417 results found
Liu YH, Wu ZQ, Brandon NP, 2011, Application of SOFCs to Electric Power System, Asia-Pacific Power and Energy Engineering Conference (APPEEC), Publisher: IEEE, ISSN: 2157-4839
Zhao Y, Shah N, Brandon NP, 2011, Comparison between two optimization strategies for Solid Oxide Fuel Cell-Gas Turbine hybrid cycles, International Journal of Hydrogen Energy, Vol: in press
This paper compares the performance characteristics of a combined power system with solid oxide fuel cell (SOFC) and gas turbine (GT) working under two thermodynamic optimization strategies. Expressions of the optimized power output and efficiency for both the subsystems and the SOFC-GT hybrid cycle are derived. Optimal performance characteristics are discussed and compared in detail through a parametric analysis to evaluate the impact of multi-irreversibilities that take into account on the system behaviour. It is found that there exist certain new optimum criteria for some important design and operating parameters. Engineers should find the methodologies developed in this paper useful in the optimal design and practical operation of complex hybrid fuel cell power plants.
Brett DJL, Brandon NP, Hawkes AD, et al., 2011, Fuel cell systems for small and micro combined heat and power (CHP) applications, Small and micro combined heat and power (CHP) systems, Editors: Beith, Cambridge, UK, Publisher: Woodhead Publishing Limited, Pages: 233-261
Matian M, Marquis A, Brandon NP, 2011, Model based design and test of cooling plates for an air-cooled polymer electrolyte fuel cell stack, Int. Journal of Hydrogen Energy
Offer GJ, Contestabile M, Howey DA, et al., 2011, Techno-economic and behavioural analysis of battery electric, hydrogen fuel cell and hybrid vehicles in a future sustainable road transport system in the UK, Energy Policy, Vol: 39, Pages: 1939-1950, ISSN: 0301-4215
Diomampo GP, Roach H, Chapin M, et al., 2010, Integrated dynamic reservoir modeling for multilayered tight gas sand development, Pages: 1065-1080
This paper summarizes the approach used for applying integrated reservoir modeling to the tight gas sands of the Pinedale Anticline in western Wyoming. The simulation of tight gas sands such as those at Pinedale has always been challenging because of the high degree of heterogeneity that needs to be retained to replicate reservoir performance, coupled with computing constraints. Added to this, simulating the Pinedale reservoir has its own unique challenges due to its characteristically thick gross sand interval composed of multiple, heterogeneous sand bodies produced commingled in a well. An intensive data-gathering program to investigate optimum well spacing accompanied the simulation effort. A significant part of this program was the installation of pressure monitor wells1 to detect communication with surrounding producers at the hydraulic fracture stage level. This was coupled with multiple time-lapse production logs. The two data sets together allowed better definition of stage performance at producing wells. Static models were built with fine resolution to duplicate reservoir heterogeneity. However, upscaling was necessary due to computing constraints. The upscaling procedure of Li and Beckner2 was utilized to maintain substantial geologic heterogeneity. The upscaled model was calibrated to mimic fine scale well performance prior to history matching. Several sector upscale models were history matched using a statistical approach without compromising key aspects such as reservoir connectivity and proper mass withdrawal from each geologic sub layer. Hydraulic fractures in each stage were characterized through history matching. Given the geostatistical nature, an exact match on every frac stage and every pressure gauge located away from the producer should not be expected. Rather, a more statistical definition of a history match should be adapted to a level that still gives confidence in forecasting the value of future infill wells. The history-matched parameters
Konda NVSNM, Shah N, Kramer GJ, et al., 2010, Critical evaluation of H2 production technologies: When do other technologies become economically competitive with steam methane reforming?, 10AIChE - 2010 AIChE Annual Meeting, Conference Proceedings
Hydrogen is generally considered as one of the potential fuels of the future transportation. However the high production cost has remained a barrier that is yet to be overcome. There are various H2 production routes based on thermo-chemical, electrolytic and biological processes. These include steam methane reforming (SMR), coal gasification (CG), biomass gasification (BG) and water electrolysis (WE). Within the context of H2 production, while SMR, CG and WE are commercially available, BG is still in the development/demonstration stage (Ball and Wietschel, 2009). While SMR is currently the cheapest production technology, all these technologies are characteristically different in their cost foot-print. For instance, gasification can be twice as much capital intensive as reforming technology (NAE, 2004). On the other hand, the common feed-stocks used in gasification (i.e., coal and biomass) are usually less expensive than the feed-stock (i.e., natural gas, NG) used in SMR. Since the total production cost depends on both the capital investment and the price of raw-materials, the actual production cost in the future depends on the technological advancements and the future feed-stock price. While both the technological advancements and the feed-stock prices in future are uncertain, a recent study by Kramer and co-workers (Schoots, et al., 2008) has concluded, based on an extensive historical data since 1940, that the cost reduction potential on the basis of technology learning for SMR, CG and WE is limited. While they did not rule out the possibility of potential to reduce the electrolytic H2 production costs due to technological advancements (such as PEM-based electrolysis), the challenges on electrolysis are twofold as it is both capital and energy intensive. Subsequently, the renewable electricity driven H2 production route will have even more challenges (which is partly due to the competition from electricity sector) to overcome. Thus, in future, the feedstock price
Konda NVSNM, Shah N, Kramer GJ, et al., 2010, An integrated spatiotemporal modelling, design and optimization framework for the large-scale deployment of CO2 capture, transport and storage, 10AIChE - 2010 AIChE Annual Meeting, Conference Proceedings
One of the main stumbling blocks to realize large-scale deployment of carbon capture and storage (CCS) is the huge upfront costs involved. In addition, the usual geologically-dispersed nature of the large number of CO2 point-sources and sinks calls for a perspective that is beyond 'matching each source with the nearest sink' and requires a holistic-systems perspective. Furthermore, since the CO2 emission mitigation targets are expected to gradually increase over the next several decades, it is important that the CCS network is developed in harmony with the mitigation targets while ensuring that the investments are made optimally (as and when/where they are necessary) to minimising the entire lifecycle costs. Hence, in this contribution we have proposed a comprehensive optimization framework, that is spatially and temporally explicit, to design the least-cost CCS networks and their optimal evolution with time over the next four decades (i.e., until 2050). Such a long-term perspective also helps to optimally place the future fossil fuel-based plants (e.g., power plants and H2 production plants). While spatially explicit CCS networks design is not entirely new, optimization based studies are rather limited and dynamic-model based optimization studies are even more limited in the literature. In this respect, our framework is novel and helps minimize the overall costs. We have then demonstrated the applicability and usefulness of our approach with a real case study by applying it to design CCS networks for the Netherlands. A recent study (Konda et. al., 2010) has shown that CCS must be an integral part of the Dutch CO2 mitigation portfolio to comply with the local and regional (i.e., EU level) CO2 mitigation targets. Further, the availability of a number of large-scale CO2 point-sources and large storage capacity makes CCS an attractive CO2 mitigation option for the Netherlands. Potential CO2 sources considered include 110 power and industrial sources (including refineri
Cai Q, Luna-Ortiz E, Adjiman CS, et al., 2010, The Effects of Operating Conditions on the Performance of a Solid Oxide Steam Electrolyser: A Model-Based Study, Fuel Cells, Vol: 10, Pages: 1114-1128, ISSN: 1615-6854
To support the development of hydrogen production by high temperature electrolysis using solid oxide electrolysis cells (SOECs), the effects of operating conditions on the performance of the SOECs were investigated using a one-dimensional model of a cathode-supported planar SOEC stack. Among all the operating parameters, temperature is the most influential factor on the performance of an SOEC, in terms of both cell voltage and operation mode (i.e. endothermic, thermoneutral and exothermic). Current density is another influential factor, in terms of both cell voltage and operation mode. For the conditions used in this study it is recommended that the SOEC be operated at 1,073 K and with an average current density of 10,000 A m–2, as this results in the stack operating at almost constant temperature along the cell length. Both the steam molar fraction at the inlet and the steam utilisation factor have little influence on the cell voltage of the SOEC but their influence on the temperature distribution cannot be neglected. Changes in the operating parameters of the SOEC can result in a transition between endothermic and exothermic operation modes, calling for careful temperature control. The introduction of air into the anode stream appears to be a promising approach to ensure small temperature variations along the cell.
Sadhukhan J, Zhao Y, Leach M, et al., 2010, Energy Integration and Analysis of Solid Oxide Fuel Cell Based Microcombined Heat and Power Systems and Other Renewable Systems Using Biomass Waste Derived Syngas, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, Vol: 49, Pages: 11506-11516, ISSN: 0888-5885
Patcharavorachot Y, Brandon NP, Paengjuntuek W, et al., 2010, Analysis of planar solid oxide fuel cells based on proton-conducting electrolyte, SOLID STATE IONICS, Vol: 181, Pages: 1568-1576, ISSN: 0167-2738
Iora P, Taher MAA, Chiesa P, et al., 2010, A novel system for the production of pure hydrogen from natural gas based on solid oxide fuel cell-solid oxide electrolyzer, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, Vol: 35, Pages: 12680-12687, ISSN: 0360-3199
Shearing PR, Brett DJL, Brandon NP, 2010, Towards intelligent engineering of SOFC electrodes: a review of advanced microstructural characterisation techniques, INTERNATIONAL MATERIALS REVIEWS, Vol: 55, Pages: 347-363, ISSN: 0950-6608
Ivey DG, Brightman E, Brandon N, 2010, Structural modifications to nickel cermet anodes in fuel cell environments, JOURNAL OF POWER SOURCES, Vol: 195, Pages: 6301-6311, ISSN: 0378-7753
Cai Q, Brett DJL, Browning D, et al., 2010, A sizing-design methodology for hybrid fuel cell power systems and its application to an unmanned underwater vehicle, Journal of Power Sources, Vol: 195, Pages: 6559-6569, ISSN: 0378-7753
Hybridizing a fuel cell with an energy storage unit (battery or supercapacitor) combines the advantages of each device to deliver a system with high efficiency, low emissions, and extended operation compared to a purely fuel cell or battery/supercapacitor system. However, the benefits of such a system can only be realised if the system is properly designed and sized, based on the technologies available and the application involved. In this work we present a sizing-design methodology for hybridisation of a fuel cell with a battery or supercapacitor for applications with a cyclic load profile with two discrete power levels. As an example of the method's application, the design process for selecting the energy storage technology, sizing it for the application, and determining the fuel load/range limitations, is given for an unmanned underwater vehicle (UUV). A system level mass and energy balance shows that hydrogen and oxygen storage systems dominate the mass and volume of the energy system and consequently dictate the size and maximum mission duration of a UUV.
Shearing PR, Gelb J, Yi J, et al., 2010, Analysis of triple phase contact in Ni-YSZ microstructures using non-destructive X-ray tomography with synchrotron radiation, ELECTROCHEMISTRY COMMUNICATIONS, Vol: 12, Pages: 1021-1024, ISSN: 1388-2481
Shearing PR, Cai Q, Golbert JI, et al., 2010, Microstructural analysis of a solid oxide fuel cell anode using focused ion beam techniques coupled with electrochemical simulation, JOURNAL OF POWER SOURCES, Vol: 195, Pages: 4804-4810, ISSN: 0378-7753
Porous composite electrodes play a critical role in determining the performance and durability of solid oxide fuel cells, which are now emerging as a high efficiency, low emission energy conversion technology for a wide range of applications.In this paper we present work to combine experimental electrochemical and microstructural characterisation with electrochemical simulation to characterise a porous solid oxide fuel cell anode. Using a standard, electrolyte supported, screen printed Ni-YSZ anode, electrochemical impedance spectroscopy has been conducted in a symmetrical cell configuration. The electrode microstructure has been characterised using FIB tomography and the resulting microstructure has been used as the basis for electrochemical simulation. The outputs from this simulation have in turn been compared to the results of the electrochemical experiments.A sample of an SOFC anode of 6.68 mu m x 5.04 mu m x 1.50 mu m in size was imaged in three dimensions using FIB tomography and the total triple phase boundary density was found to be 13 mu m(-2). The extracted length-specific exchange current for hydrogen oxidation (97% H-2, 3% H2O) at a Ni-YSZ anode was found to be 0.94 x 10(-10), 2.14 x 10(-10), and 12.2 x 10(-10) A mu m(-1) at 800, 900 and 1000 degrees C, respectively, consistent with equivalent literature data for length-specific exchange currents for hydrogen at geometrically defined nickel electrodes on YSZ electrolytes. (C) 2010 Elsevier B.V. All rights reserved.
Shearing PR, Gelb J, Brandon NP, 2010, X-ray nano computerised tomography of SOFC electrodes using a focused ion beam sample-preparation technique, JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, Vol: 30, Pages: 1809-1814, ISSN: 0955-2219
Weng X, Brett D, Yufit V, et al., 2010, Highly conductive low nickel content nano-composite dense cermets from nano-powders made via a continuous hydrothermal synthesis route, Solid State Ionics, Vol: 181, Pages: 827-834
Cai Q, Brandon NP, Adjiman CS, 2010, Modelling the dynamic response of a solid oxide steam electrolyser to transient inputs during renewable hydrogen production, Frontiers of Energy and Power Engineering in China, Vol: 4, Pages: 211-222, ISSN: 1673-7504
Hydrogen is regarded as a leading candidate for alternative future fuels. Solid oxide electrolyser cells (SOEC) may provide a cost-effective and green route to hydrogen production especially when coupled to a source of renewable electrical energy. Developing an understanding of the response of the SOEC stack to transient events that may occur during its operation with intermittent electricity input is essential before the realisation of this technology. In this paper, a one-dimensional (1D) dynamic model of a planar SOEC stack has been employed to study the dynamic behaviour of such an SOEC and the prospect for stack temperature control through variation of the air flow rate. Step changes in the average current density from 1.0 to 0.75, 0.5 and 0.2 A/cm2 have been imposed on the stacks, replicating the situation in which changes in the supply of input electrical energy are experienced, or the sudden switch-off of the stack. Such simulations have been performed both for open-loop and closed-loop cases. The stack temperature and cell voltage are decreased by step changes in the average current density. Without temperature control via variation of the air flow rate, a sudden fall of the temperature and the cell potential occurs during all the step changes in average current density. The temperature excursions between the initial and final steady states are observed to be reduced by the manipulation of the air flow rate. Provided that the change in the average current density does not result in a transition from exothermic to endothermic operation of the SOEC, the use of the air flow rate to maintain a constant steady-state temperature is found to be successful.
Brandon NP, 2010, Understanding solid oxide fuel cell microstructure, ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, Vol: 239, ISSN: 0065-7727
Shearing PR, Howard LE, Jorgensen PS, et al., 2010, Characterization of the 3-dimensional microstructure of a graphite negative electrode from a Li-ion battery, ELECTROCHEMISTRY COMMUNICATIONS, Vol: 12, Pages: 374-377, ISSN: 1388-2481
Mermelstein J, Millan M, Brandon N, 2010, The impact of steam and current density on carbon formation from biomass gasification tar on Ni/YSZ, and Ni/CGO solid oxide fuel cell anodes, Journal Power Sources, Vol: 195, Pages: 1657-1666
Maher RC, Brightman E, Heck C, et al., 2010, Monitoring Solid Oxide Fuel Cell Processes Using In-Situ Raman Spectroscopy, 22nd International Conference on Raman Spectroscopy, Publisher: AMER INST PHYSICS, Pages: 550-550, ISSN: 0094-243X
Brandon NP, Matian M, Marquis AJ, et al., 2010, THERMAL MANAGEMENT ISSUES IN FUEL CELL TECHNOLOGY, 14th International Heat Transfer Conference, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 591-599
Zhao Y, Shah N, Brandon N, 2010, Performance investigation of a SOFC-GT hybrid system based on thermodynamic optimization strategies, Proceedings of the 23rd International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems, ECOS 2010, Vol: 5, Pages: 9-16
A thermodynamic optimization methodology is developed to model, analyze, and predict the system behaviour of a combined SOFC-GT cycle. The system efficiency and power output are used as a basis to optimize the whole hybrid power plant. The optimized performance characteristics are presented and discussed in detail through a parametric analysis. Simulations of the effects that various design and operating parameters have on system performance have led to some interesting results. This study can be considered as a preliminary investigation of more complex fuel cell and gas turbine hybrid systems incorporating additional practical irreversible losses.
Offer GJ, Howey DA, Contestabile M, et al., 2010, Comparative analysis of battery electric, hydrogen fuel cell and hybrid vehicles in a future sustainable road transport system, Energy Policy, Vol: 38, Pages: 24-29
This paper compares battery electric vehicles (BEV) to hydrogen fuel cell electric vehicles (FCEV) and hydrogen fuel cell plug-in hybrid vehicles (FCHEV). Qualitative comparisons of technologies and infrastructural requirements, and quantitative comparisons of the lifecycle cost of the powertrain over 100,000 mile are undertaken, accounting for capital and fuel costs. A common vehicle platform is assumed. The 2030 scenario is discussed and compared to a conventional gasoline-fuelled internal combustion engine (ICE) powertrain. A comprehensive sensitivity analysis shows that in 2030 FCEVs could achieve lifecycle cost parity with conventional gasoline vehicles. However, both the BEV and FCHEV have significantly lower lifecycle costs. In the 2030 scenario, powertrain lifecycle costs of FCEVs range from $7360 to $22,580, whereas those for BEVs range from $6460 to $11,420 and FCHEVs, from $4310 to $12,540. All vehicle platforms exhibit significant cost sensitivity to powertrain capital cost. The BEV and FCHEV are relatively insensitive to electricity costs but the FCHEV and FCV are sensitive to hydrogen cost. The BEV and FCHEV are reasonably similar in lifecycle cost and one may offer an advantage over the other depending on driving patterns. A key conclusion is that the best path for future development of FCEVs is the FCHEV.
Zhao Y, Shah N, Brandon NP, 2010, The Development and Application of a Novel Optimisation Strategy for Solid Oxide Fuel Cell-Gas Turbine Hybrid Cycles, Fuel Cells, Vol: 10, Pages: 181-193
A combined power system with solid oxide fuel cell (SOFC) and gas turbine (GT) is modelled and analysed thermodynamically in this paper. A novel optimisation strategy including the design of optimal parameters is proposed and applied to the hybrid system. Different sources of irreversible losses are specified, and entropy analyses are used to indicate the multi-irreversibilities existing, and to assess the work potentials of the system. Expressions of the power output and efficiency for both the subsystems and the SOFC-GT hybrid system are derived. The optimal performance characteristics are presented and discussed in detail through a parametric analysis. The developed model is expected to provide not only a convenient tool to determine the optimal system performance and component irreversibility, but also an appropriate basis to design similar complex hybrid power plants. This new approach can be further extended to other energy conversion settings and electrochemical systems. Decision makers should therefore find the methodology contained in this paper useful in the comparison and selection of advanced heat recovery systems.
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