Biogas Flow Rate Research Articles

Model-Based Analysis of Feedback Control Strategies in Aerobic Biotrickling Filters for Biogas Desulfurization

Biotrickling filters are one of the most widely used biological technologies to perform biogas desulfurization. Their industrial application has been hampered due to the difficulty to achieve a robust and reliable operation of this bioreactor. Specifically, biotrickling filters process performance is affected mostly by fluctuations in the hydrogen sulfide (H2S) loading rate due to changes in the gas inlet concentration or in the volumetric gas flowrate. The process can be controlled by means of the regulation of the air flowrate (AFR) to control the oxygen (O2) gas outlet concentration ([O2]out) and the trickling liquid velocity (TLV) to control the H2S gas outlet concentration ([H2S]out). In this work, efforts were placed towards the understanding and development of control strategies in biological H2S removal in a biotrickling filter under aerobic conditions. Classical proportional and proportional-integral feedback controllers were applied in a model of an aerobic biotrickling filter for biogas desulfurization. Two different control loops were studied: (i) AFR Closed-Loop based on AFR regulation to control the [O2]out, and (ii) TLV Closed-Loop based on TLV regulation to control the [H2S]out. AFR regulation span was limited to values so that corresponds to biogas dilution factors that would give a biogas mixture with a minimum methane content in air, far from those values required to obtain an explosive mixture. A minimum TLV of 5.9 m h−1 was applied to provide the nutrients and moisture to the packed bed and a maximum TLV of 28.3 m h−1 was set to prevent biotrickling filter (BTF) flooding. Control loops were evaluated with a stepwise increase from 2000 ppmv until 6000 ppmv and with changes in the biogas flowrate using stepwise increments from 61.5 L h−1 (EBRT = 118 s) to 184.5 L h−1 (EBRT = 48.4 s). Controller parameters were determined based on time-integral criteria and simple criteria such as stability and oscillatory controller response. Before implementing the control strategies, two different mass transfer correlations were evaluated to study the effect of the manipulable variables. Open-loop behavior was also studied to determine the impact of control strategies on process performance variables such as removal efficiency, sulfate and sulfur selectivity, and oxygen consumption. AFR regulation efficiently controlled [O2]out; however, the impact on process performance parameters was not as great as when TLV was regulated to control [H2S]out. This model-based analysis provided valuable information about the controllability limits of each strategy and the impact that each strategy can have on the process performance.

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

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

Determination and utilization of optimal diesel/n-butanol/biogas derivation for small utility dual fuel diesel engine

Aggregating pollution along with exhausting fossil fuels throughout the world has enforced the inventors to explore for an alternative fuel that can be utilized in diesel engines. Presently, investigators and professionals have originated that biodiesel in association with higher alcohols and gaseous fuel can be an alternative for the current circumstances. Anterior examinations have rendered that biodiesel and higher alcohol along with gaseous fuels can support in upgrading the performance and denigrating detrimental exhaust emanations in a diesel engine. This research aimed to investigate the impacts of engine load, n-butanol concentration, and biogas quantity on emissions and performance characteristics of a small utility compression ignition engine. The different engine load (20–100% of brake power), n-butanol concentration (0–20%) and biogas flow rate (0.5–2 kg/h) were used as input variables. The multi-criteria decision analysis based on response surface method techniques was employed to find the optimal values of engine working conditions fuelled with diesel/n-butanol/biogas fuel blends. In the optimization process, five objective functions (BTE, NOX, CO, UHC, and soot) were considered to be optimized based on the defined criteria. The addition of n-butanol in diesel has shown a favourable impact on biogas operated dual-fuel engine in terms of performance and emissions characteristics. The approach of desirability was applied to obtain the best operating conditions of the engine. The optimum value of engine load, n-butanol concentration, and biogas flow rate were found as 78.89%, 20%, and 1.37 kg/h, respectively. At this condition, the optimal value of BTE, UHC, CO, NOX, and smoke emissions were found to be 19.19%, 0.36g/kWh, 0.04%, 14.51g/kWh, and 22.32%, respectively. A high desirability value of 0.77 was obtained for the suggested condition, showing the efficiency of the derived models for response parameters.

Investigations on Biogas Fueled Dual Fuel DIesel Engine Employing Dimethyl Carbonate as a Fuel Blend

ABSTRACT In this experimental study, the center point of our work is to evaluate the impact of dimethyl carbonate (DMC) fuel blended with diesel with regard to the engine performance, emissions, and combustion characteristics in dual fuel engine fueled by biogas at various DMC proportions and biogas flow rates. A water-cooled, four stroke, single cylinder Compression Ignition (CI) engine is adjusted to run in dual fuel mode. A simulated biogas is obtained by mixing CH4 and CO2 that are kept in red and black cylinders, respectively. Throughout the experimental process the engine is run at a constant speed of 1800 rpm. Three proportions of DMC are taken which are 10, 20, and 30% by volume and blended with pure diesel. Biogas flow rates taken are 12 lpm and 16 lpm. An experimental study was performed and it is found that a maximum of 3% drop in brake thermal efficiency at high DMC proportions but at low biogas flow rates, the efficiency increased up to 2.7%. NOx emissions were observed to be low on addition of DMC and further decreased at high biogas flow rates. The maximum reduction of 57.5% is observed when compared to diesel-only mode. CO emissions increased upto 28% at high DMC fractions. In combustion characteristics, the Maximum Heat Release Rate (MHRR) decreased at high DMC fractions and high biogas flow rates but decreased, at high loads. The maximum cylinder pressure also decreased at high DMC fractions and at high biogas flow rates. The period of combustion increases when DMC fraction is increased.

Aplikasi Desain Faktorial 23 pada Kadar CO2 Proses Purifikasi Bio-gas dengan Adsorben Genteng - Zeolite

The CO2 content in biogas is an impurity, so it needs to be reduced. One way to reduce the levels of CO2 in biogas is by purification with tile-zeolite adsorbents. The purpose of this study was to determine the use of tile - zeolite as an adsorbent in the purification process to reduce CO2 levels using a 23 factorial design. The use of tile powder adsorbents (25% and 75%) - Zeolite (75% and 25%), biogas flow rates of 1 and 6 liters/minute, which were investigated at intervals of 5 and 20 minutes, to collect CO2 content data. Gas Chromatography-Mass Spectrometry (GCMS) is used to test the adsorption gas content. The results are shown by the Pareto curve resulting from biogas purification of CO2 levels, each of which has a magnitude of response to CO2 levels. Increased levels of tile-zeolite as an adsorbent and the rate of biogas flow in the purification process had an effect of reducing CO2 levels by 44.214%. Conversely, an increase in tile-zeolite levels as an adsorbent increases CO2 levels in the biogas purification process. Natural tile is a porous material that can adsorb and has ions that can be exchanged with ions from the outside.

The effects of adsorbent mass using red brick powder on the results of biogas purification

Biogas is produced by the digestion of organic waste by anaerobic bacteria. However, the application of raw biogas is not effective because it consists of impurities such as carbon dioxide (CO2), hydrogen sulfide (H2S), water vapor (H2O), and other impurity gases. Physical Adsorption is the simplest method of immobilization of biomolecules such as CO2 which is attached to the surface through the weak bonds like van der Waals forces. One of the physical adsorption means to reduce CO2 levels in biogas is to use brick powder. Increasing of brick powder adsorbent mass caused the decrease of CO2 concentration in the biogas purification. Brick is a porous material containing SiO2 - Al2O3, so it has the ability to form Van der Waals bonding forces with CO2. The goal of this research is to determine the efficiency of brick powder as a purification adsorbent to reduce of CO2 levels using the 23 factorial design method. The application of 200 and 400 grams brick powder adsorbents, with the biogas flow rate of 1 and 2 liters/minute, was researched at intervals of 5 and 20 minutes, for the CO2 concentration data and heating values of biogas. Gas Chromatography (GC) was used to determine the concentration of adsorption gases, especially CO2 and CH4. The results showed that the biggest efficiency reduction in CO2 concentration is 59.28%.

Исследование влияние состава биогаза на свойства факела

The goal of this paper was the study flame lengths dependence on biogas composition to decide if the boiler`s furnaces using natural gas need reconstruction for biogas usage or it is possible to use the already existing equipment. The analytical one-dimensional model of a diffusion straight-flow flame in unrestricted and restricted space and the numerical three-dimensional model of a turbulent flame in a swirled airflow have been applied in this research. The research has analyzed the flame length for methane content of 20 to 100% in biogas. It has been concluded that by changing the methane content in biogas the heating plant1s operating mode can be stable on the condition that the biogas flow rate is controlled to ensure constant heat production during its combustion and turbulent flame with a swirled airflow. Combustion, in this case, can be done by using the same burner and without changing the size of the furnace.

Attitude towards biogas technology, use and prospects for greenhouse gas emission reduction in southern Ethiopia

In developing countries, fuelwood extraction is one of the main drivers of deforestation, forest degradation, and greenhouse gas (GHG) emissions. This study aimed to investigate the use, management, and attitudes towards biogas technology in rural communities in Ethiopia and assess its’ potential in reducing the consumption of biomass fuels and emissions of GHG. A questionnaire survey sampled from 40 biogas user and 40 non-user households was used to collect data. The biogas flow rate was measured using a gas flow meter from three random biogas digesters. Biogas and non-biogas user households reported similar socioeconomic perspectives. Our results showed that 92.5% of biogas user households and 77.5% of non-users had a positive attitude towards biogas technology, however, 52.5% of the non-users lacked information about the technology while 25% of the non-users were deterred by biogas installation costs. The average biogas consumption of each household was from 496 to 566 m3 yr−1 for cooking and from 106 to 124 m3 yr−1 for lighting. Biogas user households consumed fuelwood and crop residue to the same extent as non-user households for baking foods. However, biogas user households differed significantly from non-user households in biomass fuel use for non-baked foods owing to the suitability of biogas stoves. Each biogas user household reduced their fuelwood and charcoal use by about 2410 kg yr−1 and 379 kg yr−1, respectively, and decreased their kerosene use (for lighting) by about 9.5 L yr−1. The GHGs emitted by each household was estimated at 10,242 kg CO2e yr−1 and 16,266 kg CO2e yr−1 for biogas user and non-user households, respectively. Thus, each household with a biogas digester has the potential to reduce 6024 kg CO2e yr−1 of GHG emission. Biogas energy can offer an opportunity to mitigate GHGs emissions through reduced pressure on forests. Its’ contribution can more than double by improving the biogas stove design to fit the traditional baked foods.

Performance analysis of a biogas operated porous radiant burner for domestic cooking application.

In this paper, the combustion characteristics of biogas in a Porous Radiant Burner (PRBBG) designed for domestic cooking appliances are presented. Developed PRBBG consists of two layers of porous matrices viz., Silicon Carbide (SiC) and Alumina (Al2O3) and operates in the biogas flow range of 177 to 530 l/h with stable equivalence ratio (ϕ) range of 0.75 to 0.95. The effects of biogas flow rate and equivalence ratio on thermal efficiency (ηth) and emission characteristics of the burner are investigated and also compared with its conventional counterpart. Overall performance assessment shows that PRBBG operating at lower equivalence ratio and lower firing power has better thermal efficiency with lower CO and NOx emissions. The performance of the burner in terms of temperature mapping suggests that firing power variation is of higher importance than that of equivalence ratio. The maximum temperature difference between the center and the periphery of the burner surface is found to be ~ 83 °C at an equivalence ratio of 0.95. The thermal efficiency varies in the range of 51-62% and its maximum is at 0.75 equivalence ratio and 177 l/h flow rate of biogas. Within the range of studied biogas flow rate range, CO emission is in the range of 29-80 ppm and NOx concentration was lower than 4 ppm. Whereas, for Conventional Burner (CB), thermal efficiency, CO, and NOx emission are found in the range of 43-52%, 211-276 ppm, and 9-15 ppm, respectively. The overall performance showed that PRBBG is capable of burning a lean biogas-air mixture with better thermal efficiency and lower emissions.

Effects of butanol blending ratio in biogas-biodiesel dual fuel engine

By the rise in population, the usage of non-renewable fuels is increasing. It led to the depletion of fossil fuels and other environmental issues. Reducing the usage of fossil fuel, enhancing performance and reducing emissions are the key areas in this research. In this experiment, a conventional single cylinder CI engine is used in dual fuel mode. In dual fuel mode, biogas is used as primary fuel and biodiesel (Palm oil) with various butanol blending ratios (10%, 20% and 30%) is used as pilot fuel. Various properties like flash and fire point, cloud and pour point, viscosity, density, calorific values are measured. Biogas flow rate and applied load are varied for each blending ratio. The effects of load, butanol blending ratio and biogas flow rate on BTE, BSFC, HC, CO and NOx emissions are analyzed and compared with diesel-only mode. Biodiesel with 30% butanol blend in dual fuel mode shows better brake thermal efficiency at 12 lpm flow rates. All test cases prove 12 lpm is better than 16 lpm biogas flow rates. Increase in biogas flow rate reduces NOx emissions. However, it increases HC and CO emissions. And this investigation proposes to intervene in the dual fuel biogas-biodiesel engine at 12 lpm biogas rate of flow.

Investigations on biogas fuelled Homogeneous Charged Compression Ignition engine with Di ethyl ether -Biodiesel-Butanol blend as Pilot fuel

The continuous and increasing in volume of fossil fuels utilization leads to an alarming increase in green-house gases emissions. Consequentially, the release of toxic agents may cause detrimental health issues and aggravate global warming effects. Biofuels, due to its reduced emission effects, are found to be a potential alternate to fossil fuels, especially for their usage in internal combustion engines under certain loading conditions. The present research work aims at investigating the effects of butanol blending ratio at different biogas flow rates on the performance and emission characteristics of a single-cylinder CI (Compression ignition) engine under Homogenous Charge Compression Ignition (HCCI) mode. Flow rates of biogas taken in the present study are 12 lpm and 16 lpm whereas the butanol is blended in biodiesel – DEE (Diethyl-ether) mixture at 10, 20 & 30% concentration by volume. The engine parameters analysed in the present work are brake thermal efficiency, Brake Specific Energy Consumption (BSEC), Hydrocarbons (HC), Carbon monoxide (CO), Oxides of Nitrogen (NOx) and Smoke emissions. Results showed that the butanol addition in the fuel reduced the NOx emissions considerably at various loads between 0.1 N-m to 15 N-m. Further increase in load resulted in knocking conditions in the engine due to multipoint ignition. Based on the experiments, it is witnessed that 30% of butanol blend in biodiesel-DEE mixture high efficiency and low smoke emissions compared to all other blends. Simultaneous reduction of NOx and smoke emissions is observed in HCCI mode.

Multi-objective optimization of performance and emissions characteristics of a variable compression ratio diesel engine running with biogas-diesel fuel using response surface techniques

ABSTRACT Rapidly intensifying necessitates of energy and depletion of accessible fossil resources has made a remarkable interest in investigation of the alternative fuels. The current investigational work was performed to examine the use of multi-objective optimization (MOP) based on response surface methodology (RSM) to investigate the impact of compression ratio (CR), biogas flow rate and engine load on the performance of dual-fuel engine. An engine load of 80%, compression ratio of 18, and biogas flow rate of 2.8 kg/h were observed to be optimal condition. According to these optimized parameters, the value of BTE, NOX, UHC, CO and smoke opacity were found to be 18.51(%), 13.5 (g/kW.hr), 0.49 (g/kW.hr), CO (0.08% vol.) and 23.6 (%), respectively. Compared with conventional diesel fuel, dual-fuel operational mode can improve brake specific energy consumption and reduce NOX as well as Smoke opacity, while producing higher emissions of CO and UHC.

Effect of Biogas Sparging Flow on Fouling Control in Anaerobic Membrane Bioreactors

Membrane fouling behaviors were investigated to different biogas sparging flows such as 0.5, 1.0, and 1.5 L biogas/min for anaerobic submerged membrane bioreactor (AnSMBR) treating synthetic wastewater in a laboratory-scale. For each different biogas flow rate, the membrane module of the same feature was used in the system and the effect of biogas sparging flow on fouling control was examined in the process. Surface area of the used membrane module was selected as 162.6 cm2. The sprarging biogas was supplied from the gas formed in reactor system. Treatment parameters were analyzed in the process of reactor operation. Also, a series of analysis, including soluble microbial products (SMP), extracellular polymeric substances (EPSs), scanning electron microscopy, energy dispersive X-ray spectroscopy, particle size distribution, and filtration resistances were performed by considering the membrane module. The AnSMBR accomplished COD removal efficiencies between 95 and 98%. Total organic carbon and sulfate concentration in permeate were found in the range of 25–56 and 90–200 mg/L, and 96–98 and 38–65% in removal percentage; respectively. TSS and VSS concentrations in permeate were less than 10 mg/L that means removal efficiencies of 98%. Methane production rate in the system was determined of 0.35 ± 0.08 LCH4/g COD removed. The results showed that differences between COD and TOC removals were negligible at different biogas sparging flows. The priority of biogas sparging flows in terms of providing high permeate fluxes were found to be 1.5 L biogas/min > 1.0 L biogas/min > 0.5 L biogas/min. The same order was found with the fluxes in terms of both SMP and EPS within cake formed on the fibers in membrane module. Studying results showed that biogas sparging flow increasing was found to effective on membrane fouling controls. It has been determined that sparging gas at an optimum flow rate (1.0 L biogas/min) can be effective in controlling membrane fouling.

Biogas upgrading through CO2 removal by chemical absorption in an amine organic solution: Physical and technical assessment, simulation and experimental validation

An experimental and modelling study of CO2 removal from a simulated biogas feed by chemical absorption in an organic solution of 2-amine-2-methyl-1-propanol in an ethylene glycol and n-propanol solvent is presented. Absorption was carried out under different temperature, feed flow rate, and feed recirculation conditions. Regeneration was carried at different temperatures. Cyclability tests showed that the absorption capacity remained stable starting from the fourth cycle. In the conditions analyzed, higher temperatures and liquid recirculation favor absorption. With all other conditions constant, the CO2 absorption efficiency increased from 72% to 87% when the temperature increased from 23 to 45°C. At 33°C, liquid recirculation enhanced the absorption efficiency from to 93%–97%.A model was developed and validated against experimental results. Absorption and desorption rates are proportional to the carbon dioxide and AMP concentrations and to the alkyl carbonate concentration, respectively. The two rate constants were fitted from the experimental data: their values at 30°C are 0.033 s−1 (kmol/m3)−1 and 1.5 × 10−6 s−1, respectively. The model indicates that the beneficial effect of temperature and liquid recirculation is due to the increased mass transfer coefficient of CO2 from the gas to the liquid solution, which increased from 4 × 10−3 s−1 at 20°C to 1.3 × 10−2 s−1 at 70°C and by a factor of 8.8 as a consequence of feed recirculation. An increase in the biogas flow rate reduced the absorption efficiency by decreasing the contact time. Higher temperatures also increased the rate of CO2 desorption.

Anaerobic co-digestion of rabbit manure and sorghum crops in a bench-scale biodigester

Any type of biomass can be used as substrate for biogas production, but the performance of the biodigestion depends on the composition of the feed, and no direct extrapolation of the yield of the process from one substrate to another can be made. In this work, the performance of a bench-scale anaerobic biodigester of 93 L installed at ambient conditions is studied. The biodigester was set up in a region where temperature varies significantly during the year, and was operated under semi-batch conditions with non-thermal control for 16 months with a feed of rabbit manure and ground sorghum grains. To our knowledge, this is the first time the co-digestion of rabbit manure with sorghum grains is considered. To evaluate the biodigestion performance, critical operational variables (pH, temperature, biogas flowrate) were monitored, and composition of substrate, digestate and produced biogas was determined. Moreover, the following variables were quantified: (a) the theoretical methane potential, (b) the specific methane yield and (c) the degree of degradation of the substrate. A 1-D non-stationary model was formulated and validated with experimental data in order to analyze, in a theoretical form, the impact of incorporating thermal insulation to the unit. The results show that is it possible to produce biogas in a bench-scale biodigester, with a novel feed of rabbit manure and ground sorghum grains, in a region with significant temperature changes along the year. Moreover, it is shown that the 1-D model constitutes a useful tool for the design or improvement of biodigesters regarding the insulation system and the warming policies.

Optimization of a chemical scrubbing process based on a Fe-EDTA-carbonate based solvent for the simultaneous removal of CO2 and H2S from biogas

The potential of a novel Fe/EDTA/carbonate-based scrubbing process for the simultaneous removal of H2S and CO2 from biogas was studied by evaluating the influence of Fe/EDTA molarity (M), carbonate concentration (IC), biogas (B), air (A) and liquid (L) flow rates on biogas upgrading performance using a Taguchi L16(45) experimental design. The ANOVA demonstrated that molarity of the Fe/EDTA solution was a significant factor influencing H2S concentration (0.035 % at 0.00 M to 0.000 % at 0.05 M). IC impacted on the concentrations of CO2 (13.1 and 4.5 % at 4000 and 10,000 mg L−1, respectively), N2 and CH4 (85.9 and 94.5 % at 4000 and 10,000 mgIC L−1, respectively). The biogas flow rate affected the concentrations of CO2 (2.5 to 13.8% at 10 and 40 mL min−1, respectively), O2, N2 and CH4 (95.9 to 85.4% at 10 and 40 mL min−1, respectively). Likewise, the recycling liquid flow rate affected CO2 (8.3 and 5.9 % at 5 and 30 mL min−1, respectively), O2, N2 and CH4 (90.5 and 93.3 % at 5 and 40 mL min−1, respectively) concentrations. Finally, the air flow rate impacted on CO2 (10.8 and 6.7 % at 800 and 1000 mL min−1, respectively), H2S, N2 and CH4 (87.9 and 92.2 % at 800 and 1000 mL min−1, respectively) concentrations. Process optimization provided the optimal conditions for each control factor. Continuous biogas upgrading operation at M2-IC1-B2-A4-L4 (0.05 M, 10,000 mgIC L−1, 10 mL min−1, 1000 mL min−1 and 30 mL min−1, respectively) provided CH4, CO2, O2, N2 and H2S concentration in the upgrading biogas of 97.4, 1.4, 0.29, 0.97 and 0%, respectively, which complied with biomethane regulations.

Investigation on the effect of intake air pressure in a biogas-diesel fueled dual-fuel engine

ABSTRACT Using biogas in IC engines takes a toll on the engine performance due to low volumetric efficiency of the dual-fuel mode and low energy density of biogas, however, some engine modifications can be employed to compensate for this loss in performance. The purpose of this study is to investigate the effect of intake air pressure on the engine characteristics of a dual-fuel engine running on biogas and diesel. A single-cylinder four-stroke CI engine is used in dual-fuel mode to perform the tests at different biogas flow rates and different engine loads. A single-stage reciprocating compressor is used to serve as a supercharger to provide air at different pressures to the intake manifold. The results show that the brake thermal efficiency improves by around 2%, and the brake specific energy consumption reduces by 1–4.5% on increasing the intake air pressure. The HC and CO emissions are observed to decrease by around 12% and 15%, respectively. However, very high intake pressures are shown to have less improvement in the HC emissions. There is an increase in the NOx emissions of around 35% with the increase in intake air pressure, however, high air pressures reduce this increase by an amount of around 7%.

Techno-economic optimization of biogas-fueled micro gas turbine cogeneration systems in sewage treatment plant

The aim of this paper is to investigate the feasibility of a combined cooling, heating, and power generation system with a micro turbine using biogas as the fuel to supply the heat and electricity demands in a real wastewater treatment plant. The plant is optimized using the system’s total cost rate and the amount of the produced biogas as objective functions. The anaerobic digester is modeled using the ADM1 model. The optimization variables include digester hydraulic retention time, compressor pressure ratio, isentropic compressor efficiency, recuperator pinch time temperature, turbine isentropic efficiency, turbine input temperature, and the number of micro turbines. In the first scenario (business as usual), the optimal values of the system’s total cost rate and the amount of the produced biogas are 0.02561 $/s and 12.6235*103m3/day, respectively. In the environmental scenario, the optimum values of the total cost rate and the biogas flow rate are 0.0652 $/sand 12.6901*103m3/day, respectively. Scenario 1 has lower values of total cost rate and levelized cost of electricity and higher CO2 emissions than scenario 2. The surplus of electricity from the plant may be exported to the grid in the first scenario. However, some electricity will be imported from the grid in scenario 2. Finally, the effects of some important parameters have been assessed on the total cost rate using Sobol sensitivity analysis. Hydraulic retention time, power purchase price, and discount rate have the highest impacts on the system’s total cost rate by 15% while AD temperature has the lowest effect on total cost rate by 6%. In general, the results of this paper could be employed as a decision support tool for policy makers in energy sector as well as wastewater treatment plant managers to supply the energy demand of their plant.

Biogas upgrading and energy storage via electromethanogenesis using intact anaerobic granular sludge as biocathode

Microbial electrochemical system is a promising CO2-to-CH4 conversion technology that can upgrade raw biogas to high calorific content for downstream applications. The development of efficient, robust, and cost-effective biocathode is the pivotal issue for its industrial application. In this study, intact anaerobic granular sludge (AGS), which was the conventional biocatalyst in anaerobic digestion processes for high-efficiency CH4 production, was for the first time employed as biocathode in electromethanogenesis system (EM) for biogas upgrading. The applied voltage (0, 3, 4, and 5 V) and biogas flow rate (5.22–23.43 mL/h) were modulated to optimize biogas upgrading performance in the AGS-EM system. The CH4 content in treated biogas could reach as high as 97.9 ± 2.3% at an applied voltage of 4 V and a gas flow rate of 17.79 mL/h. The system showed superior stability and anti-interference ability in the continuous operation mode for 2 months. 16S rRNA sequencing results showed that Methanobacterium and Azoarcus were the dominant populations in biocathode. The AGS-EM system obtained an energy benefit of 477.3 kJ/molbiogas, and economic benefit of 446.4 EUR/m3biogas. The novel AGS-EM system showed the promising perspectives for the industrial application in the field of biogas upgrading and renewable energy storage.

Novel Simulation and Optimization for the Production of Green Products I.E., Green Gasoline, Green Diesel and Green Waxes.

During the last decagon, there has been expanding international worry over the rise of anthropogenic CO2 discharge into the Earth’s atmosphere. The application of CO2 into a valuable asset is a major concern. The generation of syn gas and then usage of the syn gas into liquid fuel, seems to be one of the promising options in terms of industrial employment, as it offers several advantages: (a) reduction of CO2, (b) conversion of gases, specially bio-gas, natural gas, LPG, and etc. and CO2 into syngas (c) producing syngas with H2/CO2 ratio 1:1.9 to 1:2.1 which may further be used for the generation of valuable petrochemicals. The present research focusses on the gas to liquid conversion using the simulating software, Aspen Plus ®. The outcomes are then subjected to Design Expert ® for calculation of the optimal generation rate. The feedstocks used for the proposed present examination are bio-gas or pyro-gas, natural gas and LPG. The research scheme, gas to liquid conversion is carried out using three steps: (a) gas (feedstock) to syngas from the combination of dry reforming and steam reforming of methane, (b) Fischer Tropsch process to produce long chains of hydrocarbons and (c) usage of unconverted CO and H2 and other alcohol derivates in the CHP unit for the production of electricity. Amongst all the feedstocks natural gas production or generation is maximum followed by bio-gas or pyro-gas and then LPG. Due to non-available resources of natural gas and generation of GHG emission, for countries like India, bio-gas or pyro-gas can be used as a promising sustainable feedstock for reducing GHG emission and global warming. The outcomes of Aspen Plus ® of biogas or pyro-gas are then subjected to Design Expert ® for the prediction of the maximal production. It can be confirmed that with 6997.54 kg/h of biogas flowrate and 99.39% recycling of CO2, the production of green gasoline, green diesel and green waxes are 565.24 (kg/h), 545.45(kg/h) and 642.68 (kg/h) respectively. The outcomes are in good agreement with the theories, thus proving the process to be a realistic one in nature. Therefore, bringing its viability for India in terms of reduction in CO2 emission and development of gas to liquid conversion process.