Solid Oxide Fuel Research Articles

Performance improvements for green hydrogen-ammonia fueled SOFC hybrid system through dead-end anode recirculation and split transcritical CO2 power cycle

This paper proposes a novel green hydrogen-ammonia fueled solid oxide fuel cell (SOFC) hybrid power system by coupling dead-end anode recirculation with split transcritical CO2 power cycle (STCC). The STCC with dual-temperature heaters adopts split heat absorbing concept to recover cathode off-gas waste heat. The thermodynamic and economic performances of novel system are investigated and compared. Furthermore, the impacts of fuel ammonia mixing ratio, cell stack fuel utilization ratio, STCC CO2 split ratio, fuel price etc. on system performance are revealed. The results show that the introduction of STCC results in a 3.96% improvement in total system energy efficiency and a 0.6% reduction in total system levelized cost of electricity (LCOE) compared with standalone dead-end anode recirculated SOFC unit. The extremely high current density is not beneficial to enhance hybrid system thermo-economic performance. For every 0.1 increase in fuel ammonia mixing ratio, total system energy efficiency increases by 0.26∼0.85% and LCOE decreases by 4.6∼7.4%. The optimal STCC CO2 split ratio of recuperator declines with increasing fuel ammonia mixing ratio. Novel hydrogen-ammonia fueled hybrid system offers a high total energy efficiency of 0.7406, and its economic performance advantage over dead-end anode recirculated SOFC declines with decreasing fuel price.

Exsolved NiRu bimetallic nanoparticles induced by Ru doping in LaBaMn1.6Ni0.3Ru0.1O5+δ as a coking resistant anode catalyst layer for direct-methane solid oxide fuel cells

Due to its abundant resources and advantages in transportation and storage, methane fueled solid oxide fuel cells (SOFCs) are highly needed. In this work, an exceptional internal reforming catalyst comprising in-situ exsolved NiRu bimetallic nanoparticles and oxygen-deficient layered double perovskite LaBaMn1.6Ni0.3Ru0.1O5+δ (r-LBMNR) was prepared. Compared to the cell with LaBaMn1.6Ni0.4O5+δ (r-LBMN) catalyst, the cell with a Ru-doping r-LBMNR catalyst layer, exhibits superior peak power output of 336 mW cm−2 and better durability with a less decay rate of 0.014% per hour in CH4 fuel. The enhanced electrochemical performance can be attributed to the high oxygen ion and electron conductivities of the catalyst and the coupling of Ni and Ru sites with the oxygen-deficient r-LBMNR matrix This coupling activates CH4 and H2O, promotes the oxidation of C atoms in CH4 molecules, and enables reversible hydrogen spillover, ultimately leading to the production syngas of CO(g) and H2(g).

Study of Budding Snubber Quality Deterioration in Solid Oxide Fuel Cell‐Fed Inverter Used in Microgrid Energy Conversion

Study of Budding Snubber Quality Deterioration in Solid Oxide Fuel Cell‐Fed Inverter Used in Microgrid Energy Conversion

Thermo-Economic Analysis and Multi-Objective Optimization of a Poly-Generation System Based on Solid Oxide Fuel Cell/Gas Turbine/Multi-Effect Distillation and Absorption Chiller Using Biogas as Fuel

A poly-generation system for cooling, heating, power, and fresh water is proposed, based on SOFC/GT/MED and an absorption chiller, with biogas as fuel. The performance of the system under the designed condition is analyzed using energy, exergy, and economic methods. An efficiency of 69.02% for comprehensive energy utilization and 35.56% for exergy are demonstrated by simulation results under the designed condition. A freshwater production of 469.93 kg/h is achieved, and a cost rate of 22.51 USD/h is incurred by the system. The effects of various parameters on the system characteristics are examined. Multi-objective optimization methods are employed to determine the final optimum operating condition that yields the best results in two schemes with different objectives. In comparison to the initial design, the optimization of the first scheme results in a 4.58% increase in the comprehensive energy utilization rate and a 2.02% increase in the exergy efficiency. However, the cost rate of the entire system increases by 0.63 USD/h. On the other hand, the optimization of the second scheme leads to a 19.51 kW decrease in the total energy output, a 276.38 kg/h increase in the freshwater production rate, and a 0.42 USD/h decrease in the cost rate of the entire system.

Core-Shell Nanofiber Composites As Highly Active and Robust Anodes for Direct-Hydrocarbon Fueled Solid Oxide Fuel Cells

Direct use of methane in solid oxide fuel cells (SOFCs) can be a key to realize the high-efficiency advantage of fuel cell technologies before mature hydrogen economy. One of the most critical issues for direct-methane SOFCs is to prevent anode, particularly Ni-based, from carbon deposition (coking) that drastically degrades performance. A number of ceramic anodes have been developed to exhibit excellent coking resistance but their application is still limited by relatively low electrochemical activity. Impregnating catalytically active and high oxygen ion-conducting materials such as doped ceria to form nanoscale composites, some ceramic anodes demonstrated enhanced activity comparable to Ni-based anodes. However, fabrication methods employed so far require repetitive series of a coating and high-temperature calcination step to optimize the performance, which detrimentally affects nanoarchitectures. To address this issue, we demonstrate electrospinning as efficient route to prepare nanocomposite ceramic anodes. We successfully achieve highly active and robust anodes based on core-shell-like La0.75Sr0.25Cr0.5Mn0.5O3@Sm0.2Ce0.8O1.9 nanofibers through co-electrospinning method. Such nanoscale morphologies are maintained by the durable ceria shells at elevated temperature. Compared to the traditionally mixed counterpart, it shows nearly a half polarization resistance due to the increased active reaction sites and high stability in a wet methane at 700℃ for about 100 h.

Modelling of Ni Nitridation in NH3-Fueled Solid Oxide Fuel Cells

In the past decade NH3 fueled solid oxide fuel cells (SOFCs) are getting increasing attention. As compared to hydrogen, ammonia has the advantages of higher energy density and ease of storage and transportation. Due to the high operating temperature of SOFCs, typically in the range of 550-750C, NH3 can be easily decomposed into nitrogen and hydrogen over Ni-based cermet fuel electrodes. Previous studies have demonstrated NH3-fueled SOFCs with high power density, high efficiency and low emissions. One of the remaining challenges is the nitridation of Ni electrode. Under realistic operating conditions, Ni in the support and active layers of the fuel electrode has a tendency of being nitride when exposed to NH3, forming Ni3N and resulting in performance degradation. In this work, the thermodynamics of the Ni-N system is explored using the CALculation of PHAse Diagrams (CALPHAD) method. The kinetics of Ni3N formation in NH3-fuelled SOFCs is then predicted, taking into account the kinetics of both ammonia decomposition and Ni3N formation. The locations inside NH3-fuled SOFCs with potential risks of Ni nitridation are then predicted and strategies to avoid or reduce nitridation are further proposed.

Numerical design and evaluation of ammonia fueled solid oxide fuel cell (SOFC) power systems with different integration architecture: Efficiency, power density and thermal safety

Numerical design and evaluation of ammonia fueled solid oxide fuel cell (SOFC) power systems with different integration architecture: Efficiency, power density and thermal safety

Conception and thermo-economic performance investigation of a novel solid oxide fuel cell/ gas turbine/Kalina cycle cascade system using ammonia-water as fuel

In order to develop a zero-carbon, high-efficiency and low-cost energy system, the conception of an innovative ammonia-water fueled solid oxide fuel cell (SOFC) - gas turbine (GT) - Kalina cycle (KC) cascade power system is proposed. The performance superiority of novel cascade system is verified by comparing with SOFC system using anode off-gas recycle (AOR). The influence of system key operation parameters including fuel ammonia mass fraction on novel system total energy efficiency and levelized cost of electricity (LCOE) is revealed. The rapid prediction and multi-objective optimization of novel system thermo-economic performance are conducted based on artificial neural network - multi-objective Harris hawks optimizer (ANN-MHHO). The results show that the total energy efficiency and LCOE of novel ammonia-water fed SOFC-GT-KC system are 12.92% higher and 8.91% lower than the SOFC system using AOR under preliminary condition, respectively. Parametric analysis reveals that fuel ammonia mass fraction presents a more significant effect on novel system thermo-economic performance than cell stack fuel utilization ratio. A high cell stack fuel utilization ratio of more than 0.64 is not conducive to improving novel system economic performance. The novel system LCOE reaches the minimum of 0.13807 $/kWh at SOFC operation pressure of 9.5 bar. The multi-objective optimization results demonstrate that the novel system total energy efficiency is increased by 1.14% and LCOE is reduced by 1.23% under optimal condition compared with preliminary condition. The novel system LCOE is more sensitive to ammonia price than interest rate.

Numerical study on effects of CH4–CO2 internal reforming on electrochemical performance and carbon deposition of solid oxide fuel cell

CH4–CO2 fueled solid oxide fuel cells (SOFCs) are the high-efficiency and low-carbon power generation technology. However, carbon deposition severely hinders its application. Here, the numerical model considering the complex anode CH4 internal reforming reactions, H2 electrochemical reaction, gas diffusion and charge transfer of SOFC using CH4–CO2 fuel has been established. The CH4–CO2 internal reforming and electrochemical reactions of SOFC under different CO2/CH4 ratios and temperatures are studied to reveal the optimal operating conditions. The distributions of different reaction rates, gas components and carbon deposition activity at the anode are analyzed. The results show that the increase of CO2 concentration can decrease the carbon activity but also cause the decrease of electrochemical performance. It is found that the good comprehensive performances including power density, carbon activity and methane conversion rate can be achieved under the CO2/CH4 molar ratio of 1. The thermodynamic calculation of three different methane reforming modes shows that CH4–CO2 reforming leads to the greatest carbon deposition risk compared with CH4–H2O and CH4–O2 reforming, implying the importance of anti-carbon for CH4–CO2 fueled SOFC.

A High Performance Tubular Solid Oxide Fuel Cell for Unmanned Autonomous Systems

Small unmanned aerial systems (SUASs) have a great potential for numerous applications. The SUASs are light-weight, man-portable, and capable of delivering commercial products. Currently, small UASs are powered by lithium-ion batteries, however, flight endurance is limited and requires frequent charging battery due to low capacity and energy density. Numerous research and development efforts have focused on alternative power sources. These alternative power sources include technologies such as solar cells and hydrogen based polymer electrolyte membrane fuel cells. Additionally, polymer electrolyte membrane fuel cells still have the same technical constraints, the source of hydrogen, as it did many years ago. We have developed and examined the operational capabilities of propane fueled solid oxide fuel cell (SOFC) technology can power an sUAS. A self-sustaining miniature tubular SOFC stack provides a unique high power and high energy density for UAS. The SOFC has great potential for commercial and civilian applications, ranging from small scale systems (e.g. small unmanned air vehicle, wireless sensor networks) to large scale system (e.g. electric vehicle, wireless sensor networks, electric vehicles).

Numerical analysis of natural gas, hydrogen and ammonia fueled solid oxide fuel cell based micro cogeneration units with anodic gas recirculation

The energy sector is actively transitioning towards climate-neutral solutions, emphasizing advancements in clean power generation technologies. Cogeneration systems based on solid oxide fuel cells (SOFC) currently exhibit higher electrical efficiencies than conventional plants, but their operation can still be improved. One of the approaches to increase its efficiency is implementing anodic off-gas recirculation. In this work, a numerical model of a 10 kW SOFC installation with anodic gas recirculation was analyzed using Aspen HYSYS software. System fueled with three alternative fuels (natural gas, hydrogen, and ammonia) was tested. In this paper it was proven that anode-off gas recirculation improves the electrical and total efficiency of the system for each fuel type. The cogeneration unit with a SOFC stack can operate safely over a wide range of recirculation ratios without need for additional modifications. Ammonia-fueled units achieve electrical efficiency (55%) higher than hydrogen-based system (47.6%) but lower than installation fueled with natural gas (61.8%).

Exergoeconomic analysis and multi-objective optimization of a CCHP system based on SOFC/GT and transcritical CO2 power/refrigeration cycles

A CCHP (Combined Cooling, Heating and Power) system based on SOFC/GT (Solid Oxide Fuel Cell/Gas Turbine) and transcritical CO2 power/refrigeration cycles is proposed to efficiently provide cooling, heating and power for users under the principle of energy cascade utilization. The energy, exergy and exergoeconomic analysis is conducted to assess the effects of key parameters on the system’s thermal-economic performance. The simulation results demonstrate that the cooling, heating and net electricity outputs could reach 48.37 kW, 240.65 kW and 250.95 kW with a trigeneration cost per unit exergy of 37.12$/GJ, while the power generation and exergetic efficiencies could reach 62.65% and 62.27%. The annualized capital cost, O&M cost and fuel cost are 131 549$, 90 532$ and 162 375$, respectively. The NPV and payback period of the CCHP system are 502 824$ and 12.5 years. The effects of SOFC pressure, air flowrate, refrigerant flowrate and CO2 flowrate of the transcritical CO2 power cycle on the CCHP system characteristics are discussed. Furthermore, exergoeconomic and multi-objective optimization methods are used to find the final optimum operation condition with best results. A solution set in Pareto frontier with each fitness value superior to that of the design condition is obtained after optimization. Through the decision-making process, the total energy output and the exergy efficiency increase by 35.58 kW and 0.20%, respectively, while the unit exergy cost of trigeneration rises by 0.21$/GJ.

Sensitivity analysis of performance and thermal impacts of a single hydrogen fueled solid oxide fuel cell to optimize the operational and design parameters

In this research, the sensitivity analysis has been performed to investigate the effects of various parameters such as operating temperature, material porosity, flow configurations, air–fuel ratios, and electrolyte thickness on the performance and thermal impacts (stress and strain) generation in the porous electrodes and solid electrolyte. The already developed cell temperature base model of hydrogen-fueled solid oxide fuel cell (SOFC) is used to optimize the operational and design parameters in this study. It is recognized that operating temperature has a noticeable effect on current density and thermal impacts generation. The maximum thermal stress indicated in the middle of the solid electrolyte along the length of the cell for operating temperatures 800–1000 °C are 2088.88 MPa and 2618.18 MPa, meanwhile, the current density varies from 2556.04 A/m2 to 3366.51 A/m2. Taguchi Orthogonal Array Method has been implemented to perform the sensitivity analysis. The analysis of variance (ANOVA) shows that operating temperature has a 51.10% contribution to the overall performance of the cell followed by porosity 23.61 %, electrolyte thickness 16.45%, air–fuel ratio 6.41%, and flow configuration 2.41%.

Assessment of a new coal-fired power plant integrated with solid oxide fuel cell and parabolic trough solar collector

Despite the major challenges facing fossil fuels, they are now utilized to supply nearly 80% of the world's energy requirements. Of this amount, about 30% relies on coal-based power plants. Such power plants emit large volumes of pollutant gases into the atmosphere, which has led to serious environmental crises. Therefore, the exploitation of green technologies and/ or the integration of environmentally friendly systems in existing power plants are essential. The aim of the article is to introduce and conceptual-thermodynamic design of a lignite coal-based plant that is integrated with monoxide-hydrogen fueled solid oxide fuel cell (SOFC), and parabolic trough solar collector (PTSC) based-solar farms. The present paper provides energy, exergy, and thermodynamic analyzes with considering entropy generation and emission rate of the power plant. In addition, a comparison of system performance when using anthracite instead of lignite is also provided. Also, real climatic data (i.e., Yazd, Iran) have been used to evaluate the behavior of solar fields. The results showed that nearly 93.7 kg/s of gas is raised from the power plant after the combustion process. In addition, proposed power plant has energy and exergy efficiencies of 70.95% and 35.7%, respectively. Moreover, the PTSC2 solar farm in a lignite-fired power plant should have approximately 6.76-fold larger area than that of anthracite.

Robust Ruddlesden‐Popper phase Sr3Fe1.3Mo0.5Ni0.2O7‐δ decorated with in‐situ exsolved Ni nanoparticles as an efficient anode for hydrocarbon fueled solid oxide fuel cells

AbstractA highly efficient Ruddlesden‐Popper structure anode material with a formula of Sr3Fe1.3Mo0.5Ni0.2O7‐δ (RP‐SFMN) has been developed for hydrocarbon fueled solid oxide fuel cells (HF‐SOFC) application. It is demonstrated that a nanostructured RP‐SFMN anode decorated with in‐situ exsolved Ni nanoparticles (Ni@RP‐SFMN) has been successfully prepared by annealing the anode in reducing atmosphere similar to the operating conditions. The phase compositions, valence states, morphologies, and electrocatalytic activities of RP‐SFMN material have been characterized in detail. In addition, the in‐situ exsolution mechanism of the metallic Ni phase from the parent oxide is clearly explained by using density function theory calculation. The peak output power density at 800°C is significantly enhanced from 0.163 to 0.409 W/cm2 while the electrode polarization resistance is effectively lowered from 0.96 to 0.30 Ω cm2 by the substitution of B‐site Fe by Ni, which is attributed to the improved electrocatalytic activities induced by the in‐situ exsolved Ni nanocatalysts. Moreover, the single cell with RP‐SFMN anode exhibits good stability in 3% H2O humidified H2 and syngas for 110 and 60 h at 800°C, respectively. Our findings indicate that RP‐SFMN is a greatly promising anode candidate of HF‐SOFCs due to its good electrochemical performance and stability during the operation.

Advanced Ru‐Infiltrated Perovskite Oxide Electrodes for Boosting the Performance of Syngas Fueled Solid Oxide Fuel Cell

AbstractA promising Sr2Fe1.5Mo0.5O6‐δ‐Ce0.8Sm0.2O1.9 (SFM‐SDC) anode material is modified by infiltrating Ru catalytic particles to enhance the electrochemical performance for H2/CO electro‐oxidation. The electrode polarization resistance (Rp), which is considerably affected by the pre‐sintering temperature, shows the lowest value of 0.67 Ω cm2 at 800 °C in 3 % H2O humidified hydrogen for bare SFM‐SDC electrode calcined at 1050 °C. Furthermore, the Rp value is favorably diminished to 0.22 Ω cm2 after Ru infiltration. Meanwhile, the output power density exhibits a significant increment, proving the excellent electrocatalytic properties of Ru nano‐particles. Additionally, the single cell with infiltration presents a good short‐term stability even after redox operation.

Co-generation of liquid chemicals and electricity over Co-Fe alloy/perovskite anode catalyst in a propane fueled solid oxide fuel cell

Herein, perovskite oxide Sr2Fe1.4Co0.1Mo0.5O6-δ (SFMCo) is used as the anode of direct propane-fueled solid oxide fuel cells (SOFCs). In reducing operation, single-phase perovskite oxide SFMCo is transformed to Co-Fe bimetallic catalytic nanocatalysts decorated SFMCo composite nanomaterial. Good electrochemical performance and outstanding stability are obtained with propane as the fuel and ambient air as the oxidant. Due to the catalytic effect of the exsolved Co-Fe alloy in the SOFC system, polycyclic aromatic compounds are gathered as chemical products in the exhaust of the anode through the aromatization route. This novel anode system manifests the successful co-generation of electricity and high-value liquid chemicals from direct hydrocarbon-fueled SOFC.

Robust in situ exsolved nanocatalysts on perovskite oxide as an efficient anode for hydrocarbon fueled solid oxide fuel cells

An in situ exsolved (Pr,Ba)Ox nanoparticle structure layered perovskite oxide anode can effectively promote the fuel oxidation reaction, enabling the significantly enhanced electrochemical performance and considerable stability.

Development of Ammonia Fueled Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) can generate electricity through an electrochemical conversion of the chemical energy of fuels including hydrogen, hydrocarbons, and biogas because of high operation temperatures. Ammonia has recently been considered as a promising hydrogen carrier that is relatively convenient to store and transport and can be decomposed into hydrogen and nitrogen with no carbon emission via catalytic cracking. Thus, much effort has been made to utilize ammonia as a clean fuel to SOFCs for power generation at high efficiency. This review is aiming at delivering the current progress of developing high temperature ceramic fuel cells fed with ammonia, particularly more focused on the achievements of a direct ammonia fueled SOFC (DA-SOFC) to shed light on the challenges of degrading the performance and durability. The problems are primarily attributed to a lack of rational catalysts, thermal imbalance, and the evolution of nitrides on the components including the Ni based anode, Ni mesh as current collector, and stainless steels of metallic interconnect that are exposed to the ammonia fuel environment incurring microstructural deformations and electrical and electrochemical deteriorations. Lastly, strategic pathways to overcome the inadequate performance and the instability are suggested to accomplish a commercialization of DA-SOFCs.

Highly efficient and stable fuel-catalyzed dendritic microchannels for dilute ethanol fueled solid oxide fuel cells

Highly efficient utilization of low calorific value fuels is a major challenge for the current economic society. As an electrochemical device, solid oxide fuel cells (SOFCs) offer an efficient approach, but the performance is limited by the concentration loss. Hence, a dendritic fuel microchannels for dilute ethanol-fueled SOFCs is designed by phase inversion technique to accelerate the mass transport and improve the conversion efficiency in this study. Based on the three-dimensional X-ray computed tomography technology, the porosity of the obtained dendritic microchannels is around 40%, and the absolutely permeability is 0.31 μm2, which can guarantee the efficient fuel transport. Benefiting from the dendritic microchannels, the electrochemical performance increases from 363.1 mW cm−2 to 713.8 mW cm−2 at 750 °C using 10% ethanol as fuel, and the concentration loss can be negligible. In addition, the fuel utilization of dendritic microchannels increase from 34.6% to 97% by reducing the ethanol concentration from 30% to 10% at 0.3 V. The corresponding maximum power density only decrease 7% at 750 °C (677.1 mW cm−2 vs 632.7 mW cm−2). All the results demonstrate that the design of dendritic microchannels for SOFCs is an efficient solution to accelerate the gas diffusion and improve the conversion efficiency of the low calorific value fuels.