Hydrogen Fuel for Rail
Transport
Stuart Hillmansen
University of Birmingham
Sustainable traction drives
Overview of energy and power
• Linear motion of a railway vehicle can be
described using standard equations of motion
derived from Newton’s Laws
• Force = Mass x Acceleration (Newton)
• Work Done = Force x distance (Joule)
• Power = Work Done / time (Watt)
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Sustainable traction drives
What is a Newton, a Joule or a Watt?
If we lift the apple through 1 metre in
1 second then the power is:
P=WD / time = 1 Watt
If we lift the apple up through 1 metre
then the work done will be:
WD=F x d = 1 Newton x 1 Metre = 1
Joule
F=M x a = 0.1 kg x 10 m/s^2= 1 Newton
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Sustainable traction drives
So...
• A kettle boiling water is equivalent to 3,000
apples being lifted vertically at a speed of 1 m/s
• A Eurostar train at full power is equivalent to
12 million apples being lifted vertically as a
speed of 1 m/s
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Sustainable traction drives
How much energy is there in some
common items?
• A tin of baked beans (410 g) = 1.7 MJ
(chemical energy)
• Me climbing 1700 metres up a big hill = 1.7 MJ
(1 tin of beans) (potential energy)
• The kinetic energy of a Eurostar at 300 kph =
3000 tins of beans (kinetic energy)
• So what?
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Sustainable traction drives
• There is a lot of chemical energy locked up in
liquids and solids
• But to go fast on a train it is better not to carry
around the fuel
• The only way of delivering large quantities of
energy to a moving object is via electricity
• Power in electrical terms is voltage x current
• Common to use kWh to measure electrical energy
1 kWh = 1 kW is used for 1 hour
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Sustainable traction drives
What Price Speed?
Published in Ingenia
By the Railway Research Centre
Imperial College London
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Sustainable traction drives
Physics of traction
Traction
Resistance
Mass* Acceleration =(Traction – Resistance – slope)
2

d s
d
 ds 
 ds 
M 1    2  T   c    b    a     Mg 
  dt 

dt
dt
r




2
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Sustainable traction drives
Tractive and resistive forces
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Summary of traction
• Overall tractive effort is limited by number of
driven wheels and maximum torque of the
traction motors
• Once the constant power region is reached then
the tractive effort drops off with 1/speed
• Possible to achieve good performance with low
power and with distributed traction
• Distributed traction also improves regeneration
potential
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Sustainable traction drives
Requirements for railway traction drives
•
•
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•
•
•
•
•
•
Good torque performance
Robust and reliable
Efficient
Compatibility with other equipment
Used for braking
Low maintenance
Low cost
Able to control speed
Quiet
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Sustainable traction drives
Traction energy overview
• Energy in at pantograph
– Auxiliary
– Traction
• Losses in:
– Converters
– Motors
– Resistance to motion
– Kinetic energy recovery (last low hanging
fruit)
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Sustainable traction drives
Options for energy storage 1
• Onboard storage
–
–
–
–
–
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Diesel electric multiple units
Diesel multiple units
Locomotives
Shunting locomotives
Electric multiple units
Sustainable traction drives
Options for energy storage 2
• Wayside storage (fixed installations)
– DC railways
• Load levelling
• Regeneration capture and reuse
– AC railways – not such an important issue
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Sustainable traction drives
Vehicle spec
Route information
Speed limits Gradient
Traction Braking
Vehicle simulator
Driving style
Power vs time
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Physical
properties
Gradient profile
Sustainable traction drives
Velocity profile
1
running diagram
25
1400
1200
20
0
distance (m)
1000
velocity (m/s)
gradient slope
0.5
15
10
800
600
400
-0.5
5
200
-1
0
500
1000
distance (m)
0
1500
0
0.8
0.6
0.4
0
0
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5
10
15
velocity (m/s)
20
25
acceleration
0.5
1
1.5
Traction/Braking Power
2
Traction
Braking
1.5
1
0
-0.5
-1.5
0
time (m)
0.5
0
-0.5
-1
0.2
0
1500
power (MW)
acceleration (m/s 2)
specific forces (m/s2)
specific traction, resistance and acceleration curve
1.4
1.5
specific traction
1.2
resistance
1
acceleration
1
0.5
500
1000
distance (m)
-1
0
500
1000
distance (m)
1500
-1.5
0
500
1000
time (s)
1500
Sustainable traction drives
0.8
0.7
hybrid potential
0.6
0.5
0.4
0.3
0.2
0.1
0
0
70
20
60
40
50
60
40
80
30
20
100
distance km
Slide No: 17
speed limit m/s
Sustainable traction drives
Important features of braking
• At high speed – it is very difficult (impossible)
to capture all the braking energy.
• Constant power braking is required to get the
most out of regenerating systems
• Using constant power and all electric
regeneration will lead to longer journey times
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Sustainable traction drives
Energy Storage Capability (in MJ/kg)
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•
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•
•
•
•
•
•
•
Hydrogen
Compressed natural gas (CNG):
Petrol:
Diesel fuel:
Ethanol:
Coal:
Biomass:
Liquid petroleum gas (LPG):
Steel flywheel:
Battery:
Slide No: 19
140 MJ/kg
50 MJ/kg
44 MJ/kg
39-42 MJ/kg
30 MJ/kg
29 MJ/kg
15 MJ/kg
45-50 MJ/kg
0.014 MJ/kg
0.01-0.56 MJ/kg
Sustainable traction drives
•Taken from Professor Rod Smith, Imperial College London,
•IMechE December 2008
Slide No: 20
Sustainable traction drives
Energy Storage Devices for Hybrid Systems
• Key enabling technology for the development of
hybrid trains
• The most researched and used energy storage
technologies are:
- Chemical batteries
- Supercapacitors
- Flywheels
• Its main functions are:
- to charge during low power demands and discharge during
high power demands.
-to provide the short bursts of power (acceleration, steep grades)
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Sustainable traction drives
Energy Storage Main Requirements
• Capable of recovering energy from braking at
high input rates.
• Capable of high rates of discharge for power
assistance during acceleration.
• Capable to withstand duty cycles that require
repeated cycling at high rates.
• Long service life.
• High energy and power densities are important
so that the ESD is compact and light weight.
Slide No: 22
Sustainable traction drives
Conventional DEMU
Diesel engine
G
M
VDC
Inverter
Brake chopper
Brake resistor bank
Slide No: 23
Sustainable traction drives
Hybrid DEMU
Diesel engine
G
M
VDC
Inverter
DC/DC converter
Energy storage device
Slide No: 24
Sustainable traction drives
Hybrid Fuel Cell EMU
Fuel cell
M
VDC
Inverter
DC/DC converter
Slide No: 25
Sustainable traction drives
Interfacing energy storage with railway
traction systems
• Energy storage devices have to be put through a power
processor in order for the energy to be usefully used in the
vehicle.
– For supercaps: Terminal Voltage varies widely with State of Charge –
therefore need a wide range bidirectional DC/DC converter
– For batteries: Terminal voltage is higher than super caps and varies less
widely – but still need bidirectional DC/DC converter
– For Flywheel: Need CVT type gear box – or and electric system
• Important to factor in the efficiency of the converter – since
energy passes through the converter twice.
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Sustainable traction drives
Hayabusa
• Developed by Hitachi,
Porterbrook, Brush Traction,
and Network Rail.
• Class 43 fitted with 4 Hitachi
300 kW AC traction motors.
• Hitachi lithium-Ion batteries
used as the ESD
- 48 batteries, 960 kg battery
weight
- Capacity: 48 kWh
- Maximum power output: 1 MW
for 170 seconds
Hayabusa series hybrid scheme
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Sustainable traction drives
EMUs with energy storage
• Provides power in the event of supply failure
• Can improve energy efficiency on DC railways (with
long headways and low voltage DC supplies)
• Can power train on sections of track which are not
electrified
• No commercial main line trains are currently available
– but there are some light rail examples
• IPEMU trial
Slide No: 31
Sustainable traction drives
http://www.railtechnologymagazine.com/R
ail-News/prototype-battery-poweredipemu-carries-passengers-for-first-time
Slide No: 32
Sustainable traction drives
•Taken from Professor Rod Smith, Imperial College London,
•IMechE December 2008
Slide No: 33
Sustainable traction drives
The role for Hydrail and Fuel Cells
• 2004 paper (Hillmansen) indicated that light
rail, urban rail with modest power and energy
requirements are likely to be early adopters of
fuel cells
• Air quality could be a driver for fuel cells in the
built environment
• Important to consider the synergy between the
developments in energy storage and fuel cell
systems
Slide No: 34
Sustainable traction drives
•
Source – Global Rail news
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