Enhancing hydrogen production from propane partial oxidation via CO preferential oxidation and CO2 sorption towards solid oxide fuel cell (SOFC) applications

Life Cycle Assessment and Life Cycle Costing of a SOFC system for distributed power generation

This paper investigated the performance of a bioethanol-fed Solid Oxide Fuel Cell (SOFC) system integrated with a distillation column (SOFC-D). Excess heat from the SOFC system was directly utilized in the distillation column where bioethanol (5 mol%) was purified to a desired concentration before feeding to the SOFC system consisting of an air heater, an ethanol/water heater, a reformer, an SOFC preheater, an SOFC stack and an afterburner. The SOFC-D system was simulated using Aspen PlusTM for the distillation portion and MatlabTM for the SOFC portion. The effects of operating parameters; i.e., ethanol concentration, ethanol recovery, fuel utilization and operating voltage on the performance and energy involved in the SOFC-D system (e.g. distillation energy: QD and the net exothermic heat of the SOFC system: QSOFC,Net) were examined. In addition, the performance of the SOFC-D system at the energy sufficient point where QD = QSOFC,Net was considered. The integration of the distillation column with the SOFC system was found to offer superior SOFC performance. The ethanol recovery and fuel utilization significantly influenced the overall electrical efficiency and power density. Quite low performances are obtained when one operated the SOFC-D without an external heat source. The maximum overall efficiency and power density (~35% and 0.22 W cm-2) occured at an ethanol recovery of 80% and Uf of 90%.

Recent developments in control and integration of solid oxide fuel cells: From stack to system

Performance analysis of methanol-fueled solid oxide fuel cell system incorporated with palladium membrane reactor

Field test results of residential SOFC co-generation system at Tokyo Gas T. Ishikawa, S. Yamashita Product Development Dept., Tokyo Gas Lo., LTD., Tokyo, JAPAN We are developing residential SOFC co-generation system in order to commercialize it. One of our activities is to operate SOFC systems in field tests to make sure effects of installation and find technical issues. The detail is as below. A serious accident at nuclear power plants in Fukushima which was triggered by a huge earthquake on 11th March 2011 forces drastic re-formulation of Japan’s energy policy. In a series of discussions on the new energy policy, promoted use of distributed power generation is demanded more than ever as one of the main power systems, with extremely strong expectations for the fuel cell co-generation system. Tokyo Gas has been conducting research and development of solid oxide fuel cell (SOFC) which is expected to achieve the highest efficiency among all distributed power systems. In parallel with it, to verify the applicability of the SOFC for residential use and to identify technical challenges of SOFC, we have started field tests of SOFC systems of multiple manufacturers in the “Solid Oxide Fuel Cell (SOFC) demonstrative research project” with financial support from NEDO (Figure 1) [1][2]. We have installed a total of 23 units of four manufacturers in the field test of over four years (from 2007 to 2010), of which 14 units are still under operation as of April 30, 2012 (table 1). And the operating time has reached 18,600 hours at the longest, with 268,500 hours in total of 23 units. We have acquired the knowledge as shown below during the field tests conducted at general residences which we selected to reflect a variety of electrical and hot water demands (Figure 2). (1) Residential SOFC co-generation system contributes to the saving the preliminary energy consumptions and CO2 emissions by households in Japan (Figure 3, Figure 4). (2) SOFC system shows high electricity efficiency exceeding 45%LHV, and the transition of efficiency indicates that the durability of SOFC system including cell stack is estimated to be almost practical use (Figure 5). (3) SOFC system shows high reliability because of its simple system configuration. We will report the detailed results of SOFC field tests based on the latest data. Acknowledgments Finally, we would like to express our appreciation to NEDO, as this report is prepared mainly based on the results of the project supported by NEDO. Figure 2 Residential Demand (/Month) References [1] Solid Oxide Fuel Cell demonstrative research project final report (2011) http://www.nef.or.jp/sofc/share/pdf/h22y.pdf [2] Y. KAWABATA, T.SEYAMA, T.SOBUE, International Gas Union Research Conference ( 2011 ) Development and Field Test of Residential SOFC Co-generation System with All-ceramics-segmented Cells

Solid oxide fuel cell (SOFC) systems are the most advanced power generation system with the highest thermal efficiency. The current trend of research on the SOFC systems is focused on multikilowatt scale systems, which require either internal reforming within the stack or a compact external reformer. Even if the internal reforming within the SOFC stack allows compact system configuration, it causes significant and complicated temperature gradients within the stack, due to endothermic reforming reactions and exothermic electrochemical reactions. As an alternative solution to the internal reforming, an external compact heat exchange reformer (CHER) is investigated in this work. The CHER is based on a typical plate-fin counterflow or coflow heat exchanger platform, and it can save space without causing large thermal stress and degradation to the SOFC stack (i.e., eventually reducing the overall system cost). In this work, a previously developed transient dynamic model of the CHER is validated by experiments. An experimental apparatus, which comprises the CHER, air heater, gas heater, steam generator, several mass flow controllers, and controller cabinet, was designed to investigate steady state reforming performance of the CHER for various hot air inlet temperatures (thermal energy source) and steam to carbon ratios (SCRs). The transient thermal dynamics of the CHER was also measured and compared with simulations when the CHER is used as a heat exchanger with inert gas. The measured transient dynamics of CHER matches very well with simulations, validating the heat transfer model within the CHER. The measured molar fractions of reformate gases at steady state also agree well with the simulations validating the used reaction kinetics. The transient CHER model can be easily integrated into a total integrated SOFC system, and the model can be also used for optimal design of similar CHERs and provides a guideline to select optimal operating conditions of the CHERs and the integrated SOFC system.

Ammonia can be considered as an alternative fuel for solid oxide fuel cells (SOFCs) because it is carbon-free, it can be easily stored, and it has a high volumetric energy density. Several large-scale ammonia-fed SOFC systems have been investigated. However, small-scale systems that are applicable for distributed power generation have not been extensively studied. Therefore, we propose three small-scale ammonia-fed SOFC systems, and compare the performance of these systems with that of a standalone SOFC system. The first system is an internal combustion engine combined with an SOFC, which is termed as a SOFC-engine hybrid system. It has a simple construction and it recovers energy from anode off-gas. In the case of the second system, the water was removed from the anode off-gas to enhance the hydrogen molar fraction before supplying it to the stack. In the third system, an internal combustion engine was integrated with a recirculation SOFC system as a combination of the two above systems. An SOFC system was modeled and validated with experimental data. It was observed that the engine enhances the system efficiency by 6.2% point compared with that of the standalone SOFC system. The recirculation using a water condensation system resulted in an increase in the system efficiency to 67.4% owing to the recirculation of rich-hydrogen gas. The SOFC-engine recirculation system exhibits a higher efficiency than that of the second system. However, the maximum efficiency was 67.5%, which is slightly higher than that of the recirculation system. The obtained results proofed that NH3-fed SOFC is totally difference with others and these finding can be effectively used in further developing ammonia-fueled SOFC system.

A unified standard thermal resistance-impedance-circuit approach for dynamic characteristic analysis of grid-connected solid oxide fuel cell system

The maritime sector must lower greenhouse gas emissions to comply with both current and upcoming regulations. Solid oxide fuel cell (SOFC) systems are emerging as a promising solution for onboard power generation, offering lower emissions and enhanced system efficiency. The high operating temperature of SOFCs enables fuel flexibility, accommodating fossil, bio-derived, and synthetic fuels. Green methanol is a particularly promising, potentially carbon-neutral fuel due to its low reforming temperature, which facilitates efficient external reforming. Moreover, direct methanol reforming in SOFCs has demonstrated high performance without significant cell degradation. In this study, various SOFC system configurations for maritime propulsion using methanol, including internal and external reforming as well as anode off-gas recirculation, have been designed and simulated using Aspen HYSYS. The performance of these configurations is analyzed and compared to identify the optimal system design.This work has been partially funded by the Research Council of Norway through FME HyValue (Project No. 333151) and by the European Commission under the Erasmus+ initiative on Centres of Vocational Excellence (H2CoVE, Project No. 101143966). The views expressed in this abstract are solely those of the authors, and the Commission bears no responsibility for any use of the information contained herein.

Performance improvement of solid oxide fuel cell system using palladium membrane reactor with different operation modes

A comparative study of CO preferential oxidation over Pt and Pt0.5Co0.5 nanoparticles: Kinetic study and quantum-chemical calculations

Simulation of a tubular solid oxide fuel cell stack using AspenPlusTM unit operation models

A solid oxide fuel cell (SOFC) is an innovative power generation system that is green, efficient, and promising for a wide range of applications. The prediction and evaluation of the operation state of a solid oxide fuel cell system is of great significance for the stable and long-term operation of the power generation system. Prognostics and Health Management (PHM) technology is widely used to perform preventive and predictive maintenance on equipment. Unlike prediction based on the SOFC mechanistic model, the combination of PHM and deep learning has shown wide application prospects. Therefore, this study first obtains an experimental dataset through short-term degradation experiments of a 1 kW SOFC system, and then proposes an encoder-decoder RNN-based SOFC state prediction model. Based on the experimental dataset, the model can accurately predict the voltage variation of the SOFC system. The prediction results of the four different prediction models developed are compared and analyzed, namely, long short-term memory (LSTM), gated recurrent unit (GRU), encoder–decoder LSTM, and encoder–decoder GRU. The results show that for the SOFC test set, the mean square error of encoder–decoder LSTM and encoder–decoder GRU are 0.015121 and 0.014966, respectively, whereas the corresponding error results of LSTM and GRU are 0.017050 and 0.017456, respectively. The encoder–decoder RNN model displays high prediction precision, which proves that it can improve the accuracy of prediction, which is expected to be combined with control strategies and further help the implementation of PHM in fuel cells.

Enhancing preferential oxidation of CO in H 2 on Au/α-Fe 2O 3 catalyst via combination with APTES/SBA-15 CO 2-sorbent

Designing graded catalytic domain to homogenize temperature distribution while dry reforming of CH4