Bernd Emonts

Compact methanol reformer test for fuel-cell powered light-duty vehicles

Abstract On-board production of hydrogen from methanol based on a steam reformer in connection with the use of low-temperature fuel-cells (PEMFC) is an attractive option as energy conversion unit for light-duty vehicles. A steam reforming process at higher pressures with an external burner offers advantages in comparison to a steam reformer with integrated partial oxidation in terms of total efficiency for electricity production. The main aim of a common project carried out by the Forschungszentrum Julich (FZJ), Haldor Topsoe A/S (HTAS) and Siemens AG is to design, to construct and to test a steam reformer reactor concept (HTAS) with external catalytic burner (FZJ) as heat source as well as catalysts for heterogeneously catalyzed hydrogen production (HTAS), concepts for gas treatment (HTAS, FZJ) and a low-temperature fuel cell (Siemens). Based on the experimental results obtained so far concerning methanol reformers, catalytic burners and gas conditioning units, our report describes the total system, a test unit and preliminary test results related to a hydrogen production capacity of 50 kW (LHV) and dynamic operating conditions. This hydrogen production system is aimed at reducing the specific weight ( th or 4 kg/kW el ) combined with high efficiency for net electricity generation from methanol (about 50%) and low specific emissions. The application of Pd-membranes as gas cleaning unit fulfill the requirements with high hydrogen permeability and low cost of the noble metal.

Hydrogen from methanol for fuel cells in mobile systems: development of a compact reformer

Abstract On-board generation of hydrogen from methanol with a reformer in connection with the use of a proton-exchange membrane fuel cell (PEMFC) is an attractive option for a passenger car drive. Special considerations are required to obtain low weight and volume. Furthermore, the PEMFC of today cannot tolerate more than 10 ppm of carbon monoxide in the fuel. Therefore a gas conditioning step is needed after the methanol reformer. Our main research activities focus on the conceptual design of a drive system for a passenger car with methanol reformer and PEMFC: engineering studies with regard to different aspects of this design including reformer, catalytic burner, gas conditioning, balances of the fuel cycles and basic design of a compact methanol reformer. The work described here was carried out within the framework of a JOULE II project of the European Union (1993–1995). Extensive experimental studies have been carried out at the Forschungszentrum Julich GmbH (KFA) in Germany and at Haldor Topsoe A/S in Denmark.

Methanol steam reforming in a fuel cell drive system

Abstract Within the framework of the Joule III project a c ompact m ethanol r eformer (CMR) with a specific weight of 2 kg/kW (lower heating value of H 2 ) was developed. This CMR contains a methanol and water vaporizer, a steam reformer, a heat carrier circuit and a catalytic burner unit. A laboratory fixed-bed reactor consisting of four tubes which could be filled with different amounts of catalyst was used to investigate the catalyst performance and the ageing behaviour. A hydrogen yield of 10 m N 3 /(h l Cat ) can be achieved at 280°C. In this case, the methanol conversion rate is 95% and the dry product gas contains 0.9% CO. A linear decrease of the catalyst activity was observed which can be described by a loss of active catalyst mass of 5.5 mg/h. The catalyst was operated for more than 1000 h without having exhibited activity losses that made a catalyst change necessary. Besides, the stationary behaviour of the reforming reactor, the dynamic behaviour was studied. The time needed for start-up procedures has to be improved for reformers of a next generation. Moreover, the hydrogen production during reformer load changes will be discussed. Simulations of the power train in driving cycles show the different states of a reformer during dynamic operation.

PHOEBUS—an autonomous supply system with renewable energy: six years of operational experience and advanced concepts

Abstract The PHOEBUS demonstration plant has been supplying the Central Library of Forschungszentrum Julich (FZJ) with solar-generated electric energy all year round and independent of the public grid since 1993. The central task was to test the required storage using hydrogen as the energy carrier in conjunction with an electrolyser and a fuel cell under realistic irradiance and consumption conditions and to demonstrate the feasibility of such a zero-emission supply system. The general objective was to determine weak points from the operating experience and measured data obtained, to model the system in a component-oriented manner for simulation, to energetically optimize the plant, to achieve high operational reliability and, above all, to propose and implement cost-reducing and advanced system modifications. With the aid of validated simulation programs, it was possible to carry out optimization analyses for plant operation (annual scenarios) and plant configuration. Two advanced concepts were developed: PHOEBUS-2, a simplified system with reduced energy losses, and PHOEBUS-3, a wind–PV hybrid system supplying both electricity and heat. The advanced concepts PHOEBUS-2 and PHOEBUS-3 are the theoretical basis for applications such as a solar home system, a solar village, a scientific polar station or a storage module for grid-connected operation that can be realized in the near future.

Fuel cell drive system with hydrogen generation in test

In the future, drive systems for vehicles with polymer electrolyte membrane fuel cells (PEMFC) may be the environmentally more acceptable alternative to conventional drives with internal combustion engines. The energy carrier may not be gasoline or diesel, as in combustion engines today, but methanol, which is converted on-board into a hydrogen-rich synthesis gas in a reforming reaction with water. After removal of carbon monoxide in a gas-cleaning step, the conditioned synthesis gas is converted into electricity in a fuel cell using air as the oxidant. The electric energy thus generated serves to supply a vehicles electric drive system. Based on the process design for a test drive system, a test facility was prepared and assembled at Forschungszentrum Julich (FZJ). Final function tests with the PEMFC and the integrated compact methanol reformer (CMR) were carried out to determine the performance and the dynamic behaviour. With regard to the 50-kW(H2)-compact methanol reformer, a special design of catalytic burner was constructed. The burner units, with a total power output of 16 kW, were built and tested under different states of constant and alternating load. If selecting a specific catalyst loading of 40 g Pt/m2, the burner emissions are below the super ultra low emission vehicle (SULEV) standard. The stationary performance test of the CMR shows a specific hydrogen production of 6.7 mN3/(kgcat h) for a methanol conversion rate of 95% at 280°C. Measurements of the transient behaviour of the CMR clearly show a response time of about 20 s, reaching 99% of the hydrogen flow demand due to the limited performance of the test facility control system. Simulations have been carried out in order to develop a control strategy for hydrogen production by the CMR during the New European Driving Cycle (NEDC). Based on the NEDC, an optimized energy management for the total drive system was evaluated and the characteristic data for different peak load storage systems are described.

Operational experience with the fuel processing system for fuel cell drives

Abstract Electric motor vehicle drive systems with polymer electrolyte fuel cells (PEFCs) for the conversion of chemical into electrical energy offer great advantages over internal combustion engines with respect to the emission of hydrocarbons, carbon monoxide and nitrogen oxides. Since the storage systems available for hydrogen, the “fuel” of the fuel cell, are insufficient, it is meaningful to produce the hydrogen on board the vehicle from a liquid energy carrier, such as methanol. At the Research Center Julich such a drive system has been developed, which produces a hydrogen-rich gas from methanol and water, cleans this gas and converts it into electricity in a PEFC. This system and the operational experience on the basis of simulated and experimental results are presented here.

Life cycle costing of a self-sufficient solar-hydrogen system

In a renewable energy-based system, energy storage must match the energy demand with supply. Usually a lead-acid battery is utilised as a short-term energy buffer. A system, which has a combination of an electrolyser and a high-pressure hydrogen tank for long-term energy storage, is considered in this paper. The cost intensive components are sized considering the least cost and by performing a life cycle costing of the system. The optimum battery capacity obtained is 19 kWh, which is equivalent to 2.2 days of autonomy. At present, energy storage cost in the long-term storage is found 2.16 per kWh whereas the cost goes down to 0.92 per kWh when the target cost of the fuel cell and the electrolyser is considered. Around 15–20% of the demand is supplied by the long-term storage.