Increasing prevalence of extreme weather events and other climate related natural disasters is leading to the increased frequency of power outages. Resilient non-grid dependent power supply for residences is becoming increasingly desirable in order to maintain building management system operation during these events. One potential option for low-maintenance on-site power generation comes from the integration of solid oxide fuel cells (SOFCs) into the combustion chamber of a residential furnace/boiler yielding a combined heat and power (CHP) system. Fuel-rich combustion of natural gas or propane within furnaces/boilers provides the necessary heat as well as fuel for the SOFCs. As a result, the addition of fuel cells into this chamber is possible. The combustion chamber/heat exchanger geometry, however, introduces issues with existing fuel cell geometries that must be addressed before integration is possible. This work presents the development of novel anode supported tubular SOFCs with internal cathode and the study of their subsequent integration into a furnace/boiler including model exhaust tests as well as individual cell testing. The proposed system has tremendous potential to effect power distribution to residences, and the novel fuel cell designed in this project has many potential applications.

This work investigates the integration of solid oxide fuel cells (SOFCs) and a small methanol/nitromethane fueled piston engine as a prospective hybrid powertrain for small unmanned aerial systems (UASs). The increased chemical energy density of a liquid fuel when compared to traditional batteries, along with ease of storage, accessibility, and refuel time make the use of a liquid fuel powered UAS preferable when compared to battery only power UAS’. Currently small UAS’ of increasing interest as a research area, as they have a wide application to a variety of fields. UAS’ are currently being used for precision agricultural crop management and water resource visual inspection. UAS’ are a cost effective avenue to survey water resources and track water runoff that is contaminating water resources. UAS’ can be easily automated and fitted with sensors and cameras capable of providing actionable feedback to the user. The use of UAS’ for land management and survey is expected to continue to expand. However, nearly all UAS’ are powered by a typical lithium polymer battery pack, giving an average endurance of approximately twenty minutes. This is acceptable to most hobbyists and for short filming duration; however, it limits UAS’ to only being able to be operated in close proximity to the user. Current power plants for UAS’ are not suited for long duration missions, such as the survey of water resources. Therefore, the development of a hybrid power plant is crucial for UAS’ to be utilized to their full potential as a survey tool. This work introduces a small internal combustion engine to act as a partial oxidation fuel reformer, producing high temperature exhaust and syngas. The exhaust of this engine is then analyzed as a fuel source for tubular SOFC’s. The SOFC is integrated into the exhaust of a 3.3 cm 3 nitromethane fueled two-stroke engine, achieving a maximum power of 680 mW/cm 2 . A theoretical comparison of flight time indicates that the modular hybrid system could increase a typical small UAS’ flight time beyond 1 hour. The system is capable of achieving a significantly higher energy density than traditional lithium polymer batteries.

This paper presents a performance of a 300 kW Solid Oxide Fuel Cell Gas Turbine (SOFC-GT) pilot power plant simulator under an area of selection of the Proportional Integral Derivative (PID) controller coefficients that satisfies the stability, gain and phase margins. The performance of turbine speed and the fuel cell mass flow rate is controlled by the set of PID controller coefficients from this area. The input to the subsystems power plant are the electric load and cold air valve. The decentralized controllers are designed for each subsystems performance individually as a Single Input Single Output (SISO) system. Two of subsystem plants are the transfer functions of turbine speed over the electric load and the cold air valve. The other two subsystem plants are the transfer functions of fuel cell mass flow rate over the electric load and the cold air bypass valve. The flexibility to have an area to select PID controller coefficients is beneficial to SOFC-GT plant due to the wide range of operations and internal parameter interactions. Designing the PID controller for the specific phase and gain margins increase the reliability and robustness of the SOFC-GT with multiple uncertain parameters. The practical implementation of this methodology is presented through the software environment.

Due to the intermittent nature of the renewable power plants and the rigid operation of existing plans, the need for flexible power production is eminent. Hybrid energy systems have shown potential for flexible power production capable to fulfill the power demands and maintain the efficiency. This work studies different design cases of a 100kW Internal Combustion Engine (ICE) and Solid Oxide Fuel Cell (SOFC) hybrid system. Anode off-gas from the fuel cell stack provided the chemical energy to run the ICE. Heat management of the anode exhaust was considered to attain the operational limits of the ICE in the present configuration. A turbocharger was used to deliver the necessary air flow for both the fuel cell stack and the engine. A series of 25 design cases were chosen to analyze the performance and the potential flexibility of this cycle. The 25-design points resulted from a matrix composed of the variation of fuel utilization and reformer operating temperature, ranging from 70% to 90% and 600K to 1000K, respectively. At each design point, hardware was re-sized to match the desired conditions. The cycle performance and fuel cell distributed profiles are discussed in this paper. It is discovered that the system efficiency increases as the fuel utilization increases following a nearly linear behavior. The highest efficiency attained is 62% at a reformer operating temperature of 800K and a 90% fuel utilization. The minimum external fuel required to maintain turbocharger in operation decreases with the increase on the reformer temperature. Power contribution between ICE and SOFC follows a linear behavior closely overlapping each trend at different reforming operational temperatures. The impact of external reforming and internal on-anode reforming is also discussed. It is found that there is an optimal balance between the external and internal reforming. The optimal methane content in this work is shown to be around ∼18 vol%.

In recent years, the aircraft industry is heading towards the concept of the More Electric Airplane (MEA). Previous research has investigated the possibility of integrating Dual Chamber Solid Oxide Fuel Cells (DC-SOFC) with the auxiliary power unit (APU) of the aircraft. This paper evaluates the merits of integrating the recently proposed Flame-assisted Fuel Cells (FFCs) with the APU gas turbine system. The syngas composition for fuel-rich combustion is studied using chemical equilibrium analysis of Jet-A/air at 8 Bar and 1073 K. The results show the potential for reforming Jet-A fuel to 22% Carbon Monoxide and 18% Hydrogen in the exhaust at an equivalence ratio of 2.4. The paper also reports how the efficiency of power generation changes when FFCs are placed in the combustor of a turbine in the APU. The maximum theoretical electrical efficiency of the FFC/combustor and the area and weight of the fuel cell required to generate the design power is calculated. The FFC offers a viable substitute for the DC-SOFC to be integrated with the APU.

The design of optimal control architectures and the optimal selection of controlled variables represents a critical task for maximizing the economic profitability of operating plants. Traditionally, controlled variables are selected based on heuristics or past experiences. For cyber-physical systems (CPS), where physical and virtual components can be integrated in the same unit to evaluate the dynamic response of innovative power cycles past experiences may not be available. Trial-and-error methods can be time-consuming and costly. Besides, the selected controlled variables may not be optimal from the economic perspective. A systematic approach to the selection of controlled variable for cyber physical systems is presented here. The method is applied to a solid oxide fuel cell (SOFC)-gas turbine (GT) CPS at the National Energy Technology Laboratory (NETL) in Morgantown, WV. The main result of this work is the synthesis of optimal controlled variable sets for a cyber physical system exhibiting trade offs between economics as well as controllolability of variables.

Direct use of propane and butane in Solid Oxide Fuel Cells (SOFCs) is desirable due to the availability of the fuel source, but is challenging due to carbon coking, particularly on the commercially available Ni+YSZ anode. A novel dual chamber Flame-assisted Fuel Cell (FFC) configuration with micro-tubular SOFCs (mT-SOFCs) is proposed for direct use of higher hydrocarbon fuels. Combustion exhaust for propane and butane fuels is analyzed experimentally and compared with chemical equilibrium. mT-SOFC polarization and power density testing in the FFC configuration with propane and butane fuels is discussed. Peak power and electrical efficiency conditions are assessed by varying the fuel-rich combustion equivalence ratio and flow rate. Carbon deposition and soot formation on the Ni+YSZ anode is investigated with a scanning electron microscope. The results indicate that reasonable power density (∼289 mW.cm −2 ) can be achieved while limiting soot formation in the flame and carbon deposition on the anode. Electrical efficiency based on the higher heating value of the fuels is analyzed and future research is recommended. Possible applications of the technology include small scale power generation, cogeneration and combined cycle power plants.

In this work, the detailed model of intermediate temperature solid oxide fuel cell (IT-SOFC) and gas turbine (GT) hybrid system with biomass gas (wood chip gas) as fuel was built, with the consideration of fuel cell potential loss such as polarization loss and heat loss. Detailed performance of key component such as reformer, fuel cell and gas turbine of the hybrid system was studied under different biomass gas fuel compositions and steam/carbon ([S]/[C]) ratios. The results show that the hybrid system can reach the efficiency of 59.24% under the designed working condition. The biomass gas from different sources and processes usually have varied fuel concentrations, especially for methane (CH 4 ), hydrogen (H 2 ), carbon monoxide (CO) and water (H 2 O), which could significantly affect the performance of hybrid system. Results show that the change of H 2 proportion has the most significant influence to system output power, CO and CH 4 have similar influence trend. System electrical efficiency increases slightly with the change of H 2 proportion while decreasing significantly with the increase of CO and CH 4 proportion. The increasing composition of CH 4 , H 2 and CO in biomass gas fuel benefits the output power of hybrid system, but results in the higher risk of overheat as well, which might cause safety problems. The composition of water in biomass gas affects the [S]/[C] ratio of system, and results show that maintaining the [S]/[C] ratio at a certain level can guarantee the temperature of key components in the hybrid system below the limits, which can satisfy the safety standards. The results show this technology has a good application prospect. (CSPE)

A ceramic heat exchanger with high effectiveness and low-pressure drop is being developed for application as a cathode air preheater for a Solid Oxide Fuel Cell (SOFC). At the operating conditions of SOFCs, typical metallic alloys as those used in commercial heat exchangers may undergo chromium volatilization, which is a known cathode degradation mechanism that reduces SOFC performance and life. Use of ceramics such as alumina or alumina-silicate instead of chromium-containing metal is one approach to eliminate the effects of chromium on the SOFC cathode. This project leverages the geometric design of a heat exchanger previously prototyped and tested, and demonstrated to have a nearly constant heat transfer effectiveness of 92% with low pressure drop [1], to fabricate a novel heat exchanger made from a ceramic material. This paper calculates heat exchanger performance requirements based on state of the art SOFC operating conditions, presents a thermal-based tradeoff analysis for ceramic material selection, and presents a modular heat exchanger and its heat exchange elements. The modular concept presented allows for incremental aggregation of modules to target a broad range of operating conditions typical of present and upcoming SOFC applications (e.g., 25 to 400 kWe). A fabricated sample ceramic heat exchange element is shown to demonstrate the viability of the concept for a real SOFC application.

In this work, the detailed model of a high temperature Solid Oxide Fuel Cell (SOFC) and Gas Turbine (GT) hybrid system was established by using MATLAB/Simulink platform, based on the equations of mass and energy balance and thermodynamic characteristics, with the consideration of various polarization losses and fuel cell heat loss. Influence of different biomass gases on the hybrid system performance was studied. Results show that the electrical efficiency could reach up to over 50% with four types of gasified biomass, higher than other hybrid power system using biomass gases. Biomass gases from different sources have different composition and calorific value, which significantly affect the hybrid system performance. The system output power and efficiency fueled with wood chip gas are higher than the system fueled with other three types of fuel. Restricted by compressor surge safety zone, the adjustable range of biomass gas fuel flow rate is small. The speed of the gas turbine has a significant impact on the hybrid system parameters such as output power and efficiency. When the rotational speed of the gas turbine is lower than the rated value, the hybrid system performance parameters change significantly, on the contrary, the hybrid system performance parameters change slightly.

In this study, a complete economic analysis of integrating different types of fuel cells in Gas Turbine power plants is conducted. The paper investigates the performance of a hybrid system that comprises of a SOFC (Solid-Oxide-Fuel-Cell), a PEMFC (polymer electrolyte membrane fuel Cell), and SOFC-PEMFC which is/are integrated into a Gas Turbine power plant. Detailed modeling, thermodynamic, kinetic, geometric models are developed, implemented and validated for the synthesis/design and operational analysis of the combined hybrid system. The economic analysis is considered to be the basic concepts for thermo-economic optimization of the power plant under investigation, with the aim of finding the optimum set of design/operating parameters. Moreover, one of the aims of this paper is to present a detailed economic analysis of a highly coupled PEMFC-SOFC–GT hybrid plant, paying special attention to the sources of inefficiency and analyzing their variations with respect to changes in their operational parameters.

The purpose of this paper is to conduct a complete comparative, energy and 2nd low analyses between different types of fuel cells integrated with a gas turbine power plant. Different levels of modeling for the solid oxide fuel cell (SOFC), the proton exchange membrane fuel cell (PEMFC) and the integrated systems are to be presented. The overall system performance is analyzed by employing individual models and further applying energy and exergetic analyses for different configurations of gas turbine power cycles. The study includes applying different proposed methods and techniques to enhance the overall efficiency of the integrated cycle. After performing the complete technical management of the complete system, a comparative study between conventional and PEMFC and SOFC cycles is investigated to highlight the corresponding advantages and disadvantages of each system. The following systems are tested and evaluated: (a) Conventional Gas Turbine System with a combustion Chamber (b) Integrated SOFC Stack into a Gas Turbine System (c) The Proposed Integrated System with both SOFC and PEMFC.

The connection between combined power and heat generation, and the concept of distributed generation is a relevant issue viz. improvement of the overall efficiency of energy conversion and distribution. In this context, the use of biomass may be of particular interest due to its potentially very low CO 2 emissions as well as low kWh production cost with respect to other renewable energy sources. Traditional methods to convert biomass involve micro-turbines or steam power plants. However, both electrical and overall efficiencies may not be particularly high for both technological and thermodynamic reasons; the latter being hard to supersede. High temperature Solid Oxide Fuel Cells (SOFCs) offer an attractive solution because they are characterized by electrical efficiencies in the range of 35% to 48% [1], and present a significant potential for integrating with the biomass gasification process; thus, exploiting advantages of high operating temperatures. Moreover, thermal integration is of prime importance. In fact, optimal management of thermal integration may allow operation with high moisture content feedstocks and with high water concentration in the SOFC; thus, promoting further hydrogen production via the water gas shift reaction [2]. In this paper, an integrated solid oxide fuel cell-gasifier system is modeled to identify the main effects on fuel cell performance under several operating conditions in terms of biomass flow rates and moisture contents. The SOFC and the gasifier are modeled by a zero dimensional approach to perform a sensitivity analysis with a numerical tool which requires less computational effort compared to those previously presented. The thermochemical phenomena are taken into account with a high degree of detail, and model validation is also showed via comparison with literature available data. Results highlight the impact of biomass feedstock and its moisture content on the electrical current density value. Final performance depends on the interaction among gasifier thermal sustainability, SOFC operating temperature and chemical equilibrium concentrations, via water gas shift reactions. In particular, it has been shown that thermal integration allows operation with higher moisture content biomass, thereby further exploiting H 2 O conversion into H 2 via water gas shift reactions and high fuel utilization operating conditions. The importance of thermal integration and advanced control of SOFC based biomass fueled systems is demonstrated by this study, as well as the use of a fast and reliable zero-dimensional modeling for system design and control purpose.

In order to spread economically viable distributed generation systems for apartment buildings, it is essential to develop an efficient and low-cost heat supply system. We are developing a new cogeneration system (Neighboring CoGeneration system: NCG). The key concept of this system is to install a heat storage unit with a hot water supply and a room heating function at each household and to connect heat storage units by a single-loop hot water pipe. In this study, a simulator was developed to reproduce the dynamic performance of the NCG system that combined cogeneration with solar heat for 50 households, and the environmental load reduction effects of the system were evaluated on the condition that heat supply to all households was ensured. It showed that the gas engine system reduced the primary energy use by 18% in a year. Meanwhile, the SOFC system reduced the primary energy use by 29%.

Integrated Coal Gasification Fuel Cell Combined Cycle (IGFC) is expected to be the most efficient power generation system in coal fired power generation systems [1,2]. We have been analyzing the processes of Advanced IGFC (A-IGFC) [3] which is expected to be realized in 2040. The Advanced IGFC (A-IGFC) system can reduce the exergy loss resulting from combustion, and its ‘exergy recuperation’ [4] is appealing. The waste heat exhausted from the fuel cells is recycled to the gasifier for steam reforming in an endothermic reaction with a low exergy loss and a high cold gas efficiency. Our current study focuses on the optimization of the unit configurations of the A-IGFC including gasifier, compressor, solid oxide fuel cell (SOFC), combustor, gas turbine, heat recovery steam generator (HRSG), and steam turbine. The process simulator HYSYS®.Plant (Aspen technology Inc.) is employed in order to express the gasifier, the SOFC and the other units. The process of reforming with steam means recycled steam stream in the HYSYS® model. In the previous study [3] we found that many recycled material streams and recycled steam in the AIGFC process prevent convergence of solver. It is shown that comparison of simulation program, a trial analysis of the AIGFC process using HYSYS.Plant and the problems about convergence of solver.

A conceptual study was performed for a novel heat cycle designed to utilize fuel gases produced by a Taylor Biomass Energy (TBE) Gasification System. The system is sized to consume 500 dry tons per day Municipal Solid Waste (MSW). The heat cycle utilizes a Solid Oxide Fuel Cell (SOFC) feeding directly to a Twin-Fluidized Bed Steam Gasification Unit (TFBSGU). MSW fed into the TFBSGU is partially gasified by exhaust from the anode space of the fuel cell. The resulting gas is cooled, sour-shifted, dehydrated and compressed. The compressed gas passes through an acid-gas removal (AGR) system and then is returned to the anode space of the fuel cell. Combustion air is compressed and passes through the cathode space of the fuel cell before entering the TFBSGU in a separate stream from the fuel gas. The resulting flue gas leaves the TFBSGU and is cooled and expanded before exhausting to atmosphere. The design also features sour shift and acid gas removal from the fuel stream. The plant produces 44 net MW, converting approximately 43% of the energy in the MSW into electricity and 23% of the energy into usable thermal energy. Overnight 2009 EPC costs are estimated at $6000/net kw. Electrical production costs are estimated at 126$/MWhr. Because the plant burns MSW, it provides carbon offsets. In addition, approximately 60% of the carbon dioxide produced by the plant can be readily sequestered. The conceptual design included a heat balance, water balance, auxiliary load list, capital cost estimate, and cost of electricity estimate.

A micro cogeneration system composed of a microturbine (MGT), a solid oxide fuel cell (SOFC) and an absorption refrigerator is analyzed thermodynamically. The performance analysis is conducted on the basis of the macroscopic mass and energy balances with additional empirical correlations and operating data. First, the basic characteristics of the power generation (MGT+SOFC) section and the absorption refrigerator section are clarified. Second, under the conditions of the cell temperature of 900 °C and the turbine inlet temperature of 900 °C, the optimum design points are determined. Furthermore, the energy saving obtained by the present system through the annual operation is also evaluated in the light of the measured data in Japan. As a result, the annual fuel consumptions are reduced by 32%, 36% and 42%, for apartments, offices and hotels, respectively.

Air flow management and control in a fuel cell gas turbine hybrid power system is evaluated using the Hybrid Performance (Hyper) hardware simulation facility at the National Energy Technology Laboratory (NETL), U.S. Department of Energy. The Hyper facility at NETL is a hardware simulation of a fuel cell gas turbine hybrid power system capable of emulating systems in the range of 300kW to 900kW. The hardware portion is comprised of a modified single-shaft gas turbine, a high performance exhaust gas recuperator, several pressure vessels that represent the volumes and flow impedances of the fuel cell and combustors, and the associated integration piping. The simulation portion consists of a real time fuel cell model that is used to control a natural gas burner which replicates the thermal output of a solid oxide fuel cell. Thermal management in the fuel cell component of the hybrid system, especially during an imposed load transient, is improved through the control of cathode air flow. This can be accomplished in a fuel cell turbine hybrid by diverting air around the fuel cell system. Two methods for air flow control are presented in the paper. In this paper, the use of bleed air by-pass and cold air by-pass are characterized quantitatively in terms of compressor inlet flow, process limits, system efficiency and system performance.