SOFC CHP Research Articles

Recovery of Flared Natural Gas with High CO<sub>2</sub> Content Using SOFC CHP System: Feasibility Study for Neem-Field, Sudan

Flared natural gas emissions are one of the main sources of environmental pollution and global warming. To recover this gas, the presence of impurities like CO2 in high concentrations forces oil producers to escape from investing in such intensive processing. Several implementations of no flaring methods have been reported in the literature, however, there have been limited concerning the bulk-CO2 natural gases. This research developed an innovative idea for the use of the SOFC CHP system to recover flared bulk-CO2 associated gas of Neem-Field in Western Sudan. The exergy of the system and the performance of the SOFCs are investigated in this paper, in addition to environmental and economic analysis. The simulation (Cycle-Tempo©) results demonstrate that the proposed system can generate 1 MW electrical power and 0.068 MW thermal energy with efficiency approached 43.3% (based on LHV). The exergy analysis showed that 38% of system losses occurred in the air preheaters. Instead of conventional gas-burning, recovering the flared gas reduced the equivalent CO2 GHGs emissions by 80%. Overall, the novel solution found to be environmentally friendly, and economically appealing with a total capital investment estimated to be US$1.175 million and a cost of electricity (COE) of 4.07 cents per kWh.

Comparative study on thermodynamic analysis of solid oxide fuel cells supplied with methanol or ammonia

The increasing demand for green hydrogen and power production necessitates the development of novel and upgraded power generation technologies. The solid oxide fuel cell combined heat and power (SOFC–CHP) system is a promising solution due to its high efficiency, clean operation, and fuel flexibility. In practical terms, SOFCs can operate using a variety of fuels such as alcoholic fuel, hydrogen, ammonia, etc. Recently, methanol and ammonia have become noteworthy alternative fuel options as it possesses advantages such as low transportation cost and high hydrogen storage capacity. In this paper, we have established two SOFC–CHP models fueled by methanol or ammonia integrated with the steam Rankine cycle. A comprehensive thermodynamic model is proposed for energy and exergy analyses. Sensitivity analysis is performed to study the system's characteristics. The results show that the SOFC–CHP system fueled by ammonia exhibits superior performance, the maximum electrical power, efficiency, and exergy efficiency is 430W, 7% and 10% greater than the methanol fueled system. The operating temperature is about 30K higher in methanol supplied system. The largest thermal power difference can reach 0.65 kW. Overall, the ammonia fueled SOFC–CHP system shows greater potential than that fueled by methanol.

Status of SOC Development at Chaozhou Three-Circle

Chaozhou Three-Circle (Group) Co., Ltd. (CCTC) is a leading company in developing and manufacturing of electronic and ceramic components. Since more than 19 years ago, CCTC has been focusing on SOFC R&D and manufacturing, covering the complete value chain from powder to power. Based on anode-supported cell technology (ASC in fuel cell mode), the latest C2-stack in planar design using metallic interconnect exhibits a high efficiency of more than 69% (DC, LHV) at 1.5 kW. Long-term stack tests using pipeline natural gas have been conducted for 20,000 hours, with low degradation rates of below 0.4%/kh. In 2022, several 35 kW SOFC CHP systems were demonstrated with C2 stacks, which showed stable performance over 3,000 hours of operation. According to the verification test by Societe Generale de Surveillance S.A., the net AC efficiency of the system reached 64.1%, and the total efficiency was up to 91.2% after 1,000 hours of continuous operation. In parallel to the continuous progressing in SOFC, optimization in cells and stack designs dedicated for SOEC applications were also conducted in recent years. The status of both SOFC and SOEC development at CCTC will be presented.

Combined heat and power system based on Solid Oxide Fuel Cells for low energy commercial buildings in Qatar

Commercial buildings in Qatar account for 19% of the total energy consumption in the country. To reduce this significant amount of energy, a Solid Oxide Fuel Cell Combined Heat and Power (SOFC CHP) system with natural gas as fuel is studied. An office building model is created in eQuest energy modeling package. Several baseline cases were considered to optimize the HVAC system and loading profile to utilize the SOFC to its full extent. These baselines are: electric chiller, absorption chiller, and combined electric-absorption chiller systems. Performance curves were analyzed for a range of SOFC CHP system capacities (25–250 kW) in terms of energy produced, utilized thermal energy, overall efficiency and annual energy costs to assess potential cost savings. Results showed that using SOFC CHP with combined electric-absorption chiller system can reduce the annual energy cost by 67% compared to the baseline case with electric chiller. Moreover, optimum overall efficiency of the system can reach 73%. Finally, an environmental impact assessment was evaluated in terms of CO2, NOx, and SO2 emissions. It was found that application of SOFC CHP system resulted in reductions in CO2 emissions of 30%, NOx of 90%, and SO2 of 90%.

Field Test Result of Residential SOFC CHP System Over 10 Years, 89000 Hours

The maximum operating time, without stack replacement, residential SOFC power generation unit (manufactured by Kyocera in 2009), which was installed by Osaka Gas in a house in 2009, has exceeded over 10 years, 89,000 power generating hours. It may be the first data as a SOFC system to succeed in operating in the actual field for 10 years. We will report performance results for 10 years. In 2004, Osaka Gas and Kyocera started joint development of residential SOFC CHP system and from 2007, we conducted series of field test in the SOFC demonstration project operated by NEDO and NEF. At that time, various technical issues still remained, and after joint development with Aisin and Toyota Motor, it was mass-produced and commercialized in 2012. We also mention current status of residential SOFC (Manufactured by Aisin, Stack supplied by Kyocera), which have sold more than total 80,000 units at Osaka Gas.

Field Test Result of Residential SOFC CHP System Over 10 Years, 89000 Hours

The maxmum operating time without stack replacement, residential SOFC power generation unit (manufactured by Kyocera in 2009), which was installed by Osaka Gas in a house in 2009, has exceeded over 10 years, 89000 power generating hours. In 2004, Osaka Gas and Kyocera started joint development of residential SOFC CHP system and from 2007, we conducted series of field tests in the SOFC demonstration project operated by NEDO and NEF. At that time, various technical issues remained, and after joint development with Aisin and Toyota Motor, it was mass-produced and commercialized in 2012. We also mention the current status of residential SOFC (Manufactured by Aisin, SOFC stack supplied by Kyocera). Osaka Gas has sold more than a total of 88,000 residential SOFC CHP systems as of October 2020.

Operation of an SOFC CHP System with Wood Gas from a Fixed-Bed Updraft Gasifier

This paper will show the results of operating an SOFC system with the product gas from a biomass gasifier for more than 200 hours under constant and dynamic operation. The SOFC system was operated at different load cases, 50 % and 100 % load, and achieved a gross electrical efficiency of 42 %. It shows a high dynamic behavior, so that electric load changes could be performed within a few seconds from full load to part load. Furthermore, AVL developed a simulation software by which a SOFC stack model can be simulated dynamically. A comparison of the measured and simulated values of the stack module will be presented. By using the results of the test runs the software could be validated successfully.

Progress of SOFC Residential CHP System: Over 50,000 Units Market Experience of Osaka Gas

Osaka Gas began selling the second-generation residential SOFC CHP “ENE-FARM type S” in April 2016, which was developed in collaboration with Aisin Seiki, Kyocera and Noritz. In April 2018, power efficiency when the rated output can be stably is improved 53.5 % (net AC, LHV) from 52.0 % (net AC, LHV). The cumulative sales volume of Osaka Gas’s the residential fuel cell CHP system as in March 2019 was over 100,000. The cumulative number of SOFC-type was more than half. We have been trying to improve its quality and specifications, and reduce its cost. For example, we have improved the merchantability by adding a self-sustaining power generation function and using the Internet. ENE-FARM type S performed at approximately 2,000 customer homes though a power failure occurred mainly in Osaka due to Typhoon in 2018. It was an opportunity that one of the benefits in residential CHP was socially recognized.

Development of a Highly Flexible SOFC CCHP System Towards Demand-Oriented Power Generation from Renewable Fuels

This paper presents the current development status of AVLs stationary SOFC CCHP (combined cooling, heat and power) platform with special focus on the coupling of an SOFC with an absorption heat pump. Furthermore, the SOFCs fuel capability was extended towards the utilization of multiple renewable fuels such as biogas, biomass product gas and synthetic diesel. In the past AVL developed a natural gas operated SOFC CHP platform in the power range of 5 – 10 kWel with an electrical efficiency of >55 % using the Plansee/IKTS stack technology. For certain applications such as buildings, a heat driven operation mode leads to low operating hours per year for conventional CHP systems due to the low heat demand during summer season. The option to generate cooling power in addition to heat will increase the annual operating hours per year and thus economic efficiency significantly. This work will show the coupling of a stationary 6 kWel SOFC CHP system developed by AVL using an IKTS stack module with a 5 kWcooling absorption heat pump developed by TU Graz, Institute of Thermal Engineering. The exhaust gas heat from the SOFC which is available at >200 °C will be used to operate the thermally driven heat pump. The SOFC exhaust gas heat is transferred in the generator of the absorption heat pump to be converted to cooling power. To maximize the cooling power output of the SOFC CCHP system it is important to utilize as much SOFC exhaust gas heat as possible in the absorption heat pumping process. Furthermore, it is important to optimize the energy efficiency ratio of the absorption heat pump. In this context the influence of the cold and cooling water temperatures of the absorption heat pumping process on the system size and system total efficiency were investigated. It can be shown that for cold and cooling water temperatures as required in office buildings and hospitals a ratio between electrical power and cooling power of 4 - 6 can be achieved by the SOFC CCHP system. This analysis presents the capability of the SOFC CCHP system for a flexible and demand-oriented generation of electricity, heat and cooling power. As the electrical efficiency of the SOFC determines the exhaust gas heat output the system performance was further investigated towards the operation of renewable fuels. Biogas or synthetic diesel for instance may lead to lower electrical efficiencies compared to natural gas. Therefore, the type of fuel also influences the SOFC exhaust mass flow and temperature which is the main driving power for the absorption heat pump. In this work the fuel capability of the platform was extended from natural gas to renewable fuels. From economic point of view it is desired to benefit from volume effects for stacks and balance of plant components which is why AVLs system development approach is oriented towards a multi-fuel platform which requires only minor design adaptions when it comes to the utilization of different fuels including renewables. As a technology provider this approach is certainly a major advantage for customers who are used to a power generation technology that can be easily applied in various regions all over the world while facing varying fuel specifications. Therefore, this work will provide an overview of the most relevant renewable fuels and its composition for stationary SOFC CHP applications. Consequently, design synergies regarding the process design of the hot anode gas recirculation loop in terms of the recirculation ratio and reforming temperature which are influenced by the specific fuel, are shown. A comparison of system performance results based on process simulations will be discussed. The process simulation uses results from specific reforming tests for e.g. biogas and diesel which will be shown. Furthermore, compared to natural gas based systems a considerably higher effort has to be done in terms of the gas cleaning for biogas and biomass product gas. In case of biogas the main impurities are S, Cl, NH3 which need to be eliminated before sending the fuel to the steam reformer and stack respectively. A low cost gas cleaning concept for biogas based on several low temperature adsorption steps was developed by TU Graz. It can be shown that the absorption efficiency is highly depending on the fuel mixture. The influence of CH4, CO2 and H2O was identified to allow a proper design of the gas cleaning unit. Finally, the build-up of the prototype including first test results will be shown in this work.

Development and Commercialization of New Residential SOFC CHP System

Osaka Gas began selling the new version residential SOFC CHP system “ENE-FARM type S” in April 2016, which is developed in collaboration with Osaka Gas, Aisin Seiki, Kyocera and Noritz. Kyocera manufactures SOFC stacks, Aisin Seiki manufactures power generation units, and Noritz manufactures boiler and remote-control units. The electrical efficiency is 52% (net AC, LHV), whereas that of the previous model was 46.5%.The previous system comprised two units: a power generation unit and a heat recovery unit. The latter unit contained the hot-water storage tank and the boiler. The new power generation unit contains the hot-water storage tank. This tank is configured for connection to a normal household boiler. The system size is minimized to facilitate its use as a residential CHP system. Moreover, it is possible to install the new system in a housing complex, where the available space is limited. This feature expands the market for this system because the previous model could only be installed in a single-family house. To achieve the high electrical efficiency of 52% (net AC, LHV) and the cost reduction, three technical issues were addressed. The first was the improvement of the fuel cell performance, the second was the optimization of the fuel utilization rate, and the third was the improvement in durability. Kyocera reduced the internal electrical resistance of the fuel cell stack. In addition, a new coating technology, i.e., electropainting, which is developed by Osaka Gas and Kyocera, was used for current collectors. Consequently, both an increase in power density (reducing the number of cells) and an improvement in the electrical efficiency have been achieved. Current collectors are oxidized at a high temperature because they comprise stainless steel. Their durability has been considerably improved by the electropainting coating technology. Aisin Seiki optimized the system controls, resulting in enhanced electrical efficiency. Osaka Gas conducted field tests in the Kansai area in Japan. We installed the systems in the houses of several employees for evaluating the system behavior. The results made it possible to accelerate product development. In accordance with the liberalization of the power market in Japan in April 2016, if customers use natural gas provided by Osaka Gas, the electrical power from the unit can be sold back to Osaka Gas. We consider that 2016 is a transition period for residential CHP from the market introduction stage to the autonomous market spread stage. We are currently focusing on achieving further developments in the technology, which will enable cost reduction and higher power generation efficiency in order to maximize the target market.

Development and Commercialization of New Residential SOFC CHP System

In April 2016, Osaka Gas began the marketing of “ENE-FARM type S,” which was an advanced version of the residential SOFC CHP system. Osaka Gas developed this system in collaboration with Aisin Seiki, Kyocera, and Noritz. The electrical efficiency of the new model was 52 % (net AC, LHV), whereas that of the previous model was 46.5 %. The system size was minimized to facilitate its use as a residential CHP system. We reduced the maintenance, stack, and system costs. In this paper, we describe the developments and features of new residential SOFC CHP system.

Development of a Highly Flexible SOFC CCHP System Towards Demand-Oriented Power Generation from Renewable Fuels

The coupling of AVLs 6 kWEL SOFC CHP system using an IKTS stack module with a 5 kWCOLD absorption heat pump developed by TU Graz will be presented. The exhaust gas heat from the SOFC which is available at >200 °C will be used to operate the thermally driven heat pump. The SOFCs fuel capability was extended towards renewable fuels such as biogas, and synthetic diesel using a novel gas cleaning concept. For buildings, a heat driven operation mode leads to low operating hours per year for conventional CHP systems during summer season. Generating cooling power in addition to heat will increase the annual operating hours per year and thus economic efficiency significantly. This analysis presents the capability of the SOFC CCHP system for a flexible and demand-oriented generation of electricity, heat and cooling power and shows how cold and cooling water temperatures influence the overall system size

AVL SOFC Systems on the Way of Industrialization

The AVL SOFC Auxiliary Power Unit development program has reached significant milestones within the last year. The performance of the system has been significantly increased to 30% electrical efficiency and up to 4kW net electrical power. The first successful vehicle demonstration has been performed. Operation on sulfur containing fuels is possible. A commercial product launch is planned for 2016. In parallel also the AVL SOFC CHP system showed significant progress. The system is designed for 5-10kW electrical power based on electrolyte supported stacks from Plansee/IKTS and a hot gas anode recirculation process. The system is since early 2013 continuously in operation and shows very promising results like an electrical efficiency around 50%.

Durability Verification of Residential SOFC CHP System

Osaka Gas started joint development of the residential SOFC CHP system with Kyocera in FY2004, and Aisin Seiki Co., Ltd. and Toyota Motor Corporation also took part in out development. Development for commercialization was completed at the end of the 2011 fiscal year, and product commercialization was started. Most significant issue for commercialization was durability. Osaka Gas has conducted durability verification of a large number and long time test for stacks, material, and SOFC generation units in order to establish 10 years life time. As these results, we judged that durability SOFC power generation unit which uses latest stack, hot module design, and control reached durability target.

SOFCOM Project: Proof-of-Concept of WWTU Plant Feeding a SOFC CHP System Integrated with CO2 Removal

SOFCOM is an applied research project (FCH JU Grant Agreement 278798) devoted to demonstrate the technical feasibility, the efficiency and environmental advantages of CHP plants based on SOFC fed by different typologies of biogenous primary fuels (locally produced), integrated by a process for the CO2 separation from the anode exhaust gases. The research activity is devoted to the scientific, technical and economic management of the proof-of-concept of a complete energy systems based on SOFCs, integrated in a waste water treatment plant (WWTU), with CO2 management. Several issues are addressed, like high efficiency integration designs, impact of the fuel pollutants on the SOFC and fuel processing units operation, gas cleaning, carbon sequestration module, operation in CHP configuration, maintenance and repair strategies, lessons learned for pre-normative issues and scale-up analysis. The paper develops general presentation of the SOFCOM project, and outlines the WWTU–SOFC–CO2 management demonstration plant.

Development of Residential SOFC CHP System with Flatten Tubular Segmented-In-Series Cells Stack

Since 2004, stationary SOFC CHP systems using flatten tubular segmented-in-series (FT-SIS) cells stacks have been developed by Tokyo Gas Co., Ltd., Gastar Co., Ltd., Rinnai Corporation and Kyocera Corporation to construct small-scale CHP systems which excel in performance and durability. In 2008, we have succeeded in producing a residential system which consists of a power generation unit using FT-SIS cells stacks and a heat recovery unit. Electric power and hot water are produced efficiently in the system, and by adopting electric load following operation, the produced energy is supplied to the residence with minimal loss. Since 2009, we have installed the systems into residences to collect operation data under practical use conditions. A part of the tests are conducted under NEDO SOFC Demonstration Program. From the operational data, environmentally-enhancing potentials and superior durability of the FT-SIS SOFC systems are verified.

Development of Residential SOFC CHP System with Flatten Tubular Segmented-In-Series Cells Stack

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Development and Field Test Results of Residential SOFC CHP System

At 2004, Osaka Gas Co., Ltd. and Kyocera Corporation launched joint development of residential SOFC CHP system. In order to fit Japanese urban market, we decided rated output of system as 700W and have reduced the size of a power generation. At rated power, ac 700W, net ac efficiency and hot water heat recovery efficiency is 45% (LHV) and 40% (LHV), respectively. From FY2007, we took part in the "Demonstrative Research on Solid Oxide Fuel Cells" hosted by the New Energy Foundation in 2007. Osaka Gas installed SOFC systems into 45 sites in FY2007 and FY2008. We demonstrated high energy saving effect for various houses and improved durability and reliability of system. Hereafter, new joint development, Osaka Gas, Toyota Motors, Kyocera and Aisin Seiki, aims early commercialization of residential SOFC CHP system.

Prototype SOFC CHP System (SOFIT) Development and Testing

Electric Power Development Co., Ltd. (JPOWER) started Tubular Type SOFC module development in collaboration with Mitsubishi Heavy Industries, Ltd. (MHI) in 1991. Since 2001 proof of concept of module structure, which was designed through the various trial and error, has been verified using the 5kW class cartridge and the 25kW class Sub module composed of 4 cartridges. The concept of module structure was verified with more than 1,400hrs operation using the 5kW class cartridge in 2003, followed by more than 500hrs operation of the 25kW class Sub module in 2006. Then the verification demonstration of the 150kW class atmospheric SOFC CHP system using accomplished module structure was planned. The prototype system was installed in 2006 and commissioning and operation test were started at the beginning of 2007. In this paper, the prototype atmospheric SOFC CHP system development and its operation test result are introduced.

Prototype SOFC CHP System (SOFIT) Development and Testing

not Available.