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| Hydrogen proclaimed 'fuel of the future' Munich
International Airport Boasts June 1999 CryoGas International (Subscribe) Passengers landing at Munich International Airport are breathing a bit easier these days and it has nothing to do with being back on terra firma following a "white knuckle" flight. Rather, it's what greets them on the ground that's contributing to an air of excitement surrounding the airport these days -- environmentally friendly, hydrogen-powered shuttle buses and passenger cars operating out of the world's first public hydrogen filling station that opened there last month. The facility, part of an elaborate four-year, $20 million pilot program, will test on-site production and storage of gaseous hydrogen, the fully automatic refueling of cars with liquid hydrogen and the use of airport buses for passenger transport under the safety requirements of an international airport. The aim of the program is to gain insight into the routine use and economic feasibility of hydrogen as an automotive fuel. Germany is 10 giant steps ahead of the rest of the world with regard to developmental work on hydrogen technology for use as an automotive fuel. While other countries, particularly the United States and Canada, have been looking at natural gas as the logical alternative to gasoline powered vehicles, Germany's automotive manufacturers -- namely BMW and DaimlerChrysler -- have been busy developing hydrogen engines and vehicles. Hydrogen powered buses have been successfully used in several major German cities for nearly two years. The project is being funded by a consortium - known as ARGEMUC - comprised of 14 German industrial companies in partnership with the Free State of Bavaria, which provided 50 percent of the finances from public funds. The business/industry partners include Aral, BMW, FMG, GHW/HEW, Grimm, HDW, IAW, Linde AG, MAN Nutzfahzeuge, MAN Technologie, Mannesmann, Neoplan, Siemens and TUV Suddeutschland. Besides being a renewable energy source, hydrogen is environmentally friendly in that it helps reduce emissions of CO, HC and -- with lean operating combustion engines -- NOx to near-zero levels. In addition, hydrogen engines completely eliminate soot emissions, the use of carcinogenic additives such as benzene, and - provided they are lean burners the use of catalytic converters. In other words, they help us all breathe a bit easier! The major problems associated with its use as a fuel are production costs and related safety issues. The economics of hydrogen production is of the utmost concern and future developmental work by the consortium will focus on non-fossil fuel technologies. In the long term, regenerative primary energy production, hopefully, will form a closed production cycle, permitting cost-effective management.
Filling station will test two supply schemes The Munich facility will run two simultaneous tests during the course of the next four years. Airport shuttle buses will be fueled with gaseous hydrogen (GH2) produced on-site by electrolysis and automobiles will be "gassed up" with liquid hydrogen (LH2) supplied by Linde TG. The LH2 will be delivered by tanker truck from Ingolstadt and stored in a 12,000 liter cryogenic storage tank. Innovative technology utilized in GH2production/storage The gaseous hydrogen will be produced on-site using newly developed, high-performance pressure electrolyzers manufactured by GHW, a joint venture company of Motorenund Turbinen-Union (MTU), Norsk Hydro Electroylsers and the Hamburg Electric Works (HEW). The new electrolyzers can produce up to 94M3/hr at outlet pressures of 30 bar. A downstream purification and drying plant is supplied by HDW (Howaldtswerke-Deutsche Werft). The GH2 is then stored in a hydride storage system which, in turn, supplies a downstream membrane compressor with a constant 30 bar inlet pressure with the help of a special heating and cooling system. The hydrogen is compressed to 350 bar and loaded into high-pressure storage cylinders manufactured by MDEU (Mannesmann Demag Energie-und Umweittechnik). The storage cylinders have a total capacity of 10 cubic meters and a pressure rating of 350 bar. GH2 is delivered to the filling station via a dispenser manufactured by Mannesmann. For cost reasons, the capacity of the high-pressure storage facility was designed for a single day's consumption. A back-up system has been designed that allows the buses to use gasified LH2 in emergency situations. The GHW pressure electrolysis technology was developed for the decentralized production of hydrogen fuel (e.g. at filling stations) by means of main-powered electrolyzers. The systems have features that permit network control and power management functions to be performed at any point on the electrical grid while making it possible to generate hydrogen of high purity in a highly efficient manner. The control characteristics of the electrolysis system are advantageous for the electricity generator and make it possible to utilize cheap electricity. The development has reached a stage that permits the production of systems with an output of up to about one MW. These systems will initially be used for demonstration projects in key areas. The goals of GHW are:
Major features of the GHW electrolyzer are its high efficiency, the purity of the gases it generates, its broad control range, its quick control response and its operating pressure of 30 bar. Development was financed in part by HDW which has been working on hydrogen propulsion and hydrogen storage for 18 years. Class 212 German submarines, which are fitted with hydrogen drives, are currently being built. The HDW purification and storage system serves as a link between the electrolyzer and the hydrogen compressor. The hydrogen from the electrolyzer passes through the purification system. Aerosols are removed from the gas stream by a filter, and any residual oxygen in the crude gas is converted into water by reacting it with hydrogen in a catalytic converter. The metal-hydride cylinder is made up of coaxial tubes. The inside tube contains the metal hydride, while the space between the inner and the outer tubes serves as a conduit for the cooling and heating water, which transports the thermal energy needed for charging and discharging processes. In accordance with the concentration pressure isotherms, a metal hydride can store large amounts of hydrogen. The pressure and quantity are controlled by regulating the temperature. When the hydrogen is fed to the high-pressure compressor, the compressor inlet pressure is regulated by raising the temperature in the hydride storage cylinder in such a way that maximum upstream pressure is achieved irrespective of the quantity in the hydride storage cylinder. This permits efficient, energy-saving operation of the compressor. The hydride storage cylinders are clustered in two groups, which can be alternately charged and discharged. If necessary, the cylinders can also be operated in parallel. Depending on the mode of operation, the hydride storage cylinders can hold up to 2000 cubic meters of hydrogen. Another HDW component is the measurement and control technology, the aim of which is the fully automatic, unmonitored operation of the hydrogen gas pathway downstream from the electrolyzer. The system is designed to allow remote monitoring over an ISDN line. A two-stage horizontal membrane compressor is used to compress the gaseous hydrogen to the storage pressure of 350 bar. The required inlet pressure is 15 to 30 bar. The purified hydrogen gas is supplied from the hydride storage cylinders with the process data required for the compressor. The delivery rate of the compressor is 125 M3 at an inlet pressure of 30 bar. The maximum outlet pressure is 400 bar. The compressor and gas store are installed in a housing to protect them from the elements. The high-pressure storage cylinder consists of five vessels supplied as a module with complete pipework. Each cylinder has an outside diameter of 559 mm; wall thickness of 27 mm, length of 10,870 mm; weight of 4500 kg and an operating pressure of 350 bar. The high-pressure units, manufactured and supplied by Mannesmann Cylinder Systems, are divided into three banks charged to a pressure of 350 bar. The storage volume is divided as follows: the low-pressure bank, 6.0 M3; the medium-pressure bank, 2.0 M3; and the high-pressure bank, 2.0 M3. The logistic system is divided into three banks (priority switching) to accommodate for rapid fueling. A priority switch ensures that a high differential pressure always exists between the vessels of the gas storage system and the vehicle tank during filling. This results in faster refueling. As a matter of fact, refueling takes only about ten minutes. The automatic sequence switch that opens and closes the valve system in accordance with the three-bank strategy is controlled by a high-performance electronic dispenser. The hydrogen dispenser resembles a conventional filling station pump for liquid fuel. The dispenser is a joint product of Mannesmann and Aral. The housing, as well as the metering mechanism, is manufactured by Aral, while the remaining components are supplied by Mannesmann. This new generation of dispensers for the European market was developed in cooperation with Kraus Industries, Canada. The dispenser operates independently and only needs to be connected to the power supply and the gas supply at the filling station. The following functions are carried out by integrated information circuitry: measurement and summation; sequence control of three-bank storage modules; pressure and temperature compensation; safety shutoff in the event of overfill or overflow; and serial interface for remote servicing. The buses are refueled with the help of a dispenser supplied by Aral in cooperation with Mannesmann Demag. Mannesmann is responsible for the gas technology, Aral for the housing, the display module, the card reader and the connection to the filling station management system. The design of the dispenser resembles that of a conventional filling station pump with adaptations for the necessary explosion protection. To refuel the bus, the flexible hose of the dispenser is connected and locked to the filler neck of the vehicle tank. A manual lever is then actuated to initiate the automatic refueling operation. The main valve of the dispenser is opened, and the compressed GH2 flows into the vehicle tank. The gas flow is monitored by a mass flow meter integrated in the dispenser. The refueling operation is ended automatically as soon as the filling pressure calculated by the temperature compensator is reached. The dispensed gas (in kg), the final price (in DM) and the price per unit dispensed (in DM/kg) are displayed on the electronic display of the dispenser. Both bus designs are powered by horizontally mounted six-cylinder in-line engines with a displacement of 12 liters and a power rating of 140 kW/190 HP. Since few gradients have to be negotiated and the top speed is 30 km/h, the engine power of 190 HP is sufficient. Exhaust emissions are well below current and foreseeable limits. The engines produce no carbon dioxide (C02) and, in the case of the Neoplan bus, nitrogen oxide (NOx) levels are far below Euro III limits and are further reduced by an integrated catalytic converter. The gas storage tanks, mounted on the roof, consist of 15 aluminum vessels with a full wound carbon-fiber jacket. They are distributed between the front and rear vehicle sections and have a storage capacity of 2580 liters at a pressure of 250 bar. This volume is sufficient for uninterrupted daily operation at the airport. Both ends are fitted with a 2-in. 12 UN-2B connection thread that can be sealed with an end plug or reduced. Each tank has an internal volume of 172 liters and weighs 62 kg. The operating pressure is 250 bar at 15' C. Testing for certification of the tanks has been completed under the supervision of TUV. Automobile fill-up is completely automated BMW has been using liquid hydrogen as a fuel in experimental cars since the 1970s. Although it is seen by the public as an innovative fuel, the industry has several decades of wide-ranging experience with LH2. In projects for automotive applications to date, no problems have been encountered with regard to the handling of liquid hydrogen. On April 12, 1996 a world first was achieved when an LH2-powered bus developed by MAN and Linde took up regular passenger service in Erlangen, Germany. The bus later demonstrated its suitability for routine use in Munich. Now, after nearly three years of faultless service, it may be concluded that there are no problems with the handling of liquid hydrogen in practical use. A further important step towards the routine use of liquid hydrogen under the stringent safety requirements of an airport has been taken with the development of a new robot dispenser. In applications so far, the liquid hydrogen was mainly handled by trained specialists. Thanks to the use of the robot dispenser, laypeople can now refuel the vehicles for the first time, since operator errors are ruled out by the automation. There is even a gain in convenience for customers compared to today's filling stations, since the tank cap no longer has to be opened and the filler nozzle inserted manually. The customer does not even have to get out of the vehicle during the procedure. This progress has been achieved thanks to years of refinement of the cryocomponents at the interface between the vehicle and the filling station. During the first refueling experiments the hoses had to be evacuated, inertized and cooled before the actual refueling operation could begin. The cold-drawable coupling developed by Linde does away with these time-consuming procedures and has shortened the original refueling time from about one hour to the time normally needed to fill up with gasoline. In the most recent experiments it took about one and a half minutes to fill a 120-liter tank mounted on a specially designed BMW 7-Series. The process of automatically docking and undocking the coupling takes just a few seconds. This progress was made possible by the refueling procedure, during which the gas cushion in the vehicle tank is almost completely condensed. Modern technology has made flushing with helium and icing of the hoses things of the past, and the external parts of the dispenser remain at ambient temperature throughout the process. The refueling process can be divided into the following steps: clearance of the refueling bay by a traffic light system; vehicle recognition and authorization of the customer by an ID card; docking and refueling; and undocking, receipt issuing and driving off. The safety concept of the robot includes mechanically activated panels that activate safety switches in the event of a collision. In addition, gas sensors on the robot and below the roof of the filling station ensure safe operation of the robot. Aral and BMW were responsible for supplying the robotics and Linde for supplying the hydrogen-handling components. The necessary inspections of the station and safety-relevant interfaces between the robotics and the hydrogen-handling components are conducted by TUV. The aim is to adapt the Aral robot dispenser for conventional fuels to the requirements of hydrogen. The robotics are installed above the pavement on an island in an above-floor version. The kinematics are mobile in four axes so that the end effector is freely moveable within a limited envelope (1000 x 800 x 200 mm). Mounted at the end effector (end point of the robot arm) are the LH2 coupling, the coupling activation elements, the docking sensors and the opening and closing mechanism. The LH2 hose is routed externally, the electrical cables and other control lines are routed internally through the robot arm to the end effector. Safety and infrastructure Within the project, Aral was responsible for setting up the entire infrastructure. The aim in planning and implementing the construction measures was to adopt the standardized construction of conventional Aral filling stations wherever possible. Special requirements of the participating partners in setting up the system components, complying with safety regulations and connecting to the road network were linked with standard components and taken into account in the implementation. The master control and measurement system for the overall project is manufactured by Siemens. The necessary engineering was provided by Linde. In order to ensure a comprehensive overview of the integrity of the system at all times, hydrogen sensors manufactured by Grimm Labortechnik were installed at all safety-relevant locations. TUV of Southern Germany is responsible for all safety aspects of the project. A PLAYERS' WHO'S WHO Just who are the members of the ARGEMUC consortium and what does each bring to the table where the $20 million hydrogen filling station was conceived and implemented? Some of the names are more familiar than others, but most are not widely known outside Germany. The majority partner is the Bavarian Ministry for Economic Affairs, Transport and Technology. The Bavarian government has a 50 percent stake, financed with public funds. Following is a complete list of the consortium business and industry members and their contributions to the planned four-year long study project:
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