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Hydrogen and power generation via integrated bio-oil sorption-enhanced steam reforming and solid oxide fuel cell systems: Economic feasibility analysis
(2021-03-19)
Wiranarongkorn, Kunlanan
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Patcharavorachot, Yaneeporn
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Panpranot, Joongjai
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Assabumrungrat, Suttichai
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Arpornwichanop, Amornchai
A solid oxide fuel cell (SOFC) is a promising technology for generating electricity and heat with high efficiency and environmental friendliness. The use of a bio-oil as a renewable and low-cost feedstock for an external reforming SOFC system can reduce fossil fuel consumption and greenhouse gas emissions. From a technical perspective, high-purity hydrogen (H<inf>2</inf>) for SOFCs can be produced from the sorption-enhanced steam reforming (SESR). In this study, an economic analysis of a bio-oil SESR and SOFC integrated system (160 kW alternating current electricity production) is performed to evaluate the feasibility of the designed process. An economic comparison of the systems with different configurations, i.e., SESR-SOFC integrated systems with and without anode gas recirculation and a conventional reforming-based SOFC system (CON-SOFC), is presented in terms of their net present cost (NPC) and levelized cost of energy (LCOE). According to the results, the SESR-SOFC system with anode gas recirculation is more favorable than the CON-SOFC system and SESR-SOFC system without recirculation. Nevertheless, it remains economically infeasible because its NPC in the 20th year is approximately 6.13% higher than that of the combined heat and power (CHP) system (a base case). However, it can attain economic equivalence with the CHP system when a carbon tax of at least $15 t<inf>CO<inf>2</inf></inf>−1 is considered or when the SOFC capital cost, interest rate, and bio-oil cost are separately reduced by 14%, 21%, and 37%, respectively. In addition, an increase in feed-in tariff has the highest impact on the NPC reduction of the renewable bio-oil SESR-SOFC integrated system with recirculation.
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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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Design of SOFC based oxyfuel combustion systems with anode recycling and steam recycling options
(2017-11-01)
Mahisanana, Chanon
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Authayanun, Suthida
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Patcharavorachot, Yaneeporn
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Arpornwichanop, Amornchai
A solid oxide fuel cell (SOFC) based power plant incorporating an oxyfuel combustion process to reduce carbon dioxide emissions is analyzed. The effects of key parameters, such as the steam-to-carbon ratio, fuel utilization factor, and temperature, on the current density, voltage, heat production, and requirements of each unit are investigated. In addition, the overall performance of the SOFC–oxyfuel integrated systems with anode recycling and steam recycling are studied and compared. The SOFC system with anode recycling provides better electrical efficiency than that with steam recycling because of the high utilization of fuel in the SOFC and the ability to integrate a fuel turbine. In the SOFC with steam recycling, a fuel turbine cannot be implemented because there is insufficient heat for preheating the inlet streams, which is primarily used to vaporize the recycling stream. The conditions for SOFC–oxyfuel combustion in systems with anode or steam recycling that provide the optimum electrical efficiency are also analyzed.

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