectively remove CO2 combined with continuous renal replacement therapy (CRRT). Preclinical, proof-of-concept study. An extracorporeal circuit where 200 mL/min of blood flowed through a hemofilter connected to a closed-loop dialysate circuit. An ion-exchange resin acidified the dialysate upstream, a membrane lung to increase Pco2 and promote CO2 removal. Six, 38.7 ± 2.0-kg female pigs. Different levels of acidification were tested (from 0 to 5 mEq/min). Two l/hr of postdilution CRRT were performed continuously. The respiratory rate was modified at each step to maintain arterial Pco2 at 50 mm Hg. Increasing acidification enhanced CO2 removal efficiency of the membrane lung from 30 ± 5 (0 mEq/min) up to 145 ± 8 mL/min (5 mEq/min), with a 483% increase, representing the 73% ± 7% of the total body CO2 production. Minute ventilation decreased accordingly from 6.5 ± 0.7 to 1.7 ± 0.5 L/min. No major side effects occurred, except for transient tachycardia episodes. As expected from the alveolar gas equation, the natural lung Pao2 dropped at increasing acidification steps, given the high dissociation between the oxygenation and CO2 removal capability of the device, thus Pao2 decreased. This new extracorporeal ion-exchange resin-based multiple-organ support device proved extremely high efficiency in CO2 removal and continuous renal support in a preclinical setting. Further studies are required before clinical implementation.

CO2 biogeochemical investigation and microbial characterization of red wood ant mounds in a Southern Europe montane forest

Red wood ants are ecologically important species in Europe that form large colonies. Their nest mounds are characterized by stable microclimatic conditions, that are favourable to the development of rich invertebrate and microbial communities. Through their respiration processes, all these inhabitants contribute to the total gas emissions of the mounds. Quantifications of red wood ant mounds CO2 production are only available from Northern and Central Europe, and the Alps, where these ants are common. During the second half of the last century some species were transplanted from the Alps to southernmost sites, where they were not present, to be employed as biocontrol agents. No information on the contribution of these low-latitudes populations to the local forest CO2 production is available. The microbial communities living within red wood ant mounds are also poorly known. In this study, we investigated the CO2 gas emissions and the microbiome of the mounds of an introduced population of the red wood ant Formica paralugubris in a Southern Europe montane forest. We found that ant mounds produced more CO2 than the forest soil, and that their CO2 efflux as well as internal concentration were higher during summer than winter, with a lighter CO2 carbon isotopic signature in summer than winter, likely due to an increased ant activity. Moreover, the top part of the mound was characterised by higher CO2 efflux and lower CO2 internal concentration compared to the bottom, probably due to its internal structure and conditions. The isotopic signature of the mound material was similar between summer and winter, suggesting a metabolic similarity of the microbial communities. Also, we estimated the ants’ relative contribution to the total mound CO2 production to be 83%, whereas the microbiota CO2 contribution was estimated at 17%. Finally, the mound microbiome composition varied between summer and winter, though no seasonal difference in the diversity indexes or β-diversity was found. Our results demonstrate the impacts of the introduced red wood ants on the carbon dynamics of the recipient ecosystem.

Addition of spherical‐style packing improves the production of conidia by Metarhizium robertsii in packed column bioreactors

AbstractBACKGROUNDConidia from Metarhizium are part of the commercial formulations used worldwide for insect pest control. Among the alternatives proposed to improve conidia production, the use of packed column bioreactors allows controlled processes with higher levels of production and productivity than those obtained with the traditional process in plastic bags. However, problems associated with overheating, low CO2 removal, and inadequate oxygen supply in packed columns limit the scale‐up and operation at an industrial scale.RESULTSPacked densities, up to 1.5 times higher than those obtained in lab‐scale column bioreactors, negatively affected growth and conidia production by Metarhizium robertsii (ENCB‐MG‐81). Therefore, a spherical‐style packing was added to decrease packed density and improve the culture conditions in packed column bioreactors. The addition of spherical‐style packing reduced the axial temperature gradient (up to 50%), increased the maximum CO2 production rate and the total CO2 production (up to 2.5 times), and enhanced the volumetric conidia productivity in packed column bioreactors from 5.28 ± 1.36 to 6.77 ± 0.89 × 108 conidia cm−3.CONCLUSIONThe use of spherical‐style packing within the culture bed in column bioreactors improves the production of conidia by Metarhizium robertsii, as well as the gas exchange and heat removal from the bed. © 2021 Society of Chemical Industry (SCI).

Evaluation of threonine requirements in mature horses fed 1:1 ratio of forage to concentrate using the indicator amino acid oxidation technique

Threonine has been considered as the second limiting amino acid in equine diets following the first limiting amino acid, lysine, and its digestibility and bioavailability may be affected by dietary fiber content. Therefore, evaluation of threonine requirements in horses fed different diet compositions will improve diet formulation. The objective of this study was to evaluate threonine requirements in mature horses fed a 1:1 ratio of timothy hay and concentrate using the indicator amino acid oxidation (IAAO) technique. Six threonine intake levels [45, 56, 67, 79, 90, and 102 mg/kg body weight (BW)/day] were prepared by mixing two experimental concentrates containing different threonine concentrations (2.9 and 14.8 g of threonine/kg of concentrate). Each of six treatments was administrated to six Thoroughbred mares (4–16 years old; 580.1 ± 47.2 kg) in a randomly determined order. After 5 days of adaptation to each treatment, pre-feeding and 90 min post-feeding blood samples were collected on day 6 to evaluate plasma amino acid concentrations using high performance liquid chromatography. The IAAO procedure was conducted on day 7 of each experimental period. During the first two hour intravenous infusion of [13C]sodium bicarbonate, total CO2 production was evaluated from breath samples. From the subsequent four-hour oral administration of [1-13C]phenylalanine, blood and breath samples were collected to estimate phenylalanine oxidation to CO2. Plasma [13C]phenylalanine concentration and breath 13CO2 enrichment were evaluated using gas chromatography–mass spectrometry and an infrared isotope analyzer, respectively. Experimental data were analyzed using a one-way analysis of variance, including orthogonal linear and quadratic contrasts, in the mixed procedures of SAS version 9.3. Increased threonine intake resulted in higher plasma threonine concentration before and 90 min after feeding (P > 0.05), indicating higher bioavailability of threonine. However, phenylalanine oxidation rate was not affected by threonine consumption as evidenced by the lack of a breakpoint (P > 0.05). The results suggest that threonine requirements might be lower than 45 mg/kg BW/day in mature horses fed a 50% concentrate diet.

The Dual Effect of Coordinating −NH Groups and Light in the Electrochemical CO2 Reduction with Pyridylamino Co Complexes

AbstractCO2 electroreduction could be improved by applying conceptualized strategies to overcome catalytic bottlenecks. In this regard, we report two new cobalt(II) complexes [Co(Py2RN3)(OTf)](OTf) (CoR, R=H, Me) based on a new C2‐symmetric pentacoordinate chiral ligand that are active on the electrochemical CO2 reduction to CO. One of the complexes has a N−H group oriented towards the CO2 binding site (CoH), while the other has a N−Me group with the same orientation (CoMe), as showed by X‐ray diffraction. We have studied the effect of introducing hydrogen bonding sites, i. e. N−H in CoH, as a strategy to stabilize reaction intermediates. The complex bearing coordinating unprotected N−H group (CoH) displays catalytic CO2 reduction at the CoII/I redox potential (−1.9 V vs. Fc, ca. 40 % FYCO) whereas CoMe shows CO2 reduction at the CoI/0 redox pair. FTIR‐SEC and DFT calculations identified a [CoI−CO]+ cation as catalytic intermediate. The beneficial effect of the N−H group has been attributed to the stabilization of reaction intermediates or transition states and by the larger electron‐donating capacity, thus enhancing the nucleophilic character of the CoI intermediate. The study also points to the CO dissociation from the Co(I)−CO resting state intermediate as one of the bottlenecks of the catalytic cycle, which can be overcome with light irradiation, resulting in an increase of the total CO production (−1.9 V, 81 % FYCO, 11.2 TONCO) at the CoII/I redox potential.

Techno-economic assessment of solar steam reforming of methane in a membrane reactor using molten salts as heat transfer fluid

This paper reports the results obtained in a techno-economic analysis of the Steam Methane Reforming (SMR) technology aided with solar heat, developed and demonstrated in the European FCH JU project CoMETHy: a compact membrane reformer heated with molten salt up to 550 °C allowed to simultaneously carry out methane steam reforming, water-gas-shift reaction and hydrogen separation. This reactor can be integrated with new generation Concentrating Solar Thermal (CST) systems to supply the process heat. Experimental validation of the technology has been successfully achieved in a pilot scale plant and the results recently published. In this paper, we introduce a fully-integrated scheme and operation strategies of a plant on the 1500 Nm3/h hydrogen production scale. Then, techno-economic analysis of this new solar-driven process is presented to evaluate its competitiveness. Considering a plant capacity of 1500 Nm3/h (pure hydrogen production) and today's costs for the methane feed and the CST technology, obtained Hydrogen Production Cost (HPC) are in the range of 2.8–3.3 €/kg for a “solar-hybrid” system with high capacity factor (8000 h/year operation) and 4.7 €/kg for a “solar-only” case, while HPC≅1.7 €/kg can be obtained with the conventional route under equivalent assumptions. However, a sensitivity analysis shows that the expected drop of the cost of the CST technology will bring the HPC around 2.4 €/kg for the “solar-hybrid” case and close to 3.4 €/kg for the “solar-only” case, thus making the cost of solar reforming closer to conventional SMR with CO2 capture and with wind/solar electrolysis in the future. In the “solar-hybrid” case total CO2 production can be reduced by 13–29% with 58–70% of produced CO2 recovered as pure stream (at 1.3 bar); in the “solar-only” case total CO2 production can be reduced by 52% and 100% of produced CO2 recovered as pure stream (at 1.3 bar). However, compared to the conventional route, CO2 avoidance costs are still relatively high (≥137 €/tonCO2) and process optimization measures required. Therefore, optimization measures have been outlined to increase the overall process efficiency and further reduce the HPC.

Preparation of soybean root-like CNTs/bimetallic oxides hybrid to enhance fire safety and mechanical performance of thermoplastic polyurethane

The three main fatal factors considered when Thermoplastic polyurethane (TPU) products catch fire are massive heat radiation, suffocation by smoke inhalation, and poisoning by toxic gases (CO and HCN). In this study, to weaken these adverse impacts, soybean root-like zeolitic imidazolate frameworks (ZIFs)-derived carbon nanotubes/bimetallic oxides (CNTs/BMO) hybrids are designed and prepared. In addition, we studied its performance in improving the fire safety of TPU. The in-situ growth of ZIFs on the surface can suppress the entanglement of CNTs (main roots), enhancing a uniform dispersion in the hybrid. Porous BMO and ultrathin N-doped CNTs (N-CNTs) functioned as conversion stations for organic and inorganic, similar to the root nodules and root hairs, respectively, resulting in the increased generation of char residues and suppressed emissions of smoke and toxic gases. Compared with neat TPU, there are 32.11%, 27.91%, and 41.91% reductions in peak heat-release rate, total smoke production, and total CO production, respectively, with 1 wt% of well-dispersed CNTs/BMO hybrids. In addition, the soybean root-like hybrids also have enhanced the mechanical performance of composites. On the basis of the satisfactory mechanical strength of neat TPU, the tensile strength and elongation (at break) of the soybean root-like hybrids are further increased by 70.61% and 16.49%, respectively. This work provides a feasible method to construct a well-dispersed inorganic hybrid with complex structure and excellent performance, which will deliver a new perspective for the development of multifunctional polymer composites.

Metal‐organic frameworks derived ZnO@MOF@PZS flame retardant for reducing fire hazards of polyurea nanocomposites

Transition metal as flame retardant has attracted intense interests in recent years. In this work, ZnO@MOF@PZS was prepared via hydrothermal and polycondensation methods. ZnO nanoflowers played the role as a template for growth of MOF@PZS and zinc source for formation of MOF. Subsequently, the obtained ZnO@MOF@PZS was mixed into polyurea (PUA) to investigate its flame retardancy and toxicity suppression properties. The cone calorimeter test (CCT) showed that ZnO@MOF@PZS significantly improved the flame retardancy of PUA composites. The addition of 3 wt% ZnO@MOF@PZS into PUA could result in peak heat release rate (PHRR), total heat release (THR) and total CO production (TCO) of 28.30%, 19.59% and 36.65%, respectively. The result of universal testing machine showed that ZnO@MOF@PZS‐add PUA had better mechanical properties. It is notable that the improved flame retardant properties for PUA composites are mainly attributed to ZnO@MOF@PZS promoting the formation of dense char residue.

Solid-state fermentation enhances inulinase and invertase production by Aspergillus brasiliensis

Extracellular inulinase and invertase production by Aspergillus brasiliensis was evaluated in solid-state fermentation (SSF) and submerged fermentation (SmF) with a high sucrose concentration. The parameters estimated from online CO2 analysis revealed a lower Lag phase in SSF compared to SmF; the specific CO2 production rate (μCO2) decreased in both systems as the sucrose concentration increased. The highest maximum CO2 production rate (10.45 ± 0.72 mg/h mL) and total CO2 production (138.53 ± 6.48 mg/mL) were obtained in SSF with a sucrose concentration of 210 g/L. Inulinase and invertase production (1.13 ± 0.02 and 5.84 ± 0.12 U/mL, respectively) in SmF was independent of the initial sucrose concentration; meanwhile, both activities increased in SSF as the sucrose concentration increased, reaching maximum values of 5.88 ± 0.78 and 41.69 ± 3.60 U/mL, respectively, at the highest sucrose concentration (210 g/L). The zymographic analysis showed one band of inulinase and two bands of invertases involved in sucrose hydrolysis.

Alkali-Activated Materials and Geopolymer: a Review of Common Precursors and Activators Addressing Circular Economy

IntroductionThe vast increase in CO2 and waste generation in recent decades has been a major obstacle to sustainable development and sustainability. In construction industry, the production of ordinary Portland cement is a major greenhouse gas emitter with almost 8% of total CO2 production in the world. To address this, Alkali-activated materials and geopolymer have more recently been introduced as a green and sustainable alternative of ordinary Portland cement with significantly lowered environmental footprints. Their use to replace Portland cement products generally leads to vast energy and virgin materials savings resulting in a sustainable concrete production. In doing so, it reuses the solid waste generated in industrial and manufacturing sectors, which is aligned with circular economy. In turn, it reduces the need for ordinary Portland cement consumption and its subsequent CO2 generation.ObjectiveTo provide further insight and address the challenges facing the substitution of ordinary Portland cement, this article reviews different types, mechanisms, and result of mechanical and durability properties of alkali-activated materials and geopolymer reported in literature. Finally, it discusses future projections of waste materials that have cementitious properties and can replace ordinary Portland cement and be used in alkali-activated materials and geopolymer.Graphical abstract

Effect of By-Products from Selected Fruits and Vegetables on Gluten-Free Dough Rheology and Bread Properties

The aim of the study was to investigate the effect of using various by-products (orange and apple pomace, tomato peel, pepper peel, prickly pear peel, and prickly pear seed peel) on the dough rheology and properties of gluten-free bread. The by-products were incorporated into a gluten-free bread formulation based on corn and chickpea flours (2/1 w/w). Different levels of each by-product (0, 2.5, 5, and 7.5% in the basic replacement) were tested. Wheat bread and gluten-free bread without the addition of by-products were used as controls. The results indicated that the by-products increased the maximum dough height, the total CO2 production, and CO2 retention coefficient compared to unenriched gluten-free dough. The highest K-value consistency coefficient was observed for the dough enriched with the prickly pear peel. The addition of by-products significantly improved (p &lt; 0.0001) the specific volume of gluten-free bread, with values increasing from 1.48 to 2.50 cm3/g. The hierarchical cluster analysis and the constellation plot showed four groups: the wheat bread group, the second group containing the gluten-free control bread, the group with bread enriched by pomace, and the group with bread enriched with peels, exhibit the same effect on gluten-free bread and the peels exhibit the same effect on gluten-free bread.

Activity and structure of methanogenic microbial communities in sediments of cascade hydropower reservoirs, Southwest China

Freshwater reservoirs are an important source of the greenhouse gas methane (CH4). However, little is known about the activity and structure of microbial communities involved in methanogenic decomposition of sediment organic matter (SOM) in cascade hydropower reservoirs. In this study, we targeted on sediments of three cascade reservoirs in Wujiang River, Southwest China. Our results showed that the content of sediment organic carbon (SOC) was between 3% and 11%, and it's positively correlated with both C/N ratio and recalcitrant organic carbon content of SOM. Meanwhile, SOC content was positively correlated with CH4 production rates but had no significant correlation with total CO2 production rates of the sediments, when rates were normalized to sediment volume. Resultantly, the sediment anaerobic decomposition rates hardly significantly increase along with the SOC content. These results suggested that the terrestrial organic matter accumulated after damming stimulated CH4 production from the reservoir sediments even though its decomposition rate was limited. Meantime, high throughput sequencing of 16S rRNA genes indicated that not only the hydrogenotrophic and acetoclastic, but also the methylotrophic methanogens (Methanomassiliicoccus) are abundant in the reservoir sediments. Moreover, metagenomic sequencing also suggested that methylotrophic methanogenesis are potentially important in the sediment of cascade reservoirs. Finally, the hydraulic residence time of the reservoir could be the key controlling factor of the structures of bacterial and archaeal communities as well as the CH4 production rates of the reservoir sediments.

Comparative uptake of exogenous thiamine and subsequent metabolic footprint in Saccharomyces cerevisiae and Kluyveromyces marxianus under simulated oenological conditions

Managed inoculation of non-Saccharomyces yeast species is regarded as a practical way to introduce new characteristics to wine. However, these yeasts struggle to survive until fermentation is complete. Kluyveromyces marxianus IWBT Y885 is one such yeast. Although it displays interesting oenological properties, a longer persistence during alcoholic fermentation would warranty a stronger impact on wine composition. A key factor for survival, growth and sustained metabolic activity of all yeasts is their nutrient requirements. Thus, identifying nutrients that are essential for maximising fermentation performance, and subsequently ensuring adequate levels of nutrients, is a means to ensure significant contribution of yeasts to wine properties. This study aimed to identify essential nutrients, other than previously studied sugars and nitrogen, for maximum impact of K. marxianus Y885, as well as to characterise the outcomes of their utilisation.A multifactorial experimental design was employed to investigate the impact of nutrient concentrations on fermentation performance with K. marxianus Y885 in synthetic must. B-complex vitamins most significantly impacted fermentation performance of K. marxianus Y885 compared to other nutrient groups investigated. Considering the well-established role of the vitamin, thiamine, for maximum fermentation performance during winemaking and the fact that it may be supplemented to wine fermentations legally, the responses to specifically exogenous thiamine concentration for K. marxianus Y885 and Saccharomyces cerevisiae EC1118 were compared in terms of population viability, fermentation rate, total sugars utilised, thiamine assimilation kinetics, and final wine composition. A saturation effect for initial thiamine concentration of K. marxianus Y885 fermentations was characterised, with a maximum fermentation rate and over 90% of available sugars utilisation obtained at 0.25 mg/L. An appreciably larger comparative increase in exponential cell growth rate, maximum population, fermentation rate and total CO2 production for K. marxianus Y885 compared to S. cerevisiae EC1118 revealed a greater necessity for thiamine to ensure maximum fermentation performance. A delayed uptake of thiamine at higher concentrations for K. marxianus Y885 suggested differential regulation of thiamine uptake compared to S. cerevisiae EC1118. In addition, different trends in metabolites produced between species suggest that thiamine concentration impacts the carbon metabolic flux differently in these two yeasts, potentially impacting final wine properties.

Thermal behaviour and kinetic study of co-pyrolysis of microalgae with different plastics

The coexistence of plastics and microalgae in the ocean has brought great challenges to the environment. Therefore, co-pyrolysis of microalgae Dunaliella salina (DS) and typical plastics (polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and polyvinyl chloride (PVC)) were investigated using thermogravimetric analyzer with Fourier transform infrared spectrometer. The results showed that the coating effect of the molten plastics promoted the pyrolysis of DS. The solid residue amounts of DS-PP, DS-PS, and DS-PET blends were reduced by 1.55 wt%, 1.39 wt%, 1.69 wt%, respectively, as a result of the hydrogenation reaction between the unsaturated products generated by plastics and biochar. While for DS-PVC, attributed to the physical and chemical effects during the co-pyrolysis process, the solid residue was increased by 1.36 wt%. For the other three blends, the solid residues were reduced due to the hydrogenation reaction between the unsaturated products generated by plastics and biochar. FTIR analysis of gaseous products indicated the total CO2 production increased significantly for DS-PET. Besides, the alkyls generated by DS reacted with HCl during DS-PVC co-pyrolysis, the resulting products were then fixed in biochar. Kinetic results suggested that due to the co-pyrolysis with DS, the activation energies of PP, PS, and PET were reduced by 1/2, 1/3, and 3/4, respectively, and this value for PVC in its second stage was reduced by 1/4. Our results indicated the advantage to co-pyrolyze the microalgae and marine plastics.

Evaluation and mitigation analysis of carbon footprint for an airline operator: Case of Nepal airlines corporation

This paper deals with evaluation and analysis of carbon footprint of an airline operator, Nepal Airlines Corporation (NAC) by using its actual flight and maintenance data from 2016 to 2019. NAC is a multi-fleet operator, of both turboprop and turbofan aircrafts. Carbon footprint in terms of Carbon Dioxide (CO2) emission has been calculated for NAC’s airline operations per individual aircraft, fleet-type and operating sector (i.e., international and domestic), and total ground handling operations. In each of the study years, contribution to NAC’s total CO2 production from its domestic fleet was found out to be very small (below 6% of yearly total), even though its fleet number outnumbered that of international fleet. This indicates better optimization opportunities for international-sector (turbofan) aircrafts than domestic-sector (turboprop) aircrafts. Reductions in fuel on-board as per prescribed levels, better airport slot management and selection of long-haul flight destinations have been identified as potential mitigation strategies for CO2 emission from international sector. Smaller aircrafts operating in domestic sectors are more prone to variations in occupancy rate and as such, NAC could focus on optimizing its commercial strategy to improve its CO2/passenger rate in domestic sector.

The Effect of Ratio-Based Incentive on Wind Capacity Development and Investment Risk of Wind Units: A System Dynamics Approach

Different capacity incentives like feed-in-tariff have been considered to encourage companies to invest in wind power units. One of the main challenges of the electricity market policymakers is the determination of this fixed payment based on limited funding in a way that the investment cost of wind units is compensated and the associated investment risk is reduced. The main contribution of this paper is the introduction of a method to manage the amount of payment or incentives during a time horizon to reach the targeted wind capacity and reduce its investment risk. In this regard, the ratio-based incentive is introduced. To study the effects of such a policy, the long-term behavior of the electricity market is simulated by a dynamic model, which is a useful tool for policymakers to analyze the effects of their policies. Then, conditional value at risk and value at risk concepts are used to measure the risk of wind capacity investment. The results illustrate that the ratio-based incentive is more effective than the feed-in-tariff in the context of decreasing the risk of investment, reducing total CO2 production, electricity price reduction, and speed of providing higher amounts of wind capacity.

Methanol Production from Silicomanganese Off-Gas of Arc Submerged Furnace

The Erdos group with silicomanganese (SiMn) capacity of 3.3x105t/a by-produces off-gas approaching to about 4.48x108Nm3/a. These off-gases were usually combusted in lime or pellet production or for power generation. However, the thermal efficiency of such utilization is not high, and the added value is comparably low. In addition, all the CO is combusted into CO2 and discharged to the atmosphere. Although the CO direct emission has been solved, it cannot reduce the total CO2emission.To increase the value of silicomanganese off-gas (SMOG) and reduce CO2 emission, Erdos Power & Metallurgical Group (EPMG ) has implemented an off-gas high-efficient utilization project, including the first operating SMOG to methanol plant in China and a food-grade CO2 plant. The units in the methanol plant mainly consists of gas dedusting, washing, compression, one-step fine desulphurization, sulphur-free isothermal water-gas shift(WGS), pressure swing adsorption(PSA) decarbonization, methanol synthesis and rectification. The methanol plant can treat 3.44x108Nm3/a of SMOG producing methanol and by-producing enriched CO2 gas and steam. The methanol can be used as automotive fuel additive or feedstock for producing olefins and other chemicals. Besides, enriched CO2 gas is transported to Erdos food-grade CO2 Plant as raw material, and all steam is used for district heating. This project can reduce about 3.575x105t/a of CO2 emission, which accounts for 64% of total CO2 production from Erdos SiMn production. Its new annual profit is estimated to be more than 100 million RMB. The Chinese silicomanganese industry holds more than 20 million tons of annual production capacity, and its off-gas flow rate exceeds 120 billion Nm3/a. Accordingly, the information presented in this report provide a significant reference on high-efficient off-gas utilization for Chinese silicomanganese manufacturers.