Bavarian PEM Fuel Cell Bus Project
R. Wurster, M. Altmann, Ludwig-Bölkow-Systemtechnik GmbH [LBST],
Daimlerstr. 15, D-85521 Ottobrunn
D. Sillat, Linde AG, Werksgruppe Technische Gase, Seitnerstr. 70,
D-82049 Höllriegelskreuth
K.-V. Schaller, Ch. Gruber, MAN Nutzfahrzeuge AG, P. O. Box 500620, D-80976 München
K.-W. Kalk, MAN Technologie AG, P. O. Box 1347, D-85751 Karlsfeld
A. Hammerschmidt, W. Bette, Siemens AG, KWU BSPT,
P. O. Box 3220, D-91050 Erlangen
E. Holl, J. Fetzer, Siemens AG, VT 51, P. O. Box 3240, D-91050 Erlangen
Abstract
An MAN low-floor bus NL 163 FC will be equipped with the components for a fuel cell
drive system [1, 2, 3]. The PEM fuel cell was developed by the power generation division of
Siemens. Four fuel cell modules deliver a net electrical output of 120 kWe to the two electric
motors (2x75 kWe), which are linked by a summation gearbox by the Siemens Transportation Systems Division. MAN Technologie AG has been responsible for the compressed hydrogen storage system allowing for a driving range of around 250 km, while Linde AG took
care of the hydrogen periphery and delivers the hydrogen for the test operation scheduled for
the second half of the year 2000. Project coordination is done by Ludwig-Bölkow Systemtechnik GmbH.
The project is divided into four phases. The conceptual design phase has been completed at
the end of 1997. The four PEM fuel cell modules by Siemens have been built, tested and
were system integrated into a dummy of the rear truss frame of the bus in order to check
integration related implications. This system integration phase ended at the end of 1999. The
transfer of the entire propulsion system into the final bus body will be performed during the
first quarter of 2000. The subsequent testing and commissioning phase is scheduled to last
over the second quarter of 2000, and prepare the public test operation with a bus operator in
Germany during the second half of 2000.
During the conference the progress in commissioning the PEMFC bus system will be reported.
Keywords
Bus, City traffic, Fuel Cells, Hydrogen PEM FCEV, PEMFC (Proton exchange membrane
fuel cell), Public transport, ZEV (Zero Emission Vehicle)
1.
Introduction
In 1994, a group of interested Bavarian industry started work on fuel cell propulsion for city
buses and urban delivery vehicles. A feasibility study was carried out and detailed specifications were elaborated by LBST [2] in collaboration with the industry partners, funded by the
Bavarian State Ministry for Economic Affairs, Transport and Technology [BStMWVT]. In
late 1996, the realization of a fuel cell city bus prototype was started by Siemens Power
Generation (KWU), Siemens Transportation Systems, MAN Nutzfahrzeuge, MAN Technol-
ogie and Linde. The project receives a 50 % funding by BStMWVT in the context of the
Hydrogen Initiative Bavaria [4, 5]. It is coordinated by LBST.
The construction of the prototype fuel cell bus will last until the end of the first quarter of
2000 followed by a test and commissioning phase. Test operation is planned for the second
half of 2000 in the city of Erlangen in Bavaria, Germany.
2.
The fuel cell bus
The general concept of the fuel cell bus has been presented at the last World Hydrogen Energy Conference in Buenos Aires, Argentina, in 1998 [3].
The PEM fuel cell system is integrated into a regular low floor city bus. The electric energy
from the fuel cell is fed to two asynchronous motors transmitting their power to the rear axle
via a summation gearbox and a cardan shaft. Hydrogen is stored in composite materials pressure bottles with inner aluminum liner.
The technical data are presented in Table 1.
3.
Integration of the fuel cell propulsion system
The results reported in this manuscript are as of January 2000.
The four fuel cell modules were manufactured by Siemens in 1998 (see Figure 1). The four
stacks together deliver a continuous gross power of 160 kW and can deliver a short term
peak power of 200 kW. The maximum net power of the fuel cell system is 120 kW (continuous).
At the beginning of 1999, Siemens started integrating the fuel cell system and the powertrain
into a dummy of the rear truss frame of the bus in order to check integration related implications (see Figures 2 to 5). This has been preceded by comprehensive simulation work by
MAN on the integration of all components.
A major problem faced during the integration work was electromagnetic compatibility of the
various components. A strategy for solving these problems had to be developed and implemented, resulting in delays in the time schedule. It turned out that two independent sources
of problems with electromagnetic compatibility existed, which were solved subsequently.
The fuel cell system including the electric powertrain now performs satisfactorily in the
dummy rear truss frame.
The fuel cell modules are situated in the lower left part of the rear of the bus (see Figure 6).
The air compressor delivering air to the fuel cells is located in the upper left of the bus rear.
There, a compartment is separated from the passenger space of the bus. In the future, smaller
components and more advanced integration concepts will make it possible to integrate all
components into the lower rear of the bus and on the roof, leaving even more space to the
passenger compartment than the diesel engine.
The electric motors are situated below the floor of the bus behind the rear axle, to which the
motors are connected via a summation gear box and a cardan shaft. The power electronics is
located on the roof of the bus, together with the breaking resistances.
The cooling system consists of a primary and a secondary circuit. The primary circuit cools
the fuel cell modules and transfers the heat to the secondary circuit in a heat exchanger in the
lower right of the rear of the bus. The secondary cooling circuit transfers the heat to the ambient air in a heat exchanger with blower fan located on the roof of the bus.
The auxiliary systems of a bus such as the steering support pump, air compressors for actuating the doors etc. are mechanically connected to and driven by the diesel engine in a conventional bus. In the fuel cell bus, these auxiliary systems had to be replaced by electric motor
driven systems. Existing electric motors fulfilling the requirements of the auxiliary systems
are units for application in the industry and therefore they are far from being optimized for
the application in vehicles. This is one aspect where significant improvements will be
achieved in the future when fuel cell powertrains will be established in series production.
The hydrogen storage system consists of nine pressure cylinders with a maximum pressure of
25 MPa and a total geometric storage volume of 1,530 l, allowing for a driving range of more
than 250 km. The storage system is located on the front part of the roof of the bus. The filling hose is located at the right hand side of the bus close to the front axle . A valve box and
a pressure reduction unit are located directly adjacent to the storage system, from where the
hydrogen is delivered to the fuel cell.
At the beginning of the year 2000, the transfer of the fuel cell system and the electric powertrain from the dummy rear truss into the bus started. It is scheduled to be finished by April
2000. Then, the bus will receive the seats and the outer design. Subsequently, the vehicle will
undergo a comprehensive testing and commissioning phase.
4.
Public operation of the fuel cell bus
Public operation of the fuel cell bus is scheduled to begin in the second half of this year. The
bus shall be included in commercial line operation in the Bavarian city of Erlangen, where it
is planned to run for six months.
5.
Outlook
MAN is continuing its fuel cell bus activities with a second generation fuel cell bus already
in progress.
Acknowledgements
All partners would like to express their thanks to the Bavarian State Ministry for Economic
Affairs, Transport and Technology for funding this project.
References
[1] HyWeb: http://www.fuelcellbus.com, http://www.Brennstoffzellenbus.de
[2] LBST: Feasibility study on fuel cell propulsion for urban city buses and delivery trucks,
Proceedings of the 11th World Hydrogen Energy Conference, Stuttgart, Germany, June
1996
[3] LBST: Fuel Cell Propulsion for Urban Duty Vehicles – Bavarian Fuel Cell Bus Project,
Proceedings of the 12th World Hydrogen Energy Conference, Buenos Aires, Argentina,
June 1998
[4] BStMWVT: Developing hydrogen-based power technologies, Count N. Stillfried, Bavarian State Ministry for Economic Affairs, Transport and Technology, Proceedings of
the 11th World Hydrogen Energy Conference, Stuttgart, Germany, June 1996
[5] WIBA: http://www.wiba.de (in German)
Tables
Table 1: Technical Data
Vehicle
MAN Nutzfahrzeuge AG
Model
NL 163 FC low-floor bus
Length
12 m
Gross weight (permissible)
18 t
Vehicle drive system
Siemens AG Transportation Technologies
ELFA drive system
Asynchronous motors, model 1 PV5135
Max. output of traction motor
2 x 75 kW via summation gearbox and cardan shaft to rear axle
Traction motor converter
IGBT pulse-controlled inverter, model
ELFA-DUO
Fuel cell system
Siemens AG Power Generation (KWU)
Fuel cell modules
4 modules
Rated output
120 kW in total
Voltage at max. output
approx. 400 V
Operating temperature
60 °C
Operating pressure, air
1.5 barabs
Air ratio
2
Hydrogen consumption at rated
output
8 kg/h
Hydrogen storage system
MAN Technologie AG
Max. filling pressure
250 bar
Number of cylinders
9
Total capacity
approx. 1530 l
Operating range
250 km
Hydrogen fuelling system, periphery
Linde AG
Gas tract in vehicle
Main shut-off cock, fuelling coupling, pressure reducer etc.
Hydrogen filling station
Storage and fuelling system including safety
devices
Figures
Figure 1: Siemens PEMFC stacks for MAN FC bus NL 163 FC
Figure 2: Integration of the fuel cell system into the rear of the bus
Installation of Siemens fuel cell system and electric
drive in the A21 low-floor bus
Air filter
(standard in A21)
Water trap
Fuel cell air
compressor
Water pump
Water/water heat exchanger
Fuel cell modules
(4x30kW)
Traction motors with
summation gearbox
(2x75 kW)
Air trap
Figure 3: Fuel cell system integrated into a dummy of the rear truss frame of
the bus
Figure 4: Fuel cell modules ready for integration into the bus.
Figure 5: Integration of the fuel cell modules into the bus
Figure 6: Integration of all the components of a fuel cell drive into a low floor
city bus
Low floor bus with Siemens fuel cell
cooling system
Compressed
hydrogen storage
(250 bar)
Power electronic
for onboard power supply
Braking resistor
Air filter
Air compressor
Fuel cell stacks
Deioniser
for water
Heat exchanger