Bavarian Liquid Hydrogen Bus Demonstration Project

- Safety, Licensing and Acceptability Aspects

R. Wurster (Author)

L-B-Systemtechnik GmbH
Daimlerstrasse 15, D-85521 Ottobrunn, Germany
Phone: +49/89/608110-33; Fax.: +49/89/6099731
E-mail: wurster@lbst.tnet.de

H. Knorr and W. Prümm (Co-Authors)

MAN Nutzfahrzeuge Aktiengesellschaft
Vogelweiherstrasse 33, D-90441 Nürnberg, Germany
Phone: +49/911/420-2221; Fax.: +49/911/ 420-1950, E-mail: Werner_Pruemm@mn.man.de

Publication for ‘Hydrogen Power Now’ – 9^th Canadian Hydrogen Conference,

February 7-10, 1999, Vancouver, BC, Canada

ABSTRACT

A regular 12 m city bus of the MAN SL 202 type with an internal combustion engine adapted to hydrogen operation and auxiliary gasoline operation was demonstrated in the Bavarian cities of Erlangen and Munich between April 1996 and August 1998. Three bus operators, Erlanger Stadtwerke, Stadtwerke München and Autobus Oberbayern were testing the bus in three different operating schemes.

In order to be able to perform this worldwide first public demonstration of a liquid hydrogen (LH₂) city bus in regular service, several requirements with respect to safety, licensing, training and acceptability had to be fulfilled. These activities were focusing mainly on the hydrogen specific issues such as

• Integration of onboard LH₂ storage vessels, piping and instrumentation,
• Implementation of storage and refueling infrastructure in the operators’ yards
• adaptation of the maintenance garages
• training of operating and maintenance personnel

During phase II of the demonstration activity a poll was performed on passengers traveling onboard the hydrogen-powered city bus in order to determined the level of acceptance among the users of the bus.

The bus was designed and manufactured by MAN Nutzfahrzeuge Aktiengesellschaft. The cryogenic fuel storage and the refueling equipment were designed and manufactured by Linde AG. The realization of the hardware was financially supported by the European Commission (EC) within the Euro-Quebec Hydro-Hydrogen Pilot Project. The demonstration phase was financially supported by EC and the Bavarian State Government. Ludwig-Bölkow-Systemtechnik performed project monitoring for both funding organizations.

The presentation will summarize the most important results of this demonstration phase and will address the measures undertaken in order to get the bus, the refueling infrastructure and the maintenance and operating procedures approved by the relevant authorities.

1.) Technical Concept of the MAN LH₂ City Bus

A full size 2 axle high floor city bus of the MAN SL 202 series with an empty weight of 11.5 tonnes and a maximum operating weight of 17.6 tonnes was converted to liquid hydrogen operation by MAN Nutzfahrzeuge, Nürnberg, Germany, until summer 1994.

A six cylinder 4-stroke internal combustion engine with spark ignition and a displacement of 12 liters of the natural gas series-production type MAN E 2866 DUH was converted to quantitative (air/ fuel ratio just under l = 1) operation. The built-in three way catalytic converter functions as a reduction catalytic converter leading to very low NO_x emissions (European 13 mode test: 0,4 g/ kWh). The engine is suited for gaseous hydrogen and unleaded gasoline and provides a power output of approx. 140 kW at 2,200 rpm when operated with hydrogen. Two sequentially-working, multi-point fuel injection systems are used. Each cylinder has one gasoline and one hydrogen injection nozzle. The LH₂ is evaporated and gaseous hydrogen is injected into the intake manifold. The injection nozzles are controlled by a Bosch Motronic M3.3 engine control unit.

The Hydrogen system consists of three vacuum-superinsulated LH₂ cryo-tanks of elliptical cross section and of 200 l geometrical volume each (total of 570 l of LH₂ volume), which are connected by superinsulated hoses. The delivery of the fuel is executed with one bubble lift pump per tank. In case of high fuel demand additional heater elements (one per tank) are activated in order to rise the pressure level. A heat exchanger operated with the cooling water of the engine heats the gaseous hydrogen to ambient temperature level before it is conducted to the engine.

That equipment is mounted in the area between front and rear axles under the floor. This configuration guarantees optimum protection in case of accidents (front and rear collision, roll over); in addition to that, a reinforced frame offers protection for possible side impacts.

A conventional gasoline tank and fueling system is also implemented in the bus and allows for optional dual fuel operation. The operation mode with unleaded gasoline enables the transfer of the bus from one demonstration site to another.

Test bed tests of a one cylinder 2 liter engine were conducted successfully in June and July of 1993 on the BMW liquid hydrogen engine test bed in Munich. The results obtained from these tests were transferred to the full size engine. The full 6-cylinder engine modified to hydrogen never was tested on a test bed before implementation into the city bus since MAN Nutzfahrzeuge at that time did not dispose of a test bed qualified and licensed for operation with hydrogen fuel (as available at MAN now since 1997). Therefore, the engine which was fine-tuned onboard the vehicle is not completely optimized as it could have been when tested and optimized thoroughly on a test bed. In-company testing of the LH₂ city bus was started in late fall of 1994. This testing and optimization period extended until end of 1995, providing the necessary experience for an improvement of the bus engine and fuel supply system as well as of the refueling station infrastructure.

Linde AG developed both the onboard LH₂ fuel supply system and a new LH₂ refueling station with a clean break filler connection for very low LH₂ transfer times (of around 15-20 minutes). The refueling station is skid-mounted and transportable. It consists of a transfer unit and a cylindrical 12,000 l LH₂ storage tank. Cooling down respectively heating up of the tank filler coupling before and after the refueling procedure as well as flushing of the coupling is completely avoided with this design for subsequent refueling procedures and leads to significant time savings. The design of this system is based on the knowledge available in the early 1990s. Presently developed systems are even more advanced, i.e. more efficient and faster.

The LH₂ SL 202 Bus accommodates 92 passengers in total, thereof 41 seated. Depending on the transmission gear ratio applied the maximum velocity can reach 85 km/h. For city driving usually a gear ratio is used which provides favorable acceleration characteristics better than high maximum velocity.

Experts regard the danger of hydrogen used competently as not being higher than using petrol, natural gas or other flammable gases. In order to minimize all risks in regular line service, MAN has developed a comprehensive safety concept for the bus in co-operation with TÜV Automotive and has implemented this concept in the construction of the bus. (Discharge and safety valves in the tank unit, hydrogen sensors in the area of the storage tanks and in the passenger compartment, automatic roof lights).

The construction of the project was supported by the European Commission through cost shared funding. The demonstration of the bus in Bavaria between April 1996 and August 1998 was supported at approx. equal parts by the European Commission and by the Bavarian Ministry for State Planning and Environmental Affairs.

Demonstration of the bus system in regular public transport started in the small Bavarian city of Erlangen by April 1996 and continued there until February of 1997. Then the bus was overhauled and transferred to Munich. Also the LH₂-refueling station was moved to Munich and installed in the yard of the bus operating company SWM where it served the bus during demonstration phases two and three. The demonstration of a metropolitan inner-city driving profile by SWM started in April 1997 and lasted until December 1997. During January of 1998 some technical defects of the fuel injection system were repaired. From February 1998 to August 1998 the bus was operated by Autobus Oberbayern based in Munich and mainly served the shuttle bus line between Munich’s new fair ground and Munich Intl. Airport. An important route in view of creating international public awareness. The accumulated driving experience with LH₂ fuel in public operation during this time amounted to about 42,000 km.

2.) Safety Concept and Licensing of the Bus

Today, with the exemption of a few test and research vehicles, hydrogen is not used as a fuel for road vehicles. Consequently, a binding set of regulations, standards and codes of practice for hydrogen vehicles does not exist, nor in Germany nor Europe-wide. According to the leading specialist in hydrogen and gas technology hydrogen is not regarded as more dangerous than conventional fuels, such as gasoline, natural gas and liquid petrol gas.

For the LH₂ city bus a comprehensive safety concept has been drawn up in cooperation with TÜV Süddeutschland (technical inspection authority) with the aim to eliminate all potential risks.

The following opportunities for hydrogen to escape were identified:

• Release of large volumes of hydrogen (breaking of connecting lines between tank and shut-off device; rupture of the tank due to an accident or due excessive pressure build-up caused by total loss of insulating vacuum)
• Escape of moderate or small quantities of hydrogen (leaking fittings or connections)

When analyzing incidents of hydrogen release the following peripheral conditions should be taken into account:

• The hydrogen’s aggregate condition
• The volume of hydrogen released
• The rate of release
• The spatial conditions (confined, semi-confined, unconfined)
• Conditions likely to create turbulences (wind, surface roughness, airflow obstruction)
• Ignition conditions (ignition sources, moment of ignition, ignition energy)

With regard to the possible effects of the mishap, the following distinctions must be made:

• Mechanical effects caused by pressure waves (e.g. turbulent deflagration) and airborne fragments
• Effects of temperature, e.g. burns or freezing, softening of materials, interruptions to flow or blockages caused by icing up, material embrittlement
• Risk of suffocation in enclosed spaces from hot steam or reduction in oxygen level as a result of H₂ combustion and air displacement
• Poisoning caused by fumes from secondary fires

Estimation of hazard potentials:

• Effects of temperature and fire (for LH₂ the extent of deflagration is larger than for gasoline; the burn-off area for a gasoline fire is larger than for LH₂; the effect of heat radiation over a certain distance is larger for a gasoline fire, since the total energy content, the duration of burning and the proportion of radiated flame energy are all higher than for LH₂)
• Effects of pressure waves (TÜV Süddeutschland came to the conclusion that blast effects from possible explosions constitute a significant hazard potential for road users and for vehicles and buildings in the vicinity. In this respect, the hazard potential of vehicles fueled by gasoline is comparatively low)

Mishap scenarios:

• Damage to tank system in a road accident (possible damage of the LH₂ tank or fuel lines in the event of an accident)

• Collision with moving vehicles (injury accident statistics for public buses show the following distribution: 71% occur at the front of the vehicle, 12% at the rear, 17% at the sides, only 3% occur between the front and rear axles)
• Collisions with stationary vehicles and fixed obstructions (includes buildings, walls, bridges, trees, rocks, curbsides, etc.)
• Vehicle roll-over or free-fall crash (only long-distance buses and coaches are involved in roll-over accidents)
• Loads applied from above (buildings, bridges or trees falling on top)

• Pressure build-up in tank system beyond operating pressure

• Tank: breakdown of vacuum caused by leak of outer jacket, by leak of inner jacket, by pipe break, by leak at evacuating valve or inability to switch off the heating
• Tank system: engine coolant is not reaching the heat exchanger, which is therefore not heated; the first shutoff valve leading to the engine does not open; the overflow valve does not open; the level alarm fails; the non-return flap valve in the filler nozzle fails

The following measures in general are regarded as worthwhile in preventing road accidents: Antilock braking system (ABS), automatic transmission and power-assisted steering.

Furthermore, according to the German standard regulation VDE 0165 /3/ explosion-prevention zones for flammable gases, vapors and mists are defined as follows:

Zone 0: Areas in which dangerous explosive atmospheres are present all the time or for long periods.

Zone 1: Areas in which the occasional occurrence of dangerous explosive atmospheres is to be anticipated.

Zone 2: Areas in which dangerous explosive atmospheres are only expected to occur rarely and then for short periods only.

After the discussion with TÜV Süddeutschland the following explosion-proofed zones were determined for the bus:

• The area around the tank filler was classified as Zone 2; the shut-off fitting on the filler neck is to be sealed additionally with a blanking-off cap.
• The area around the hydrogen tanks has also been classified as Zone 2. Precautions are to be taken that detachable connectors are checked for leaks at regular intervals (at least once a month)
• The area around the blow-off pipe outlets on the roof of the bus is classified Zone 1. The area in question is hemispherical in shape, with a radius of 1 m. There are no roof openings permitted within this area.
• The passenger area is regarded as an explosion-proofed zone if the following conditions are satisfied:

• It is to be sealed off gas-tight from components through which gas passes, and which have adequate ventilation and air extraction
• Suitable gas sensors to detect explosive mixtures must be provided in the passenger area, since the hydrogen storage vessels are accommodated underneath the passenger compartment and if a leak occurs hydrogen might enter into the compartment.

The engine compartment is classified as an explosion-proofed zone. However, care must be taken to ensure an exchange of air at a rate of more than once per hour when the vehicle is standing still. This is achieved by locating the ventilation openings as high as possible, with a cross-section of not less than 1% of the engine compartment’s area.

Liquid hydrogen tanks and peripheral components have to comply with the technical rules on pipes (TRR 100) and the technical rules on gases (TRG).

Taking into account the hazards inherent in liquid hydrogen (explosion, fire, frostbite of cryogenic hydrogen) the vehicle was equipped with a maximum of safety features. The overall goal is to avoid fault wherever possible, and if fault occur, to minimize the potential damage.

The safety features foreseen are sub divided into mechanical devices and instrumentation and control devices (I&C).

Mechanical Safety Devices:

As the hydrogen storage tanks are located between the front and rear axle, they are well protected against head-on or rear-end collision as well as against roll-over. Against side-on collisions the tanks are mounted more than 200 mm from the external surface of the bus and additionally protected by a reinforced frame structure. Derived from a study it could be concluded that series-production buses without reinforced frame structures in a side-on collision never suffered deformations reaching even 200 mm. Protective panels fitted beneath the LH₂ tanks prevent stone chipping damage.

The tank coupling in the bus is mounted on a type of sledge which in case of a side-on impact allows it to slide in order to prevent it from tearing off. The coupling and the three LH₂ tanks are connected with vacuum-superinsulated flexible hoses (instead of a rigid tube).

The tanks are hermetically enclosed by partition panels which prevent hydrogen from spreading across the vehicle’s floor assembly in the event of a leakage. This enclosed area is ventilated by slits in the side flaps beneath the floor. The gas-tight floor ensures that hydrogen gas cannot enter the passenger compartment.

The potential build-up of excessive pressure in the tank system is avoided by the implementation of one overflow valve and two safety valves. Any excess gas forming is permitted to escape to the open atmosphere through the vent stack on the vehicle’s roof top.

Instrumentation & Control Safety Devices:

The pressure in the hydrogen tank system is monitored by a pressure sensor. Three level sensors, one in each LH₂ tank, measure the liquid gas level according to the capacitive principle. The stored program control system (SPS) processes the pressure signal and the filling level signal and activates the heating elements. Thus the SPS keeps the pressure constant within the system and the filling levels in the various tanks equal. The hydrogen line to the engine is monitored by a pressure switch in order to detect possible breaks in the line. Furthermore, the temperature in this line is monitored. The flow of the engine coolant through the heat exchanger is also monitored by a flow monitor the output of which is connected to the SPS. This temperature and flow monitoring shall ensure the detection of a possible, but unlikely to occur, breakthrough of LH₂. In case one of the sensors responds (e.g. pressure drop in the line), the tanks system is shut down via closing of the solenoid valves by the SPS.

Shutt-off of the hydrogen system means:

• Blocking of the bubble lift pump and the heating elements
• Closing of the magnetic valves
• Automatic switching of the engine to gasoline operation
• Display of hydrogen malfunction and gasoline operation mode via lamps in the dashboard

The SPS has its own electric power supply independent of the vehicle’s electric system, consisting of two 12 V batteries which are recharged by the vehicle’s alternator. These batteries only serve as buffer batteries which shall prevent the voltage from dropping below 24 V (e.g. when starting the vehicle) since the SPS does not function properly below 24 V. The feed voltage is supervised by means of a undervoltage control relay.

The LH₂ tanks are protected by two safety valves which open at a pressure of 0.6 MPa, absolute.

Additional hydrogen sensors are installed near the tanks (2) and in the passenger compartment (2). In case one of the sensors is activated by detecting hydrogen, the tank system is shut off and the bus skylights open automatically. At any time, the driver can cut the hydrogen operating mode by actuating an ‘emergency off’ switch or by actuating the fuel selection switch. If any fault occurs while operating the bus in hydrogen mode, the driver can switch to gasoline mode while the vehicle is in motion.

While refueling and being connected to the filling station, a starter interlock prevents anybody from driving the bus away.

All safety devices were installed in accordance with the basic rules of safety engineering:

• fail-safe circuitry
• on-board diagnostics monitoring operational functions
• all equipment individually type-tested or type-approved
• duplicates of all functions which might pose a safety hazard if they failed (standby functions)

The bus system’s correct operating condition is assured by regular maintenance and inspection.

Detailed bus operating instructions are to be drawn up for maintenance personnel and drivers.

Detailed training is to be foreseen in order to prevent operating errors and lay down the correct behavior in the event of malfunction.

For registration as a bus without restrictions, the vehicle must comply with the following regulations:

• StVZO: German motor vehicle registration regulation,
• Regulation on the operation of transport companies in public transport (BOKraft),
• 3^rd section on the vehicle’s equipment and properties

Finally, once all stipulations of the hydrogen technology department of the TÜV Süddeutschland, the inspection authority responsible for Bavaria, had been fulfilled and a leak test conducted on the vehicle system, the LH₂ onboard storage and supply system of the bus was approved and certified by TÜV Süddeutschland on January 23^rd 1995. An inspection book was started at the same time.

3.) Safety Measures for the Storage and Refueling Infrastructure at the Bus Operator’s Yard

An upright cylindrical tank for liquid hydrogen supply with a capacity of 12,000 litres was erected at the respective service yards of the transport utilities together with a transfer station. This transportable filling system (manufactured by Linde and owned by MAN), rented from MAN, was connected to the cylindrical LH₂ storage system. These tasks were executed by Linde AG who also assumed the task of the regular LH₂ supply by trailer. This "filling station" does not require external energy for refueling the bus with LH₂ with exemption of the electricity to operated the vacuum pump for helium inertizing. The existing valves are operated pneumatically, the required pressure being provided by nitrogen pressure gas bottles. Besides regular filling procedures also the procedures "first refueling (evacuation, purging, cooling down of tanks)" and "taking out of operation (emptying LH₂ and inertizing)" can be performed. The pneumatic control of the system is configured in such a way the a filling procedure can be performed only if the filling nozzle is correctly connected.

The technical directives and regulations applicable to filling stations are the technical rules on gases (TRG Technische Regeln Gase): and the construction codes for tube of metallic materials (TRR).

The examination by TÜV Süddeutschland for the Industrial Inspectorate (Gewerbeaufsicht) was conducted on the basis of the "operating instructions for an LH₂ refueling station with storage tank" provided by Linde AG.

The permit was granted under the following preconditions:

Erection: The refueling station has to be erected according to the presented documentation. The ground for parking the bus should not have a slope larger than 1:50. At least two wheels of the bus have to be positioned in a hollow in the ground in order to define the exact position for refueling. The vehicle to be refueled has to be positioned in such a way that it does not have to cross the defined explosion-proof zones. Around the detachable connections of the refueling station a spherical safety zone of the zone 1 type with a radius of 1 m has to be observed. Zone 2 connects in a tangential way in conical form upward. The base plane of the cone lies 3 m above the source. Within the sphere of action of the filling hose, the safety distances of the safety protection zones and the storage vessel no inflammable substances must not be stored. A sign has to indicate that smoking and the use of open fire is prohibited. Within the protection zones of the refueling station no open drains, sewers or openings to underground spaces are permitted or have to be covered during refueling in order to avoid intrusion of possible LH₂ spillages. The filling station including the above ground tubes has to be protected against mechanical damage or corrosion. The installation has to be protected against collision with the vehicles to be refueled by elevating it onto a base and by installation of defenders. Safety relevant measurement and control functions must not implemented via EPROMs but via fixed wires according to VDE 0116. Relief tubes and exhaust lines of safety valves have to be dimensioned for the occuring pressures, at least for 10 bar (PN 10). The filling station has to be illuminated sufficiently (³ 100 lux). All installations have to be earthed against electrostatic charges. In case of emergency, the electric installations of the filling station have to be shut-off from a place which can be reached quick and without obstruction. The filling connections have to be designed in such a way that a safe connection can be established between filling hose and receptacle. Only type approved components or components separately approved by an expert shall be used. Welders employed for tube welding have to be qualified according to EN 287. The persons employed at the filling station shall be protected as far as possible against precipitation and wind.

Equipment:: All equipment , appliances, tubes and hoses used in the filling station have to be approved. The exhaust lines of the safety valves and ventilation lines or ducts have to be installed such that the gases to be extracted can be relieved without causing danger (e.g. in sufficient height). Within a sphere with a radius of 1 m around the orifice no ignition sources are permitted. Manometers in case of becoming untight shall not injure any person. Close to the filling station a fire-alarm post has to be in easy reach. Suitable fire extinguishing equipment has to be foreseen; at least a fire extinguisher for classes A, B and C. Details have to clarified with the fire brigade. All electric equipment has to be laid out in a suitable form and obtain a PTB-certificate. Ignition by electrostatic charges has to be avoided by appropriate measures.

Operation: The filling of the onboard pressure vessels with cryogenic liquid hydrogen is permitted only by instructed personnel (at least 18 years of age, knowledgeable, reliable). The instruction of these persons by an expert has to be performed before they take up their duties and in regular intervals, at least once per year., and comprises knowledge about pressurized gases, safety regulations, measures in case of accident, fire fighting and operation and maintenance of the filling station. The instruction has to be documented in written form. The vehicle to be refueled has to be secured against rolling off and the engine and onboard heating have to be shut off during refueling. The vehicle onboard pressure storage vessels may be filled if they are marked with the testing sign and the testing date by the expert, if the testing term is mentioned and the deadline not yet expired, if the storage system has no defects which might endanger third parties and if the pressure vessels are licensed for cryogenic LH₂. It has to be ensured that the vehicle onboard pressure vessels cannot be overfilled, either by a shut-off automatic control or by safety measures specified in TRG 380. In case of emergency the vehicle to be refueled has to be withdrawn from the area of action of the filling station and therefore the evacuation path must not be obstructed. The filling procedure has to be documented in an operating instruction which has to be displayed together with safety instructions visibly and permanently at the filling post. The state and functionality of the filling station has to be maintained and necessary repair has to be executed immediately. The proper functioning of shut-off equipment not used frequently has to be tested in reasonable regular intervals.

Examinations: Before operating the filling station the first time, the station has to be examined according to § 28 (1) pressure vessel code (DruckbehV) by an expert defined in § 31, paragraph 1, N° 1 pressure vessel code (DruckbehV). In the course of this testing an entire vehicle refueling with an LH₂ operated vehicle has to be performed. The filling station has to be checked on tightness according TRG 402, N° 9.1, by an expert. Before their first use and then recurring every year, flexible pipes have to be checked on their proper functioning according to TRG 402, N° 9.2, The test results have to be documented and to be stored onsite. Tubes have to be checked by an expert according to pressure vessel code § 30 a. The stationary onsite LH₂ storage vessel has to undergo and approval examination by an expert before its first filling and use (pressure vessel code § 9, para 1 pressure vessel code together with Appendix II of § 12, N° 26, pressure vessel code). A recurring testing by an expert according to N°26 of Appendix II of § 12 is required. The storage vessel has to undergo an external testing by a knowledgeable person every two years. Before first use, the electric installations have to be examined by an expert on explosion proofness and on discharging electrostatic charges. The filling station has to undergo recurring testing by an expert every 4 years, the electric equipment every 3 years.

4.) Safety Measures for the Maintenance Facilities

For safety reasons the bus was always parked outdoors on a specially secured place and not left overnight in the bus depot. An earth cable was installed for grounding the bus during the refueling process as well as an external power outlet for the vehicle's gas warning system was provided.

Inside the service building for minor maintenance work on the LH₂ bus (maintenance of tires, light system, vehicle cleaning and washing, etc.) the following safety precautions are taken:

• A specially marked parking space is to be provided.
• A blow-off stack (drain line) located above the vehicle and leading outside to the open atmosphere, which is to be connected to the blow-off aperture of the filling system on the bus roof.
• Limit switches which interrupt the starter motor line on the bus prevent the vehicle from setting off while the drain lines are still attached.
• Roof hatches and roller doors are partially opened to ensure adequate ventilation in the building (one change of air per hour).
• A mobile gas warning instrument installed in a suspended cage above the vehicle, which made an expensive gas warning system for the building unnecessary (the sensor is calibrated for hydrogen and inspected at regular intervals). If one sensor is triggered, the roof hatches are opened completely to enable hydrogen to escape to the atmosphere.
• The gas sensors in the vehicle are activated. When the battery is disconnected, an external power supply is required.
• All work must be performed by trained personnel.
• Non-sparking tools must be used for all work.
• Smoking is to be prohibited in the service installations during maintenance work is executed on the bus.
• Persons working on the vehicle must be equipped with personal gas warning devices.

Those installations/ precaution measures were necessary, since despite the vacuum insulation of the tank hydrogen evaporates during extended parking times and may be blown off, then normally escaping through the blow-off apertures on the vehicle's roof. Inside the service building, however, it was not possible to have the hydrogen escape directly to the inner atmosphere of the building.

Remark: Practically all permits granted in this project are based on non-hydrogen specific rules, regulations and standards and are granted to a fleet operated vehicle used in public operation, though refueled and maintained by trained personnel. The refueling station was always installed in the operators’ yards and thus not on public ground. The permit procedure but especially the obligations to obtain this permit may be different in case the refueling station would be installed in an area which can be accessed by the public.

5.) Personnel Training

In order to operate the bus in a public transport system under realistic conditions all measures were coordinated with the Industrial Inspectorate (Gewerbeaufsicht), the Berufsgenossenschaft Bahnen (professional association) and TÜV (inspection authority); the scheduled route was analyzed for possible incidents by the fire brigade and the police before the start of the line operation.

Finally, extensive training sessions for the driving and workshop staff by representatives of the companies Linde and MAN with comprehensive training material were part of the preparation for the operation phase of the LH₂ bus. Particular emphasis was put on safety aspects (safe handling of hydrogen, especially LH₂) and on driving practices and refueling. The staff was equipped with manuals and safety instruction material. The subject matter was even tested during a written examination.

6.) Acceptance Study

Starting point and goal of the study

The spread of a new technology is not least dependent on being accepted by possible users. It has already been investigated for various technologies whether the general public considers them dangerous, rejects them, or greets them. There is, as of yet, little information of this kind on the subject of hydrogen-powered transportation. For example, there is the question of whether transportation of this kind arouses any fears – for example of a possible danger of explosion – or whether the positive aspects are more prominent in people‘s thoughts – e.g. the environmental friendliness.

The study pursued three overall questions:

• What level of acceptance is there for hydrogen technologies?
• What knowledge is there about hydrogen technologies or what is associated with the term "hydrogen"?
• Is there a demand for information about hydrogen technologies?

The study was carried out by Ludwig-Bölkow-Systemtechnik GmbH (LBST) in co-operation with the Ludwig-Maximilians University of Munich. LBST has developed in HyWeb a comprehensive information system about hydrogen technologies which has been available in the Internet under www.HyWeb.de since April 1997. The goal of HyWeb is to increase both the knowledge and acceptance of hydrogen technologies. Thus, a goal of the study was to draw conclusions from the results of the study, which are of consequence to the design of HyWeb.

The three "part-studies"

Study 1

Since secondary school students represent a specific target group of the information system HyWeb, Study 1 investigated this population segment. A total of 410 students were questioned about their acceptance of, their knowledge of, and need for information about hydrogen technologies.

Study 2

The use of the worldwide first hydrogen-powered bus in regular public service in summer of 1997 in Munich offered the chance to complement the data obtained from the students with a passenger poll in the hydrogen bus.

Study 3

What effect does it have on the acceptance of hydrogen technologies when a person comes into direct contact with hydrogen-powered transportation? This question was in the foreground in Study 3. The evaluations of acceptance by the students who were interviewed in the bus were compared with those of the students asked in the classroom.

Study II – Polling of the passengers on a hydrogen-powered bus

The polling of the bus passengers was similar to the questioning of the student, but had fewer questions. The average age of the interviewed passengers was 40 years.

The majority of the persons was aware of the special nature of the bus. This was due to the different than usual design of the bus and to some information posters on the inner walls.

Acceptance of the hydrogen bus

A high level of acceptance for the hydrogen-powered bus could be found among the passengers of the bus: The average value on the scale for acceptance was 4.28 (SD .53) (theoretical minimum: 1; theoretical maximum: 5).

There was almost unanimous agreement that the hydrogen-powered bus should be implemented more in the future. The use of the first hydrogen bus in Munich was also overwhelmingly greeted. However, as already seen in the questionnaires of the students, the "dangerousness" of hydrogen technologies was assessed most critically. Nevertheless, this is to be looked at relative to the other answers; on average those polled agreed only "partly" to the statement "Hydrogen is connected with a danger of explosion". Altogether, based on these data, a positive assessment of hydrogen-powered transportation can be assumed.

Relationship between acceptance of hydrogen technologies and environmental awareness

There is a weak positive relationship between environmental attitudes and the acceptance of hydrogen technologies

Associations with hydrogen

At the beginning of the interview the passengers were asked for their spontaneous associations with "hydrogen". 40% of the items mentioned related to the environmental benefits of hydrogen. Associations to danger were very few (5%), "Hindenburg", "Zeppelin", and the like were hardly mentioned at all.

Demand for information and sources of information about hydrogen

About two thirds of the passengers had not heard or read any information about hydrogen technologies before.

Of the remaining third, more than half had heard or read about it in the mass media, a fifth at school and a sixth had seen information provided by the bus operator. A majority of the passengers was interested in more information about hydrogen.

REMARK: Methodology and results of Study I and Study III are not presented here.

Discussion of results

Several general conclusions can be drawn from the results of the present hydrogen acceptance study.

First of all and most importantly, hydrogen technologies enjoy a high level of acceptance among hydrogen bus passengers and among secondary level school students in Germany. People are in favor of the further development of hydrogen technologies, they support their deployment and they see their environmental benefits. Even though people see a certain danger of explosions in hydrogen technologies, the study does not reveal potentially severe acceptance problems. It is noteworthy that hydrogen is very rarely associated to danger spontaneously; only when people are asked to assess the risk of explosions they tend to see a certain risk.

It can be stated clearly that in contrast to most hydrogen experts’ opinion people do not associate hydrogen to past accidents or catastrophes such as the Hindenburg disaster. At least in Germany, hydrogen is almost free of this negative burden.

The study shows a general tendency towards higher acceptance of hydrogen technologies when people are in direct contact to them. School students interviewed in the bus made significantly more positive evaluations than students in the classroom.

Other items do not have such a clear influence on the level of acceptance of hydrogen technologies: A high priority given to environmental issues and a high level of knowledge on hydrogen only have a weak positive influence on the acceptance.

The test of hydrogen knowledge of school students showed that the general level of knowledge is rather poor. This result is confirmed by the bus passengers, half of which had not had information about hydrogen before. At the same time, people are interested in knowing more on the subject.

Conclusions and recommendations

Both the direct contact to hydrogen technologies such as taking a hydrogen bus, and learning about hydrogen technologies at school have a significant positive effect on people’s acceptance of hydrogen technologies.

At the same time, knowledge on hydrogen technologies and its environmental advantages is not very wide-spread. And hydrogen is neither spontaneously associated to danger nor to past accidents.

From the acquired results the following recommendations for the introduction of hydrogen technologies can be distilled:

• Hydrogen technologies enjoy an "advance" trust and are better accepted when a direct contact to the technology is made. Public field tests, demonstration and pilot projects, should thus be increasingly implemented and be accompanied in particular by comprehensive measures to introduce information.
• Questions of safety should represent a priority in the development of technologies, not, however, in the public relations. It is probable that an intensified treatment of the existing safety risks induces assessments of danger, even when making the point that the danger is very slight. The focus should be much more on the environmental advantages of hydrogen, which increases the acceptance.
• There exists a large deficit of information. Therefore offerings of information like HyWeb should be built on and advertised. That the Internet represents an appropriate place of information of this kind follows from the results of the studies with the students: The Internet is considered as a potential source of information.
• An intensified education of teachers and other multiplicators in the field of hydrogen technologies is necessary for reducing the large knowledge deficit among students.

For detailed discussion of the results of the entire study please see:

http://www.hyweb.de/accepth2/

 

7.) Literature:

/1/ H. Knorr, W. Prümm, H. Rüdiger, The MAN Hydrogen Propulsion System for City Buses, Hydrogen Energy Progress XI, Stuttgart, 23-28 June 1996, pp. 1611

/2/ R. Wurster, Hydrogen City Bus Demonstration Projects, VDI/GET-Fachtagung, Darmstadt, February 1995

/3/ K. Langwieder and T. Hummel, Unfälle von Omnibussen, Auftretensformen und Folgen für die Businsassen, Der Nahverkehr, 1/88

/4/ H. Knorr, W. Prümm, MAN Reports on "Development of a Liquid Hydrogen Propulsion System for City Buses, Munich Bus Project", Euro-Quebec Hydro Hydrogen Pilot Project, funded by the European Commission under contract N° 4547-9-11 EL ISP D, 1992-1996

8.) Figures:

Figure 1: Frequencies in percent, with which the specific categories of associations were mentioned on average by the passengers

Figure 2: MAN LH2 City Bus at Bus Operator’s Yard in Erlangen