Transport Research Laboratory
Hydrogen-powered vehicles: review of
type-approval legislation on vehicle
safety Interim report
by C Visvikis, M Pitcher and B Hardy
CPR711
ENTR/05/17.01
CLIENT PROJECT REPORT
Transport Research Laboratory
CLIENT PROJECT REPORT CPR711
Hydrogen-powered vehicles: review of type-approval legislation on vehicle safety
Interim report
by C Visvikis, M Pitcher and B Hardy (TRL)
Prepared for: Project Record: ENTR/05/17.01
Hydrogen-powered vehicles: review of
type-approval legislation on vehicle
safety
Client: European Commission, DG Enterprise and
Industry
Peter Broertjes
Copyright Transport Research Laboratory January 2010
This report has been prepared for the European Commission. The views expressed are
those of the author(s) and not necessarily those of the European Commission.
Name Date
Approved
Project
Manager James Nelson 08/01/2010
Technical
Referee Iain Knight 08/01/2010
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When purchased in hard copy, this publication is printed on paper that is FSC (Forest
Stewardship Council) registered and TCF (Totally Chlorine Free) registered.
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Contents
Executive summary vii
1 Introduction 1
1.1 Background on hydrogen-powered vehicles 1
1.2 Overview of the legislation for hydrogen-powered vehicles 2 1.2.1 EC type-approval 2 1.2.2 UNECE regulations 2
2 Review of type-approval directives and regulations on vehicle safety 5
2.1 Fuel tanks and rear under-run protection: Directive 70/221/EEC and
UNECE Regulation 34 5 2.1.1 Overview 5 2.1.2 Compatibility with hydrogen-powered vehicles and safety
risks 7 2.1.3 Proposals for amendments 7
2.2 Radio interference (electromagnetic compatibility): Directive
72/245/EEC and UNECE Regulation 10 7 2.2.1 Overview 7 2.2.2 Compatibility with hydrogen-powered vehicles and safety
risks 10 2.2.3 Proposals for amendments 11
2.3 Identification of controls, tell-tales and indicators: Directive
78/316/EEC and UNECE Regulation 121 12 2.3.1 Overview 12 2.3.2 Compatibility with hydrogen-powered vehicles and safety
risks 13 2.3.3 Proposals for amendments 14
2.4 Frontal impact: Directive 96/79/EC and UNECE Regulation 94 / Side
impact: Directive 96/27/EC and UNECE Regulation 95 14 2.4.1 Overview 14 2.4.2 Compatibility with hydrogen-powered vehicles and safety
risks 15 2.4.3 Proposals for amendments 16
2.5 Buses and coaches: Directive 2001/85/EC and UNECE Regulations 66
and 107 17 2.5.1 Overview 17 2.5.2 Compatibility with hydrogen-powered vehicles and safety
risks 18 2.5.3 Proposals for amendments 19
3 The use of mixtures of natural gas and hydrogen to power vehicles 21
3.1 The present situation 21
3.2 State-of-the-art 21
3.3 Review of the hydrogen regulation and implementing measures 22
3.4 Proposals for amendments 22
4 Regulating the type-approval of L category vehicles 25
4.1 The present situation 25
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4.2 The state-of-the-art 27
4.3 Review of the hydrogen regulation and implementing measures 27
4.4 Proposals for amendments 29
5 Conclusions 31
Acknowledgements 33
References 33
Appendix A Review of Regulation (EC) No. 79/2009 Annex IV
(Installation of hydrogen components and systems) 35
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Executive summary
Directive 2007/46/EC establishes a framework for the approval of motor vehicles, and of
systems and components intended for such vehicles. Until recently, there were no
specific provisions for hydrogen-powered vehicles within the framework directive.
However, on 4th February 2009, Regulation (EC) No. 79/2009 on the type-approval of
hydrogen-powered vehicles was published in the Official Journal of the European
Communities. The hydrogen regulation amends certain annexes of Directive 2007/46/EC
with the aim of specifying harmonised safety requirements for hydrogen-powered
vehicles.
The hydrogen regulation contains general requirements for the type-approval of
hydrogen systems and components. These are fundamental provisions laid down by the
European Parliament and the Council and adopted through the co-decision procedure.
Detailed test procedures and technical specifications that implement the fundamental
provisions will be laid down in a separate regulation adopted by the European
Commission with the assistance of a regulatory committee. The Commission has
developed a draft regulation (known as the “implementing measures”) with the
assistance of the Hydrogen Working Group. The working group is made up of
representatives of EU Member States, the automotive industry, component
manufacturers and hydrogen associations.
The hydrogen regulation and corresponding implementing measures will set out type-
approval requirements in relation to the safety of hydrogen storage on board the vehicle
(and any components in contact with hydrogen). However, in order to accommodate
fully hydrogen-powered vehicles in the type-approval framework, it will be necessary to
review and possibly amend a number of other separate directives and regulations on
other aspects of vehicle construction.
The Commission awarded a project to TRL to review the type-approval legislation on
vehicle safety for hydrogen-powered vehicles. The objectives of the project are:
To provide technical input to the evaluation of separate type-approval directives
and regulations on vehicle safety with a view to their possible amendment to
accommodate hydrogen-powered vehicles;
To provide technical input to the development of new type-approval requirements
and the evaluation of the issues identified in the hydrogen regulation (EC No.
79/2009).
The review of type-approval directives and regulations on vehicle safety is focussing on
M and N category vehicles. The Commission highlighted six safety directives that may
need to be amended. This interim report presents an initial review of each directive (and
the corresponding UNECE regulation). The main focus was on their compatibility with
hydrogen-powered vehicles, and any safety risks that might result from incompatible
test methods or requirements. Other regulations and standards relating to the topic of
each directive were also reviewed. The aim was to identify examples of the way that
hydrogen-vehicles had been dealt with elsewhere. Finally, the scientific literature was
examined to find robust technical data to support recommendations for amending each
directive.
Two issues are identified in the hydrogen regulation: Firstly, the use of mixtures of
natural gas and hydrogen as a fuel in internal combustion engines, and secondly, the
regulation of hydrogen-powered L category vehicles (i.e. light two, three or four wheel
vehicles). The study is considering whether legislative action on these issues is timely
and what form it might take.
This interim report summarises the work carried out so far and the initial findings. The
remaining work will focus on completing any outstanding analyses. In addition, TRL will
meet a limited number of stakeholders on an individual basis, before presenting the
findings of this interim report at a stakeholder workshop. As mentioned above, the
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intention will be to gain feedback on the proposals and to identify any further topics that
may need to be included.
The review of type-approval directives and regulations on vehicle safety has covered:
fuel tanks, radio interference, identification of controls, frontal impact, side impact and
buses and coaches. This has revealed that:
Hydrogen-powered vehicles should be exempt from fuel tank requirements
because the risks are dealt with by the hydrogen regulation and (draft)
implementing measures.
The radio interference legislation includes performance requirements, but
references international standards for the test methods. Some of the
standards have procedures to deal with electric vehicles (which could be
applied to hydrogen fuel cell vehicles). However, some potential issues were
raised, such as the vehicle load conditions and antenna positions.
Amendments to the frontal and side impact legislation are needed to
accommodate hydrogen-powered vehicles. The amendments will need to
cover:
i. The test procedure including the fuelling conditions for the impact test.
ii. The post-crash requirements including hydrogen leakage limits.
There are no symbols in the legislation that must be used with controls, tell-
tales and indicators for the hydrogen system in a hydrogen-powered vehicle.
Furthermore, no symbols are available in the main international standard.
New symbols will be needed for hydrogen-powered vehicles. However, the
current optical indicator and tell-tale colour meanings set out in the legislation
and the standard are appropriate.
The bus and coach requirements are largely independent of the power train.
However, additional provisions may be needed for the stability and strength of
superstructure tests and for the electrical safety of the driver and passengers.
Internal combustion engines that run on natural gas produce fewer harmful emissions
than petrol engines, but they are less efficient. Adding hydrogen to produce a blended
fuel can increase the efficiency compared with natural gas alone. Further work will be
carried out in this project with a view to providing the Commission with
recommendations on the technical amendments needed to accommodate mixtures of
natural gas and hydrogen in the type-approval legislation. There are several important
issues that need to be resolved. For instance, it is necessary to determine what mixing
ratio is likely to be used. Various different ratios have been examined in the literature. It
might be the case that a standard ratio is used in the future, or that vehicles will be
capable of running on different ratios (within certain limits). The effect of the mixing
ratio on engine performance and emissions needs to taken into account and the safety
implications of each ratio need to be understood. The project will focus on these areas.
Two, three and some four wheel vehicles are not included in the framework directive for
M and N category vehicles (Directive 2007/46/EC). Instead, these are termed L category
vehicles and a different framework directive applies: Directive 2002/24/EC. Currently,
there are no specific provisions for hydrogen-powered L category vehicles in Directive
2002/24/EC or in the separate technical directives. A manufacturer who wishes to place
such a vehicle on the market may face difficulties, therefore, with the present situation.
L category vehicles might be early adopters of hydrogen as a fuel, but it will be essential
to identify any safety risks and to consider how these risks should be mitigated. The
main concern is the safety of hydrogen storage on-board the vehicle (and any
components in contact with hydrogen). Regulation (EC) No. 79/2009 (the hydrogen
regulation) and the draft implementing measures mitigate these concerns for M and N
category vehicles. While it would be inappropriate to include L category vehicles in the
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hydrogen regulation and implementing measures (because they are part of a separate
legislative framework), they might form the basis for new type-approval requirements
for L category vehicles. These issues and their implications will be examined further in
the remainder of the project.
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1 Introduction
The European Commission (EC) has awarded a project to TRL to review the type-
approval legislation on vehicle safety for hydrogen-powered vehicles. The specific
objectives of the project are:
To provide technical input to the evaluation of separate type-approval directives
and regulations on vehicle safety with a view to their possible amendment to
accommodate hydrogen-powered vehicles;
To provide technical input to the development of new type-approval requirements
and the evaluation of the issues identified in the hydrogen regulation (EC No.
79/2009).
The review of type-approval directives and regulations on vehicle safety is focussing on
M and N category vehicles. The study will consider whether the requirements are
compatible with hydrogen-powered vehicles and the potential safety risks of any
incompatible legislation.
Two issues are identified in the hydrogen regulation: Firstly, the use of mixtures of
natural gas and hydrogen as a fuel in internal combustion engines, and secondly, the
regulation of hydrogen-powered L category vehicles (i.e. light two, three or four wheel
vehicles). The study will consider whether legislative action on these issues is timely and
what form it might take.
This interim report summarises the work carried out so far and the initial findings. The
report has been prepared for the EC, but with the understanding that it will be circulated
among stakeholders. Initial recommendations have been made for amendments that
may be needed to the type-approval legislation on vehicle safety. TRL anticipates that
these initial proposals will generate a great deal of feedback from stakeholders. This is
very much welcome and will be taken into account in the remainder of the research.
The remaining work will focus on completing any outstanding analyses. In addition, TRL
will meet a limited number of stakeholders on an individual basis, before presenting the
findings of this interim report at a stakeholder workshop. As mentioned above, the
intention will be to gain feedback on the proposals and to identify any further topics that
may need to be included.
1.1 Background on hydrogen-powered vehicles
Hydrogen-powered vehicles can be based around an internal combustion engine or a fuel
cell. Hydrogen internal combustion engine vehicles tend to have a limited range and
reduced luggage space compared with conventional vehicles. However, there is
extensive knowledge in engine design and performance and the fundamental technology
is available today. Some internal combustion engines can run on hydrogen as well as on
conventional fuels, or various blends can be used. They are often considered, therefore,
a bridging technology towards the more widespread use of hydrogen. Burning hydrogen
in combustion engines produces nitrous oxides, but these can be up to 90% lower than
petrol engines because the engine can operate in the so-called “lean-burn” mode with an
excess of air (International Energy Agency, 2005). Such engines can achieve an overall
efficiency of 38%, which is 20-25% better than a typical petrol engine (Ahluwalia et al.,
2004).
Hydrogen fuel cell vehicles have an electrical powertrain. Hydrogen (or a hydrogen-rich
fuel) is chemically converted into water, electricity and heat. The process is highly
efficient and there are no harmful emissions at the point of use. Fuel cells are often seen
as a longer term stage in the development of road vehicles. Nevertheless, a number of
major manufacturers have fuel cell cars at the prototype technology demonstration
stage.
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The storage of hydrogen on-board the vehicle represents a technical challenge. In order
to achieve a reasonable energy density it is currently stored as a compressed gas or as a
liquid at very low temperature. Research is also being carried out into solid-state
storage, using absorbers such as hydrides.
1.2 Overview of the legislation for hydrogen-powered vehicles
1.2.1 EC type-approval
European Commission (EC) Whole Vehicle Type-Approval is based around EC directives
and provides for the approval of whole vehicles, in addition to systems and components.
A framework directive lists a number of separate technical directives that the vehicle
must comply with in order to gain type-approval. The framework directive also lists
United Nations Economic Commission for Europe (UNECE) regulations that are
considered to be acceptable alternatives to certain EC directives. The scheme was
introduced in the 1970s through Directive 70/156/EEC and it became mandatory for M1
category vehicles (i.e. passenger cars) in 1998. A recast new framework directive,
2007/46/EC, has since been published and extends the scheme to larger passenger (M2
and M3 category) and goods vehicles (N category).
Until recently, there were no specific provisions for hydrogen-powered vehicles within
the framework directive. This meant that manufacturers were unable to gain type-
approval for their vehicles and may have faced difficulties with the national schemes of
individual member states. However, on 4th February 2009, Regulation (EC) No. 79/2009
on the type-approval of hydrogen-powered vehicles was published. The regulation
amends certain annexes of Directive 2007/46/EC with the aim of establishing
harmonised safety requirements for hydrogen-powered vehicles.
Regulation (EC) No. 79/2009 contains general requirements for the type-approval of
hydrogen systems and components. These are fundamental provisions laid down by the
European Parliament and the Council. Detailed test procedures and technical
specifications that implement the fundamental provisions will be laid down in a separate
regulation adopted by the Commission with the assistance of a regulatory committee.
The Commission has developed a draft regulation (known as the “implementing
measures”) with the assistance of the Hydrogen Working Group. The working group is
made up of representatives of EU Member States, the automotive industry, component
manufacturers and hydrogen associations.
The hydrogen regulation and corresponding implementing measures will set out type-
approval requirements in relation to the safety of hydrogen storage on board the vehicle
(and any components in contact with hydrogen). However, in order to accommodate
fully hydrogen-powered vehicles in the type-approval framework, it will be necessary to
review and possibly amend a number of other separate directives and regulations on
other aspects of vehicle construction.
In 2014, around 50 base directives covering vehicle safety issues will be repealed. Their
requirements will be carried over to Regulation (EC) No. 661/2009 (on the general safety
of motor vehicles) and replaced, where appropriate, with reference to the corresponding
UNECE regulations. This is intended to simplify type-approval legislation in line with the
recommendations contained in the final report of the CARS 21 High Level Group
(European Commission, 2006).
1.2.2 UNECE regulations
UNECE regulations provide for the approval of vehicle systems and separate
components, but not whole vehicles. Many duplicate EC directives, although the EC
directive often lags behind the UNECE regulation. There are no UNECE regulations for
hydrogen systems and components. However, a global technical regulation on hydrogen-
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powered vehicles is being developed under the auspices of the UNECE. It is being
administered by the World Forum for Harmonisation of Vehicle Regulations (WP 29),
which is a subsidiary body of the UNECE. This has been possible through the 1998 Global
Agreement, which seeks to promote international harmonisation through the
development of global technical regulations. The 1998 Agreement is open to countries
that are not signatories to the 1958 Agreement and hence do not recognise UNECE
regulations. The global technical regulation for hydrogen-powered vehicles specifies both
their safety and their environmental performance. Two subgroups have been formed to
assist in the development of the regulation. A subgroup on safety reports to the Working
Party on Passive Safety (GRSP) and a subgroup on environmental aspects reports to the
Working Party on Pollution and Energy (GRPE).
An informal working group on electric safety (ELSA) has been set up under GRSP to
revise UNECE Regulation 100 (battery electric vehicles). One of the main objectives of
the ELSA is to extend the scope and requirements to all kinds of power train types above
a certain working voltage level. This would include hydrogen-powered fuel cell vehicles.
In addition, a group of interested experts on electric vehicles post-crash provisions
(EVPC) are preparing amendments to UNECE Regulations 94 (frontal impact) and 95
(side impact). Once again, the aim is to extend the scope to all power trains above a
certain voltage.
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2 Review of type-approval directives and regulations
on vehicle safety
The EC highlighted six safety directives that may need to be amended. The following
sections present an initial review of each directive and the corresponding UNECE
regulation, although it is understood that each of the directives will be repealed in 2014
when Regulation (EC) No. 661/2009 (on the general safety of motor vehicles) takes
effect.
For each directive/regulation, the main focus was on their compatibility with hydrogen-
powered vehicles, and any safety risks that might result from incompatible test methods
or requirements. Other regulations and standards relating to the topic of each directive
were also reviewed. The aim was to identify examples of the way that hydrogen-vehicles
had been dealt with elsewhere. Finally, the scientific literature was examined to find
robust technical data to support recommendations for amending the legislation.
2.1 Fuel tanks and rear under-run protection: Directive 70/221/EEC and UNECE Regulation 34
2.1.1 Overview
Directive 70/221/EEC (as amended) comprises two separate parts. The first part relates
to liquid fuel tanks (where the fuel is liquid at ambient temperature conditions). It
outlines a number of general design and installation requirements and assesses the
performance of the tank in a series of tests. For instance, the directive states that the
design of the tank must be such that excess pressure can be compensated for
automatically, by a relief valves (or otherwise). The tank‟s ability to achieve this is
validated by a hydraulic pressure test. Other design requirements include ensuring the
tank and filler system are completely separate from the occupant, luggage and engine
compartments and that fuel leakage is keep to a minimum, including when the vehicle is
inverted (validated by an overturning test). Finally, the installation of the tank in the
vehicle should provide protection against damage caused by a front or rear impact to the
vehicle as well as minimising the risk of fire and avoiding the build up of static electricity.
The types of tests that are carried out depend on the construction of the fuel tank. Metal
fuel tanks are subjected to the following tests:
Hydraulic internal pressure test
The pressure inside a tank, completely filled with a non-flammable liquid (e.g.
water), is increased to double the working pressure (at least 0.3 bar) and maintained
for 1 minute. The tank must not crack or leak during the test, however it may
permanently deform.
Overturning test
Tests are conducted with a tank 90% full and also 30% full of non-flammable liquid
(e.g. water). The tank is rotated 90° in both directions, each time being held for 5
minutes. The tank is then completely inverted and again held for 5 minutes. The fuel
leakage must not exceed 30 g/min during the test.
There are also a series of additional tests that are conducted on fuel tanks made out of
plastic:
Fuel permeability
The tank is filled with fuel to 50% of its capacity and stored at 40°C for eight weeks.
The average loss of fuel must not be more than 20 g per 24 hours of testing time.
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Resistance to fuel
After the fuel permeability test, the tank must still be capable of passing the impact
resistance and mechanical strength tests (described below).
Impact resistance
The tank (filled with a fuel substitute and kept at -40°C) is impacted by a pendulum:
the tank must not leak.
Mechanical strength
This is identical to the hydraulic internal pressure test, but the tank is filled with
water at 53°C, the tank must not crack or leak, but may permanently deform.
Resistance to fire
The tank (50% full of fuel) is heated directly and indirectly by a fire: the tank must
not leak after the test.
Resistance to high temperature
The tank (50% full of water) is stored at a temperature of 95°C for 1 hour, after
which the tank should not leak or be seriously deformed.
Markings on the fuel tank
The tank needs to have marking clearly legible when installed on the vehicle.
The second part of the directive sets requirements to provide rear under-run protection
for large vehicles. It is intended to prevent smaller vehicles from under-running them in
the event of a collision. The rear of the vehicle must provide effective protection, either
by the vehicle bodywork itself or by a specific rear bumper device.
The EC recognises UNECE Regulation 34 (as amended) as an alternative to the fuel tanks
part of Directive 70/221/EEC. The main purpose of the regulation is to prevent fire risks
by establishing design and performance requirements for liquid fuel systems. The
regulation comprises four main parts:
Part 1 Approval of vehicles with regard to their fuel tanks
This part applies to all M and N category vehicles and is practically identical to the
fuel tanks part of Directive 70/221/EEC.
Part 2 Approval of vehicles with regard to the prevention of fire risks in frontal
and/or lateral and/or rear collision
This part applies at the request of the manufacturer to all M and N category vehicles
that are approved to parts 1 and 4 of the regulation. It contains requirements for the
installation of liquid fuel tanks that cover both the fuel installation and the electrical
installation. The fuel installation requirements cover the protection of components
from obstacles on the ground and from abnormal stress brought about by twisting
and bending movements, and vibrations of the vehicle‟s structure. The components
must also remain leak-proof under the various conditions of use of the vehicle. The
electrical installation requirements are intended to protect the wiring insulation from
damage (at points where electrical wires pass through walls or partitions) and from
corrosion.
This part of the regulation also contains frontal, lateral and rear-end impact tests and
associated post-collision leakage requirements. The frontal impact test procedure
comprises a full-width test against a rigid barrier from 48.3 to 53.1 km/h. However,
the test procedure in annex 3 of UNECE Regulation 94 can be used instead. The
lateral impact test is performed according to annex 4 of Regulation 95 (i.e. there is
no test procedure in UNECE Regulation 34). Finally, the rear-end impact test
procedure involves the vehicle being struck by a rigid impacting surface from 35 to
38 km/h. This can take the form of a moving barrier or a pendulum test. In each
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case, no more than “a slight leakage of liquid in the fuel installation” is permitted,
and if there is a continuous leakage after the collision, it must not exceed 30 g/min.
In addition, the (auxiliary) battery must be kept in position by its securing device.
Part 3 Approval of tanks for liquid fuel as technical units
This part lists the requirements of part 1 of the regulation that must be met when
approving liquid fuel tanks as separate units.
Part 4 Approval of vehicles with regard to the installation of approved tanks
This part lists the requirements of part 1 that must be met when installing an
approved fuel tank.
2.1.2 Compatibility with hydrogen-powered vehicles and safety risks
While some of the design and installation requirements in Directive 70/221/EEC (and
UNECE Regulation 34) are relatively general and could be applied to any type of fuel
tank, it is clear that the performance tests were not designed for a fuel with the
properties of hydrogen. The directive does not consider many of the risks associated with
the use of hydrogen, nor does it take into account the properties of hydrogen in the test
methods. In fact, a number of the tests could be dangerous to persons and property if
they were attempted with a hydrogen container without proper precautions.
Other alternative fuel vehicles are dealt with by separate regulations. For instance,
Liquefied Petroleum Gas (LPG) vehicles and Compressed Natural Gas (CNG) vehicles are
not covered by Directive 70/221/EEC, but must meet the requirements of UNECE
Regulation 67 (LPG) and UNECE Regulation 110 (CNG).
Regulation (EC) No. 79/2009 and the (draft) implementing measures establish
requirements that were developed specifically for hydrogen containers. Similar
requirements are being prepared in the draft global technical regulation on hydrogen. It
appears, therefore, that while Directive 70/221/EEC (Annex 1) and UNECE Regulation 34
are inappropriate for hydrogen-powered vehicles, significant amendment is not
necessary because another regulation will apply that does adequately consider the issues
relevant to hydrogen.
2.1.3 Proposals for amendments
The framework directive, 2007/46/EC, requires a hydrogen-powered vehicle to meet the
requirements of Regulation (EC) No. 79/2009. Hydrogen-powered vehicles should
therefore be exempt from the first part (i.e. Annex 1) of Directive 70/221/EEC (or any
part of UNECE Regulation 34), because the risks are covered by the hydrogen regulation.
The second part of Directive 70/221/EEC (on under-run protection) is still appropriate for
hydrogen-powered vehicles and can be applied without amendment.
2.2 Radio interference (electromagnetic compatibility): Directive 72/245/EEC and UNECE Regulation 10
2.2.1 Overview
Directive 72/245/EEC (as amended) specifies the minimum standards of electromagnetic
compatibility for whole vehicles and for electrical/electronic sub-assemblies (i.e.
components or separate technical units intended to be fitted in vehicles). It includes
requirements regarding the control of radiated emissions from the vehicle, and also the
immunity of the vehicle itself to radiated disturbances. For electrical/electronic sub-
assemblies, conducted emissions and conducted disturbances are assessed. Both
broadband and narrowband emissions and immunity are assessed; narrowband
emissions are primarily those produced by on-board electronic modules.
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Test methods are included in a series of annexes. A CISPR (Comité International Spécial
des Pertubations Radioélectriques; in English, International Special Committee on Radio
Interference) or ISO (International Organisation for Standardisation) standard is
referenced for aspects of the method or for a detailed procedure.
UNECE Regulation 10 (as amended) is equivalent to the directive, and the requirements
are almost identical. Regulation 10 covers vehicle categories L (two or three-wheel
motor vehicles), M (passenger vehicles), N (goods vehicles) and O (trailers), whereas
Directive 72/245/EEC only covers categories M, N and O (category L being covered
within Directive 97/24/EC). Approval to the UNECE regulation is a recognised alternative
to an EC type-approval granted under Directive 72/245/EEC.
Directive 72/245/EEC will be repealed on 1 November 2014 (by Regulation (EC) No.
661/2009). From that date, UNECE Regulation 10 will be the only option for obtaining
EC automotive type-approval for electromagnetic compatibility.
Radiated broadband emissions from vehicles
This test is carried out to measure the broadband emissions generated by electrical or
electronic systems fitted to the vehicle (such as the ignition system or electric motors).
The test method in Directive 72/245/EEC describes the vehicle state during the test and
the test conditions; however, it also notes that the test should be performed according
to CISPR 12:2001 (the fifth edition).
Several revisions and amendments have been made to CISPR 12 since 2001. The first
amendment was made in 2005 and a consolidated version of the standard was
published: CISPR 12:2001+A1:2005. In 2007, a sixth edition was published:
CISPR 12:2007, which has also been amended. It seems that the latest version of the
standard is: CISPR 12:2007+A1:2009. UNECE Regulation 10 uses a later version of
CISPR 12 than the directive (fifth edition, amendment 1, of 2005), but is still not using
the latest edition. Andersen (2009) reports that the sixth edition of CISPR 12 has
removed the broadband / narrowband differentiation. Updating the directive and
regulation to use the sixth edition would therefore require changes beyond just updating
the references to the CISPR document, as both the directive and regulation have
separate broadband and narrowband annexes.
The engine state is probably the most important aspect of the test method (for the
purposes of this study). If the vehicle is equipped with an internal combustion engine,
the engine is operated at 1,500 r/min for a multi-cylinder engine and 2,500 r/min for a
single cylinder engine. If it is equipped with an electric motor, the vehicle is driven on a
dynamometer without a load, or on axle stands, at a constant speed of 40 km/h (or at
maximum speed if less than 40 km/h). These test conditions are set out in
CISPR 12:2001, the version used by the directive. The 2005 amendment (the version
used by the UNECE regulation) adds specific instructions for hybrid vehicles.
Radiated narrowband emissions from vehicles
This test is carried out to measure the narrowband emissions such as those that might
emanate from microprocessor-based systems or other narrowband sources. Once again,
the test method in the directive describes the vehicle state and test conditions. Unless
otherwise stated, the test is performed according to CISPR 12:2001 or to CISPR 25:
2002 (the second edition). The narrowband emissions of a vehicle are measured with the
ignition switched on, but without the engine operating.
UNECE Regulation 10 again refers to the fifth edition, amendment 1, of 2005, of
CISPR 12, but it refers to the same version of CISPR 25 as the directive.
The latest version of CISPR 25 is the third edition, CISPR 25:2008, including
corrigendum 1. As with the sixth edition of CISPR 12, this has had the broadband /
narrowband differentiation removed. Updating the directive and regulation to use the
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latest editions would therefore require changes beyond just updating the references to
the CISPR documents.
Immunity of vehicles to radiated disturbances
This test is intended to assess the immunity of the vehicle‟s electronic systems. The
vehicle is subjected to electromagnetic fields and monitored during the test. The test is
performed according to ISO 11451-2:2005 (third edition), unless otherwise stated in the
directive. This appears to be the current version of the standard. ISO 11451-2 can be
applied regardless of the vehicle‟s propulsion system (e.g. spark ignition engine, diesel
engine, electric motor). References are also made to ISO 11451-1:2005 (third edition)
for aspects of the test conditions. The latest version of this is ISO 11451-1:2005/Amd
1:2008. In both cases, UNECE Regulation 10 refers to the same edition as the directive.
The vehicle is operated during the test at a steady speed of 50 km/h. The immunity
type-approval limits are probably the most important aspect of this test (for the
purposes of this study). The directive sets the field strength at 30 V/m RMS in over 90%
of the 20 to 2,000 MHz frequency band and a minimum of 25 V/m RMS over the whole
20 to 2,000 MHz frequency band. These figures represent the strength of the
electromagnetic radiation that the vehicle must be capable of withstanding. The vehicle
must demonstrate no degradation in the performance of „immunity-related functions‟.
However, TRL understands that vehicle manufacturers test with much higher field
strengths (typically 80 to 90 V/m). Testing is performed to these higher levels to satisfy
product liability concerns.
Radiated broadband emissions from electrical/electronic sub-assemblies
This test is intended to measure broadband emissions from sub-assemblies which may
be subsequently fitted to vehicles that have passed the whole vehicle test. The test is
performed according to CISPR 25:2002. As noted above, the latest version of this
standard is CISPR 25:2008. UNECE Regulation 10 uses the same edition as the directive.
Radiated narrowband emissions from electrical/electronic sub-assemblies
This test is intended to measure narrowband emissions from sub-assemblies which may
be subsequently fitted to vehicles that have passed the whole vehicle test. The test is
performed according to CISPR 25:2002 in both the directive and the regulation.
Immunity of electric/electronic sub-assemblies to radiated disturbances
This test assesses the immunity of electrical/electronic sub-assemblies. The sub-
assemblies may comply with the requirements of any combination of the following test
methods at the manufacturer‟s discretion (in both the directive and the regulation):
Absorber chamber test according to ISO 11452-2:2004;
TEM cell testing according to ISO 11452-3:2001;
Bulk current injection testing according to ISO 11452-4:2005;
Stripline testing according to ISO 11452-5:2002;
Stripline testing according to the method in the directive.
The sub-assembly is exposed to electromagnetic radiation in the 20 to 2,000 MHz
frequency range at the intervals specified in ISO 11451-1:2005.
Immunity of electrical/electronic sub-assemblies to conducted disturbances
This test is intended to assess the immunity of sub-assemblies to transient disturbances
conducted along supply lines. The directive and the regulation state that certain test
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pulses must be applied to the sub-assembly according to ISO 7637-2:2004. The pulses
are applied to the supply lines as well as to other connections that may be operationally
connected to the supply lines. ISO 7637-2:2004 specifies bench tests for equipment
fitted to passenger cars and light commercial vehicles equipped with a 12 V electrical
system or to commercial vehicles equipped with a 24 V electrical system. It applies to all
these vehicles irrespective of the propulsion system.
Conducted emissions from electrical/electronic sub-assemblies
This test measures the conducted transient emissions from sub-assemblies to the vehicle
power supply. For both the directive and the regulation, measurements are performed
according to ISO 7637-2:2004 on supply lines as well as on other connections that may
be operationally connected to supply lines.
2.2.2 Compatibility with hydrogen-powered vehicles and safety risks
The current practices for measuring electromagnetic emissions and immunity were
developed for internal combustion engines. However, hydrogen fuel cell vehicles have an
electrical power train. This differs greatly from conventional automotive electrical system
components. The power required by an electrical power train is much higher than the
power demand of the electrical system in conventional vehicles (Guttowski et al., 2003).
Power electronic systems are likely to be the main source of electromagnetic interference
within electrical power trains. In particular, high-speed switching devices could be an
important source of emissions.
Directive 72/245/EEC and UNECE Regulation 10 do not include any specific provisions for
hydrogen-powered vehicles or any vehicles with an electrical power train. However, the
directive and the regulation reference several important CISPR and ISO standards when
describing the test methods. These standards, or parts of them that are referenced,
effectively become part of the legislative test methods. At least one of these standards
(CISPR 12:2001+A1:2005) has been amended to take some account of vehicles with
electrical power trains. In this standard, broadband emission measurements for vehicles
with electrical propulsion are made using a steady-state dynamic test at a constant
speed of 40 km/h. The equivalent test for vehicles with internal combustion engines
would require the engine to be running but not propelling the vehicles.
There are relatively few published studies of the electromagnetic compatibility of
hydrogen-powered vehicles (or vehicles with electrical power trains). Nevertheless, there
is some evidence to suggest that acceleration, deceleration (regenerative braking) and
charging cycles may result in higher electromagnetic emissions (Ruddle, 2002). There
would be significant practical difficulties in making measurements under transient
conditions such as acceleration and deceleration. The current approach seems to offer
greater reliability and consistency. Nevertheless, it may be appropriate at least to
consider these options as possible enhancements of the standards.
UNECE Regulation 10 is equivalent to Directive 72/245/EEC and is practically identical.
However, a different version of CISPR 12 is referenced for the broadband emissions
tests. The directive refers to the fifth edition of the standard (CISPR 12:2001), while the
regulation refers to the fifth edition, including the 2005 amendment
(CISPR 12:2001+A1:2005). The latest version is the sixth edition including a 2009
amendment (CISPR 12:2007+A1:2009).
The directive includes testing for both the immunity of electrical and electronic systems
to transient disturbances and for their emissions. Transient disturbances fall into three
general categories: those generated by electrical and electronic systems on the vehicle,
electrostatic discharges and lightning. A vehicle with an electrical power train is
potentially a source of many transient disturbances, due to the large number of high
power components. There are already a number of electronic systems fitted to vehicles
that control safety critical applications. The transient performance of the vehicle can
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therefore have a significant effect on vehicle safety (Simmons and Noble, 1996). TRL is
seeking further literature on this subject.
2.2.3 Proposals for amendments
The provisions for the electromagnetic compatibility of vehicles are effectively split
between the legislative documents (Directive 72/245/EEC and UNECE Regulation 10) and
the CISPR and ISO standards. Proposals to amend the provisions might be more
appropriately taken forward through CISPR and ISO, rather than by seeking
amendments to the legislation. Nevertheless, TRL proposes the following areas for
amendment, based on our own analysis and ideas obtained from the literature. In
particular, a number are proposals of, or ideas discussed by Ruddle (2002).
Update the directive and the regulation to refer to the latest versions of the
CISPR and ISO standards, unless there is good reason not to. This would then
make use of any recent changes to CISPR or ISO standards that have specifically
addressed issues concerning vehicles with electrical power trains.
o Rather than continually updating the legislation, the requirement could be
changed to require always the use of the latest version of the standard.
Alternatively, use of the latest version could be optional. However, either
option would carry the risk of changes effectively being made without the
approval of the legislative authorities. Also, it could generate
inconsistencies between the documents. For instance, CISPR 12, sixth
edition, has removed the broadband/narrowband differentiation; this
would require changes to the legislation with its separate broadband and
narrowband annexes, beyond merely updating the references to the CISPR
document.
Consider whether it would be worthwhile to include also testing under
acceleration and regenerative braking. While these conditions may potentially
produce broadband emissions that exceed the steady-state limits, the benefits of
testing to control such emissions may be inadequate to justify the increased costs
of testing. Also, conventional vehicles may also exceed the limits at high engine
speeds, as they are only required to meet the limits at a steady 1,500 r/min
(assuming a multi-cylinder engine); so requiring limits under acceleration for
hydrogen fuel cell vehicles only could be considered to be discriminatory.
Alternatively, conventional vehicles could also be tested under such conditions.
o Higher emissions during acceleration may be caused by the higher power
used or by the higher motor speed, rather than being a direct
consequence of the acceleration. If this is the case it would be more
sensible to use a constant vehicle speed, under load conditions that
simulated acceleration.
Such simulated acceleration would probably be a worst case, so if it
were introduced it should be possible to drop the existing steady
speed requirement.
o However, it might possibly be that varying the power during acceleration
or at the beginning or end of the acceleration phase might be a greater
problem for emissions, if the controller is a significant source.
o As for acceleration, generative braking could potentially be simulated
under constant speed conditions, in this case by powering the vehicle from
the dynamometer.
The antenna in the emissions tests is currently aligned with the centre of the
engine. This is presumably because spark-ignition engines are likely to provide
the principal source of vehicle emissions. However, the electric motor may not be
the principal source of emissions for hydrogen fuel cell vehicles. Consideration
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should be given to aligning on whichever component is normally the principal
source, or perhaps finding a compromise position.
2.3 Identification of controls, tell-tales and indicators: Directive 78/316/EEC and UNECE Regulation 121
2.3.1 Overview
Drivers must understand and operate a range of controls and instrumentation. There are
the main driving controls and various other buttons and switches that activate
equipment in the vehicle. There are also increasing numbers of information and warning
indicators, particularly with the introduction of active safety systems in recent years.
Directive 78/316/EEC (as amended) describes the symbols to be used for identifying
these controls, tell-tales and indicators. A number of other specifications must be met to
gain approval. These relate to the characteristics of the symbols (such as their colour
and size), or their position.
The directive applies to all M and N category vehicles. The purpose is to harmonise the
symbols used by vehicle manufacturers and hence reduce the risk of drivers being
distracted. For instance, a driver may become distracted from the driving task while
trying to find a control or understand the meaning of a tell-tale or indicator, particularly
in an unfamiliar vehicle. The following definitions are used:
A „control‟ is the hand-operated part of a device that allows the driver to bring
about a change in the state or functioning of a vehicle;
An „indicator‟ is a device which presents information on the functioning or
situation of a system (or part of a system);
A „tell-tale‟ is an optical signal which indicates that a device has been activated, is
functioning correctly or not, or has failed to function at all.
There are 23 controls, tell-tales and indicators that must be identified whenever they are
fitted. The directive includes symbols to be used (which it states are in accordance with
ISO 2575:1982, fourth edition) along with tell-tale colours where applicable. These
mandatory symbols deal with lighting and signalling, visibility and key aspects of the
maintenance, engine and fuel system of vehicles.
There are a further 11 controls, tell-tales and indicators that may be identified whenever
they are fitted, but it is not mandatory. However if they are identified, symbols that
conform to the directive must be used. The symbols for optional controls deal with rear
visibility, security, safety systems, the engine and fuel system. Controls, tell-tales and
indicators that are not listed in the directive can be identified using any other symbol,
provided there is no danger of confusion with those listed in the directive.
The most recent amendment to Directive 78/316/EEC was made in 1994. Since that
time, the Commission has acceded to UNECE Regulation 121 (as amended) on the
location and identification of hand controls, tell-tales and indicators. The regulation
applies to all M category vehicles and also to N1 category vehicles. It lists over 40
controls, tell-tales and indicators and the symbols that must be used to identify them. It
also includes a number of other specifications. These are similar to those in the directive,
but are more comprehensive. For example, the regulation contains specifications relating
to the illumination of controls, which do not appear in the directive.
Many of the symbols are identical to those in the directive, but there are additional
symbols, which typically relate to safety systems and the engine. If a control, tell-tale or
indicator is not listed in the regulation, it recommends that a symbol intended for the
same purpose in ISO 2575:2000 is used. However, a manufacturer may use its own
symbol if no suitable symbol can be found, provided that it does not cause confusion
with any symbol specified in the regulation.
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2.3.2 Compatibility with hydrogen-powered vehicles and safety risks
There are no symbols in Directive 78/316/EEC or in UNECE Regulation 121 that deal
specifically with a hydrogen system. The directive permits any other symbol to be used
when a control, tell-tale or indicator is not listed, but there can be no possibility of
confusion with a listed symbol. UNECE Regulation 121 takes a slightly different approach
to the directive and recommends that a symbol from ISO 2575:2000 is used (if
available) and that all symbols follow ISO 2575:2000 guidelines.
ISO 2575:2000 has been withdrawn; the current version is ISO 2575:2004, with
amendments 1:2005, 2:2006, 3:2008 and 4:2009. The standard (together with its
amendments) includes thirteen symbols that relate to the fuel system. Many of these are
developed from the traditional fuel symbol (i.e. a fuel pump). For example, there is a
symbol for the fuel type, which comprises the traditional fuel symbol with a label
underneath. Hydrogen is listed as one of the example fuels, but it is unclear whether it
should be written in full, or whether the letter “H” or “H2” could be used. None of the
remaining symbols mention hydrogen specifically, but they could be applied to a
hydrogen vehicle. For example, there are symbols for fuel system failure, fuel shut-off
and fuel pressure. The standard also includes symbols for electric vehicles (for example,
electric motor failure), which could be applicable to hydrogen fuel cell vehicles.
A hydrogen-powered vehicle may use a number of relatively basic controls, tell-tales and
indicators. For example, there will be a hydrogen fuel level indicator and there might
also be a power level indicator. Symbols currently in the legislation, or in the standard,
may need to be amended or new symbols may be needed. A hydrogen vehicle may also
use more complex controls tell-tales and indicators, such as those linked to a critical
safety feature. It is likely that these will be guided by the requirements of Regulation
(EC) No. 79/2009 (the hydrogen regulation) and the draft implementing measures.
Regulation (EC) No. 79/2009 requires that an automatic shut-off valve is fitted on or
within the hydrogen container. The valve must close if there is a malfunction of the
hydrogen system, if an event occurs that results in the leakage of hydrogen, or if the
vehicle is involved in a collision. Although the draft implementing measures do not refer
to a warning system to alert the driver to the activation of the valve, manufacturers may
decide to fit a tell-tale.
The draft implementing measures require that a warning system is fitted to alert the
driver to a failure of the boil-off management system (in a liquid hydrogen vehicle). No
further requirements are made; however, a corresponding symbol may be needed.
Similarly, the implementing measures also require a warning for the driver in the event
of a failure of the electronic vehicle control system.
The draft global technical regulation for hydrogen-powered vehicles must also be
considered. This requires that the driver is warned in the event of hydrogen leakage that
results in concentration levels above a certain threshold. The driver must also be warned
if there is a failure in the detection system. The details of the requirements have not
been finalised yet, but TRL understands that both scenarios will be dealt with by a single
tell-tale. It has been agreed that the colour of the light for the system working correctly
should be green. A malfunction of the detection system should display an amber/orange
light and activation of the emergency shut-off valve should be red. No symbol has been
agreed for the tell-tale at the present time.
In the absence of well-defined symbols for the controls, tell-tales and indicators of a
hydrogen system, there is a risk that each manufacturer might use different symbols in
their vehicles. This could result in a range of symbols in the marketplace, which might be
confusing for consumers. It might also pose a safety risk if, for instance, a driver doesn‟t
recognise a warning or tell-tale that relates to a safety system. There might also be a
risk to emergency services, who may need to understand quickly the meaning of certain
controls, tell-tales and indicators.
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2.3.3 Proposals for amendments
Directive 78/316/EEC and UNECE Regulation 121 do not include any symbols to identify
the different controls, tell-tales and indicators that will be needed for a hydrogen-
powered vehicle. UNECE Regulation 121 recommends that symbols listed in ISO
2575:2000 are used wherever possible, but a manufacturer may design its own symbols.
There are two possible avenues for amending the type-approval legislation. Firstly, the
legislation could be amended to refer to the latest version of ISO 2575. This is currently
ISO 2575:2004 (seventh edition), including amendments 1:2005, 2:2006, 3:2008 and
4:2009. It is likely that most manufacturers (and their technical services) are already
aware of the latest version of the standard; nevertheless, this would bring the legislation
up-to-date and point all manufacturers towards the latest symbols, such as those for
electric vehicles. TRL understands that ISO 2575:2010 (eighth edition) is under
development and hence it may be worthwhile to wait for this version to be published.
TRL has been unable to determine whether ISO 2575:2010 will include any symbols for a
hydrogen system, but enquiries are being made. In the absence of legislative
requirements, or clear industry standardisation, there is a risk that different symbols will
emerge in the market. With this in mind, a second possible avenue to consider is to
amend the legislation to include the symbols that are needed for hydrogen-powered
vehicles. However, this would require a great deal of industry cooperation, particularly as
the industry standards do not appear to have been amended for hydrogen. Also,
evidence would be needed that any new symbols can be understood by the public before
they are made mandatory.
For certain symbols, such as the hydrogen fuel level, it may be possible to use symbols
already in the directive and regulation, but with modifications. For example, “Hydrogen”
or “H2” could be added somewhere within the current symbol. For other symbols, such
as those that relate to particular features of the hydrogen system, new symbols will be
needed. These symbols must be consistent with the warning requirements in the
hydrogen regulation and draft implementing measures and should also be harmonised
with the draft global technical regulation. The global requirements are still being
developed and every effort should be made to introduce a harmonised global symbol for
hydrogen detection/leakage.
2.4 Frontal impact: Directive 96/79/EC and UNECE Regulation 94 / Side impact: Directive 96/27/EC and UNECE Regulation 95
2.4.1 Overview
Directive 96/79/EC (as amended) and Directive 96/27/EC (as amended) were reviewed
together (along with their corresponding UNECE regulations) because they present
similar challenges for the type-approval of a hydrogen-powered vehicle. Both directives
(and regulations) include dummy and vehicle performance requirements, which are
assessed by means of a full-scale crash test. Directive 96/79/EC and UNECE Regulation
94 (as amended) set the minimum standard for the frontal impact performance of cars
(they apply to M1 vehicles only with a mass less than or equal to 2.5 tonnes). During the
impact test, the car is propelled into an offset, deformable barrier at 56 km/h. The car
overlaps the barrier face by 40%, with first contact with the barrier on the steering
column side. Directive 96/27/EC and UNECE Regulation 95 (as amended) control the
side impact performance of cars and light goods vehicles (they apply to all M1 and N1
vehicles where the reference point of the lowest seat is less than or equal to 700 mm
from the ground). During the test, a mobile deformable barrier is propelled into the side
of the vehicle at 50 km/h. The centre of the barrier is aligned with the reference point on
the driver‟s seat.
The fuel tank is filled with water to 90% of its capacity for both the frontal and the side
impact tests. All other vehicle systems, such as the brakes or the cooling system may be
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empty. However, the vehicle must reach its unladen kerb weight and hence the mass of
any liquids that are removed must be compensated for. Occupant injury protection is
assessed using instrumented crash test dummies. There are also some important vehicle
performance requirements. Most notably (for the purposes of this study), both directives
(and their corresponding regulations) permit a small leakage from the entire fuel
system, but it must not exceed 5x10-4 kg/s. If the liquid from the fuel system mixes with
liquids from other systems, and the various liquids cannot easily be separated, all the
liquids are taken into account.
In October 2010, a group of interested experts on „Electric Vehicles Post Crash (EVPC)
provisions for regulation‟ was formed. The aim of the group is to derive amendments to
update UNECE Regulations 94 and 95 so that they are appropriate for the assessment of
electric vehicles. The group is formed mainly of experts in electrical safety from the
GRSP informal working group on electrical safety and experts in crash safety from the
GRSP informal working group on frontal impact. The group is focussing on electric
vehicles only, although the proposed amendments aim to extend the scope of the
regulations to power train types above a certain working voltage level. This will include
vehicles with an “electric energy conversion system” such as hydrogen fuel cell vehicles.
Some of the amendments proposed for electric vehicles will be applicable to hydrogen
fuel cell vehicles too. However, the EVPC group is not preparing detailed proposals for
hydrogen-powered vehicles.
2.4.2 Compatibility with hydrogen-powered vehicles and safety risks
The hydrogen regulation and draft implementing measures provide for the safety of
hydrogen storage on-board vehicles. However, full-scale crash testing will also be
important to ensure that mass-produced hydrogen-powered vehicles provide a level of
safety comparable to that of other vehicles. Both the frontal and the side impact tests in
these directives and regulations are generally appropriate for hydrogen-powered
vehicles, but amendments will be required to the test set-up procedures and to the post-
test requirements.
The fuelling condition for the test is a particularly important issue. Hydrogen could pose
a risk to personnel and property in the crash test laboratory, particularly when the
vehicle is equipped with a compressed hydrogen storage system; a fuel substitute will
probably be needed. This would be consistent with the approach currently taken in the
directives and regulations whereby water is used in place of conventional liquid fuels (for
the same reason). The draft global technical regulation on hydrogen requires helium to
be used in place of compressed gaseous hydrogen. Nitrogen is used in place of liquid
hydrogen. The purpose of the crash testing described in the draft global technical
regulation is to demonstrate the integrity of the fuel system. The particular crash tests
that are carried out are those already applied in the respective jurisdictions.
Helium is also used (for compressed gaseous containers) in the Japanese regulation,
Attachment 17, Technical Standard for Fuel Leakage in Collisions. SAE J2578,
Recommended Practice for General Fuel Cell Safety allows hydrogen or helium to be
used and offers different pressure options. Helium or hydrogen can be used at full
service pressure, or hydrogen can be used at low pressure. Certain cylinders (Type IV
composite cylinders) are more vulnerable to impact at low pressure (Hennessey and
Nguyen, 2009). At high pressure, the cylinders are more resistant to deformation and
hence a low pressure option might be a “worst case”. However, the draft global technical
regulation requires gas containers to be filled to a minimum of 90% of the nominal
working pressure.
Testing with low pressure hydrogen might mitigate some of the risks associated with its
use in a crash test and would allow the post-crash electrical output and isolation of the
fuel cell to be monitored (Hennessey and Nguyen, 2009). A fuel cell depends on the flow
of hydrogen through the stack for the electrochemical reaction with oxygen to take place
and generate an electric current. Hennessey and Nguyen (2009) discuss the possible use
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of a megohmmeter to apply an external voltage to an inactive fuel cell, but also
recognise that testing of such an approach is required. The draft global technical
regulation refers to electrical isolation and the safety and protection against electric
shock (post-crash) in the action plan, but there does not appear to be any requirements
in the text of the regulation for the latest draft (dated January 2010).
Post-crash fuel leakage is another important issue. An appropriate measurement time
and leakage rate is needed to reduce the risks to occupants (and also to emergency
services) following a collision. The draft global technical regulation proposes a limit for
the rate of gas leakage of 118 NL/min (normal litres per minute) within 60 minutes of
the crash test. The amount of gas leakage is determined by measuring the pressure loss
of the compressed gas storage containers. In the case of liquid hydrogen, the storage
system must be “tight, i.e. bubble-free if using a detecting spray”.
SAE J2578 includes guidance on the allowable amount of gas that can escape following a
crash test. This was determined by allowing the same release of energy (on a lower
heating value basis) as FMVSS 301 for gasoline. The allowable amount of hydrogen
resulting from this “equivalent energy” corresponds to an average leak rate of 120 L/min
over the 60 minute period (Scheffler et al., 2009). The Japanese regulations prescribe a
limit of 131 NL/min over 60 minutes.
While there appears to be a general consensus concerning the leakage rate and time
across the different standards mentioned above, Hennessey and Nguyen (2009) pointed
out that the properties of hydrogen are very different from other fuels and may pose a
lesser or greater risk of fire following a crash. Hydrogen dissipates quickly if unconfined,
but has a wide range of flammability. Limits that are based on energy equivalence limits
for other fuels may not be appropriate for hydrogen. Very little published research has
been found so far. However, Maeda et al. (2007) investigated leaks with a flow rate of
131 NL/min (the allowable leakage rate in Japanese regulations) and concluded there
was no significant risk to people.
2.4.3 Proposals for amendments
Ideally, proposals to amend the frontal or side impact directives would draw on the
findings of an experimental study. Very few (if any) vehicles are available on the open
market for purchase and testing and hence it would be difficult to specify and conduct
research tests in the future. The cooperation of manufacturers would be required and it
is likely that the vehicles would be very expensive. Unfortunately, relatively few data are
available in the published literature. Crash tests are sometimes mentioned with respect
to hydrogen-powered vehicles, but the details about the test procedure and post-crash
outcome are not usually presented.
In the absence of experimental data, harmonisation with the draft global technical
regulation seems to be the most sensible approach for the European type-approval
legislation. The crash test procedure would therefore need to be amended to describe
the fuelling conditions for a hydrogen-powered vehicle. In the case of a vehicle that runs
on compressed gas, the container would be filled with helium to 90% of its nominal
working pressure. A liquid hydrogen cylinder would be filled with liquid nitrogen to the
minimum mass equivalent of the maximum quantity of liquid hydrogen that may be
contained in the inner vessel and then the system would be pressurised with gaseous
nitrogen up to typical operating pressure. The post-crash leakage limit and time
proposed in the draft global regulation could also be applied in the directives:
118 NL/min.
The draft global technical regulation is still very much under development and the
content is subject to change. It is important, therefore, to monitor the progress of the
regulation during the remainder of the project before developing detailed proposals for
the European type-approval legislation. In addition, TRL will continue to monitor the
literature and will discuss these initial proposals with stakeholders.
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2.5 Buses and coaches: Directive 2001/85/EC and UNECE Regulations 66 and 107
2.5.1 Overview
Directive 2001/85/EC applies to passenger vehicles that carry 8 passengers or more
(single deck, double deck, rigid or articulated vehicles of category M2 or M3). It sets out a
series of design requirements for exits, interior arrangements, lighting, handrails and
markings, as well as requirements for the protection against fire. There is also a stability
test for all vehicles and a test of the strength of the superstructure for single deck
vehicles that carry seated passengers. The directive also requires that electrical
equipment is well-insulated and that an isolation switch is provided where the voltage
exceeds 100 V RMS.
Stability Test
The stability test assesses the roll stability of the vehicle. During this test, the vehicle is
tilted in line with the longitudinal axis. The main requirement is that the point at which
overturning occurs must be greater than 28°, when tilted to either side. The tested
vehicle must be equal to its normal running mass and contain masses representing
passengers placed in each passenger seat, or uniformly distributed over the standee
area at the correct centre of gravity. Where a vehicle is equipped to carry luggage on the
roof, a uniformly distributed mass representing the baggage is attached to the roof.
Alternatively, a calculation can be used to verify whether the vehicle would pass the test.
Strength of Superstructure
This part of the directive applies to single deck vehicles that carry seated passengers.
However, if the vehicle has been approved to UNECE Regulation 66, it is said to comply
with the requirements of this test. Four test methods are described to assess the
strength of the superstructure of the vehicle:
Roll-over test on complete vehicle
The whole vehicle, with a correct centre of gravity and mass distribution, is rotated at
no more than 5 deg/s from a platform with a minimum drop of 800 mm onto a
concrete impact area. Fuel, battery acid and other combustible, explosive or
corrosive material may be substituted by other materials as long as the mass
distribution is unaffected.
Roll-over test on a body section(s)
A bodywork section of the vehicle is subjected to the same test as above. The
percentage of total energy absorbed by the bodywork section shall not be less than
the percentage of the total mass of the vehicle as specified by the manufacturer.
Pendulum test on a body section(s)
A rectangular shaped steel pendulum strikes the vehicle body section at a speed
between 3 and 8 m/s. The energy to be applied is a proportion of the energy
declared by the manufacturer to be allocated to each cross-sectional rings included in
that particular bodywork section.
Calculations based on the data obtained from a test on a bodywork section may be
used to demonstrate the acceptability of another bodywork section which is not
identical as long as there are many common structural features.
Verification of strength by calculation
A superstructure or sections of a superstructure may be shown to meet the testing
requirements by calculation. The validity of the calculation method can be established
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by comparing the results with physical tests, such as a previously tested similar
vehicle.
The vehicle meets the requirements of the test (or calculation) if there is no intrusion
into a defined space in the passenger compartment, and if no part of this space projects
outside the deformed structure. Additional test methods or calculations may be required
if the test method (or calculation) that was used cannot take account of variations in
sections of the roof. These variations might be brought about by, for example, the
installation of an air conditioning system on the roof. If no additional information is
available, the technical service may require that a roll-over test of the complete vehicle
is carried out.
There are two UNECE regulations that are recognised as alternatives to the directive for
EC type-approval: UNECE Regulation 66 (Strength of superstructure of large passenger
vehicles) and UNECE Regulation 107 (General construction of M2 and M3 vehicles). Both
regulations would be needed to gain approval. Regulation 66 (as amended) is based
around the same strength of superstructure test as the directive. Regulation 107 (as
amended) contains the same stability test as the directive and the more general
requirements relating to the construction of vehicles.
2.5.2 Compatibility with hydrogen-powered vehicles and safety risks
The main requirements and tests in Directive 2001/85/EC (and the corresponding UNECE
regulations) are generally unrelated to the vehicle‟s power train. Both the directive and
the regulations should, for the most part, be compatible with hydrogen-powered
vehicles; the main test methods can be carried out irrespective of the type of fuel that
the vehicle uses. For example, there is no specific reference to the fuelling condition in
the stability test method, but the vehicle must be at its “mass in running order” (with
the addition of certain loads to represent passengers, crew and luggage). TRL
understands that the “mass in running order” includes 90% of the fuel capacity. It seems
likely, therefore, that a technical service would simply add an appropriate mass to the
vehicle.
In the case of a hydrogen-powered vehicle, the fuel container is likely to be located on
the roof and may therefore have a greater influence on the stability of the vehicle than a
traditional fuel tank. Furthermore, the level or pressure of hydrogen in a roof-mounted
container might affect the tilting behaviour of the vehicle in the real world. More detailed
test procedures might be needed for hydrogen-powered vehicles.
The strength of superstructure test may have to be performed on a complete vehicle
because a roof-mounted hydrogen system could lead to significant variations in the
sections of the vehicle. The test procedure allows fuel, battery acid and other
combustible, explosive materials to be substituted, provided that the vehicle is
representative of the mass in running order.
Directive 2001/85/EC (and UNECE Regulation 107) also set out provisions for the
protection against fire risks. These include:
The engine compartment
The engine compartment requirements are essentially a series of precautions against
flammable materials coming into contact with fuel or sources of heat. Further analysis is
required to determine whether they are sufficient for a hydrogen-powered vehicle.
Electrical equipment and wiring
These comprise a series of electrical protection measures. They were probably not
developed with a hydrogen-powered vehicle in mind. Nevertheless, some of the
requirements seem appropriate, irrespective of the type of equipment and wiring. For
example, insulation is required, there must be a fuse and circuit breakers and the cables
must be protected from damage. For example, the legislation also states that there must
be a manually-operated isolating switch capable of disconnecting all circuits from the
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main electrical supply wherever the voltage exceeds 100 V RMS. This could have
implications for a fuel cell vehicle.
UNECE Regulation 100 deals with some (but not all) of these topics in its vehicle
construction requirements, but fire risks are not mentioned explicitly.
Batteries
The directive and the regulation do not say whether the battery requirements relate to
an auxiliary battery only, or whether they would apply to a propulsion battery that forms
part of a fuel cell system. The requirements are quite broad: the batteries must be well-
secured and easily accessible; the battery compartment must be separated from the
driver and passenger compartments and well-ventilated; and the battery terminals must
be protected against short circuit.
Once again, this is similar to the content of UNECE Regulation 100, although the
requirements of the regulation are focussed on the protection against electric shock.
2.5.3 Proposals for amendments
Directive 2001/85/EC (and the corresponding UNECE regulations) can be applied to a
hydrogen-powered vehicle and TRL understands that some vehicles have been approved
already (HyFLEET:CUTE, 2009). The main requirements and performance tests are
unrelated to the type of power train. However, further investigation is needed in the
remainder of the project to understand the fuelling conditions in the stability and
strength of superstructure tests and the fire protection requirements.
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3 The use of mixtures of natural gas and hydrogen to
power vehicles
3.1 The present situation
Hydrogen-powered vehicles must meet the requirements of Regulation (EC) No.
79/2009. Vehicles that run on compressed natural gas must meet the requirements of
UNECE Regulation 110. Neither of these type-approval regulations includes provisions for
vehicles that use mixtures of natural gas and hydrogen. It is unclear, therefore, how
such a vehicle would gain approval.
The composition of natural gas can vary, depending on its source. These variations can
affect the performance and emissions of an engine. Methane is the main component of
natural gas (typically 88-96%), with a proportion of non-methane alkanes (i.e. ethane,
propane, butane, etc). Other components are nitrogen, carbon dioxide, water, oxygen
and trace amounts of lubricating oil, and sulphur compounds. There may even be small
quantities of hydrogen (i.e. 0.1%).
Gas composition is mentioned in UNECE Regulation 110 with respect to the service
conditions that each cylinder should be capable of withstanding. The regulation states
that each cylinder should be designed to tolerate being filled with natural gas meeting
one of three sets of conditions. The first set of conditions is SAE J1616 (a natural gas
quality standard). The second set of conditions relate to a dry gas (i.e. water vapour
normally limited to less than 32 mg/m3) and include limits for hydrogen of 2% by
volume when the cylinders are manufactured from a steel with an ultimate tensile
strength exceeding 950 MPa. The final set of conditions relates to a wet gas (i.e. water
content greater than above) and limits hydrogen to 0.1%.
The hydrogen regulation (EC No. 79/2009) and the natural gas regulation (UNECE
Regulation 110) include requirements and tests that are appropriate to storage systems
for compressed gaseous fuels. However, each regulation is aimed at the particular
properties of each fuel. This is particularly important for the hydrogen regulation due to
the characteristics of hydrogen and the potential implications for vehicle safety.
3.2 State-of-the-art
Internal combustion engines fuelled with natural gas produce fewer regulated pollutants
and carbon dioxide emissions than petrol engines (Ristovski et al., 2004). However,
some disadvantages have been reported, such as a lower efficiency (Mello et al., 2006).
The addition of small amounts of hydrogen to natural gas (5-30% by volume) has the
potential to overcome this trade-off, thus increasing efficiency and reducing emissions
(Ortenzi et al., 2008). Furthermore, some stakeholders have suggested that the use of
hydrogen in such mixtures might encourage the building of the infrastructure required
for more widespread use of hydrogen in the automotive sector.
There is a substantial body of research on the use of mixtures of natural gas and
hydrogen. The studies tend to be based around experiments using an engine test bed.
The fuels are mixed at various ratios using a gas mixer. However, in real vehicle
applications, it seems more likely that the fuel will be pre-mixed. This would reduce the
complexity of the vehicle by removing the need for separate fuel tanks and mixing
equipment and software.
Mixtures of natural gas and hydrogen have already reached commercialisation. One
example is Hythane®, a blend of 80% natural gas and 20% hydrogen. The Hythane
Corporation intends to deploy the Hythane System, which integrates the technology into
existing natural gas fuelling stations and vehicles, in cities throughout the world
(www.hythane.com). Fuel stations have recently been set up in India in collaboration
with the Indian Oil Company. In the scientific literature, Morrone and Unich (2009)
presented a schematic of a plant layout for hydrogen production in a compressed natural
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gas fuel station. The work was part of a cost analysis to evaluate the economic aspects
of localised medium quantity hydrogen production plants for use in blended fuels. The
gaseous fuel mixture would be stored in tanks and delivered to road vehicles when
required.
The level of hydrogen content in Hythane® and in the experimental blends described in
the literature, mean that natural gas cylinders and engines can be used with relatively
few modifications. However, most of the studies on hydrogen mixtures are based around
combustion analyses that focus on the environmental and performance benefits of the
blended fuel. It appears that the safety implications have not been examined in any
detail. The fuels have very different properties and although natural gas (which is the
major component of the blend) is less reactive than hydrogen, there could be significant
risks.
The NaturalHy project included some work on the safety of natural gas and hydrogen
mixtures, although it was not related directly to vehicle-based applications. NaturalHy
was partially funded by the Commission as an Integrated Project of the Sixth Framework
Programme. The project studied the potential for natural gas pipeline networks to
transport hydrogen from manufacturing sites to hydrogen users. The hydrogen would be
introduced into the pipeline network and mix with the natural gas. The mixture could
then be used directly as a fuel within existing gas-powered equipment, with the benefit
of lower carbon emissions. Alternatively, the hydrogen could be extracted for use in
hydrogen-powered engines or fuel cell applications. The project included a safety work
package that examined the risks of using this existing infrastructure in this new way.
The overall conclusion was that up to 30% by volume of hydrogen could be added to the
natural gas within the current gas infrastructure without adversely affecting the risk to
the public significantly and without any additional mitigation measures (NaturalHy,
2009). However, it is unclear whether this finding is at all relevant to vehicle-based
applications where the hydrogen is stored at high pressure.
3.3 Review of the hydrogen regulation and implementing measures
The hydrogen regulation (EC No. 79/2009) identifies hydrogen mixtures as a potential
transition fuel towards the use of pure hydrogen, to facilitate the introduction of
hydrogen-powered vehicles in member states where the natural gas infrastructure is
good. On that basis, the regulation states that the Commission should develop
requirements for the use of mixtures of hydrogen and natural gas/biomethane.
Particular consideration must be given to the mixing ratio of hydrogen and gas which
takes account of the technical feasibility and environmental benefits.
Based on the analysis conducted so far, it appears that most current blends can be used
in what are essentially natural gas systems and vehicles. Consideration must be given,
therefore, as to the most appropriate approach to take for any future requirements. The
hydrogen regulation and draft implementing measures could be applied to vehicles
intended to run on mixtures, but it may be the case that the requirements are more
stringent than are necessary for a blended fuel. Similarly, the natural gas regulation
(UNECE Regulation 110) could be applied, but it may not address certain properties of
hydrogen, which may be important, even when it is present in relatively small volumes.
Further analysis will be completed in the remainder of the project; although it has been
noted that relatively little published research is available of the safety aspects of
hydrogen mixtures.
3.4 Proposals for amendments
Further work will be carried out with a view to providing the EC with recommendations
on the technical amendments needed to accommodate mixtures of natural gas and
hydrogen. There are several important issues that need to be resolved. For instance, it is
necessary to determine what mixing ratio is likely to be used. Various different ratios
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have been examined in the literature. It might be the case that a standard ratio is used
in the future, or that vehicles will be capable of running on different ratios (within certain
limits). The effect of the mixing ratio on engine performance and emissions needs to
taken into account and the safety implications of each ratio need to be understood. The
project will focus on these areas.
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4 Regulating the type-approval of L category vehicles
4.1 The present situation
Two, three and some four wheel vehicles are not included in the framework directive for
M and N category vehicles (Directive 2007/46/EC). Instead, these are termed L category
vehicles and a different framework directive applies: Directive 2002/24/EC. This became
mandatory in May 2003 and draws on a number of separate technical directives in much
the same way as 2007/46/EC does. It applies to light vehicles intended to be used on
the road with a maximum speed greater than 6 km/h. The following system of
classification is used in Directive 2002/24/EC to distinguish between the different types
of L category vehicles:
Category L1e – Two-wheel moped with a maximum speed of 45 km/h and:
o maximum cylinder capacity of 50 cm3 for an internal combustion engine
vehicle, or
o maximum continuous rated power of 4 kW for an electric vehicle.
Category L2e – Three-wheel moped with a maximum speed of 45 km/h and:
o maximum cylinder capacity of 50 cm3 for a spark ignition internal
combustion engine vehicle, or
o maximum net power output of 4 kW for any other internal combustion
engine vehicle, or
o maximum continuous rated power of 4 kW for an electric vehicle.
Category L3e – Two-wheel motorcycle without a sidecar:
o Cylinder capacity greater than 50 cm3 for an internal combustion engine
vehicle and/or a maximum speed greater than 45 km/h.
Category L4e – Two-wheel motorcycle with a sidecar:
o Cylinder capacity greater than 50 cm3 for an internal combustion engine
vehicle and/or a maximum speed greater than 45 km/h.
Category L5e – Three-wheel motor tricycle:
o Cylinder capacity greater than 50 cm3 for an internal combustion engine
vehicle and/or a maximum speed greater than 45 km/h.
Category L6e – Four-wheel light quadricycle:
Maximum unladen mass of 350 kg, not including the mass of batteries in an
electric vehicle, maximum speed of 45 km/h, and
o maximum cylinder capacity of 50 cm3 for a spark ignition internal
combustion engine vehicle, or
o maximum net power output of 4 kW for any other internal combustion
engine vehicle, or
o maximum continuous rated power of 4 kW for an electric vehicle.
The technical requirements of a three-wheel moped (category L2e) apply unless
specified differently in a particular directive.
Category L7e – Four-wheel quadricycle:
Maximum unladen mass of 400 kg (550 kg for a goods vehicle), not including the
mass of the batteries in an electric vehicle, and a maximum net power of 15 kW.
The technical requirements of a motor tricycle (category L5e) apply unless
specified differently in a particular directive.
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It is interesting to note that provisions are made for electric vehicles in Directive
2002/24/EC. For instance, electric vehicles are included in the descriptions of mopeds
(categories L1e and L2e) and quadricycles (categories L6e and L7e). This may reflect the
growing use of electric powertrains in these vehicles. Electric vehicles are not included in
the definitions of motorcycles (categories L3e and L4e) or motor tricycles (category L5e).
Currently, there are no specific provisions for hydrogen-powered L category vehicles in
Directive 2002/24/EC. A manufacturer who wishes to place such a vehicle on the market
may face difficulties with the present situation. It is likely that the vehicle will be
considered outside the scope of 2002/24/EC, because of the exemption clause set out in
Article 16.3. The exemption relates to vehicles that incorporate new technologies which
cannot, due to their nature, comply with the separate technical directives. A hydrogen-
powered L category vehicle might fit into this category. This is because the directives
were written for vehicles with internal combustion engines or for battery electric
vehicles. The use of hydrogen may result in additional risks, which are not considered by
2002/24/EC.
Although a hydrogen-powered category L vehicle could be exempt (for the reasons
described above), the framework directive does allow vehicles featuring new
technologies to obtain type-approval. However, it is necessary to demonstrate to the
relevant authority, a level of safety and environmental protection that is equivalent to
that in the technical directives. This could prove very challenging technically both for the
manufacturer and for the relevant authority.
With the current arrangement, the relevant authority in each member state would have
to derive the appropriate tests required to demonstrate an equivalent level of safety
and/or address any additional risks in order to approve the vehicle in their territory.
However, it is likely that their national legislation will also not provide for hydrogen-
powered vehicles. Some member states could choose to effectively ban the vehicle (in
the absence of an appropriate testing regime), while others may approve it on an
individual vehicle basis, if it was intended to be made in very low numbers. Such an
approval could be invalid in other member states.
Robinson et al. (2009) examined the costs and benefits of a series of policy options for L
category vehicles. These included options to accommodate hydrogen-powered L category
vehicles. Three scenarios were considered: no change; legislation at European Union
level; legislation at national level. Unfortunately, insufficient data were available to
complete a full cost-benefit analysis. Nevertheless, Robinson judged that legislation at
European Union level would be likely to deliver both economic and environmental
benefits. However, stakeholders provided a mixed response. Some favoured European
legislation because it would establish uniform requirements. However, others were
concerned that regulatory activity could stifle innovation and delay the conversion of
these vehicles to hydrogen.
The Commission carried out a public consultation on the proposals for L category
vehicles and published the results on-line (European Commission, 2009). Forty-one
stakeholders took part in the consultation. They were asked whether EU legislation on
hydrogen-powered L category vehicles is needed. Twenty-nine percent were favourable
or relatively favourable towards EU legislation, while 20% were not favourable. Fifty-one
percent did not reply to the question. The unfavourable responses tended to come from
the motorcycle industry. The typical view was that EU legislation is not needed since
vehicles could be individually type-approved at national level or subject to an exemption
from 2002/24/EC. While ad-hoc authorisation at national level could be more flexible,
TRL‟s view is that it could lead to problems. For instance, if a vehicle obtains national or
single type-approval in one member state, it is not guaranteed that the vehicle will be
authorised in other member states. In fact, member states may even establish different
requirements, potentially resulting in a fragmented internal market, with costly and
complicated approval procedures.
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4.2 The state-of-the-art
One of the challenges for hydrogen-powered vehicles is to deliver the range and
performance that consumers have come to expect from their motor vehicles. Although
there are clear efficiency and environmental benefits of hydrogen (depending on the way
it is produced), it has a lower energy density than conventional fuels, even when it is
compressed. However, L category vehicles are lighter and need less energy than larger
vehicles. Introducing hydrogen for these vehicles might, therefore, be less demanding.
The main developments have been in two-wheel vehicles and have focussed on fuel cells
rather than hydrogen internal combustion engines. Typically, a hybrid system is used
that combines the fuel cell with a battery. The main advantage of this arrangement is
that the size (and hence cost) of the fuel cell can be reduced (Lin 2000). In many
applications, the average speed is relatively low and hence a reduced power fuel cell
stack can meet the power requirements of the vehicle (Mirzaei et al., 2007).
Some important studies have been carried out in Europe, with the support of the
Commission. For instance, the FRESCO project was partially funded by the Commission
under the Fifth Framework Programme. The project demonstrated the technical
feasibility of fuel cell propulsion for scooters. A dedicated fuel cell system was developed
and integrated in a mass-produced Piaggio scooter. The scooter was capable of a top
speed of 45 mph with a range of 75 miles (Fuel Cells Bulletin, 2006). The fuel cell stack
produced 6 kW of electric power and was combined with a 45 Wh supercapacitor, with
regenerative braking to boost overall efficiency. The on-board hydrogen supply
comprised a 525 bar tank with a carbon-reinforced liner. However, the vehicle was
driven on a test circuit only: no attempt was made to gain type-approval. Unfortunately,
the vehicle did not progress beyond the FRESCO project. Instead, Piaggio has
concentrated on hybrid vehicles that combine a conventionally-fuelled combustion
engine with a small battery.
The HYCHAIN MINI-TRANS project is a more recent Integrated Project of the Sixth
Framework Programme (www.hychain.org). The project is deploying several fleets of
innovative fuel cell vehicles in four regions of Europe (in France, Spain, Germany and
Italy). The vehicles include scooters, tricycles, small utility vehicles, minibuses and
wheelchairs. The project comprises two phases: 2006 – 2007 was spent manufacturing
the vehicles and developing the infrastructure and in 2008 – 2010, the vehicles will be
tested under real world conditions. The scooter runs on a hydrogen-fuelled hybrid
system with a 2 kW fuel cell stack. The hydrogen is stored at 700 bar in an
exchangeable cartridge. Participants in the project have reported difficulties with the
current regulatory situation with respect to L category vehicles and the implications for
the deployment of fleets in Europe (Barth, 2006).
Powered two-wheel vehicles can play an important role in urban transportation. They are
particularly popular in Asian cities. Attempts to tackle increasing air and sound pollution
from these vehicles have included the development of fuel cell vehicles. These
developments are interesting because they do not always employ the most conventional
methods of hydrogen storage in vehicles (i.e. compressed gaseous or liquid hydrogen).
For example, Lin (2000) presented a conceptual fuel cell scooter design with compact
metal hydride storage. A battery hybrid system was developed, which allowed a smaller
fuel cell to be used and energy to be stored through regenerative braking. Samsung
Engineering developed and pilot-tested a fuel cell scooter that used hydrogen storage
technology based on a solution of sodium borohydride (Fuel Cells Bulletin, 2005). Mirzaei
et al. (2007) described the modelling and optimisation of a hybrid fuel cell system for a
motorcycle based on more conventional compressed hydrogen storage.
4.3 Review of the hydrogen regulation and implementing measures
L category vehicles might be early adopters of hydrogen as a fuel, but it will be essential
to identify any safety risks and to consider how these risks should be mitigated. The
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main concern is the safety of hydrogen storage on-board the vehicle (and any
components in contact with hydrogen). Regulation (EC) No. 79/2009 (the hydrogen
regulation) and the draft implementing measures mitigate these concerns for M and N
category vehicles. While it would be inappropriate to include L category vehicles in the
hydrogen regulation and implementing measures (because they are part of a separate
legislative framework), they might form the basis for new type-approval requirements
for L category vehicles.
The requirements of the hydrogen regulation are set out in a series of Articles. In some
cases, the Article references a separate Annex. The key technical Articles are:
Article 5: General requirements for hydrogen components and systems;
Article 6: Requirements for hydrogen containers designed to use liquid hydrogen;
Article 7: Requirements for hydrogen components, other than containers,
designed to use liquid hydrogen;
Article 8: Requirements for hydrogen containers designed to use compressed
(gaseous) hydrogen;
Article 9: Requirements for hydrogen components, other than containers,
designed to use compressed (gaseous) hydrogen;
Article 10: General requirements for the installation of hydrogen components and
systems.
The main elements of the hydrogen regulation are relevant for L category vehicles. The
requirements for hydrogen components and systems (i.e. Articles 5 to 9) could be
adopted relatively easily. However, the requirements for the installation of hydrogen
components and systems (Article 10) might need to be amended for certain L category
vehicles.
A similar judgement was made in a white paper prepared during the HYCHAIN project.
This concluded that many of the provisions and specifications in the hydrogen regulation
are independent of vehicle type and could therefore be applied to hydrogen-powered
L category vehicles without amendment (HYCHAIN, 2007). However, some potentially
vehicle-specific requirements were found in Annex VI of the hydrogen regulation. This
Annex is referenced by Article 10 and sets out general requirements for the installation
of hydrogen components and systems. There are 16 requirements and these are
reviewed in full in Appendix A. The list below highlights the requirements that may need
to be amended for L category vehicles:
1. The hydrogen system must be installed in such a way that it is protected against
damage. It must be isolated from heat sources in the vehicle.
While this requirement is appropriate for L category vehicles, it might be challenging
for certain categories. For instance, the frame and bodywork of a typical two-wheel
vehicle is unlikely to provide the same level of protection as the chassis and
bodywork of a three or four wheel vehicle.
2. The hydrogen container may only be removed for replacement with another
hydrogen container, for the purpose of refuelling or for maintenance. In the case
of an internal combustion engine, the container must not be installed in the
engine compartment of the vehicle.
This requirement is generally independent of vehicle type or category. However,
some L category vehicles, such as two or three wheel vehicles, may not have a
clearly defined engine compartment. This requirement would need to be reworded to
reflect the layout of two and three wheel L category vehicles.
5. The hydrogen container must be mounted and fixed so that the specified
accelerations can be absorbed without damage to the safety related parts when
the hydrogen containers are full.
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The draft implementing measures set out specific accelerations according to (M and
N) vehicle category. The provisions do not apply if the vehicle is approved according
to the front and side impact directives. L category vehicles are lighter than M and N
category vehicles and might be subjected to higher accelerations, although their
impact scenarios are also likely to be different. It may be necessary to specify
acceleration levels according to each L category.
11. The venting or heating system for the passenger compartment and places where
leakage or accumulation of hydrogen is possible must be designed so that
hydrogen is not drawn into the vehicle.
Some L category vehicles do not have a passenger compartment. It could be argued,
therefore, that these vehicles are not exposed to the risks associated with the
accumulation of hydrogen in an enclosed space. Nevertheless, it may be necessary to
reword this requirement for L category vehicles.
13. The passenger compartment of the vehicle must be separated from the hydrogen
system in order to avoid accumulation of hydrogen. It must be ensured that any
fuel leaking from the container or its accessories does not escape to the
passenger compartment of the vehicle.
As discussed above, some L category vehicles do not have passenger compartments;
however, hydrogen accumulation may not be a problem in these vehicles.
14. Hydrogen components that could leak hydrogen within the passenger or luggage
compartment or other non-ventilated compartment must be enclosed by a gas-
tight housing or by an equivalent solution as specified in the implementing
measures.
As above, some L category vehicles do not have passenger or luggage
compartments.
16. Labels or other means of identification must be used to indicate to rescue
services that the vehicle is powered by hydrogen and that liquid or compressed
(gaseous) hydrogen is used.
This requirement is independent of category and could be applied to L category
vehicles. However, there may be issues to consider regarding the size and placement
of such labels for smaller L category vehicles.
The analysis completed so far has focussed on Regulation (EC) No. 79/2009 (the
hydrogen regulation). These fundamental provisions could be adopted for L category
vehicles relatively easily. However, some adjustments would be needed to take account
of the particular features of L category vehicles, especially those with two or three
wheels. A similar analysis of the draft implementing measures will be made during the
remainder of the project. In addition, stakeholders will be contacted with a view to
establishing a working group to discuss requirements for the type-approval of hydrogen-
powered L category vehicles.
4.4 Proposals for amendments
Further work will be carried out on L category vehicles in the remainder of the project.
The aim of this section of the interim report was twofold: firstly, to present initial
suggestions for areas in the legislation for L category vehicles that may need to be
amended for hydrogen; and secondly, to provide a basis for further discussions with
stakeholders.
Some hydrogen-powered L category vehicles will be produced in very low numbers.
Individual approval at member state level may be appropriate for these vehicles.
However, some vehicles have the potential for mass production and Europe-wide sale.
Manufacturers need a European regulatory framework in place to provide uniform safety
and environmental requirements and prevent the need for multiple approvals in separate
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countries. Such a framework could include provisions for vehicles produced in low
numbers only and should, therefore, not inhibit the development of new vehicles by
increasing the cost of approval unduly.
The framework directive for L category vehicles (Directive 2002/24/EC) would need to be
amended to accommodate hydrogen-powered vehicles. Potential amendments include
specific mention of hydrogen within the articles of the directive, such as within the
descriptions of each L category. In the case of fuel cell vehicles, consideration is needed
as to the implications of the current situation whereby electric vehicles are not included
in the definition of certain categories.
It may also be necessary to add new technical requirements for hydrogen storage. The
hydrogen regulation and draft implementing measures are being examined in this study
with a view to the Commission introducing requirements relating to hydrogen in the
type-approval framework for L category vehicles. However, the hydrogen regulation and
implementing measures are part of the type-approval framework for M and N category
vehicles. While the requirements may largely be appropriate for L category vehicles it
would be inappropriate to simply amend these acts to include L category vehicles.
Nevertheless, they could form the basis for new requirements.
A new regulation for hydrogen-powered L category vehicles could be developed and
referred to in the framework directive for L category vehicles. It is likely that the new
regulation would be very similar to the present hydrogen regulation for M and N category
vehicles. Another approach might be to amend the technical directive for fuel tanks
(Directive 97/24/EC). This could either include detailed requirements for hydrogen-
powered vehicles or a series of references to the hydrogen regulation and implementing
measures. These issues and their implications will be examined further in the remainder
of the project.
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5 Conclusions
1. TRL has performed the first part of a project for the European Commission to review
the type-approval legislation on vehicle safety for hydrogen-powered vehicles. An
initial review has been completed and the findings are summarised below. The next
part of the project will involve liaison with stakeholders, including a workshop, to
present the findings of the work to date for comment. Following this, the review will
be completed and recommendations made for necessary legislative action; in
particular amendments for current legislation.
2. The review focussed on the type-approval legislation for vehicle safety and on two
issues identified in the hydrogen regulation (EC No. 79/2009).
The safety legislation covered: fuel tanks, radio interference, identification of
controls, frontal impact, side impact and buses and coaches.
The issues identified in the hydrogen regulation covered: the use of mixtures
of natural gas and hydrogen as a fuel in internal combustion engines and the
regulation of hydrogen-powered L category vehicles.
3. The review of safety legislation revealed that:
Hydrogen-powered vehicles should be exempt from fuel tank requirements
because the risks are dealt with by the hydrogen regulation and (draft)
implementing measures.
The radio interference legislation includes performance requirements, but
references international standards for the test methods. Some of the
standards have procedures to deal with electric vehicles (which could be
applied to hydrogen fuel cell vehicles). However, some potential issues were
raised, such as the vehicle load conditions and antenna positions.
Amendments to the frontal and side impact legislation are needed to
accommodate hydrogen-powered vehicles. The amendments will need to
cover:
i. The test procedure including the fuelling conditions for the impact test.
ii. The post-crash requirements including hydrogen leakage limits.
There are no symbols in the legislation that must be used with controls, tell-
tales and indicators for the hydrogen system in a hydrogen-powered vehicle.
Furthermore, no symbols are available in the main international standard.
New symbols will be needed for hydrogen-powered vehicles. However, the
current optical indicator and tell-tale colour meanings set out in the legislation
and the standard are appropriate.
The bus and coach requirements are largely independent of the power train.
However, additional provisions may be needed for the stability and strength of
superstructure tests and for the electrical safety of the driver and passengers.
4. The review of issues identified in the hydrogen regulation revealed that:
Fuel mixtures of natural gas and hydrogen typically contain between 5% and
30% hydrogen by volume. With such blends, the fuel could be used in what
are essentially natural gas systems and vehicles. However, the legislation for
natural gas systems may not deal with certain properties of hydrogen, which
may be important, even when it is present in relatively small volumes.
The framework directive L category vehicles (Directive 2002/24/EC) would
need to be amended to accommodate hydrogen-powered vehicles. It may also
be necessary to develop new technical requirements for hydrogen storage on
L category vehicles: the hydrogen regulation and implementing measures are
generally appropriate for L category vehicles, but they are part of the type-
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approval framework for M and N category vehicles. It would be inappropriate
to simply amend these acts to include L category vehicles, but they could
form the basis for new requirements.
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Acknowledgements
The work described in this report was carried out in the Vehicle Safety Group of the
Transport Research Laboratory. The authors are grateful to Iain Knight who carried out
the technical review and auditing of this report.
References
Ahulwalia R K, Wang X, Rousseau A and Kumar R (2004). Fuel economy of hydrogen fuel
cell vehicles. Journal of Power Sources 130 (1), pp.192-201.
Barth, F. (2006). Development of innovative fuel cell vehicle fleets to initiate use of
hydrogen as an alternative fuel in early markets. Presented at the HarmonHy Final
Conference, 4 October 2006.
European Commission. (2009). CARS 21 A competitive automotive regulatory system for
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Appendix A Review of Regulation (EC) No. 79/2009
Annex IV (Installation of hydrogen components and systems)
1. The hydrogen system must be installed in such a way that it is protected against
damage. It must be isolated from heat sources in the vehicle.
While this requirement is appropriate for L category vehicles, it might be challenging
for certain categories. For instance, the frame and bodywork of a typical two-wheel
vehicle is unlikely to provide the same level of protection as the chassis and
bodywork of a three or four wheel vehicle.
2. The hydrogen container may only be removed for replacement with another
hydrogen container, for the purpose of refuelling or for maintenance. In the case of
an internal combustion engine, the container must not be installed in the engine
compartment of the vehicle.
This requirement is generally independent of vehicle type or category. However,
some L category vehicles, such as two or three wheel vehicles, may not have a
clearly defined engine compartment. This requirement would need to be reworded to
reflect the layout of two and three wheel L category vehicles.
3. Measures must be taken to prevent misfuelling (sic) of the vehicle and hydrogen
leakage during refuelling and to make sure that the removal of a removable
hydrogen storage system is done safely.
This requirement is not vehicle-specific and could be applied to L category vehicles.
4. The refuelling connection or receptacle must be secured against maladjustment and
protected from dirt and water. The refuelling connection or receptacle must be
integrated with a non-return valve or a valve with the same function. If the refuelling
connection is not mounted directly on the container, the refuelling line must be
secured by a non-return valve or a valve with the same function which is mounted
directly on the container.
This requirement is independent of category and could be applied to L category
vehicles.
5. The hydrogen container must be mounted and fixed so that the specified
accelerations can be absorbed without damage to the safety related parts when the
hydrogen containers are full.
The draft implementing measures set out specific accelerations according to (M and
N) vehicle category. The provisions do not apply if the vehicle is approved according
to the front and side impact directives. L category vehicles are lighter than M and N
category vehicles and might be subjected to higher accelerations, although their
impact scenarios are also likely to be different. It may be necessary to specify
acceleration levels according to each L category.
6. The hydrogen fuel supply lines must be secured with an automatic shut-off valve
mounted directly on or within the container. The valve shall close if a malfunction of
the hydrogen system so requires or any other event that results in the leakage of
hydrogen occurs.
This requirement is independent of category and could be applied to L category
vehicles.
7. In the event of an accident, the automatic shut-off valve mounted directly on or
within the container shall interrupt the flow of gas from the container.
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This requirement is independent of category and could be applied to L category
vehicles.
8. Hydrogen components, including any protective materials that form part of such
components, must not project beyond the outline of the vehicle or protective
structure. This does not apply to a hydrogen component which is adequately
protected and no part of which is located outside this protective structure.
This requirement is independent of category and could be applied to L category
vehicles.
9. The hydrogen system must be installed in such a way that it is protected against
damage so far as is reasonably practicable, such as damage due to moving vehicle
components, impact, grit, the loading or unloading of the vehicle or the shifting of
loads.
This requirement is independent of category and could be applied to L category
vehicles. However, it may be more challenging for certain L category vehicles.
10. Hydrogen components must not be located near the exhaust of an internal
combustion engine or other heat source, unless such components are adequately
shielded against heat.
This requirement is independent of category and could be applied to L category
vehicles.
11. The venting or heating system for the passenger compartment and places where
leakage or accumulation of hydrogen is possible must be designed so that hydrogen
is not drawn into the vehicle.
Some L category vehicles do not have a passenger compartment. It could be argued,
therefore, that these vehicles are not exposed to the risks associated with the
accumulation of hydrogen in an enclosed space. Nevertheless, it may be necessary to
reword this requirement for L category vehicles.
12. In the event of an accident, it must be ensured so far as is reasonably practicable
that the pressure relief device and the associated venting system remain capable of
functioning. The venting system of the pressure relief device must be adequately
protected against dirt and water.
This requirement is independent of category and could be applied to L category
vehicles.
13. The passenger compartment of the vehicle must be separated from the hydrogen
system in order to avoid accumulation of hydrogen. It must be ensured that any fuel
leaking from the container or its accessories does not escape to the passenger
compartment of the vehicle.
As discussed above, some L category vehicles do not have passenger compartments;
however, hydrogen accumulation may not be a problem in these vehicles.
14. Hydrogen components that could leak hydrogen within the passenger or luggage
compartment or other non-ventilated compartment must be enclosed by a gas-tight
housing or by an equivalent solution as specified in the implementing measures.
As above, some L category vehicles do not have passenger or luggage
compartments.
15. Electrically operated devices containing hydrogen must be insulated in such a manner
that no current passes through hydrogen containing parts in order to prevent electric
sparks in the case of a fracture.
This requirement is independent of category and could be applied to L category
vehicles.
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16. Labels or other means of identification must be used to indicate to rescue services
that the vehicle is powered by hydrogen and that liquid or compressed (gaseous)
hydrogen is used.
This requirement is independent of category and could be applied to L category
vehicles. However, there may be issues to consider regarding the size and placement
of such labels for smaller L category vehicles.