Fuel Cell Cogeneration System Research Articles

Performance assessment of fuel cell micro-cogeneration systems for residential buildings

The reduction of greenhouse gas emissions in the building sector to a sustainable level will require tremendous efforts to increase both energy efficiency and the share of renewable energies. Apart from the lowering of energy demand through better insulation and fenestration, small combined heat and power (micro-cogeneration) systems may help improve the situation on the supply side by cutting both the non-renewable energy demand for residential buildings and peak loads in the electric grid. Though still on the brink of market entry, fuel cells are the focus of interest as the prime technology for such systems. In this study, a methodology for assessing the performance of such systems in terms of primary energy demand and the CO 2 emissions by transient computer simulations is established, and demonstrated for a natural gas driven solid oxide fuel cell (SOFC) and, to a lesser extend, a polymer electrolyte fuel cell (PEFC) home fuel cell cogeneration system. The systems were evaluated for different grid electricity generation mix types and compared to traditional gas boiler systems. The interaction with hot water storage and solar thermal collectors, and the impact of storage size and predictive control was analyzed. Typical heat and electricity demand load profiles for different types of residential buildings and occupancy were considered, and the sizing of the fuel cell system in relation to the heat demand of the building was analyzed. Primary energy savings decline for cases with lower heat demand and for cases with solar thermal systems, and peak for fuel cell systems sized in accordance with the heat demand of the building. Future assessments of fuel cell systems will need a refined methodology, and depend on realistic performance characteristics and models that accurately consider dynamic conditions.

Study of a Small-Scale Fuel Cell Cogeneration System with Methanol Steam Reforming Considering Partial Load and Load Fluctuation

Performance analysis and cost estimation are carried out for a cogeneration system consisting of a solid high-polymer-film-type fuel cell with a methanol reformer applied to individual houses. For the operation of the fuel cell under a partial load, a unique point of this system is the shifting of the driving point by the electric heater. Considering the annual energy cost for an average house in Sapporo, Japan, the energy cost of this system is shown to be 1.42 times that of conventional systems in which a cogeneration system is not installed.

家庭用燃料電池世界初の市場投入(水素利用システム,<メカライフ特集>エネルギー)

家庭用燃料電池世界初の市場投入(水素利用システム,<メカライフ特集>エネルギー)

Development of Fuel Cell Co-generation System with Heat-pump System in Consideration of Transient Response of Electric Power

Development of Fuel Cell Co-generation System with Heat-pump System in Consideration of Transient Response of Electric Power

C-61 実証実験に基づく自然エネルギー・燃料電池活用型住宅用複合システムの開発と総合評価 : (第8報)水素貯蔵システムの導入可能性評価

C-61 実証実験に基づく自然エネルギー・燃料電池活用型住宅用複合システムの開発と総合評価 : (第8報)水素貯蔵システムの導入可能性評価

Development of Thermodynamic, Geometric, and Economic Models for Use in the Optimal Synthesis/Design of a PEM Fuel Cell Cogeneration System for Multi-Unit Residential Applications

Thermodynamic, geometric, and economic models are developed for a proton exchange membrane (PEM) fuel cell system for use in cogeneration applications in multi-unit residential buildings. The models describe the operation and cost of the fuel processing sub-system and the fuel cell stack sub-system. The thermodynamic model reflects the operation of the chemical reactors, heat exchangers, mixers, compressors, expanders, and stack that comprise the PEMFC system. Geometric models describe the performance of a system component based on its size (e.g., heat exchanger surface area), and, thus, relate the performance at off-design conditions to the component sizes chosen at the design condition. Economic models are based on data from the literature and address the cost of system components including the fuel processor, the fuel cell materials, the stack assembly cost, the fuel cost, etc. As demonstrated in a forthcoming paper, these models can be used in conjunction with optimization techniques based on decomposition to determine the optimal synthesis and design of a fuel cell system. Results obtained using the models show that a PEMFC cogeneration system is most economical for a relatively large cluster of residences (i.e. 50) and for manufacturing volumes in excess of 1500 units per year. The analysis also determines the various system performance parameters including an electrical efficiency of 39% and a cogeneration efficiency of 72% at the synthesis/design point.

Optimal Synthesis/Design of a Pem Fuel Cell Cogeneration System for Multi-Unit Residential Applications–Application of a Decomposition Strategy

The application of a decomposition methodology to the synthesis/design optimization of a stationary cogeneration proton exchange membrane (PEM) fuel cell system for residential applications is the focus of this paper. Detailed thermodynamic, economic, and geometric models were developed to describe the operation and cost of the fuel processing sub-system and the fuel cell stack sub-system. Details of these models are given in an accompanying paper by the authors. In the present paper, the case is made for the usefulness and need of decomposition in large-scale optimization. The types of decomposition strategies considered are conceptual, time, and physical decomposition. Specific solution approaches to the latter, namely Local-Global Optimization (LGO) are outlined in the paper. Conceptual/time decomposition and physical decomposition using the LGO approach are applied to the fuel cell system. These techniques prove to be useful tools for simplifying the overall synthesis/design optimization problem of the fuel cell system. The results of the decomposed synthesis/design optimization indicate that this system is more economical for a relatively large cluster of residences (i.e. 50). Results also show that a unit cost of power production of less than 10 cents/kWh on an exergy basis requires the manufacture of more than 1500 fuel cell sub-system units per year. Finally, based on the off-design optimization results, the fuel cell system is unable by itself to satisfy the winter heat demands. Thus, the case is made for integrating the fuel cell system with another system, namely, a heat pump, to form what is called a total energy system.

Japanese collaboration on residential fuel cell cogeneration

In Japan, Tokyo Gas has commenced joint development of fuel cell cogeneration systems for the home in separate collaborations with Ebara Corporation and Matsushita Electric Industrial. The PEM fuel cell cogeneration systems will be the first such residential systems fueled by natural gas. This is a short news story only. Visit www.re-focus.net for the latest renewable energy industry news.

Residential fuel cell energy systems performance optimization using “soft computing” techniques

Stationary residential and commercial fuel cell cogeneration systems have received increasing attention by the general public due to their great potential to supply both thermal and electrical loads to the dwellings. The reported number of field demonstration trials with grid connected and off-grid applications are under way and valuable and unique data are collected to describe the system’s performance. While the single electricity mode of operation is relatively easy to introduce, it is characterized with relatively low efficiency performance (20–35%). The combined heat and power generation mode is more attractive due to higher efficiency +60%, better resources and fuel utilization, and the advantage of using a compact one box/single fuel approach for supplying all energy needs of the dwellings. While commercial fuel cell cogeneration applications are easy to adopt in combined mode of operation, due to the relatively stable base power/heat load throughout the day, the residential fuel cell cogeneration systems face a different environment with uneven load, usually two peaks in the morning and in the evening and the fact that the triple load: space, water and power occur at almost the same time. In most of the cases, the fuel cell system is not able to satisfy the triple demand and additional back up heater/burner is used. The developed ‘’soft computing” control strategy for FC integrated systems would be able to optimize the combined system operation while satisfying combination of demands. The simulation results showed that by employing a generic fuzzy logic control strategy the management of the power supply and thermal loads could be done appropriately in an optimal way, satisfying homeowners’ power and comfort needs.

Study of fuel cell co-generation systems applied to a dairy industry : Leal, E. M. and Silveira, J. L. Journal of Power Sources, 2002, 106, (1–2), 102–108

Study of fuel cell co-generation systems applied to a dairy industry : Leal, E. M. and Silveira, J. L. Journal of Power Sources, 2002, 106, (1–2), 102–108

Optimal unit sizing of cogeneration systems in consideration of uncertain energy demands as continuous random variables

An optimal unit sizing method for cogeneration systems is proposed using energy demands as continuous random variables. In this method, design variables such as equipment capacities and maximum contract utility demands are determined together with the systems' operational strategies so as to minimize an expected value of the annual total cost subject to the satisfaction of all the possible energy demands. In evaluating the expected value, decision variables and the objective function are considered as piece-wise linear functions of energy demands by applying a sensitivity analysis in linear programming and an enumeration method in mixed-integer programming. This optimization problem is formulated and solved based on a hierarchical optimization algorithm. A numerical study is carried out on a fuel cell cogeneration system installed in an office building. Through the study, the influence of uncertainties in energy demands on a system's economics and optimal equipment capacities are clarified.

Study of fuel cell co-generation systems applied to a dairy industry

This paper presents a methodology for the study of a molten carbonate fuel cell co-generation system. This system is applied to a dairy industry of medium size that typically demands 2100 kW of electricity, 8500 kg/h of saturated steam ( P=1.08 MPa) and 2725 kW of cold water production. Depending on the associated recuperation equipment, the co-generation system permits the recovery of waste heat, which can be used for the production of steam, hot and cold water, hot and cold air. In this study, a comparison is made between two configurations of fuel cell co-generation systems (FCCS). The plant performance has been evaluated on the basis of fuel utilisation efficiency and each system component evaluated on the basis of second law efficiency. The energy analysis presented shows a fuel utilisation efficiency of about 87% and exergy analysis shows that the irreversibilities in the combustion chamber of the plant are significant. Further, the payback period estimated for the fuel cell investment between US$ 1000 and US$ 1500/kW is about 3 and 6 years, respectively.

Economic Viability Study of a Polymer Electrolyte Fuel Cell Cogeneration System for Household Application by an Optimization Approach.

Economic viability on using a polymer electrolyte fuel cell (PEFC) as a cogeneration unit for household application is investigated. The PEFC cogeneration unit is installed with a thermal storage tank. An optimization approach is adopted to rationally evaluate the viability. Design variables such as equipment capacities are determined together with the system's operational strategies so as to minimize the annual total cost subject to satisfy all the possible energy demands. This optimization problem is formulated as a large scale mixed-integer linear programming problem by using appropriate approximation. Numerical studies are carried out with some parameters such as energy efficiency and capital unit cost of the PEFC cogeneration unit, unit cost of natural gas energy charge and load factor of household energy demands. Through the studies, it is found that the relationships between the ecomomic viability of PEFC cogeneration system and the aforementioned parameters are clarified.

Analysis of a molten carbonate fuel cell: cogeneration to produce electricity and cold water

The fuel cell is an emerging cogeneration technology that has been applied successfully in Japan, the USA and some countries in the European Union. This system performs direct conversion of the chemical energy of the oxidation of hydrogen from fuel with atmospheric oxygen into direct current electricity and waste heat via an electrochemical process relying on the use of different electrolytes (phosphoric acid, molten carbonate and solid oxide, depending on operating temperature). This technology permits the recovery of waste heat, available from 200°C up to 1000°C depending on the electrolyte technology, which can be used in the production of steam, hot or cold water, or hot or cold air, depending on the associated recuperation equipment. In this paper, an energy, exergy and economic analysis of a fuel cell cogeneration system (FCCS) is presented. The FCCS is applied in a segment of the tertiary sector to show that it is a feasible alternative for rational decentralized energy production under Brazilian conditions. The technoeconomic analysis shows a global efficiency or fuel utilization efficiency of 86%. Analysis shows that the exergy losses in the fuel cell unit and the absorption refrigeration system are significant. Furthermore, the payback period estimated is about 3 and 5 years for investments in fuel cells of 1000 and 1500 US$/kW, respectively.

Development of Polymer Electrolyte Fuel Cell Cogeneration Systems for Residential Applications

From the viewpoint of environmental protection, the polymer electrolyte fuel cell (PEFC) cogeneration system, which contributes to the reduction of CO2 and NOx emission, is drawing attention as the next-generation residential power source. In recent years, automobile manufacturers have been energetically developing PEFC as the energy source of electric vehicles on account of its good start-up performance due to a relatively low operating temperature and its high power density [1‐3]. PEFC is also promising for residential cogeneration systems when combined with a small-scale natural gas fuel processor [4]. In this review, the current status of the development of PEFC cogeneration systems for residential use including the fuel processor is reported.

Development of Polymer Electrolyte Fuel Cell Cogeneration Systems for Residential Applications

Development of Polymer Electrolyte Fuel Cell Cogeneration Systems for Residential Applications

S01 家庭用燃料電池の開発(家庭用コージェネレーションシステム)

S01 家庭用燃料電池の開発(家庭用コージェネレーションシステム)

606 メタノール水蒸気改質型燃料電池コジェネレーションシステムの出力特性の検討(OS5-2 低環境負荷エネルギーシステム-2)(OS5 環境とエネルギー問題)

606 メタノール水蒸気改質型燃料電池コジェネレーションシステムの出力特性の検討(OS5-2 低環境負荷エネルギーシステム-2)(OS5 環境とエネルギー問題)

99/01297 Optimal unit sizing of fuel cell cogeneration systems in consideration of performance degradation : Ito, K. et al. Energy Research, 1998, 22, (12), 1075–1089

99/01297 Optimal unit sizing of fuel cell cogeneration systems in consideration of performance degradation : Ito, K. et al. Energy Research, 1998, 22, (12), 1075–1089

Optimal unit sizing of fuel cell cogeneration systems in consideration of performance degradation

The influence of the life of a cell stack due to performance degradation on a system's economy is investigated in unit sizing of fuel cell cogeneration systems. An optimal unit sizing method proposed by the authors is extended to this case so that it enables the life and performance degradation of the cell stack to be considered. In the method, equipment capacities and maximum contract demands of utilities such as electricity and natural gas are determined so as to minimize the annual total cost leveled for a whole planning period based on the annualized costs method, in consideration of operational strategies which change with performance degradation of the cell stack. Numerical studies are carried out for normally and highly pressurized phosphoric acid fuel cell cogeneration systems installed in two urban areas. Through the studies, it is found that the life of the cell stack greatly influences system' economics and equipment capacities. © 1998 John Wiley & Sons, Ltd.