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Comparative energy, economic, and environmental analyses of power-to-gas systems integrating SOECs in steam-electrolysis and co-electrolysis and methanation
(2023-07-01)
Patcharavorachot, Yaneeporn
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Chatrattanawet, Narissara
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Arpornwichanop, Amornchai
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Saebea, Dang
The integration of solid oxide electrolysis cells (SOEC) and methanation as a power-to-gas system is a promising technology for renewable energy storage and CO<inf>2</inf> utilization. SOEC can operate in both modes: water electrolysis for hydrogen production and water/carbon dioxide co-electrolysis for syngas production. The operating conditions and performance of the integrated systems between the methanation and SOECs with both modes are different. To study the direct and indirect utilization of CO<inf>2</inf> in the methanation integrating SOEC with both modes, this study focuses on the comparative analysis of two integrated systems between the methanation and SOECs with water electrolysis mode and co-electrolysis mode for green natural gas production from fermentation waste in all aspects such as energy and economic analyses. Additionally, heat integration of both integrated systems with pinch analysis is studied. Results indicate that the methane yield of mixed CO and CO<inf>2</inf> methanation is higher than that of CO<inf>2</inf> methanation. The integrated system between the methanation and SOEC with co-electrolysis mode achieves a higher system efficiency, compared to that of a system using SOEC with water electrolysis mode. The efficiency of both systems can be improved by heat integration which increases by 4.60–6.09%. Moreover, the levelized cost of the product in the system using SOEC with water electrolysis of 201.35–211.86 $/MWh is lower than that of the system using SOEC with co-electrolysis mode. The CO<inf>2</inf> emission intensities of the system using SOEC with co-electrolysis mode by power consumption sources from the wind turbine are the lowest about 1.37 kgCO<inf>2</inf>,e/kWh.
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Performance assessment of a 10 kW pressurized solid oxide fuel cell integrated with glycerol supercritical water reforming
(2022-08-01)
Patcharavorachot, Yaneeporn
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Chatrattanawet, Narissara
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Saebea, Dang
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Arpornwichanop, Amornchai
In this work, the integrated system of pressurized solid oxide fuel cell (SOFC) and supercritical water reforming of glycerol was proposed. The syngas from the reforming process has high temperature and pressure and thus, it can be used as fuel for the SOFC. The performance of an integrated system was determined through the Aspen Plus simulator in which the electrochemical equations were also included. The developed model was employed to examine the performance of the integrated system with respect to the wider ranges of operation of the reformer and SOFC. In this work, the desired power output of an SOFC stack is set as 10 kW and thus, the area of an SOFC is determined. A smaller area is required as it normally leads to a lower fabrication cost for the SOFC. The simulation results revealed that the smallest SOFC area can be provided when the reformer is operated at 800°C and 240 atm with a ratio of supercritical water to glycerol as 50 whereas the SOFC operation is at 900°C and 4 atm with the current density as 7000 A/m2. Under these operating conditions, the integrated system can provide the cell voltage, required area, fuel utilization, and SOFC efficiency as 1 V, 1.42 m2, 75% and 61%, respectively. From the exergy analysis, it was found that the compressor, heater, and turbine are the highest exergy destruction units whereas the reformer has the lowest exergy destruction, followed by the SOFC stack.
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Methanation Process for Methane Synthesis from Waste Gas: Process Simulation
(2022-01-01)
Saebea, Dang
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Chatrattanawet, Narissara
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Soisuwan, Soipatta
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Arpornwichanop, Amornchai
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Patcharavorachot, Yaneeporn
Waste gas from the fermentation of bioethanol production consists of high carbon dioxide concentration. The CO<inf>2</inf> emissions cause global climate change. The conversion of carbon dioxide to chemical products or fuels is an interesting solution for reducing the amount of carbon dioxide emissions. The methane synthesis via carbon dioxide methanation reaction has attracted much attention. The suitable operation of the methanation process for methane synthesis from waste gases should be studied. This work aims to investigate the methane production from the waste gas of the fermentation process. The composition of impurities in waste gases on the performance of the methanation process is investigated. The effects of hydrogen to carbon dioxide ratio and operating temperature on the carbon dioxide conversion and methane yield of the methanation are also studied. The simulation results from the thermodynamic analysis show that the methane yield of the methanation from waste gases is 3.11 - 4.61 % higher than that from pure carbon dioxide in the temperature range of 300 - 500 °C. The methane yield of the methanation process decreases with increasing temperature. The increase in the hydrogen to carbon dioxide ratio of 1 to 4 and the operating pressure of 1 to 8 bar have a significant effect on the enhancement of carbon dioxide conversion and methane yield.
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Syngas production from sugarcane leftover gasification integrated with absorption process for green liquid production
(2019-10-20)
Chatrattanawet, Narissara
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Authayanun, Suthida
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Saebea, Dang
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Patcharavorachot, Yaneeporn
The aim of research is to present favorable operating conditions for the clean syngas production from sugarcane leftover through the gasification process by using AspenPlus™ software. In order to obtain the suitable syngas for liquid fuel production, this process should be integrated with gas cleaning. The simulation was performed by comparing three gasifying agents, i.e., steam, air, and steam-air. To find favorable operating conditions that provide the highest syngas molar flow rate, the effect of operating conditions in gasifier was also examined. In addition, the possibility of syngas production operated under a thermal self-sufficient condition was studied. The gasification results showed that the syngas production significantly increases with the increase of temperature. The proper gasifying temperature for three processes is at 750 °C. When the maximum syngas molar flow rate was considered, it was found that the use of steam (at S/B of 0.6) and steam-air (at S/B of 0.8 and A/B of 0.04) in gasification can achieve this criterion. Both processes can provide syngas molar flow rate as ∼149 kmol/h. However, it was found that thermal self-sufficient operation is possible when air and steam-air are used as gasifying agent. The result indicated that syngas molar flow rate obtained from air gasification (at A/B of 1.309) is more than that from steam-air gasification (at S/B of 0.1 and A/B of 1.375). In order to obtain the cleaner production of syngas, the absorption process with capturing CO<inf>2</inf> and H<inf>2</inf>S was studied via using monoethanolamine (MEA) as solvent. The optimal column pressure is 40 bars and the number of trays equals to 10. To obtain the H<inf>2</inf>S content below 0.1 mg/m3, the MEA molar flow rates are 325, 450, and 465 kmol/h for steam, air, and steam-air gasification processes, respectively.
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Optimization of hydrogen production from three reforming approaches of glycerol via using supercritical water with in situ CO2 separation
(2019-01-22)
Patcharavorachot, Yaneeporn
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Chatrattanawet, Narissara
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Arpornwichanop, Amornchai
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Assabumrungrat, Suttichai
A pathway for hydrogen production from supercritical water reforming of glycerol integrated with in situ CO<inf>2</inf> removal was proposed and analyzed. The thermodynamic analysis carried out by the minimizing Gibbs free energy method of three glycerol reforming processes for hydrogen production was investigated in terms of equilibrium compositions and energy consumption using AspenPlus™ simulator. The effect of operating condition, i.e., temperature, pressure, steam to glycerol (S/G) ratio, calcium oxide to glycerol (CaO/G) ratio, air to glycerol (A/G) ratio, and nickel oxide to glycerol (NiO/G) ratio on the hydrogen production was investigated. The optimum operating conditions under maximum H<inf>2</inf> production were predicted at 450 °C (only steam reforming), 400 °C (for autothermal reforming and chemical looping reforming), 240 atm, S/G ratio of 40, CaO/G ratio of 2.5, A/G ratio of 1 (for autothermal reforming), and NiO/G ratio of 1 (for chemical looping reforming). Compared to three reforming processes, the steam reforming obtained the highest hydrogen purity and yield. Moreover, it was found that only autothermal reforming and chemical looping reforming were possible to operate under the thermal self-sufficient condition, which the hydrogen purity of chemical looping reforming (92.14%) was higher than that of autothermal reforming (52.98%). Under both the maximum H<inf>2</inf> production and thermal self-sufficient conditions, the amount of CO was found below 50 ppm for all reforming processes.
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Performance and environmental study of a biogas-fuelled solid oxide fuel cell with different reforming approaches
(2018-03-01)
Chatrattanawet, Narissara
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Saebea, Dang
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Authayanun, Suthida
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Arpornwichanop, Amornchai
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Patcharavorachot, Yaneeporn
In this work, solid oxide fuel cells (SOFCs) using biogas as the fuel with two different reforming approaches, i.e., external and internal reforming, were studied to determine the optimal operation conditions for each approach. Thermodynamic analysis was performed using a flowsheet simulator. The equilibrium gas composition was calculated by minimizing the Gibbs free energy. An electrochemical model that includes three voltage losses (i.e., activation, ohmic, and concentration losses) was used to predict the performance of the SOFCs. The simulation results showed that the reformer in the external reforming SOFC should be operated at a temperature of 973 K, a pressure of 1 atm, and a steam-to-carbon molar ratio of 0.5. In performance analysis, the simulation results indicated that both approaches have the same optimal operating conditions, i.e. a temperature of 1173 K, a pressure of 3 atm, and a current density of 5000 A/m2. Under the same operating conditions, the internal reforming SOFC exhibited better electrical efficiency than that of the external reforming SOFC. Considering the CO<inf>2</inf> and CO emissions, the exhaust gas obtained from the anode side of the internal reforming SOFC contained 7.4% CO<inf>2</inf> and 37.9% CO, which are higher values than those for the external reforming SOFC (1.9% CO<inf>2</inf> and 32.5% CO).
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Electrochemical performance assessment of low-temperature solid oxide fuel cell with YSZ-based and SDC-based electrolytes
(2018-01-01)
Saebea, Dang
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Authayanun, Suthida
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Patcharavorachot, Yaneeporn
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Chatrattanawet, Narissara
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Arpornwichanop, Amornchai
In this work, solid oxide fuel cells (SOFCs) based on different electrolytes, i.e., the yttria-stabilized zirconia (YSZ) and the samaria-doped ceria (SDC), were investigated to study their performances at low-temperature operation. The predicted performance of both SOFCs was validated with the experimental results. The verified models were implemented to study the impact of operating conditions, i.e., cell temperature, pressure, thicknesses of cathode, anode, and electrolyte, on their performances. The decrease in the operating temperature from intermediate range (800–900 °C) to low range (550–650 °C) has a considerable effect on the performance of the YSZ-based SOFC as conventional type, which dropped from 0.67–1.40 W/cm2 to 0.027–0.13 W/cm2. Under the low operating temperature range, the performance of SDC-based SOFC was superior to that of the YSZ-based SOFC, due to the lower ohmic loss. Nevertheless, the SDC-based SOFC has higher concentration overpotentials than the YSZ-based SOFC. The concentration overpotentials of the SDC-based SOFC can be reduced by the thinner anode and cathode thicknesses. In addition, the SDC-based SOFC at low operating temperature with the pressurized operation could significantly improve its power density, about 20% at 2 bar, which was close to that of YSZ-based SOFC at intermediate temperature of 800 °C.
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Biomass steam gasification of sugarcane leftover for green diesel production
(2018-01-01)
Chatrattanawet, Narissara
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Kanjanasorn, Worameth
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Authayanun, Suthida
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Saebea, Dang
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Patcharavorachot, Yaneeporn
Biomass gasification is one of attractive processes for syngas production. In this research, sugarcane leftover is selected to use as feedstock. The produced gas has a purpose to use for green liquid fuels production through Fischer-Tropsch process. Consequently, this search aims to develop the model of syngas production from sugarcane leftover by using AspenPlus™ simulation software. In order to obtain syngas that suitable for producing liquid fuel, the content of some contaminants, i.e., CO<inf>2</inf> and H<inf>2</inf>S must be concerned and thus, this process should be integrated with gas cleaning. The simulation was performed by using steam as gasifying agent. The effect of operating conditions in gasifier was also examined to find optimal conditions that provide the highest cold gas efficiency. The results showed that syngas content increases significantly with an increase in temperature and it reaches a stable at temperature higher than 750 °C. The optimal steam to biomass molar ratio is 0.6. Moreover, the absorption process by monoethanolamine (MEA) was studied to reduce H<inf>2</inf>S in syngas (below 0.1 mg/Nm3). Under this requirement, it was found that the optimal operating condition of adsorber is pressure of 40 bar and tray number of 10 by using MEA molar flow rate of 325 kmol/h.

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