Fuel Cell Hybrid Power System Research Articles

Thermoeconomic Optimization of a Solid Oxide Fuel Cell and Proton Exchange Membrane Fuel Cell Hybrid Power System

A hybrid system that combines a solid oxide fuel cell (SOFC) with a proton exchange membrane fuel cell (PEMFC) is presented in this paper. The SOFC stack acts as both an electricity producer and the fuel reformer for the PEMFC stack to generate additional power. A thermoeconomic model for the design optimization of a 220 kW SOFC-PEMFC hybrid system is developed in this work. Optimization of two objectives, i.e., the life cycle cost and the net electrical efficiency, are considered individually to find the optimum system configuration and component designs. Then, a multiparameter sensitivity analysis is performed to estimate the relative importance of the decision variables on the objectives. The optimization results indicate that the life cycle cost of the hybrid system is 3800–5,600 $/kW, and the maximum net electrical efficiency can reach around 63%, which is higher than an SOFC-only system, a reformer-PEMFC system, and an SOFC-gas turbine (GT) system with a similar output power. The sensitivity analysis shows that minimizing the size of the SOFC is most crucial to the system cost optimization. The hydrogen utilization factor in the SOFC is found to be sensitive to the net electrical efficiency.

1.5kW 연료전지 복합발전 시스템의 듀얼 컨버터 설계

In this paper, parallel input / serial output dual converter is designed appropriately for fuel cell hybrid power system. In case of proposed converter, zero voltage switching condition is designed without additional resonance device using leakage inductance of transformer and output capacitance of switch, and zero voltage switching method is used. Also, the system method is for increasing power by connecting half-bridge in parallel and increasing output voltage by connecting secondary output of transformer in serial. Through this method we can increase power and decrease volume of system. So in this paper, dual converter is designed. 1.5㎾ fuel cell hybrid power system was implemented, and system operation and stability was verified through experiment.

A mobile off-grid platform powered with photovoltaic/wind/battery/fuel cell hybrid power systems

Cross utilization of photovoltaic/wind/battery/fuel cell hybrid-power-system has been demonstrated to power an off-grid mobile living space. This concept shows that different renewable energy sources can be used simultaneously to power off-grid applications together with battery and hydrogen energy storage options. Photovoltaic (PV) and wind energy are used as primary sources and a fuel cell is used as backup power. A total of 2.7 kW energy production (wind and PV panels) along with 1.2 kW fuel cell power is supported with 17.2 kWh battery and 15 kWh hydrogen storage capacities. Supply/demand scenarios are prepared based on wind and solar data for Istanbul. Primary energy sources supply load and charge batteries. When there is energy excess, it is used to electrolyse water for hydrogen production, which in turn can either be used to power fuel cells or burnt as fuel by the hydrogen cooker. Power-to-gas and gas-to-power schemes are effectively utilized and shown in this study. Power demand by the installed equipment is supplied by batteries if no renewable energy is available. If there is high demand beyond battery capacity, fuel cell supplies energy in parallel. Automatic and manual controllable hydraulic systems are designed and installed to increase the photovoltaic efficiency by vertical axis control, to lift up & down wind turbine and to prevent vibrations on vehicle. Automatic control, data acquisition, monitoring, telemetry hardware and software are established. In order to increase public awareness of renewable energy sources and its applications, system has been demonstrated in various exhibitions, conferences, energy forums, universities, governmental and nongovernmental organizations in Turkey, Austria, United Arab Emirates and Romania.

Fundamental Study on the Improvement of Efficiency of a Fuel Cell Hybrid Power System for Agricultural Electric Vehicles

Fundamental Study on the Improvement of Efficiency of a Fuel Cell Hybrid Power System for Agricultural Electric Vehicles

Configuration of solar-hydrogen mild hybrid fuel cell power systems for electric vehicles

This paper considers the evaluation of a configuration of solar-hydrogen mild hybrid fuel cell power systems for electric vehicles. The primary objectives are to relieve the prerequisite need on the infrastructure for hydrogen supply and reduce the cost of fuel cell module compared to the conventional fuel cell electric vehicles. The advantage of the proposed vehicle power system configuration is addressed in terms of the criteria of availability and affordability. Availability considers issues of energy resource and engineering technology. Affordability considers issues of operational cost and environmental cost. With regard to issues of implementation, a cost-benefit ratio is defined and used to evaluate the feasibility of the proposed mild hybrid power systems. A demonstration is conducted based on four exemplary vehicles. The value of the computed cost-benefit ratio can be used to determine the suitability of implementation of the proposed configuration of a hybrid power system for electric vehicles. The presented costs are based on per/unit prices as cited by manufacturers on the Internet and are useable guidelines for further development. In actual practice, substantial further efforts would be needed to facilitate safe, reliable cost-efficient operation of the proposed system.

선박동력용 SOFC/ST 하이브리드시스템의 성능 평가

연료전지시스템의 고효율화를 목적으로 수소가 가진 화학적 에너지를 최대한 전력화하기 위하여 연료전지에서 발생하는 폐열을 적극 활용할 필요가 있다. 이런 목적에 폐열을 이용하는 증기터빈과 연료 전지를 결합시킨 SOFC/ST 하이브리드시스템이 적합하다. 본 논문은 SOFC/ST 하이브리드시스템에 대한 셀의 작동온도와 전류밀도, 연소기 출구 온도, 보일러 출구 가스온도가 시스템의 성능에 미치는 영향 등을 시뮬레이션을 통하여 검토한 것으로 증기터빈의 일정 조건에서는 연료전지 스택에서 다량의 폐열이 발생하는 경우가, 연료전지의 일정 조건에서는 연소기에 추가적 연료 공급을 억제하는 경우에서 하이브리드시스템의 효율이 증가됨을 확인하였다.

Multicascoded Sources for a High-Efficiency Fuel-Cell Hybrid Power System in High-Voltage Application

This paper presents a high-efficiency multicascoded hybrid power system for high-voltage application. For a cascoded configuration, the source is serially connected to the output terminal of a converter to increase the voltage conversion gain by one. In addition, parts of the energy from the sources are supplied directly to the output load with high-efficiency features. Based on these, a three-cascoded hybrid power system integrating the fuel cell (FC), battery, and ultracapacitor module is presented. A two-loop active FC control strategy is proposed to manage the power flows of the proposed system. The whole efficiency and hybrid power flows of the multicascoded system are discussed and demonstrated under different hybrid situations. Finally, the experimental results from a prototype circuit of the FC hybrid power system show that the hybrid system can provide 200 V of output voltage, 500 W of rated power, and about 1 kW/25 min long-term overload power. In addition, the whole efficiency of the proposed hybrid power system can achieve 93.6%.

Analysis, Design, and Control of Bidirectional Cascoded Configuration for a Fuel Cell Hybrid Power System

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper presents a cascoded configuration combining a fuel cell (FC), a battery, and an ultracapacitor module (UCM) to create a hybrid power system. A cascoded configuration is constructed using a modified bidirectional flyback converter, which connects the battery and UCM in cascode to efficiently provide hybrid power. An active FC voltage control strategy is presented to manage the power flows of the proposed cascoded system. In this paper, the simulated hybrid power of the motion of an electric vehicle is illustrated in different situations. The experimental results show that the power flows using the proposed control strategy verify the theoretical analysis. In addition, the overall efficiency of the proposed hybrid power system at overload operation is much higher than the conventional one, and it can achieve 96%. </para>

A sizing-design methodology for hybrid fuel cell power systems and its application to an unmanned underwater vehicle

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.

125 固体酸化物形燃料電池・マイクロガスタービン複合発電システムにおける各種燃料毎の総合効率評価とシステム最適化(学生賞IV,一般講演)

125 固体酸化物形燃料電池・マイクロガスタービン複合発電システムにおける各種燃料毎の総合効率評価とシステム最適化(学生賞IV,一般講演)

Advances in Design of Solid Oxide Fuel Cell Hybrid Power Systems for Underwater Applications

A hybrid propulsion system for torpedo propulsion applications was developed. The hybrid system utilizes a solid oxide fuel cell (SOFC) to provide low power propulsion and hotel loads supplemented by a high power turbine for high speed pursuit, with both systems using common fuel and oxidant sources. A solid LiClO4 oxidant source was investigated. Individual subsystems including the SOFC stack and LiClO4 oxidant source were physically tested. Trade studies were performed comparing various fuel, oxidant, low power, and high power sources, based on testing performance of the subsystems. The SOFC low power system was demonstrated to provide the longest low power range while maintaining the necessary high power reserve for target pursuit.

Control and real-time optimization of an automotive hybrid fuel cell power system

A real-time optimization method is used to find the point of maximum fuel efficiency of a hybrid fuel cell power system, in an automotive application. The controller performs as the master control in cascade with lower level controls. The lower level controls distribute the power between the ultra-capacitor and the fuel cell, during transients, to find the optimum operating point of the power system. The ultra-capacitor is used to protect fuel cell health and improve phase characteristics of the system. In simulations, the controller is able to find the optimum operating point for the hybrid system without requiring previous knowledge of the system dynamics or explicit representation of the optimization function.

A Hybrid Fuel Cell Power System

This paper proposes a hybrid fuel cell power system, which consists of a fuel cell, an isolated unidirectional converter, a bidirectional converter, an inverter, and a battery. The fuel cell and the battery are connected to the same voltage bus through an appropriate hybrid full-bridge LLC resonant unidirectional converter and a three-level buck/boost bidirectional converter, respectively. The battery is an auxiliary energy source, powers the load during the system's start state to make it easy for the system to cold start, and provides or absorbs the dynamic power when the load varies and the fuel cell cannot respond immediately, so the system dynamic characteristics are improved. Furthermore, the battery can also provide peak power at overload, so the power rating of the fuel cell can be decreased, which reduces the total system cost. In order to ensure that the system operates with high efficiency, this paper also proposes a power management control scheme, which controls the bidirectional converter operating under buck, boost, or shutdown mode according to the operation condition of the fuel cell and battery, so that the battery can be charged or discharged. The operation of the system during cold start and overload are analyzed in detail. A 1-kW fuel cell power system was built in the laboratory. Experimental results are shown to verify the theoretical analysis.

208 液化石油ガスを燃料とするマイクロガスタービン・固体酸化物形燃料電池ハイブリッド発電システムの熱的性能解析(熱力学2)

208 液化石油ガスを燃料とするマイクロガスタービン・固体酸化物形燃料電池ハイブリッド発電システムの熱的性能解析(熱力学2)

Operation of a PEM fuel cell with LaNi 4.8Sn 0.2 hydride beds

A series of measurements were performed using metal hydride sorbent beds to operate a 1.0 kW capacity proton electrolyte membrane (PEM) fuel cell hybrid power system. Two sorbent beds were filled with LaNi 4.78Sn 0.22 alloy and each unit had a maximum storage capacity of ∼280 sL hydrogen. A single sorbent bed was able to supply hydrogen gas for ∼20–25 min operation at 30 A net current and ∼900 W output power. These hydride beds were also capable of supplying sufficient hydrogen flows and pressures to produce up to ∼1.1 kW output power from the fuel cell for shorter durations. Good correlations for hydrogen consumption rates and power outputs were obtained and boundaries parameters for continual operation were identified. Various input and output parameters were recorded and analyzed to relate hydride bed, fuel cell, and battery behavior and assess their dynamic interactions.

Optimal Power Control of Hybrid Fuel Cell Systems for an Accelerated System Warm-Up

Key technical challenges in hybrid fuel cell power system applications are the power management and the thermal control. In this paper, a charge-sustaining supervisory power controller is developed, which minimizes the warm-up duration of a fuel cell/battery hybrid power system by optimally controlling the power split between the fuel cell system and the battery, as well as the operation of an auxiliary heater. The controller is implemented as a model-predictive feedback law. First, a control-oriented, mathematical model of the system is established and partially validated with experimental data. An optimal control problem is then stated, and from the necessary conditions of Pontryagin's minimum principle a solution is derived. The operation of the controller is demonstrated in the simulation, and the controller's functionality is analyzed in detail. As the controller has a feedback structure and as it requires only low computing power, it is adequate for an on-board, real-time application

Current Management in a Hybrid Fuel Cell Power System: A Model-Predictive Control Approach

The problem of oxygen starvation in fuel cells coupled with air compressor saturation limits, is addressed in this paper. We propose using a hybrid configuration, in which a bank of ultracapacitors supplements the polymer electrolyte membrane fuel cell during fast current transients. Our objective is to avoid fuel cell oxygen starvation, prevent air compressor surge and choke, and simultaneously match an arbitrary level of current demand. We formulate the distribution of current demand between the fuel cell and the bank of ultracapacitors in a model predictive control framework, which can handle multiple constraints of the hybrid system. Simulation results show that reactant deficit during sudden increase in stack current is reduced from 50% in stand-alone architecture to less than 1% in the hybrid configuration. In addition, the explicit constraint handling capability of the current management scheme prevents compressor surge and choke and maintains the state-of-charge of the ultracapacitor within feasible bounds

Electric power system for Chinese fuel cell city bus

A state-of-the-art Chinese fuel cell city bus using a hybrid power system is proposed. This comprises a PEM fuel cell and Ni/MH batteries to combine the high energy density of fuel cells with the high power density of batteries. A DC/DC converter is placed between the fuel cell and the battery to control the electric power flow. This article presents a novel control strategy for efficient fuel cell operation and optimization of the hybrid power system for the bus. The control strategy is able to regulate the output current of the fuel cell and the charging current or voltage for the battery, while limiting the discharge current of the battery. It can achieve a higher efficiency, longer fuel cell lifetime and higher drive performance. The hybrid fuel cell power system and the proposed control strategy were verified using dynamometer and road test experiments. The experimental results demonstrate that the control strategy has great flexibility and generality, and also validate that the peak power capacity of the active hybrid power source and the vehicle drive performance can be significantly enhanced.

Electric power system for a Chinese fuel cell city bus

A state-of-the-art Chinese fuel cell city bus, using a hybrid power system is proposed. This comprises a proton exchange membrane fuel cell and Ni/MH batteries to combine the high energy density of fuel cells with the high power density of batteries. A dc/dc converter is placed between the fuel cell and the battery to control the electric power flow. This paper presents a novel control strategy for efficiency of the fuel cell operation and optimization of the hybrid power system for the bus. The control strategy is able to regulate the output current of the fuel cell and the charging current or voltage for the battery while limiting the discharge current of the battery. It can achieve a higher efficiency, longer fuel cell lifetime, and higher drive performance. The hybrid fuel cell power system and the proposed control strategy were verified by using dynamometer and road test experiments. The experimental results demonstrated that the control strategy has great flexibility and generality, and also validated that the peak power capacity of the active hybrid power source and the vehicle drive performance can be significantly enhanced.

Thermoeconomic analysis of a fuel cell hybrid power system from the fuel cell experimental data

An innovative configuration of fuel cell technology is proposed based on a hybrid fuel cell system that integrates a turbogenerator to overcome the intrinsic limitations of fuel cells in conventional operation. An analysis is done of the application of molten carbonate fuel cell technology at the Guadalix Fuel Cell Test Facility, for the assessment of the performance of the fuel cell prototype to be integrated in the Hybrid Fuel Cell System. This is completed with a thermoeconomic analysis of the 100 kW cogeneration fuel cell power plant which was subsequently built. The operational results and design limitations are evaluated, together with the operational limits and thermodynamic inefficiencies (exergy destruction and losses) of the 100 kW fuel cell. This leads to the design of a hybrid system in order to demonstrate the possibilities and benefits of the new hybrid configuration. The results are quantified through a thermoeconomic analysis in order to get the most cost-effective plant configuration. One promising configuration is the MCFC topper where the fuel cell in the power plant behaves as a combustor for the turbogenerator. The latter behaves as the balance of plant for the fuel cell. The combined efficiency increased to 57% and NOx emissions are essentially eliminated. The synergy of the fuel cell/turbine hybrids lies mainly in the use of the rejected thermal energy and residual fuel from the fuel cell to drive the turbogenerator in a 500 kW hybrid system.