Article

Design and technoeconomic performance analysis of a 1 MW solid oxide fuel cell polygeneration system for combined production of heat, hydrogen, and power

Authors:
  • Bright Energy Storage Technologies
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

This work focuses on the design and performance estimation of a methane-fueled, 1 MW SOFC combined heat, hydrogen, and power (CHHP) system operating at steady-state. Two methods of hydrogen purification and recovery from the SOFC tail-gas are analyzed: pressure swing adsorption (PSA) and electrochemical hydrogen separation (EHS). The SOFC electrical efficiency at rated power is estimated at 48.8% (LHV) and the overall CHHP efficiency is 85.2% (LHV) for the EHS design concept. The EHS energy requirement of 2.7 kWh kg(-1) H(2) is found to be about three times lower than PSA in this system. Operating the system to produce additional hydrogen by flowing excess methane into the SOFC subsystem results in increased efficiency for both of the hydrogen separation design concepts. An economic analysis indicates that the expected cost of SOFC-based distributed hydrogen production (4.4 $ kg-1) is on par with other distributed hydrogen production technologies, such as natural gas reforming, electrolysis, and molten carbonate fuel cell CHHP systems. The study illustrates that 'spark spreads' (cost of electricity in it $ kWh(-1) minus cost of natural gas in $ MMBtu(-1)) of five or more offer near-zero or negative hydrogen production costs for distributed SOFC CHHP plants with total installed capital costs near 3950 $ kW.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... In order to increase the energy efficiency, Becker et. al. [3] investigated SOFC systems with anode recycle and hydrogen separation, which were estimated to achieve 46-52% of power efficiency and 83-86% of net efficiency with hydrogen production. Next, Pérez-Fortes et. ...
... In order to evaluate the co-production of electricity and hydrogen using fuel cells, a system combining a solid oxide fuel cell (SOFC) and a pressure swing adsorption (PSA) separation, as shown in Fig. 1, is proposed based on Ref. [3]. Moreover, a base scenario consisting in a SOFC system dedicated to power generation, as illustrated in Fig. 2, is also analyzed for comparison. ...
... Then, after compressing, cooling and separating the condensed water, the synthesis gas produced in the shift reactor is sent to a pressure swing adsorption system to separate hydrogen at high purity. Since the hydrogen concentration in the PSA inlet should be above 70% molar for technical and economical viability [3], a portion of the hydrogen separated should be recycled to attain this specification. Next, the PSA purge gas is mixed with the cathode outlet stream and reacted at a specific stoichiometric ratio to provide heat, similar to the power generation case, while hydrogen is compressed and cooled to ambient temperature. ...
Conference Paper
Biogas is a promising renewable and distributed source of energy derived from the anaerobic treatment of organic residues. Although this biofuel can provide substantial benefits for the environment, its application may be restricted to large industrial facilities due to the lack of efficient conversion systems at low production scales. A possible solution is the use of high temperature fuel cells, such as solid oxide fuel cells (SOFC), to directly convert biogas into electricity, heat and syngas. Besides the expected increase in power efficiency, this technology could also provide an alternative source of hydrogen by purifying the anode exhaust gas. However, the use of biogas in these polygeneration systems and the effects of carbon dioxide dilution were rarely studied in recent literature. Thus, a thermodynamic model for a biogas fuelled SOFC with internal reforming (quasi-2D) and hydrogen co-production is proposed and analyzed in this research work. Moreover, comparisons with a power generation system and replacing biogas with natural gas were also examined and discussed. The results indicate that, depending on the operational conditions, an exergy efficiency of 56-67% and a net power density of 1753-3719 W/m 2 , could be achieved by a fuel cell system co-producing electricity and hydrogen. In general, hydrogen production can achieve competitive net power density with high exergy efficiencies compared with power generation systems, which may lead to solutions with higher economic viability. The energy integration analysis could ensure the possibility for waste heat recovery while the exergy destruction analysis pinpointed major losses in the heat exchanger network (32.3-49.7%), fuel cell (8.8-12.1%), catalytic burner (12.9-20.6%) and emissions (10.
... USD/kg) [18]. Since electricity can be a significant operational cost or a valuable product, some researchers have also proposed hybrid solutions using fuel cells to deliver power alongside hydrogen refuelling stations [19,20]. For instance, Minutillo et al. [21] have estimated a maximum exergy efficiency of 59% for some hybrid systems, a possible 18% increase compared with biogas-fed SOFC systems. ...
... As a consequence, the inlet and outlet temperatures for a cold stream are bounded by the temperature interval in which the heat exchange occurs (T k.low , T k,high ) or the stream target/ source temperature (T c,source , T c,target ), as shown in Eqs. (19) and (20). Fig. 7 e Model results for H 2 -CO 2 mixtures and experimental data reported by Jiang and Virkar [24]. ...
... Moreover, the hydrogen recovery assumed in this study, which is based on values reported by Papadias et al. [26] and NREL [27], is significantly higher than those calculated by Marcoberardino et al. [17]. On the other hand, Becker et al. [19] reported a hydrogen cost of 1.8 USD/kg for a hybrid system coproducing electricity and hydrogen from natural gas. The use of natural gas and electrochemical hydrogen separation associated with the project scale (1 MW) could explain the significantly lower costs. ...
Article
The design of solid oxide fuel cells (SOFC) using biogas for distributed power generation is a promising alternative to reduce greenhouse gas emissions in the energy and waste management sectors. Furthermore, the high efficiency of SOFCs in conjunction with the possibility to produce hydrogen may be a financially attractive option for biogas plants. However, the influence of design variables in the optimization of revenues and efficiency has seldom been studied for these novel cogeneration systems. Thus, in order to fulfill this knowledge gap, a multi-objective optimization problem using the NSGA-II algorithm is proposed to evaluate optimal solutions for systems producing hydrogen and electricity from biogas. Moreover, a mixed-integer linear optimization routine is used to ensure an efficient heat recovery system with minimal number of heat exchanger units. The results indicate that hydrogen production with a fuel cell downstream is able to achieve high exergy efficiencies (65-66%) and a drastic improvement in net present value (1346%) compared with sole power generation. Despite the additional equipment, the investment costs are estimated to be quite similar (12% increase) to conventional steam reforming systems and the levelized cost of hydrogen is very competitive (2.27 USD/kgH2).
... However, the limited efficiency of conventional technologies for power conversion severely restricts the economic viability of biogas plants in general. A promising alternative is to design systems using fuel cells to directly convert biogas into electricity, since this process can be very efficient at small scales [1] and adapted to produce hydrogen as a byproduct [2]. The production of electricity, hydrogen and heat may increase the efficiency of biogas conversion and provide an additional source of revenue [3], while increasing the sustainability of hydrogen production and fuel cell technology. ...
... They observed that an optimized design for a SOFC system is able to achieve energy efficiencies between 34% and 44%. Becker, et al. [2] indicated that a conventional SOFC system could attain higher energy efficiencies (83.5-86.1%) by including a separation step to export hydrogen as a byproduct. ...
... More recently, Pérez-Fortes, et al. [5] reported energy efficiencies as high as 81.4% for a SOFC system co-producing hydrogen, electricity and heat under different operating conditions. It is important to highlight that the efficiency values from the aforementioned studies [2,4,5] are calculated based on energy. Therefore, they do not take into account the limits derived from the second law of thermodynamics. ...
Article
Although biogas has many qualities as a source of renewable and distributed energy, most full-scale applications are large facilities due to the lack of efficient small-scale systems. In this context, solid oxide fuel cells (SOFC) have been promoted as an alternative to convert biogas into electricity and heat with high efficiency. However, few studies have considered the use of the anode exhaust gas to co-produce green hydrogen together with electricity and heat, which could increase the performance and profitability of these systems. Thus, since there is a lack of studies focusing on these systems, this research proposes a new approach to model SOFC with direct internal reforming to produce power, hydrogen and heat. The results indicate that the proposed system is capable of reaching exergy efficiencies between 57% and 69% depending on the methane content of biogas. Hydrogen separation reduces the amount of fuel that has to be burned, which leads to less destruction of exergy in multiple processes (e.g., mixers, burners and heat exchangers). However, this design change also diminishes the amount of heat delivered by the system (-82% compared with conventional cogeneration), which may negatively affect the energy integration with anaerobic digestion. In addition, major performance improvements can be achieved by optimizing the hydrogen recovery of the pressure swing adsorption and the SOFC operating temperature.
... The authors [38] suggest pressure swing adsorption (PSA) technology with the further development of hydrogen membranes [39]. Becker et al. [40] designed a SOFC based trigeneration system producing electricity, heat, and hydrogen. The hydrogen can be used for end uses such as PEM fuel cell-powered vehicles. ...
... As the difference is high, it appears that the assumed stack temperature gradient is too high, and that the difference should be below 150e200 C. In addition, constant values are set for the exchange current density of the anode and cathode, which as previously discussed may make the results unreliable. Regarding the actual voltage, Becker et al. [40] use equation (3) ...
... where T, P and F are the cell temperature, partial pressure and Faraday constant, respectively. Besides introducing two methods of hydrogen recovery (electrochemical hydrogen separation and pressure swing adsorption), Becker et al. [40] provide a scenario exploring the effect of producing excess hydrogen by feeding extra methane to the system. Although Yan et al. [41] comprehensively formulated the concentration polarization, constant values are considered for anode and cathode exchange current densities. ...
Article
No one can disagree the growing attention to developing and utilizing high temperature fuel cells partly due to their potential for multi-service applications. Recently, much focus can be observed on examination of the integration of solid oxide fuel cell (SOFC) or molten carbonate fuel cell (MCFC) systems with other subsystems to propose polygeneration plants. Literature review prove that, to propose a polygeneration concept based on SOFC and MCFC systems, there is not a typical way commonly used by researchers. So it is tried to categorize and survey the current challenges of the high temperature fuel cell polygeneration plants. In this regard, the most common concepts and some unique system designs are reviewed and investigated in terms of fuel type, plant scale, electrical efficiency, overall efficiency and other performance indicators. It is figured out that similar to the typical CCHP system, the most common polygeneration designs are those utilizing the potential of exhaust gases from the natural gas fed fuel cell system in a heat recovery unit and a refrigeration system. A notable observed trend in recent years is the coupling of biofuels with polygeneration concepts. We found that there are still great challenges regarding how to predict the fuel cell actual cell voltage influencing the overall efficiency of polygeneration plants. It is also observed that attendance of researchers to analyze the polygeneration systems from the viewpoints of economic and environmental is less in comparison with the investigation of the systems from the thermodynamics point of view.
... Ainsi, utiliser du méthane comme combustible du procédé semble judicieux du point de vue de l'efficacité énergétique globale du procédé. Ensuite, Becker et al. (2012) ont étudié un procédé de tri-génération de chaleur, d'électricité et d'hydrogène, alimenté par du méthane, voir figure 1.29. Le méthane est mélangé à une partie des gaz anodiques sortant de la pile à combustible riches en espèces oxydées. ...
... La puissance de la pile à combustible est de 1 MW. L'hy- Figure 1.29 -Procédé de tri-génération incluant une pile à combustible, (Becker et al., 2012). drogène est produit à partir du gaz sortant de l'anode par la réaction du gaz à l'eau et est isolé par un système Pressure Swing Adsorption PSA. ...
... Dans le cas où on souhaite produire massivement de l'hydrogène de grande pureté, les procédés de purification par Pressure Swing Adsorption sont classiquement utilisés (Molburg et Doctor, 2003;Becker et al., 2012). Il s'agit d'un procédé discontinu comportant une ou plusieurs colonnes chargées d'un adsorbeur solide, comme par exemple des zéolites. ...
Article
Full-text available
The present work focuses on a Power-to-SNG process, especially on its energy efficiency and its economic competitiveness in the current context. It also aims at determining if the reversibility with a Gas-to-Power working mode is interesting from energy and financial considerations. The main steps required into a Power-to-SNG process, identified thanks to a review of the state of the art, are steam electrolysis for hydrogen production, followed by methane production thanks to the Sabatier reaction and a final step of gas purification to meet the composition requirements for gas network injection. Here, electrolysis is led into solid oxide cells. Power-to-SNG process simulations, led with ProsimPlus 3, indicate that the thermal coupling between methanation and the generation of steam to feed the electrolyzer is pertinent, the process energy efficiency achieving 75.8%. Concerning the Gas-to-Power process, its solid oxide fuel cell is pressurized to use additional thermodynamic cycles. The fuel cell is fed with pure hydrogen stream due to reversibility considerations, this limiting the energy efficiency, which highest value here is evaluated at 44.6%. The economic analysis includes experimental based data concerning electrochemical performances and degradation. They are obtained on a commercial cell tested at the thermoneutral voltage with a high steam conversion rate, these conditions being close to what can be expected for industrial process. They are used to calculate the levelized cost of the SNG produced by the Power-to-SNG process and the levelized cost of electricity produced by the reverse process. Investment and operating cost of these processes are important, leading to a high levelized cost of electricity. In the conditions of this study, adding the Gas-to-Power working mode to a Power-to-SNG process is not economically pertinent
... Becker et. al. have analysed a combined heat, hydrogen and power generation by combining SOFC with successive 1-or 2-stage water gas shift reactors and hydrogen upgrading via PSA or membrane technologies [22]. Such a system is now under design and demonstration in EU H2020 project CH2P for driving H2 and electricity refilling stations [23]. ...
... The main novelty of this work lies in the system design concept. We propose the use of a "hybrid" SOFC system for simultaneous heat, hydrogen and power production [22], [23]. The combined storage capacity of hydrogen tanks and batteries allows for operating the SOFC at close to constant load, hence ensuring the system efficiency and durability. ...
... The SOFC system proposed by Becker et al. [22] is used, where the composition of the unconverted gas out of the SOFC is adapted by water-gas shift reactors to enhance the hydrogen content, then the enriched hydrogen is upgraded by a pressure swing absorption (PSA) unit for high achieving high H2 purity. The unreacted gas after the PSA is combusted and the generated heat is utilized within the system and for direct satisfaction of heat load. ...
Conference Paper
Full-text available
The growing trend of the cruise ship industry, together with increasing concerns over its impact on the environment, makes these ships a much relevant target for the efforts toward increasing ship energy efficiency, thus ultimately reducing fuel consumption and emissions of carbon dioxide and other air pollutants. In a context of rising discussions concerning the use of cleaner fuels such as LNG and methanol in shipping, fuel cells are expected to become an increasingly viable solution for onboard power generation. In particular, solid oxide fuel cells (SOFC) can offer high electrical efficiency, power density and reliability with the possibility of combined heat, hydrogen and power production, which make them suitable for energy-intensive applications with a diverse demand (e.g., cruise ships) by integrating other complementary technologies. In this paper, we investigate the potential for energy and emission savings in relation to the use of SOFCs on cruise ships. Given the limited ability of SOFCs to deal with fast load changes and start/stop cycles, the SOFCs are expected to tackle the baseload, while a combination of batteries and internal combustion engines are complementary for handling peak loads. The proposed system is tested and optimized for a case study of a cruise ship operating in the Baltic Sea. Based on reference operational profiles for heat and electricity demand, the design of the system is optimized. The system proves particularly performant, with an overall efficiency close to 70% and a potential lifetime economic performance in line with conventional systems powered by Diesel engines.
... The concept, involving the coupling of a SOFC and a SOEC as separate units, proved quite challenging to control. Becker et al. (2012) introduced instead the concept of purifying the anode off-gas of a SOFC to produce hydrogen as a useful system output, achieving close to 70% efficiency in the combined generation of power and hydrogen, and over 85% efficiency when waste heat was also accounted. Similar results were obtained by Leal and Brouwer (2005), who also showed that internal reforming is more appropriate for this types of systems, if estimated based on first-law efficiencies. ...
... The cost of the hybrid SOFC was determined based on the estimations proposed by Becker et al. (2012), using the following equation for the component scaling: ...
... where the values of all cost parameters apart from the SOFC itself are taken from what reported by Becker et al. (2012). It should be noted that in the system proposed by Becker et al. (2012) the cost is estimated for a unit where the hydrogen is purified using an electrochemical hydrogen separation (EHS) unit. ...
Article
Full-text available
Solid oxide fuel cells (SOFC) have developed to a mature technology, able to achieve electrical efficiencies beyond 60%. This makes them particularly suitable for off-grid applications, where SOFCs can supply both electricity and heat at high efficiency. Concerns related to lifetime, particularly when operated dynamically, and the high investment cost are however still the main obstacles toward a widespread adoption of this technology. In this paper, we propose a hybrid cogeneration system that attempts to overcome these limitations, in which the SOFC mainly provides the baseload of the system. Introducing a purification unit allows the production and storage of pure hydrogen from the SOFC anode off-gas. The hydrogen can be stored, and used in a proton exchange membrane fuel cell (PEMFC) during peak demands. The SOFC system is completed with a battery, used during periods of high electricity production. We propose the use of a mixed integer-linear optimization framework for the sizing of the different components of the system, and particularly for identifying the optimal trade-off between round-trip efficiency and investment cost of the battery-based and hydrogen-based storage systems. The proposed system is applied and optimized to two case studies: an off-grid dwelling, and a cruise ship. The results show that, if the SOFC is used as the main energy conversion technology of the system, the use of hydrogen storage in combination with a PEMFC and a battery is more economically convenient compared to the use of the SOFC in stand-alone mode, or of pure battery storage. The results show that the proposed hybrid storage solution makes it possible to reduce the investment cost of the system, while maintaining the use of the SOFC as the main energy source of the system.
... The system is assumed to have a total life of 20 years and an annual total capacity factor of 65%, translating to 356 mode-change cycles per year for a 16 h total cycle time. A plant life of 20-30 years is commonly assumed for solid oxide fuel cell systems [72][73][74], and 65% is a reasonable capacity factor for an energy storage system with an 8 h discharge duration intended for frequent use [71]. The operations and maintenance cost includes stack replacement and is adjusted relative to reference [72] to account for system scale. ...
... A plant life of 20-30 years is commonly assumed for solid oxide fuel cell systems [72][73][74], and 65% is a reasonable capacity factor for an energy storage system with an 8 h discharge duration intended for frequent use [71]. The operations and maintenance cost includes stack replacement and is adjusted relative to reference [72] to account for system scale. Capital costs for the stack, tanks, and balance-of-plant components are taken from literature. ...
Article
The increase of intermittent renewable energy contribution in power grids has urged us to seek means for temporal decoupling of electricity production and consumption. A reversible solid oxide cell (r-SOC) enables storage of surplus electricity through electrochemical reactions when it is in electrolysis mode. The reserved energy in form of chemical compounds is then converted to electricity when the cell operates as a fuel cell. A process system model was implemented using Aspen Plus® V8.8 based on a commercially available r-SOC reactor experimentally characterized at DLR. In this study a complete self-sustaining system configuration is designed by optimal thermal integration and balance of plant. Under reference conditions a round trip efficiency of 54.3% was achieved. Generated heat in fuel cell mode is exploited by latent heat storage tanks to enable endothermic operation of reactor in its electrolysis mode. In total, out of 100 units of thermal energy stored in heat storage tanks during fuel cell mode, 90% was utilized to offset heat demand of system in its electrolysis mode. Parametric analysis revealed the significance of heat storage tanks in thermal management even when reactor entered its exothermic mode of electrolysis. An improved process system design demonstrates a system round-trip efficiency of 60.4% at 25 bar.
... The system is assumed to have a total life of 20 years and an annual total capacity factor of 65%, translating to 356 mode-change cycles per year for a 16 h total cycle time. A plant life of 20-30 years is commonly assumed for solid oxide fuel cell systems [72][73][74], and 65% is a reasonable capacity factor for an energy storage system with an 8 h discharge duration intended for frequent use [71]. The operations and maintenance cost includes stack replacement and is adjusted relative to reference [72] to account for system scale. ...
... A plant life of 20-30 years is commonly assumed for solid oxide fuel cell systems [72][73][74], and 65% is a reasonable capacity factor for an energy storage system with an 8 h discharge duration intended for frequent use [71]. The operations and maintenance cost includes stack replacement and is adjusted relative to reference [72] to account for system scale. Capital costs for the stack, tanks, and balance-of-plant components are taken from literature. ...
Article
Reversible solid oxide cells may be a cost competitive energy storage technology at the distributed scale. Leveraging C–O–H chemistry and operating near 600 °C allows the cells to be exothermic in both modes, improving efficiency and operability. This study characterizes ReSOC balance-of-plant hardware off-design performance to investigate component mode compatibility, the effect of tank dynamics, and part-load performance for a 100 kW/800 kWh plant. We also introduce a variable volume floating piston tank concept to improve energy storage density and evaluate operability advantages. Results show that with proper system design, balance-of-plant components are compatible, and tank dynamics have minimal impact when tanks are uninsulated and designed for storage near ambient temperature. System AC roundtrip efficiency is between 53% and 54%, depending on the tank technology selected and the compressor operating approach. Energy density is 84.4 kWh/m3 for rigid tanks, and 146.1 kWh/m3 for the variable volume tank concept at 100 bar storage pressure. This study also shows that ReSOC systems can maintain high efficiency at part-loads as low as 15% of rated capacity. Economic analysis of the system estimates an installed capital cost of $422–452/kWh, and a levelized cost of storage of 18.8–19.6 ¢/kWh, values competitive with state-of-the-art battery technology.
... The increased interest in energy developments is focused on newtechnology systems, which can serve more demand with optimum energy source utilization. 1 Apart from increasing the overall efficiency of the energy generation, the new-technology system can be beneficial in decreasing the primary energy consumption as well as the energy cost of the system. 2 Therefore, implementation of systems with new technology to generate more than one energy type has been a favorable development for office, hospital, university, school, and residential applications. ...
... Becker et al. developed a 1 MW polygeneration system which employs SOFC as the prime mover to generate power, heat, and hydrogen. 2 These works demonstrated the promising use of fuel cells, specifically the high-temperature fuel cell such as SOFC to be a prime mover in polygeneration systems. ...
Article
Integration between supplies for stationary power and vehicles is potentially useful for increasing the efficiency and the reliability of energy generation systems. Solid oxide fuel cell is one matured technology, which is suitable for a polygeneration system and provides an integration of supply for stationary power and vehicles. However, a combination of solid oxide fuel cell with photovoltaic thermal and thermoelectric generation increases the complexity of a polygeneration system. The system needs a management strategy for dispatching the energies produced. Therefore, in this work, a fuzzy energy management strategy was applied for this polygeneration system by considering two different configurations: an off-grid system with electric vehicle supply and an on-grid system with hydrogen vehicle supply. A two-stage fuzzy energy management strategy considering optimization and management of multi-parameters of the polygeneration components was considered. The evaluation of the optimum fuzzy was analyzed based on energy, economic, and environmental criteria. From the results obtained, the optimal strategy increased the reliability, energy, and system cost savings by 22.05%, 22.4%, and 32.58%, respectively. Moreover, the optimum management reduced the power loss of the polygeneration system by about 48.82%, which was achieved by the configuration with electric vehicles supply and off-grid connection.
... A DG system is modeled in MATLAB/Simulink to examine the effect of SOFC&PV-based DG system on PQ. Fig. 1 shows this DG [29,33,34]. Some special operating conditions in PV and SOFC systems will cause PQ problems. ...
... For solving the initial model F 0 minimization problem SGBT uses the steepest descent algorithm. The new additional model is derived with equation (28) and step length g m given with equation (29) chosen with line search. In this study, a multinomial deviance loss function was used for classification. ...
Article
Full-text available
In this study, a new hybrid machine learning (ML) method is developed to classify the power quality disturbances (PQDs) for a hydrogen energy-based distributed generator (DG) system. The proposed hybrid ML method uses a new approach for the feature extraction by using a pyramidal algorithm with an un-decimated wavelet transform (UWT). The pyramidal UWT method is used and investigated with the Stochastic Gradient Boosting Trees (SGBT) classifier to classify PQD signals for a Solid Oxide Fuel Cell & Photovoltaic (SOFC&PV)-based DG. The overfitting problem of SGBT in noisy signals is eliminated with the features extracted by pyramidal UWT. Mathematical, simulative and real data results confirm that the developed UWT-SGBT method can classify PQDs with high accuracy of up to 99.59%. The proposed method is also tested under noisy conditions, and the pyramidal UWT-SGBT method outperformed other ML with wavelet transform (WT)-based methods in the literature in terms of noise immunity.
... A novel cogeneration system has recently been developed by the present authors integrating solar energy and SOFC in order to supply thermal and electrical energy (Akikur et al. 2014). Besides, many studies on system design and model-based fuel cell technology have also been presented in the literature (Becker et al. 2012;Chen and Ni 2014;Lamas et al. 2013;Naimaster and Sleiti 2013;Tanaka et al. 2014;Xu et al. 2012). Summary of some of those studies has been provided as follows: Chen and Ni (2014) presented a cogeneration/trigeneration system based on SOFC in Hong Kong for load supply in a hotel. ...
... They also revealed that if the hydrogen could be produced from renewable sources, about 42.3 % of primary energy reduction would be possible compared to the natural gasfuelled SOFC system. Becker et al. (2012) carried out a study on 1 MW of SOFC in a polygeneration system for combined production of heat, power and hydrogen. The SOFC was used for the cogeneration system, and then hydrogen was separated for further application using a gas stream. ...
Article
Full-text available
The current study presents a concept of a cogeneration system integrated with solar energy and solid oxide fuel cell technology to supply electrical and thermal energy in Malaysia. To appraise the performance, the system is analysed with two case studies considering three modes of operation. For the case-1, typical per day average electricity and hot water demand for a single family have been considered to be 10.3 kWh and 235 l, respectively. For the case 2, electricity and hot water demand are considered for the 100 family members. Energy cost, payback period, future economic feasibility and the environmental impact of the system are analysed for both cases using an analytical approach. The overall system along with individual component efficiency has been evaluated, and the maximum efficiency of the overall system is found to be 48.64 % at the fuel cell operation mode. In the present study, the proposed system shows 42.4 % cost effectiveness at higher load. Energy costs for case-1 and case-2 have been found to be approximately $0.158 and $0.091 kWh−1, respectively, at present. Energy costs are expected to be $0.112 and $0.045 kWh−1 for the case-1 and case-2, respectively, considering future (i.e. for the year 2020) component cost.
... Ali and Salman [6] provide a comprehensive review of the fuel cell technologies and the current state of the art of the hydrogen energy economy. Becker et al. [7] report that the solid oxide fuel cell (SOFC) combined heat, hydrogen and power (CHHP) systems are capable of an electrical efficiency of 48.4%, and an overall efficiency of 85. 2%. This is a significant improvement over the existing technology and has higher energy efficiency and lower emissions for the amount of power generated. ...
... Bradley PLC (Micro 820/Micrologix 1100 or equivalent), Allen Bradley C400 interface and necessary I/O 2. Valves and piping for manual isolation, air-operated isolation manual vent and safety relief 3. Gas aftercooler 4. Inlet and discharge pressure transducers 5. Discharge thermocouple 6. Inlet and discharge pressure gauges. 7. Cooling water isolation valves, flow switch and sight meter as shown in Fig. 4. ...
Article
This paper provides a design of a drop-in hydrogen fueling station. Drop-in stations are expected to be an important factor in the introduction of hydrogen fueling infrastructure. The stations not only allows a streamlined introduction of hydrogen in the vehicle fueling infrastructure, but also, acts as mini pilot plants that can allow for detailed control studies. The effect of the location and availability of utilities, the closeness to residential area, unintended safety concerns, people outlook towards hydrogen, etc. are some of the factors that can be readily studied with such drop-in stations. The proposed design of a drop-in station mainly considers off-the-shelf items and is conceptualized to be implemented at the Missouri University of Science and Technology. The modular design approach, with the off-the-shelf items allows for a design with the capability of mass production, and ease in transport and integration.
... The standard electrode potential is calculated using Eq. (5) as used in Becker et al. [32] E ...
... These systems assume near adiabatic conditions around the stack as conduction and surface radiation play a minor role, Braun et al. and Lisbona et al. both assign empirical percentage values (3-7%) to these thermal losses [46,34]. As such, conventional SOFC system models assume the stack temperature is equal to either the cathode inlet, exhaust or average temperature depending on the flow configuration [32,34,47,46]. The unique design and application of the Geothermic Fuel Cell modules result in significant heat loss from the stack via radiative heat transfer to the inner housing. ...
Article
The United States Geological Survey estimates that over four trillion barrels of crude oil are currently trapped within U.S. oil shale reserves. However, no cost-effective, environmentally sustainable method for oil production from oil shale currently exists. Given the continuing demand for low-cost fossil-fuel production, alternative methods for shale-oil extraction are needed. Geothermic Fuel Cells™ (GFC) harness the heat generated by high-temperature solid oxide fuel cells during electricity generation to process oil shale into “sweet” crude oil. In this paper, a thermo-electrochemical model is exercised to simulate the performance of a 4.5 kWe (gross) Geothermic Fuel Cell module for in situ oil-shale processing. The GFC analyzed in this work is a prototype which contains three 1.5 kWe solid oxide fuel cell (SOFC) stack-and-combustor assemblies packaged within a 0.3 m diameter, 1.8 m tall, stainless-steel housing. The high-temperature process heat produced by the SOFCs during electricity generation is used to retort oil shale within underground geological formations into high-value shale oil and natural gas. A steady-state system model is developed in Aspen Plus™ using user-defined subroutines to predict the stack electrochemical performance and the heat-rejection from the module. The model is validated against empirical data from independent single-stack performance testing and full GFC-module experiments. Following model validation, further simulations are performed for different values of current, fuel and air utilization to study their influence on system electrical and heating performance. The model is used to explore a wider range of operating conditions than can be experimentally tested, and provides insight into the competing physical processes at play during Geothermic Fuel Cell operation. Results show that the operating conditions can be tuned to generate desired heat-flux conditions as needed across applications.
... The standard electrode potential is calculated using Eq. (5) as used in Becker et al. [32] E ...
... These systems assume near adiabatic conditions around the stack as conduction and surface radiation play a minor role, Braun et al. and Lisbona et al. both assign empirical percentage values (3-7%) to these thermal losses [46,34]. As such, conventional SOFC system models assume the stack temperature is equal to either the cathode inlet, exhaust or average temperature depending on the flow configuration [32,34,47,46]. The unique design and application of the Geothermic Fuel Cell modules result in significant heat loss from the stack via radiative heat transfer to the inner housing. ...
Article
The United States Geological Survey estimates that over four trillion barrels of crude oil are currently trapped within U.S. oil shale reserves. However, no cost-effective, environmentally sustainable method for oil production from oil shale currently exists. Given the continuing demand for low-cost fossil-fuel production, alternative methods for shale-oil extraction are needed. Geothermic Fuel Cells™ (GFC) harness the heat generated by high-temperature solid oxide fuel cells during electricity generation to process oil shale into “sweet” crude oil. In this paper, a thermo-electrochemical model is exercised to simulate the performance of a 4.5 kWe (gross) Geothermic Fuel Cell module for in situ oil-shale processing. The GFC analyzed in this work is a prototype which contains three 1.5 kWe solid oxide fuel cell (SOFC) stack-and-combustor assemblies packaged within a 0.3 m diameter, 1.8 m tall, stainless-steel housing. The high-temperature process heat produced by the SOFCs during electricity generation is used to retort oil shale within underground geological formations into high-value shale oil and natural gas. A steady-state system model is developed in Aspen Plus™ using user-defined subroutines to predict the stack electrochemical performance and the heat-rejection from the module. The model is validated against empirical data from independent single-stack performance testing and full GFC-module experiments. Following model validation, further simulations are performed for different values of current, fuel and air utilization to study their influence on system electrical and heating performance. The model is used to explore a wider range of operating conditions than can be experimentally tested, and provides insight into the competing physical processes at play during Geothermic Fuel Cell operation. Results show that the operating conditions can be tuned to generate desired heat-flux conditions as needed across applications.
... The energy consumption of such systems is 2.3-7 kWh/m 3 . According to literature, the consumption of the existing units in Patmos Island is 5.5 kWh/m 3 , as seen in Table 5 [28,29]. To provide sufficient and efficient water production on Patmos island it is also important to investigate the application of thermal desalination technologies, notably the multi-effect distillation desalination unit, MED, which would use the heat generated by the SOFC unit. ...
Article
Full-text available
Liquefied natural gas (LNG) is regarded as the cleanest among fossil fuels due to its lower environmental impact. In power plants, it emits 50–60% less carbon dioxide into the atmosphere compared to regular oil or coal-fired plants. As the demand for a lower environmental footprint is increasing, fuel cells powered by LNG are starting to appear as a promising technology, especially suitable for off-grid applications, since they can supply both electricity and heating. This article presents a techno-economic assessment for an integrated system consisting of a solid oxide fuel cell (SOFC) stack and a micro gas turbine (MGT) fueled by LNG, that feeds the waste heat to a multi-effect desalination system (MED) on the Greek island of Patmos. The partial or total replacement of the diesel engines on the non-interconnected island of Patmos with SOFC systems is investigated. The optimal system implementation is analyzed through a multi-stage approach that includes dynamic computational analysis, techno-economic evaluation of different scenarios using financial analysis and literature data, and analysis of the environmental and social impact on the island. Specific economic indicators such as payback, net present value, and internal rate of return were used to verify the economic feasibility of this system. Early results indicate that the most sensitive and important design parameter in the system is fuel cell capital cost, which has a significant effect on the balance between investment cost and repayment years. The results of this study also indicate that energy production with an LNG-fueled SOFC system is a promising solution for non-interconnected Greek islands, as an intermediate carrier prior to the long-term target of a CO₂-free economy.
... In this framework, polygenerative systems are particularly interesting in terms of energy supply decentralization, reduction of greenhouse gas (GHG) emissions, energy security and avoided electricity transmission and distribution networks [1]. Polygeneration technology is usually based on gas or steam turbines, nevertheless also some new technologies based on fuel cells [2,3] and renewable energy sources [4] are currently under investigation. Fuel Cell (FC) technologies have been optimized in recent years due the modelling, simulation and experiments [5,6], such improvement has been performed for PEM [7], Solid Oxide Fuel Cell (SOFC) [8], Molten Carbonate Fuel Cell (MCFC) [9] and microbial units [10]. ...
... Second law of thermodynamics efficiency is calculated as [75] Another approximate for SMR and WGS [76] $ follows: ...
Article
A combined system containing solid oxide fuel cell-gas turbine power plant, Rankine steam cycle and ammonia-water absorption refrigeration system is introduced and analyzed. In this process, power, heat and cooling are produced. Energy and exergy analyses along with the economic factors are used to distinguish optimum operating point of the system. The developed electrochemical model of the fuel cell is validated with experimental results. Thermodynamic package and main parameters of the absorption refrigeration system are validated. The power output of the system is 500 kW. An optimization problem is defined in order to finding the optimal operating point. Decision variables are current density, temperature of the exhaust gases from the boiler, steam turbine pressure (high and medium), generator temperature and consumed cooling water. Results indicate that electrical efficiency of the combined system is 62.4% (LHV). Produced refrigeration (at −10 °C) and heat recovery are 101 kW and 22.1 kW respectively. Investment cost for the combined system (without absorption cycle) is about 2917$ kW−1.
... The PSA at the OCSD plant operates between 10 and 40 bar with an electric load of 58 kW, met by the nearly 300 kW electric output of the MCFC. Alternative techniques for hydrogen separation such as membrane separation and electrochemical separation could achieve similar integration with carbon recovery at higher net electrical efficiencies [26]. ...
... Most systems utilize air as the oxidant, although FuelCell Energy Ò has developed a pure oxygen powered system for undersea applications [21]. High FTE efficiency concepts (60-75% LHV) have been developed including poly-generation [22], FC-GT hybrids [23], coal gasification with carbon capture [24], and supercritical carbon dioxide hybrid cycles [25]. Each of these high temperature fuel cell systems realizes a different degree of thermal integration with, typically, an external fuel processor or gasifier. ...
... Energy ef ciency of system has been calculated at about 50% for 0.4 degree of recirculation of the exhaust anode gas at 0.6 degree of fuel consumption. Becker et al. [18] focused on the design and performance estimation of a methane-fueled, 1 MW SOFC combined heat, hydrogen, and power system. Two methods of hydrogen puri cation and recovery from the SOFC have been analyzed in their research. ...
Article
Full-text available
Fuel  exibility is a signi cant advantage of solid oxide fuel cells (SOFCs) and can be attributed to their high operating temperature. The eligibility of a combined heat and power (CHP) system has been investigated as a new power generation method, in this study. Natural gas fueled SOFC power systems employing methane steam reforming (MSR) yield electrical conversion ef ciencies exceeding 50% and may become a viable alternative for distributed generation in Iran. Since the heat to power ratio of a common SOFC system is 2:1, an ef cient heat recovery system has been considered to supply the heat required by the steam producer and recuperative heat exchangers. All the main components in the comprehensive system were modeled and then simulated. Results showed high total energy ef ciency along with minimum heat loss are feasible in the proposed cycle. Moreover, desirable methane and hydrogen conversion ratios have been attained when utilizing this system for commercial power generation purposes. Lastly, a cathode recycling effect on the MSR combustor operation has been indicated.
... As efficiency of fuel cell is high, it has potential to be used for electricity generation, though novel material is required and it is highly sensitive to impurities [28,29,132]. In this case input fuels should have high level of purity. ...
Article
Integrating multiple utility outputs to obtain better efficient system has been a good option. After cogeneration and trigeneration, polygeneration emerges as a possible sustainable solution with optimum resource utilization, better efficiency and environment friendliness. Several possible polygeneration has been conceptualized, performance assessed theoretically as available in literature. Both inputs and outputs vary in these reported works. A few prototype development and experimental result analysis are also reported. Several optimization tools based on objective function are used to develop efficient polygeneration. Assessment criteria of polygeneration are also multi dimensional and may be defined on a case to case basis with definite objective. In this paper a comprehensive review of available literature is done to assess the status of polygeneration as a possible sustainable energy solution. Possible future research in this field is also logically predicted at the end of this review.
... This CCHP system can also be transplanted to an airport to provide cooling, heating and electricity. Other theoretical work can be referred to [164,165]. ...
... Becker et al. [17] developed and analysed a multigeneration system for producing electricity, hydrogen and heating. A 1 MW methane fueled solid oxide fuel cell was considered. ...
Article
In this study, a novel renewable energy based trigeneration system is developed based on the utilization of solar and geothermal resources in a combined manner. The present system includes the following useful outputs, namely electricity, hydrogen and cooling. A flash-steam geothermal power plant is used for producing electricity. The CuCl cycle is used for hydrogen production and an additional heat from the CuCl cycle is used in the absorption chiller for cooling. The energy efficiency of the trigeneration system is evaluated to be 19.6% while the exergy efficiency is found to be 19.1%. Furthermore, the CuCl hydrogen production cycle is determined to have an energy efficiency of 35.3% and an exergy efficiency of 35.9%. In addition, the energetic coefficient of performance of the absorption cooling system is evaluated as 0.54 and the exergetic coefficient of performance is 0.32. Moreover, several parametric studies are conducted to study the effects of varying operating conditions and system parameters on system performance.
... The prime movers of multigeneration systems including the gas turbine cycles [3], steam turbines [4], Stirling engines [5], internal combustion engines [6] and fuel cells [7]. In recent years, much research has been performed on multigeneration systems with the production of hydrogen and oxygen [8]. ...
Article
The novel multi-generation system is developed to produce power, cooling, and hydrogen. The present work is suggested to employ the geothermal energy to start a Kalina cycle and then with regard to the high temperature of the saturated liquid leaving the Kalina cycle separator, the absorption refrigeration system is employed for providing cooling as a subsystem. Also, an electrolyzer and the power production capacity of the cycle have been utilized to produce hydrogen. The proposed system is evaluated thermodynamically and exergoeconomically, and a parametric study was performed for the following parameters: geothermal heat source temperature (T HS,in), the temperature difference in vapor generator 1 (ΔT PP,vg1), the pressure of vapor generator 1 (P vg1), condenser temperature (T con), evaporator temperature (T eva) and ammonia concentration (Y B). The governing equations are coded in the EES software. In the base case, the results display that the proposed system is capable of producing 258.6 kW of cooling, and in this case, the thermal and exergy efficiencies and the unit cost of multigeneration are 22.28%, 21.37% and 29.29 $/GJ, respectively. Also, increasing the evaporator temperature does not have a significant effect on power production capacity. Moreover, condenser 1 has the most exergy destruction rate of 65.03 kW.
... Table 2 lists component design and performance parameters. These values are based on studies of intermediate temperature ReSOCs [28,52,38], large-scale SOFC and SOEC systems [61,62], and large-scale pressure swing adsorption air separation [60]. ...
Article
Electrical energy storage (EES) is necessary to enable greater penetration of renewables and as a grid-balancing solution, but current EES technologies suffer from capacity or geological limitations and high cost. Reversible solid oxide cells (ReSOCs) are an electrochemical energy conversion technology that can produce both electricity from fuel (gas-to-power) and fuel from electricity (power-to-gas), depending on resource availability and de-mand. Leveraging in situ C-O-H chemistry and operating at intermediate temperature (600 C) and elevated pressure (10–20 bar) enables these cells to be mildly exothermic, eliminating the need for external heat input or high over-potential (low-efficiency) operation during electrolysis mode. This operating strategy also results in higher methane production during electrolysis, facilitating easier integration with natural gas pipeline infra- structure over steam/hydrogen electrolytic processes. This study proposes a ReSOC system integrated with both natural gas pipeline and carbon capture and storage (CCS) infrastructure to render a flexible, grid energy management resource. In gas-to-power mode, the system takes natural gas from a pipeline to produce electricity. Un-utilized fuel is combusted with oxygen and expanded through a turbine to produce more power. The water in the exhaust is condensed, and the remaining carbon dioxide is compressed for tanker or pipeline transportation to a carbon sequestration site. In power-to-gas mode, carbon dioxide and water are co-electrolyzed in the stack to produce methane and hydrogen, which can be injected directly into a natural gas pipeline or further refined into a purer stream of methane. We explore system design concepts, performance, and cost of a 50 MWe ReSOC system. Results indicate that synthetic natural gas (92.0% methane) can be produced at $22.7/MMBTU with a lower heating value efficiency of 81%. Alternatively, a system that net meters produced syngas and operates in power producing mode 50% of the time can generate electricity at a levelized cost of 10.5 /kWh with an efficiency of 69% (LHV), while producing exhaust that is 95.5% carbon dioxide at 40 bar. If the system operates disproportionally in gas-to-power mode the LCOE drops to near 6¢/kWh. The economic outlook for mature ReSOC systems presented herein are found to be competitive with current energy storage technologies and natural gas peaker plants.
... Consequently, the integration of ORC and biomass powered fuel cells for small to medium scale CHP might not have an immediate market impact. Instead, Becker et al. [14] proposed a tri-generation system for combined heat, hydrogen, and power (CHHP) generation. The process relies on SMR to produce the syngas feed needed for a SOFC. ...
Article
A dual-loop organic Rankine cycle (D-ORC) was used to recover waste heat from a biomass gasification process, for combined heat, hydrogen, and power (CHHP) generation. The process is based on the integration of biomass gasification with catalytic partial oxidation (CPO) and water-gas shift catalytic membrane reactors (WGS CMRs) for the simultaneous production and separation of hydrogen. The high temperature loop of the ORC was used to cool the CPO reactor effluent, while the low temperature loop was used to cool the WGS CMR retentate. Energy and exergy analyses were carried out to select the optima working fluids for this application. Hydrocarbons, siloxanes, hydrofluorocarbons (HFCs), and hydrofluoroolefins (HFOs) were examined as potential candidates in this analysis. Results indicate that the highest efficiency was obtained when n-heptane and n-pentane were used as working fluids for the high and low temperature loops, respectively. Using this combination, electric and exergy efficiencies of 13.93% and 36.41% were computed, receptively. The process generates 1.37 kW of power, and produces 1.41 kg/hr of hydrogen at 773 K and 91.32 kg/hr of hot water at 363 K. The exergy analysis has also showed that the high temperature loop turbine and condenser have contributed the most, by around 32%, to the overall system irreversibility.
Article
Although hybrid solid oxide fuel cell (SOFC) microturbine systems generate power more efficiently than stand-alone SOFC systems, hybrid systems remain in the demonstration phase. This study compares a hybrid system's exergetic and economic performance with that of a stand-alone system. Both systems meet a university building's kW-scale power demand. The hybrid system operates at exergetic efficiency, and the stand-alone system operates at exergetic efficiency. Increasing the fuel cell's operating voltage increases the systems' exergetic efficiencies, and varying the fuel cell's temperature, pressure, and fuel utilization influences the systems' exergetic performances, though to a lesser extent. This study calculates the systems' life cycle costs. We find that the systems' life cycle costs depend significantly on the systems' operation. During baseline operation, the hybrid system costs less than the stand-alone system. After optimizing the systems during cogeneration operation, the hybrid system costs slightly more than the stand-alone system. Overall, our findings support hybrid systems' continued research and development; it is recommended that future work simulate hybrid and stand-alone systems under a range of thermal-to-electric ratios to reflect different building types and operation.
Article
Transient impacts on the performance of solid oxide fuel cell / gas turbine (SOFC/GT) hybrid systems were investigated using hardware-in-the-loop simulations (HiLS) at a test facility located at the U.S. Department of Energy, National Energy Technology Laboratory. The work focused on applications relevant to polygeneration systems which require significant fuel flexibility. Specifically, the dynamic response of implementing a sudden change in fuel composition from syngas to methane was examined. The maximum range of possible fuel composition allowable within the constraints of carbon deposition in the SOFC and stalling/surging of the turbine compressor system was determined. It was demonstrated that the transient response was significantly impact the fuel cell dynamic performance, which mainly drives the entire transient in SOFC/GT hybrid systems. This resulted in severe limitations on the allowable methane concentrations that could be used in the final fuel composition when switching from syngas to methane. Several system performance parameters were analyzed to characterize the transient impact over the course of two hours from the composition change.
Article
In this study, the application of a rolling horizon optimization strategy to an integrated solid-oxide fuel cell/compressed air energy storage plant for load-following is investigated. A reduced-order model of the integrated plant is used to simulate and optimize each optimization interval as a mixed integer non-linear program. Forecasting uncertainties are considered through the addition of measurement noise and use of stochastic Monte Carlo simulations. The addition of rolling horizon optimization gives significant reductions to the sum-of-squared-errors between the demand and supply profiles. A sensitivity analysis is used to show that increasing the forecasting and optimization horizon improves load tracking with diminishing returns. Incorporating white Gaussian noise to demand forecasts has a marginal impact on error, even when a relatively high noise power of is used. Consistently over- or under-predicting demand has a greater impact on the plant's load-tracking error. However, even under worst-case forecasting scenarios, using a rolling horizon optimization scheme provides a more than 50% reduction in error when compared to the original system. An economic objective function is formulated to improve gross revenue using electricity spot-prices, but results in a trade-off with load-following performance. The results indicate that the rolling horizon optimization approach could potentially be applied to future municipal-scale fuel cell/compressed air storage systems to achieve power levels which closely follow real grid power cycles using existing prediction models.
Conference Paper
Full-text available
Organic wastes derived from agriculture represent a cheap and widely available resource for the production of energy, fertilizers and fuels for several countries. Their conversion using anaerobic digesters into biogas, for instance, is able to reduce pollution from organic waste disposal, produce liquid fertilizer and provide energy for different purposes. Although this technology has been massively adopted in recent years, new projects for biogas production plants still struggle with low productivity and energy efficiency, which limits their economic viability despite numerous benefits. Multiple technologies have been proposed to diminish these problems, however the high costs of such options may overcome their benefits if not carefully designed and optimized. Thus, in order to examine the trade-offs between productivity, efficiency and costs of complex biogas production plants, this research details a multi-objective optimization of a system converting biogas derived from swine manure into electricity by using solid oxide fuel cells. The analysis shows that the proposed system is able to achieve a levelized cost of electricity of 0.130-0.203 USD 2019 /kWh and an exergy efficiency between 17.7-19.8%. Since the anaerobic reactor and fuel cell systems comprises 65-74% of total equipment costs, the hydraulic retention time of organic wastes and the average current density of fuel cells play a major role in minimizing costs without compromising conversion efficiencies.
Article
A review of energy conversion systems which use solid oxide fuel cells (SOFCs) as their primary electricity generation component is presented. The systems reviewed are largely geared for development and use in the short- and long-term future. These include systems for bulk power generation, distributed power generation, and systems integrated with other forms of energy conversion such as fuel production. The potential incorporation of CO2 capture and sequestration technologies and the influences of potential government policies are also discussed.
Article
This paper focuses on the thermal management of a hydrogen-selective low temperature water-gas-shift (WGS) membrane reactor for simultaneous high-purity hydrogen production and carbon capture. A mathematical model of the reactor is developed consisting of a set of first-order hyperbolic PDEs. Open-loop simulations under a step change in the syngas inlet composition reveal the existence of large temperature gradients along the reactor. A control strategy is proposed whereby multiple distributed cooling zones are placed across the reaction zone in order to regulate the temperature profile. A nonlinear distributed controller is derived, and its performance is evaluated for disturbance rejection and set-point tracking case studies.
Article
The effect of co-doping of Sr and Al or Fe on the microstructure, sinterability and oxide-ion conductivity of lanthanum silicate oxyapatites is investigated in detail at 300-800 °C by the electrochemical impedance spectroscopy. The oxide-ion conductivity is 1.46 × 10−2 S cm−1 for La9.5Sr0.5Si5.5Fe0.5O26.5 (LSSFO) and 1.34 × 10−2 S cm−1 at 800 °C for La9.5Sr0.5Si5.5Al0.5O26.5 (LSSAO), respectively, which is one order of magnitude higher than 6.16 × 10−3 S cm−1 measured on La9.67Si6O26.5 (LSO) oxyapatite under the identical test conditions. The grain bulk and grain boundary resistances of co-doped oxyapatite are significantly smaller than that of LSO oxyapatite, and decrease significantly with the increase of the sintering temperature. LSSFO and LSSAO also show significantly higher density as compared to that of LSO. The results indicate that co-doping of Sr and Al or Fe significantly improves the densification, sinterability and oxide-ion conductivity of lanthanum silicate oxyapatites.
Article
Hydrogen and syngas production through a combination of solid oxide electrolysis cells (SOECs) and power from renewable energy resources is an efficient production method that has several significant advantages. However, given its relative technological infancy, understanding the intricate reactions and transport processes within SOEC devices are necessary to advance the technology and establish the optimum operating conditions for eventual cost effective design. Consequently, the main objective of this study is to simulate the complex phenomena inside a planar SOEC using a previously developed and validated model. The model takes an intermediate fidelity approach to predicting the electrochemical and thermo-fluid phenomena inside the cell. An example of the model calibration for an electrolyte supported SOEC is presented here. The model is then employed to investigate the effect of various operating parameters connected to SOEC electrochemical performance, as well as hydrogen and syngas production. The effect of the feedstock gas composition, temperature, and flow rate on performance and the important role that the reverse water-gas shift (RWGS) plays are illustrated. Although the operating temperature, fuel composition and flow rates have a direct effect on SOEC performance and power consumption, their influence on RWGS is more significant. Possible outlet syngas compositions of an SOEC and their appropriateness as a feedstock for the Fischer–Tropsch (FT) and methanation processes are also discussed.
Chapter
This chapter aims to provide some fundamental information and the state-of-the-art of combined cooling, heating and power (CCHP) systems. It focuses on different prime movers for driving the CCHP systems and three main thermally activated technologies that can be used in CCHP systems to achieve energy cascade utilization. The chapter also focuses on different system configurations according to the system capacity. It introduces conventional and novel operation strategies, and system optimization methods. The chapter discusses development of CCHP systems in three main countries namely United States, United Kingdom and People's Republic of China. To construct an economical and efficient CCHP system, the type of facilities should be firstly determined according to local resources, and current and future energy market. The system configuration varies according to different usages, including commercial buildings, residential buildings, supermarkets, universities, hospitals, and so on.
Article
The flue gas which resulted from oxidation of the fuel flow in the SOFC stack was burnt off in the catalytic combustor under the operating condition acquired by the process simulation. Conversion of the combustible components in the stack flue gas was experimentally measured at four different GHSVs in a tubular reactor packed with base-metal catalyst pellets. Optimum GHSV of 6,990 hr(-1) in the catalytic combustor was determined on the basis of reactor performance including pressure drop, carbon monoxide slip, and conversion of the combustible components.
Article
Pr2NiO4 + δ was wet infiltrated into porous LSGM scaffolds to form solid oxide cell oxygen electrodes on LSGM-electrolyte symmetrical cells. The minimum calcination temperature required to form this nickelate phase was between 950 °C and 1000 °C. X-ray diffraction measurements of electrodes tested at 650 °C showed little evidence of any phase change, in contrast to 650 °C annealed Pr2NiO4 + δ powders that decomposed to Pr4Ni3O10 and Pr6O11. Polarization resistance followed an Arrhenius temperature dependence with an activation barrier of 1.40 eV, and a value as low as 0.11 Ω ∙ cm2 was observed at 650 °C for a Pr2NiO4 + δ loading of 14 vol.%. The present resistance values appear to be the lowest reported to date for a Ruddlesden–Popper phase electrode, and are competitive with perovskite-structure electrodes. The low resistance, combined with the good stability of infiltrated Pr2NiO4 + δ and the advantages of being Co- and Sr-free, make this an exciting new contender for intermediate-temperature solid oxide cell applications.
Article
Full-text available
This part II work is built on the energy performance results of part I and focuses on the cost of producing synthetic natural gas and sensitivity scenarios around main economic variables.Capital costs for each plant section have been evaluated taking into account operational parameters such as pressure and temperature of the SOEC. The costing and financial methodology is based on a discounted cash flow analysis that was used to calculate the specific cost of synthetic natural gas (SNG) which ensures economic profitability of the investment.The co-electrolysis case has higher capital, operating and maintenance costs; however it shows a weaker dependence on the electricity cost due to its higher plant efficiency. The impact of key parameters such as electrolysis stack cost, cell degradation rate and carbon dioxide feedstock cost were further investigated. Both "state-of-the-art" and "target" scenarios were defined to account for the expected enhanced technological maturity of the SOEC technology that is expected to occur in the following decade.For the co-electrolysis case, break-even electricity prices (i.e., costs that yield an SNG cost comparable to that of fossil natural gas) of 8 $/MWh and 67 $/MWh were calculated for "state-of-the-art" and "target" scenarios, respectively.
Article
Hydrogen has been discussed as a future energy vector owing to its environmentally benign properties. Currently, due to rising fuel prices, environmental crises and energy challenges, simultaneous generation of power, heat, cooling, and hydrogen has been the subject of many investigations. In this study, an integrated process of solid oxide fuel cell (SOFC), solid oxide electrolyzer cell (SOEC), steam Rankine cycle (SRC), and organic Rankine cycle (ORC) is introduced and analyzed to tri-generate power, hydrogen, and hot water. In effect, SOFC is fed by natural gas to generate power. To exploit the waste heat of SOFC outlet, Rankine cycles are used to produce extra power. The system is designed to produce 500kW net power in conjunction with internal required power. The excess power supplies SOEC which carries out steam separation, generating pure hydrogen. To achieve an appropriate design, sensitivity analysis and economic evaluation are carried out for different parts of the integrated system. For design condition of (TSOEC=1173K,i=0.3375A/cm2,VSOEC=1.1V,andUf=0.825), value of electrical efficiency of the integrated system is found to be 49.43%. Also, SOFC voltage is obtained 0.7910 V. The system cogeneration and tri-generation LHV-efficiencies are 68.18% and 71.55%. Based on the results, H2 production flow rate in SOEC and heat recovery are 2.8230kmol/h and 34.11kW respectively.
Article
A reliability analysis methodology for a multi-stack solid oxide fuel cell (SOFC) system is presented based on physical modeling and experimental data. The constructed failure probability function is composed of three operation phases: (i) as-fabricated, (ii) start-up, and (iii) constant power generation. In-house experimental data are used to capture the behavior during start-up and normal operation, including drifts of the operating point due to degradation. The physics-based model provides a theoretical structure, but alternatives are discussed as well which are particularly suitable for experimentalists. The failure probability function can be used to calculate the reliability of a multi-stack SOFC system. The effect of operating stacks under over-load conditions in terms of degradation is discussed. It is shown that the customized failure probability function better explains the dependency on operating conditions compared to standard parametric distribution functions. The originality of this work is mainly twofold: first, the construction of the failure probability function of a multi-stack SOFC using experimental data for degradation as well as start-up on a system level; second, the focus on technological implications covered by the methodology. Hence, this systems engineering methodology aims to provide a solution for reliability analysis in which the strength of both approaches are utilized, namely keeping sufficient parameter-dependency from the physics-based approach together with the simplicity of stochastic methods. This methodology is not limited to SOFC but may also be applicable to other modular (electrochemical) systems. Besides references on SOFC from a theoretical and experimental perspective, the extended bibliography also includes references on reliability analysis and engineering design, which may act as a starting point for related system analyses.
Article
This work aims at presenting the current works concerning the polygeneration systems simulation, by specially focusing on the potential integration of different technologies into a single system. Polygeneration allows one to produce energy vectors (power, heating and cooling) as wells as other useful products (hydrogen, syngas, biodiesel, fertilizers, drinking water etc.) by converting one or multiple energy sources. Polygeneration system can be fuelled by renewable sources (geothermal, solar, biomass, wind, hydro), as well as fossil fuels (natural gas, coal, hydrogen, etc.). In this paper innovative energy technologies, such as fuel cells and conventional ones are taken into account, by also focusing on the control strategies implemented for the proper management of polygeneration systems in general. Works regarding energy, economic and exergy analyses and system optimizations are also illustrated.
Article
A new cogeneration system consisting of a hydrogen-fed SOFC (solid oxide fuel cell), a GT (gas turbine) and a GAX (generator-absorber-heat exchange) absorption refrigeration cycle is proposed and analyzed in detail. The electrochemical equations for the fuel cell and thermodynamic and exergoeconomic relations for the system components are solved simultaneously with EES (Engineering Equation Solver) software. Through a parametric study, the influences of such decision parameters as current density, fuel utilization factor, pressure ratio and air utilization factor on the performance of the system are studied. In addition, using a genetic algorithm, the system performance is optimized for maximum exergy efficiency or minimum SUCP (sum of the unit costs of products). The results show that, the exergy efficiency of the proposed system is 6.5% higher than that of the stand-alone SOFC. It is also observed that the fuel cell stack contributes most to the total irreversibility. The exergoeconomic factor, the capital cost rate and the exergy destruction cost rate for the overall system are observed to be 27.3%, 10.63 $/h and 28.3 $/h, respectively. It is observed that for each 6 $/GJ increase in the hydrogen unit cost, the optimum sum of the unit costs of products is increased by around 62.5 $/GJ.
Article
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 (H2) 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 tCO2−1 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.
Article
In recent years, sustainable production of environmentally friendly electricity has become a major topic of discussion and research worldwide. One promising technology is the solid-oxide fuel cell (SOFC) power generation system. An SOFC utilizes a carbonaceous fuel gas (synthesis gas, for example) and an oxidant (typically air) to efficiently produce electrical power through an electrochemical reaction across a solid oxide barrier. There are key advantages to using SOFCs for power production. For example, the anode exhaust is mainly H2O and CO2, which are easily separated if the anode and cathode streams are not mixed downstream, and the cathode exhaust is mostly N2, which can be used for additional power generation or heat recovery and then safely vented. However, a significant disadvantage of the SOFC system is that there are currently cost-prohibitive operational challenges associated with its dynamic use, which limits the usefulness of an SOFC system for following a typical diurnal demand profile for electrical power. This work investigates a novel system that integrates a natural gas fuelled SOFC system for base load power production (Adams and Barton (2010)) with a compressed air energy storage (CAES) plant for load-following capabilities. This new system takes advantage of the already hot and compressed cathode exhaust by temporarily storing it underground with a relatively low parasitic energy penalty. The SOFC/CAES plant may be switched from storage mode (where the CAES system consumes power to store compressed cathode exhaust) to expansion mode (where the CAES system generates power by releasing stored compressed exhaust through a turbine). The plant operates in storage or expansion mode depending on whether the current power demand is lower or higher than the base power output provided by the SOFC system, respectively. The cathode and anode exhaust streams of the SOFC system are not mixed, and thus 100% CO2 capture from the anode exhaust can be maintained at all times. Simulations of the combined system under a variety of charging and discharging conditions are performed in Aspen-Plus and dynamic simulations of the load-following scenarios and dynamic mass balances on the storage cavern are executed in MATLAB. Simulation results based on real scaled market demand and pricing data show promising results for the SOFC/CAES system with regard to both its ability to provide peaking power as well as improve gross revenues due to hourly variations in electricity pricing. Moreover, the addition of CAES turbomachinery allows for effective load-following capabilities to be added to the SOFC system with very minor reductions in overall plant efficiency (∼1% HHV). Furthermore, unlike other standalone CAES plants, the SOFC/CAES hybrid plant does not require any additional air or fuel in order to operate the CAES section; all of the required electricity, heat, and compressed air can be obtained from the SOFC and its waste streams. Therefore, the SOFC/CAES system provides load-following power generation from fossil fuels with essentially zero CO2 emissions at high efficiencies. A techno-economic analysis of the combined SOFC/CAES system is also performed, and its profitability is discussed and compared to other systems.
Article
The process design, simulation, and control of a solid oxide fuel cell (SOFC)/gas turbine (GT) hybrid power generation system combined with a compressed-fuel processing unit (CFPU) are presented. Given that CO2 is the input of the CFPU, the net CO2 emissions of this hybrid power system are suppressed under 324.2 g of CO2/kWh. Using the combined heat and power (CHP) approach, the hybrid power efficiency increases from 33% to 50%. Based on a single-input-single-output (SISO) control configuration, an inferential power control strategy using a static inferential model is implemented to improve the accuracy of the power estimation and effectively regulates the SOFC power output.
Article
Solid oxide fuel cell (SOFC) is regarded as one of the promising energy conversion technologies since it enables distributed power supply based on modularity and provides a high efficiency while emitting less CO2 than conventional power systems. In this sense, a number of SOFC systems have been studied actively aiming at high efficiency with various capacity, assisted by thermodynamic system analysis. However, previous SOFC stack models are not appropriate for the thermodynamic system analysis because those models use multi-dimensional simulation tools and require gross computational resources with excessive calculation time. Thus, in this study, an 1D model that employs analytical expressions with design values and properties measured from an in-house-fabricated SOFC for thermo-electrochemistry and resolves spatially a SOFC stack is developed by using C# to investigate its electrochemical and thermal behavior. The model is validated by using experimental data and is used to elucidate the effect of key operating conditions on thermo-electrochemical performance. A parametric study is conducted with respect to various operation variables such as current density, fuel utilization, air utilization, pressure, and steam to carbon ratio in order to estimate optimal SOFC operating conditions. Considering the effect of each parameter on the 1st law efficiency and outlet gas temperature, a performance map is derived as a function of current density, fuel utilization, and air utilization. To gain the efficiency higher than 50% and outlet gas temperature lower than 900℃, it is shown that the combination of a low current density, high fuel utilization, and low air utilization is necessary at an expense of power density and thermal energy. The results obtained in this study enables capturing optimal operating conditions of a SOFC stack without performing costly experiments.
Article
Full-text available
This paper presents design and dispatch optimization models of a solid-oxide fuel cell (SOFC) assembly for unconventional oil and gas production. Fuel cells are galvanic cells which electrochemically convert hydrocarbon-based fuels to electricity. The Geothermic Fuel Cell (GFC) concept involves utilizing heat from fuel cells during electricity generation to provide thermal energy required to pyrolyze kerogen into a mixture of oil, hydrocarbon gas and carbon-rich shale coke. We formulate a continuous, non-convex nonlinear program (NLP) in A Mathematical Programming Language (AMPL) to analyze the techno-economic characteristics of the GFC system. The problem is separated into a design model (D) and a dispatch model (O). The GFC design problem determines the size and configuration of a single heater well. Specifically, we optimize the heater length and number of SOFC stacks in each assembly such that the maximum volume of oil shale is heated per well. Using the resulting design from (D), the dispatch model (O) determines daily GFC operating conditions through variation in electric current, fuel utilization, and stoics of excess air. We optimize the system operating costs and the combined-heat-and-power efficiency, subject to geology heating demands, auxiliary component electric power demands and GFC system performance characteristics. Solutions to the design and dispatch problems are obtained using the IPOPT and KNITRO solvers. A case study shows that the optimal well-head cost of oil and gas produced using the GFC technology is about $39 bbl-1, which is comparable to that from other unconventional crude oil extraction techniques. The optimal dispatch strategy results in a maximum heating efficiency of 43% and a combined-heat-and-power efficiency of 79%. The Geothermic Fuel Cell’s performance is better than current in situ upgrading technologies that rely on electricity supplied from the grid at generation-and-transmission efficiencies near 33%.
Conference Paper
Full-text available
The latest guidelines approved by the environmental protection committee of the international maritime organization (IMO) will require the shipping sector to reduce its greenhouse gas (GHG) emissions by 50% before 2050 and achieve a complete de-carbonization by the end of the century. This will require a major change in the way ships are built and operated today. In this paper, we aim at understanding what types of ship energy systems and fuels will be preferable and what will be the costs to achieve the environmental goals set by IMO for shipping. To do this, we approach the question as an MILP problem, with increasingly stringent constraints on the total GHG emissions and with the objective of minimizing the total cost of ownership. We apply this analysis to three ship types (a containership, a tanker, and a passenger ferry) and we determine what type of choice for the ship's energy systems will be the most optimal, for each ship type. The results show that the most cost-effective pathway towards the elimination of GHG emissions is composed of a first phase with LNG as fuel and with an increasing use of carbon capture and storage, while the full decarbonisation of the shipping sector will require switching to hydrogen as fuel. These results depend only marginally on the type of ship investigated and on the type of regulation enforced. While the costs required to achieve up to 75% GHG emission reduction are relatively similar to the baseline case (50-70% higher), moving towards a full decarbonisation will require a cost increase ranging between 280% and 340% higher than the business as usual.
Article
Cathode airflow regulation is considered an effective means for thermal management in solid oxide fuel cell gas turbine (SOFC-GT) hybrid system. However, performance and controllability are observed to vary significantly with different fuel compositions. Because a complete system characterization with any possible fuel composition is not feasible, the need arises for robust controllers. The sufficiency of robust control is dictated by the effective change of operating state given the new composition used. It is possible that controller response could become unstable without a change in the gains from one state to the other. In this paper, cathode airflow transients are analyzed in a SOFC-GT system using syngas as fuel composition, comparing with previous work which used humidified hydrogen. Transfer functions are developed to map the relationship between the airflow bypass and several key variables. The impact of fuel composition on system control is quantified by evaluating the difference between gains and poles in transfer functions. Significant variations in the gains and the poles, more than 20% in most cases, are found in turbine rotational speed and cathode airflow. The results of this work provide a guideline for the development of future control strategies to face fuel composition changes.
Article
Full-text available
Fuels derived from biomass feedstocks are a particularly attractive energy resource pathway given their inherent advantages of energy security via domestic fuel crop production and their renewable status. However, there are numerous questions regarding how to optimally produce, distribute, and utilize biofuels such that they are economically, energetically, and environmentally sustainable. Comparative analyses of two conceptual 2000 tons/day thermochemical-based biorefineries are performed to explore the effects of emerging technologies on process efficiencies. System models of the biorefineries, created using ASPEN Plus®, include all primary process steps required to convert a biomass feedstock into hydrogen, including gasification, gas cleanup and conditioning, hydrogen purification, and thermal integration. The biorefinery concepts studied herein are representative of “near-term” (approximately 2015) and “future” (approximately 2025) plants. The near-term plant design serves as a baseline concept and incorporates currently available commercial technologies for all nongasifier processes. Gasifier technology employed in these analyses is centered on directly heated, oxygen-blown, fluidized-bed systems that are pressurized to nearly 25 bars. The future plant design employs emerging gas cleaning and conditioning technologies for both tar and sulfur removal unit operations. A 25% increase in electric power production is observed for the future case over the baseline configuration due to the improved thermal integration while realizing an overall plant efficiency improvement of 2 percentage points. Exergy analysis reveals that the largest inefficiencies are associated with the (i) gasification, (ii) steam and power production, and (iii) gas cleanup and purification processes. Additional suggestions for improvements in the biorefinery plant for hydrogen production are given.
Conference Paper
Full-text available
Production of pure hydrogen from various gas mixtures by using Pressure Swing Adsorption (PSA) has become the state-of-the-art industrial technology. Recent ideas to increase a separation quality (product purity/recovery) and to decrease power requirements, such as the specially designed PSA processes for simultaneous production of pure H2 and CO2 from steam methane reforming off-gas (SMROG), have attracted an increasing interest. In this work, the PSA modelling framework developed in the previous work has been employed in a design and modelling of several PSA configurations for production of H2 and CO2 from SMROG. Based on the existing industrial system, new and modified PSA cycle configurations consisting of two groups of adsorption columns undergoing different cycle steps have been designed and simulated by using the modelling framework. The simulation results have been compared to the results of the existing commercial process.
Article
The H2A Production Model analyzes the technical and economic aspects of central and forecourt hydrogen production technologies. Using a standard discounted cash flow rate of return methodology, it determines the minimum hydrogen selling price, including a specified after-tax internal rate of return from the production technology. Users have the option of accepting default technology input values--such as capital costs, operating costs, and capacity factor--from established H2A production technology cases or entering custom values. Users can also modify the model's financial inputs. This new version of the H2A Production Model features enhanced usability and functionality. Input fields are consolidated and simplified. New capabilities include performing sensitivity analyses and scaling analyses to various plant sizes. This User Guide helps users already familiar with the basic tenets of H2A hydrogen production cost analysis get started using the new version of the model. It introduces the basic elements of the model then describes the function and use of each of its worksheets.
Article
This analysis developed detailed process flow diagrams and an Aspen Plus{reg_sign} model, evaluated energy flows including a pinch analysis, obtained process equipment and operating costs, and performed an economic evaluation of two process designs based on the syngas clean up and conditioning work being performed at NREL. One design, the current design, attempts to define today's state of the technology. The other design, the goal design, is a target design that attempts to show the effect of meeting specific research goals.
Article
Simultaneous hydrogen separation and compression using high-temperature (>100 °C) PEM fuel cell technology (PBI) was demonstrated for pure hydrogen, nitrogen/hydrogen mixtures and reformate feed gas mixtures containing various amounts of CO, CO2 and CH4. Gas purity measurements of the separated gas were performed and significant reductions in impurities were achieved. The effects of hydrogen concentration, inlet gas humidification, operating temperature and air bleed on the cell performance were studied and hydrogen diffusion through the polybenzimidazole membrane was measured. The hydrogen separation required relatively low energy consumption and demonstrated good dynamic response. Simultaneous separation and compression of hydrogen up to 0.65 barg was demonstrated.
Article
A quasi-two-dimensional numerical model is presented for the efficient computation of the steady-state current density, species concentration, and temperature distributions in planar solid oxide fuel cell stacks. The model reduction techniques, engineering approximations, and numerical procedures used to simulate the stack physics while maintaining adequate computational speed are discussed. The results of the model for benchmark cases with and without on-cell methane reformation are presented with comparisons to results from other research described in the literature. Simulations results for a multi-cell stack have also been demonstrated to show capability of the model on simulating cell to cell variation. The capabilities, performance, and scalability of the model for the study of large multi-cell stacks are then demonstrated.
Article
The Integrated Planar Solid Oxide Fuel Cell (IP-SOFC) is an innovative fuel cell concept which is substantially a cross between tubular and planar geometries, seeking to borrow thermal compliance properties from the former and low cost component fabrication and short current paths from the latter. In this study, a simulation model for the IP-SOFC is presented, with particular highlight on the simulation of the local reaction, taking into account the chemical and electrochemical processes occurring at the electrodes, together with mass transport issues. Some aspects of the overall reactor simulation are discussed as well. The model results have been compared to the experimental data obtained from both a small scale IP-SOFC module and a full-size prototype; in both cases the agreement is good. This electrochemical model is the basis of a detailed model of the full-scale IP-SOFC reactor to be included into a plant simulation tool designed to support thermodynamic analysis of hybrid IP-SOFC/GT (Gas Turbine) systems.
Article
The technical and economic feasibility of producing hydrogen from biomass by means of indirectly heated gasification and steam reforming was studied. A detailed process model was developed in ASPEN Plus{trademark} to perform material and energy balances. The results of this simulation were used to size and cost major pieces of equipment from which the determination of the necessary selling price of hydrogen was made. A sensitivity analysis was conducted on the process to study hydrogen price as a function of biomass feedstock cost and hydrogen production efficiency. The gasification system used for this study was the Battelle Columbus Laboratory (BCL) indirectly heated gasifier. The heat necessary for the endothermic gasification reactions is supplied by circulating sand from a char combustor to the gasification vessel. Hydrogen production was accomplished by steam reforming the product synthesis gas (syngas) in a process based on that used for natural gas reforming. Three process configurations were studied. Scheme 1 is the full reforming process, with a primary reformer similar to a process furnace, followed by a high temperature shift reactor and a low temperature shift reactor. Scheme 2 uses only the primary reformer, and Scheme 3 uses the primary reformer and the high temperature shift reactor. A pressure swing adsorption (PSA) system is used in all three schemes to produce a hydrogen product pure enough to be used in fuel cells. Steam is produced through detailed heat integration and is intended to be sold as a by-product.
Article
This study is being performed as part of the U.S. Department of Energy and Xcel Energy's Wind-to-Hydrogen Project (Wind2H2) at the National Renewable Energy Laboratory. The general aim of the project is to identify areas for improving the production of hydrogen from renewable energy sources. These areas include both technical development and cost analysis of systems that convert renewable energy to hydrogen via water electrolysis. Increased efficiency and reduced cost will bring about greater market penetration for hydrogen production and application. There are different issues for isolated versus grid-connected systems, however, and these issues must be considered. The manner in which hydrogen production is integrated in the larger energy system will determine its cost feasibility and energy efficiency.
Article
The Solid Oxide Cells (SOCs) are able to operate in two modes: (a) the Solid Oxide Fuel Cells (SOFCs) that produce electricity and heat and (b) the Solid Oxide Electrolyser Cells (SOEC) that consume electricity and heat to electrolyse water and produce hydrogen and oxygen.The present paper presents a carbon free SOEC/SOFC combined system for the production of hydrogen, electricity and heat (tri-generation) from natural gas fuel. Hydrogen can be locally used as automobile fuel whereas the oxygen produced in the SOEC is used to combust the depleted fuel from the SOFC, which is producing electricity and heat from natural gas. In order to achieve efficient carbon capture in such a system, water steam should be used as the SOEC anode sweep gas, to allow the production of nitrogen free flue gases. The SOEC and SOFC operations were matched through modeling of all components in Aspenplus™. The exergetic efficiency of the proposed decentralised system is 28.25% for power generation and 18.55% for production of hydrogen. The system is (a) carbon free because it offers an almost pure pressurised CO2 stream to be driven for fixation via parallel pipelines to the natural gas feed, (b) does not require any additional water for its operation and (c) offers 26.53% of its energetic input as hot water for applications.
Article
Electrochemical hydrogen pumping using a high-temperature (>100 • C) polybenzimidazole (PBI) membrane was demonstrated under non-humidified and humidified conditions at ambient pressures. Relatively low voltages were required to operate the pump over a wide range of hydrogen flow rates. The advantages of the high-temperature capability were shown by operating the pump on reformate feed gas mixtures containing various amounts of CO and CO 2 . Gas purity measurements on the cathode gas product were conducted and significant reductions in gas impurities were detected. The applicability of the PBI membrane for electrochemical hydrogen pumping and its durability under typical operating conditions were established with tests that lasted for nearly 4000 h.
Article
The aim of the present work is to assess the requirements of an SOFC mathematic model for system simulation. Several models can be found in the literature to predict fuel cells electrochemical and thermo-fluid-dynamic characteristics, but these models are generally based on local characteristics, such as gas concentration, temperature, pressure and so on. The equations representing these characteristics can be in a finite or differential form, but, in any case, they are locally solved using a mesh. The obtainable results can be very useful to guide future researches for FC improvements and optimization. On the other hand, most of these data are useless if the FC system has to be modeled. In this situation, in fact, what is necessary for mathematic modeling are just the discharge characteristics, such as outlet gas composition and temperature, the electric current and power provided. Moreover, calculations for micro-model solution imply numerical methods that are often complex and time consuming.Since during FC systems parametric analyses, the FC characteristics can be computed up 2 hundred times, the need for an easy model is crucial.In applying the local equations as “global”, however, some problems can arise. In the present work, a review of the most significant SOFC models is conducted and then the possibility of their use in a macro-model is evaluated. Different results can be generated according to the assumptions made when adapting micro-model equations to a macro-model. A quantitative analysis of these differences is finally performed and the reliability of the model is estimated.
Low-cost Co-production of Hydrogen and Electricity, DOE Hydrogen Energy Program FY 2008 Annual Progress Report, Presented at the Available from
  • F Mitlitsky
F. Mitlitsky, Low-cost Co-production of Hydrogen and Electricity, DOE Hydrogen Energy Program FY 2008 Annual Progress Report, Presented at the 2008 DOE Annual Merit and Peer Review, 2008. Available from: http://www.hydrogen.energy.gov/pdfs/progress08/v d 6 mitlitsky.pdf.
Integrated Gasification Fuel Cell Performance and Cost Assessment
  • K Gerdes
  • E Grol
  • D Keairns
  • R Newby
K. Gerdes, E. Grol, D. Keairns, R. Newby, Integrated Gasification Fuel Cell Performance and Cost Assessment, DOE/NETL-2009/1361, March, 2009.
H2A Hydrogen Production Analysis Software Case Study: Current (2005) Steam Methane Reformer at Forecourt 1500 kg/day
  • B D James
B.D. James, H2A Hydrogen Production Analysis Software Case Study: Current (2005) Steam Methane Reformer at Forecourt 1500 kg/day, National Renewable Energy Laboratory, 2009, Available from: http://www.hydrogen.energy.gov/h2a production.html.
FCPower CHP Production Analysis Software Case Study: Molten Carbonate Fuel Cell Case Study
  • D Steward
  • M Penev
D. Steward, M. Penev, FCPower CHP Production Analysis Software Case Study: Molten Carbonate Fuel Cell Case Study, National Renewable Energy Laboratory, Golden, CO, 2009, Available from: http://www.hydrogen.energy.gov/fc power analysis.html.
Systems Analysis Vehicle Technologies and Hydrogen Programs, Annual Merit Review and Peer Evaluation Meeting, U.S. Depart-ment of Energy
  • F Joseck
F. Joseck, Systems Analysis, 2010 Vehicle Technologies and Hydrogen Programs, Annual Merit Review and Peer Evaluation Meeting, U.S. Depart-ment of Energy, June 7–11, Washington, D.C., 2010. Available from: http://www.hydrogen.energy.gov/.
Comparison of Various Strategies for Small Scale Production of Hydrogen
  • D Steward
D. Steward, Comparison of Various Strategies for Small Scale Production of Hydrogen, Internal Report, National Renewable Energy Laboratory, Golden, CO, December 2009, personal communication, July 2011.
  • R Bove
  • P Lunghi
  • N M Sammes
R. Bove, P. Lunghi, N.M. Sammes, Int. J. Hydrogen Energy 30 (2) (2005) 181.
  • P Costamagna
  • A Selimovic
  • M D Borghi
  • G Agnew
P. Costamagna, A. Selimovic, M.D. Borghi, G. Agnew, Chem. Eng. J. 102 (1) (2004) 61.
  • K Lai
  • B J Koeppel
  • K S Choi
  • K P Recknagle
  • X Sun
  • L A Chick
  • V Korolev
K. Lai, B.J. Koeppel, K.S. Choi, K.P. Recknagle, X. Sun, L.A. Chick, V. Korolev, M. Khaleel, J. Power Sources 196 (6) (2011) 3204–3222.
  • G Eisman
  • D Neumann
  • B C Benicewicz
  • A M Galeano
  • Pump
G. Eisman, D. Neumann, B.C. Benicewicz, A.M. Galeano, H2 Pump, LLC, <http://www.h2pumpllc.com/5.html> (accessed 2011).
  • S Campanari
  • P Iora
S. Campanari, P. Iora, J. Power Sources 132 (1-2) (2004).
  • R P O'hayre
  • S W Cha
  • W Colella
  • F B Prinz
R.P. O'Hayre, S.W. Cha, W. Colella, F.B. Prinz, Fuel Cell Fundamentals, John Wiley & Sons, Inc., New York, USA, 2009.
  • M Thomassen
  • E Sheridan
  • J Kvello
  • J Nat
M. Thomassen, E. Sheridan, J. Kvello, J. Nat. Gas Sci. Eng. 2 (5) (2010) 229–234.
  • P Lisbona
  • A Corradetti
  • R Bove
  • P Lunghi
P. Lisbona, A. Corradetti, R. Bove, P. Lunghi, Electrochim. Acta 53 (4) (2006) 1920-1930.
  • M Thomassen
  • E Sheridan
  • J Kvello
M. Thomassen, E. Sheridan, J. Kvello, J. Nat. Gas Sci. Eng. 2 (5) (2010) 229-234.
Low-cost Co-production of Hydrogen and Electricity, DOE Hydrogen Energy Program FY 2008 Annual Progress Report, Presented at the 2008 DOE Annual Merit and Peer Review
  • F Mitlitsky
F. Mitlitsky, Low-cost Co-production of Hydrogen and Electricity, DOE Hydrogen Energy Program FY 2008 Annual Progress Report, Presented at the 2008 DOE Annual Merit and Peer Review, 2008. Available from: http://www.hydrogen.energy.gov/pdfs/progress08/v d 6 mitlitsky.pdf.
  • N Perdikaris
  • K D Panopoulos
  • P Hofmann
  • S Spyrakis
  • E Kakaras
N. Perdikaris, K.D. Panopoulos, P. Hofmann, S. Spyrakis, E. Kakaras, Int. J. Hydrogen Energy 35 (6) (2010) 2446-2456.
  • K Lai
  • B J Koeppel
  • K S Choi
  • K P Recknagle
  • X Sun
  • L A Chick
  • V Korolev
  • M Khaleel
K. Lai, B.J. Koeppel, K.S. Choi, K.P. Recknagle, X. Sun, L.A. Chick, V. Korolev, M. Khaleel, J. Power Sources 196 (6) (2011) 3204-3222.
Hydrogen Purification by Pressure Swing Adsorption
  • D Nikolic
  • A Giovanoglou
  • M C Georgiadis
  • E S Kikkinides
D. Nikolic, A. Giovanoglou, M.C. Georgiadis, E.S. Kikkinides, Hydrogen Purification by Pressure Swing Adsorption, PRISM EC Contract Number MRTC-CT-2004-512233, 2004.
Vehicle Technologies and Hydrogen Programs, Annual Merit Review and Peer Evaluation Meeting
  • D Steward
  • M Penev
D. Steward, M. Penev, Fuel Cell Power Model: Evaluation of CHP and CHHP Applications, 2010 Vehicle Technologies and Hydrogen Programs, Annual Merit Review and Peer Evaluation Meeting, U.S. Department of Energy, June 7-11, Washington, D.C., 2010. Available from: http://www.hydrogen.energy.gov/.
Vehicle Technologies and Hydrogen Programs, Annual Merit Review and Peer Evaluation Meeting
  • F Joseck
F. Joseck, Systems Analysis, 2010 Vehicle Technologies and Hydrogen Programs, Annual Merit Review and Peer Evaluation Meeting, U.S. Department of Energy, June 7-11, Washington, D.C., 2010. Available from: http://www.hydrogen.energy.gov/.