Towards Zero-Emission Bus Transport

Abstract

Late 2016, London Mayor Sadiq Khan announced to join 11 other major cities, including New York, Los Angeles, Copenhagen, Hamburg and Amsterdam, that have committed to begin moves to phase out their procurement of pure diesel buses by the end of 2020. With the initiative, major cities are working together to challenge bus manufacturers to produce more zero-emission buses and make cleaner bus technology less expensive. Together, these cities have committed to procuring 1,000 zero-emission buses using either electric or hydrogen technology over the next five years. In London, a 51-strong fleet of all-electric buses (BYD), and in Eindhoven, the Netherlands, a 43-strong fleet of all-electric buses (VDL) have started operation by the end of 2016. These initiatives are leading examples of scaling-up from proof of concept to large-scale operation of zero-emission bus transport.

Full text

Source: VD L Bus & Coach bv
TOWARDS ZERO-EMISSION BUS TRANSPORT
TOWARDS ZERO-EMISSION
BUS TRANSPORT
THE DIESEL ERA COMES TO AN END
Late 2016, London Mayor Sadiq Khan
announced to join 11 other major cities,
including New York, Los Angeles,
Copenhagen, Hamburg and Amsterdam,
that have committed to begin moves to
phase out their procurement of pure diesel
buses by the end of 2020. With the
initiative, major cities are working together
to challenge bus manufacturers to produce
more zero- emission buses and make
cleaner bus technology less expensive.
Together, these cities have committed to
procuring 1,000 zero-emission buses using
either electric or hydrogen technology over
the next five years. In London, a 51-strong
fleet of all-electric buses (BYD), and in
Eindhoven, the Netherlands, a 43-strong
fleet of all-electric buses (VDL) have
started operation by the end of 2016.
These initiatives are leading examples of
scaling-up from proof of concept to
large-scale operation of zero-emission bus
transport.
Buses only make up a small share of about
2% in total transport CO2 emissions. In
cities, however, they largely contribute to
CO2 and pollutant emissions (up to 20%)
and noise nuisance. While decarbonising
transport mostly depends on European
regulation, innovation by manufacturers
and adoption by users, bus transport is
typically an area in which public transport
authorities and local governments have
powerful instruments to accelerate the
transition towards low-carbon transport.
Besides, all efforts, both the few big
chunks as well as many smaller CO2
abatement options, are needed to add up
to a total transport CO2 reduction target of
60 to 75% in 2050. By choosing a cleaner
and low-carbon bus solution, local
governments and decision makers can
contribute to the decarbonisation of urban
transport and improve air quality in their
cities. In the Netherlands, the Green Deal
Zero Emission Bus Transport was launched
in 2012 and reconfirmed (‘Bestuur sakkoord’)
in 2016 by the National government,
public transport authorities and bus
transport operators. The Green Deal aims
to determine how to affordably realise this
transition to zero-emission bus transport,
by including zero emissions as a require-
ment in all new public transport bus
concessions to be defined. By 2025, diesel
should be completely phased out in the
procurement of new buses and, by 2030,
the entire Dutch bus fleet of approximately
5,300 buses has to be turned into a
zero- emission bus fleet. Currently, about
80% of this bus fleet consists of standard
12m buses and about 20% are articulated
18m buses. Looking at the average
concession period and economic lifetime of
diesel buses of about 8 years on average in
the Netherlands, this transition results in a
vehicle investment agenda of more than
1.5 billion euros and, in terms of total cost
of ownership (TCO), probably more than
3 billion euros until the year 2025. In every
next procurement, an increasing share of
zero-emission buses will have to be
included in tenders by public transport

TOWARDS ZERO-EMISSION BUS TRANSPORT
operators. To achieve a fully zero-emission
bus fleet in 2030, it is expected that
already between 2021 and 2024 in
probably most procurements diesel buses
will have been phased out. This is
illustrated by the procurement of buses for
a new concession period in Eindhoven that
started in December 2016, in which about
40% of the new buses were fully electric.
TRENDS, BARRIERS AND
OPPORTUNITIES
Currently, more and more bus
manufacturers are getting ready to scale
up for mass production of battery- electric
buses. For example, BYD will begin mass
production of zero emission buses for the
growing European market in a new
Hungarian assembly plant in the first
quarter of 2017. In the Netherlands, VDL
is showing similar capabilities, being the
supplier of the all- electric bus fleet in
Eindhoven. Nevertheless, purchasing
zero-emission buses is currently about
twice as expensive as conventional diesel
buses. Local governments and public
transport operators need to make
sustainable and cost-efficient decisions.
When selecting the most ideal zero -
emission bus system, decision-makers are
faced with dif ferent types of questions,
such as:
• What are the options available and which
energy source/technology to choose for
a bus? What are the costs of these
options?
• How to secure the reliability of the
system? What are the operational
(energy) margins and flexibility ? How to
prepare for disturbances? What happens
in winter conditions?
• Which fuels/energy sources require
installation of additional infrastructure
and what are the associated costs?
Where to place and how to dimension
charging infrastructure?
• What fueling or charging strategies are
fitting the optimized TCO given a certain
operational use? Which bus lines to
electrif y first? How to scale up (roll- out
phase)?
• Which synergies are possible with other
zero-emission mobility developments
within the urban environment, like
electric cars, city logistics, or, for
example, regarding standardization and
planning of charging infrastructure, grid
enhancements, combined energy/
charging and public transport hubs?
• Which synergies are possible with
already existing electric transport within
the urban environment (train, metro,
tram), for example regarding charging of
zero-emission buses?
• How should future tenders be defined
and assessed? How should the
warrantees of the buses be defined?
Urban bus transport systems are typically
suitable for migrating first to zero emission,
because of the repetitive nature of the
operation and well-known transport
requirements. These favourable conditions
are, for example, fixed route lengths, fixed
schedules, high utilisation rates, less
congestion due to designated bus lanes
and many stops with regenerative breaking.
On the other hand, a zero -emission bus
service is also much more complex than for
diesel buses. Many new parameters,
interactions and trade-offs are introduced
that may have a large impact on the TCO
and the quality of service of the transport
operator. Generally, the system design, the
procurement of assets, the operation and
its sensitivity to disturbances all get
interrelated with electric bus fleets.
“URBAN BUS TRANSPORT SYSTEMS ARE
TYPICALLY SUITABLE FOR MIGRATING FIRST
TO ZERO EMISSION, BECAUSE OF THE
REPETITIVE NATURE OF THE OPERATION AND
WELL-KNOWN TRANSPORT REQUIREMENTS”
2

Opportunity
Fast Charge
5–6 min @120kW
Depot Charge
5 hours @60kW
Ultra-Fast
30s @>300kW Ultra-Fast
30s @>300kW
0 10 20 30 40
Distance [km]
30
40
50
60
70
80
90
100
SoC [%]
SoC trend during a trip without opportunity charging
Empty bus
Full bus
0 10 20 30 40
Distance [km]
80
85
90
95
100
SoC [%]
SoC trend during a trip with opportunity charging
Empty bus
Full bus
0.24
0.50
0.20
0.200.20
0.80
2.82
Worst Case
Energy Use
(kWh/km)
Best case
Driving Driver
Behaviour
Road
quality
Passenger
load
Speed Topo-
graphy
Climate Total
0.80
TOWARDS ZERO-EMISSION BUS TRANSPORT
Although variations are possible, basically
three main types of configurations exist:
1 buses with a large-size battery of about
320 kWh with overnight depot charging;
2 buses with a medium- size batter y of
about 180 kWh with opportunity
charging at the end of lines, and;
3 buses with a small-size batter y of about
80 kWh with opportunity charging at
many bus stops on the street.
For opportunity charging, for instance, it is
important to know whether the timetable
and charging power allows enough time for
recharging at bus stops to run a reliable
service. For depot charging, it is, for
example, important to assess the impact
on the local power grid. In general, because
of lower costs per km than diesel, battery-
electric buses become more feasible for
bus lines with a high annual mileage. The
average annual mileage of buses in the
Netherlands is about 75,000 km.
Therefore, bus lines with annual mileages
well above 100,000 km would be the most
promising ones to start with. In addition,
other important factors are, amongst
others, the technical and economic lifetime
of the vehicles, the cost of charging
infrastructure and the driver costs.
Most impor tantly, adopting zero-emission
buses does not only concern one-time
decision making about purchasing the
appropriate vehicle, battery and charging
technologies. In addition, it will become a
continuous energy management exercise
and continuous TCO optimization effort,
taking into account the constraints of key
performance indicators like the reliability,
quality and punctuality of the transport
service.
Fig. 1. System design: battery sizes and charging strategies.
Fig. 2. Operational energy margins of zero- emission buses (sourc e: Volvo).
3

TOWARDS ZERO-EMISSION BUS TRANSPORT
There is currently a lack of wide-scale
experience and a lack of validated and
reliable cost and performance data, for
instance with respect to the energy
consumption in different environments,
battery lifetime, depreciation, etc.
A great challenge for the next few years is
to narrow down the current levels of
uncertainty. Ultimately, this will save extra
buses, extra bus drivers and extra costs,
making zero- emission bus transpor t a
feasible option for an increasing share of
the bus lines. A continuous and real-time
operations management approach is also
relevant with respect to the future public
transport system that is expected to be
reacting and adapting in real-time due to
varying passenger demand and
circumstances, also known as Mobility- as-
a-Service (MaaS). Furthermore, transitions
towards autonomous vehicles will impact
the future TCO; particularly with driver
costs removed, and the need for
automated charging.
THE WAY FORWARD
Basically, two lines of actions are needed.
First, a systems innovation is required,
which means innovation and policy
measures should not be limited to
transport technologies and costs, but
should also include governance,
procurement, finance, risk sharing,
gainsharing and operational issues.
Second, public transport operators are
expressing a need to develop a strategic
roadmap for the next 10 years with the
best fitting bus and charging concepts and
a need to develop the appropriate tooling
to easily and quickly design and optimize a
zero-emission bus service and to manage
and control the day-to-day operation.
Replacing diesel buses by battery-electric
buses does not always completely coincide
with the star t of a new concession period.
Therefore, bus operators need to be able to
make cost-effective decisions, both for new
tenders as well as during concession
periods. There are many trade-offs to be
made between the vehicle and battery
technology, the service schedule, the line
characteristics and operational conditions,
and the charging infrastructure and
recharging strategies.
TNO developed a toolset that allows to
systematically make these trade-offs and
search for the optimal match between local
characteristics and operational needs and
the type of vehicle, battery and charging
technologies. The systems approach
should address many questions, such as:
1 Which inner-city bus lines to electrify
first?
2 What is the passenger demand per line
and what is the annual mileage of buses
on that line?
3 What does the TCO look like per line?
4 Which line is feasible for depot charging
and which one for opportunity charging?
5 What might become feasible in the next
few years with improved battery
technology, in-motion charging
technology, et cetera? What are
possibilities in the years after that?
Fig. 3. TNO to olset supporting a systems approach for zero -emis sion buses.
4
TECHNOLOGY OPERATION
EXTERNAL FACTORS
KPI
Weather conditions
Passenger load
Trafc conditions
City or regional
Noise
Risk
Quality of service
Environment Costs Punctuality
Time table and stafng
Network characteristics
Battery type and size
Maintenance
Vehicle type
Charging strategy
Energy mix
Route and topography

– Strategic choices
– Technology
– Infra
– Grid
– Network
– TCO
– Market inquiry
– Cour se operat ional
planning
– System
implementation
– Testing
– Detailed
operational
planning
– Trouble shooting
– Monitoring and
optimization
Evaluation
Public Transport
Authorit y Public Transport Operators
Learning & best practices
Winning
bid Launch
Bid
Policy making Preperation OperateTendering
TOWARDS ZERO-EMISSION BUS TRANSPORT
The transition towards zero-emission bus
transport is not only characterized by a
technological transition with new products,
but especially by a broad impact that spans
all parts of a bus conces sion life cycle, see
figure 4. Dealing with the limitations of the
new technology and stronger dependencies
between the technological and operational
choices makes this transition complex.
Key in making the right choices in the
transition is to account for all involved
parameters. Making the complexity
manageable is TNO’s key market
proposition. By combining our expertise
from the fields of vehicle technolog y,
batteries, logistics and (smart-)grids, we
are able to capture the relevant
relationships for adequate choices from a
technological, operational or economic
point of view.
This expertise is captured in modelling and
simulations that are brought together for
application in any of the phases of a
concession.
In the policy making phase, TNO offers a
holistic modelling approach that captures
all relevant aspects in a suitable level of
detail that allows decision makers to make
trade- offs on a system level. Local
situations and ambitions are embedded in
the toolset’s assessment framework that
allows for back-to-back benchmarking of
transport solutions.
The tendering follows the policy making
phase. The public transport organizations
are preparing bids that are economically
viable given the local transpor t
requirements and opted transpor t system.
In that process, some ver y specific and
new choices have to be made:
• Which vehicle and charger does best fit
the transpor t system and transport
requirements?
• How do I account for the operational
limitations and interdependencies of the
new technology?
Since the majority of the market has only
experience with pilots on a limited scale
and usually in a controlled environment,
challenges are dealt with in a conser vative
way. This leads to sub-optimal solutions.
It is expected that planned redundancy
will be minimized as soon experience is
obtained on fleet level in real operation.
Until then, TNO’s assessment tools can
well reflect the limitations of zero-emission
transport in the public transport organiza-
tion’s planning processes, such as
HASTUS. This will allow for less redundancy
in the operation and hence more competi-
tive bids.
Fig. 4. The li fe cycle of a bu s conces sion.
“TNO’S TOOLSET
ALLOWS TO
BENCHMARK
PLANNED AND
ACTUAL
PERFORMANCE
AND FLAG
SITUATIONS WITH
AN INCREASED
RISK AT ANY
EARLY STAGE.
WITH THE
RESULTS, TRAFFIC
CONTROL CAN
TAKE ADEQUATE
MEASURES ON
TIME”
5
Punctuality

Power outtake
kWh
Overnight
charging
Opportunity
charging
Dawn
6
0
Power supply
kW
Noon
12
Dusk
18
Midnight
24
Sustainable
power
Coal Gas Nuclear
Base power
TOWARDS ZERO-EMISSION BUS TRANSPORT
In case a concession is won, the detailed
operational and technical preparation will
start. Specific vehicle and charger
technology has to be selected and
integrated into the planned operation
(scheduling of drivers, busses and
chargers). TNO tools, based on operational
simulation, allow the public transport
organization to perform a risk analysis for
this specific situation. Schedules can be
refined to reduce risks upfront.
Once the zero-emission fleet is in service,
monitoring is required to capture the
experience for future design and planning
purposes. On a shorter timescale,
monitoring allows to identify unplanned
deviations from the schedule. A day of bad
weather may, for example, lead to an
increased energy consumption from the
bus’s HVAC system and more passengers
in the bus. TNO’s toolset allows to
benchmark planned and actual
performance and flag situations with an
increased risk at an early stage. With the
results, traffic control can take adequate
measures on time.
We foresee that af ter a couple of years of
zero-emission bus transport, operational
margins will be reduced because of the
increased understanding of zero -emission
bus transport experience. Moreover,
real-time monitoring will allow to in-situ act
on varying situations in the transport
demand, congestion, weather conditions
and varying prices in the energ y market.
TNO’s fleet-level optimization technology
will leverage the potential for TCO,
robustness, quality of service or
sustainability optimization.
Generally, public transport operators are
very well capable of tackling many of these
issues themselves. However, due to the
complexities, there is a need for support on
the specifics of zero-emission transport.
Being currently in the early adoption phase,
the lack of experience and validated data
results in over-dimensioning: ex tra electric
buses (capital expenses) and extra bus
drivers (operational expenses) are needed
to assure the electric bus ser vice is as
reliable as the diesel bus service it
replaces. TNO’s toolset addresses the
growing need for large numbers of
modelling iterations and real-time control
of the bus service and energy system.
The toolset aims to provide a simulation
modelling framework based on predictive
modelling and real-world measurement. It
will enable to quickly assess the impact of
adjustments in the service schedules in
planning software, such as HASTUS, and to
develop operating envelopes to improve
the system’s reliability, to minimize
disturbances and to reduce
over-dimensioning.
Furthermore, the systems innovation will
require new roles and new approaches to
how public bus transport is organized.
A modernized concession system that
allows for innovation and collaboration is
needed. Public transport authorities
Fig. 5. Sustainable power supply and consumption by zer o-e mission buses (source: Vol vo).
6

Source: VD L Bus & Coach bv
TOWARDS ZERO-EMISSION BUS TRANSPORT
probably have to rethink to what extent
they want to decide about a bus solution
themselves and to what extent they allow
flexibility for the market (operators and
manufacturers) to find innovative solutions.
This requires new forms of knowledge
sharing and partnerships to exploit the
best practices from different stakeholders.
Early 2017, the Dutch public transport
authorities published a market consulta-
tion discussing the system innovations
mentioned above. The consultation
explores several options, the first of which
is extending concession periods to 10 or
15 years to increase payback periods for
the large upfront investments in battery-
electric buses. Another option is to have
flexible concession periods in tenders to
facilitate competition and to see what is
feasible in the market. Organizational
innovation could, for example, mean that
timetables no longer have to be fixed one
year in advance. This would allow adjust-
ments by bus transport operators based
on their increasing experience and
optimization of the zero-emission bus
service.
Finally, local governments and grid
operators might also look for societal
benefits and opportunities by linking bus
transport with local solar power generation,
stationary battery energy storage, grid
balancing and peak shaving. Societal
benefits may well justify co-financing by
local government.
“THE TOOLSET AIMS TO
PROVIDE A SIMULATION
MODELLING FRAMEWORK
BASED ON PREDICTIVE
MODELLING AND REAL-
WORLD MEASUREMENT”
7

LIVING ENVIRONMENT
As part of the Living Environment theme,
we apply ourselves to devising innovations
for vital urban regions. We work together
with partners to create solutions for today
and opportunities for tomorrow to enhance
the viability, accessibility and competitive-
ness of these urban regions.
AUTHORS
Robert Kok
Roel de Groot
Stephan van Zyl
Steven Wilkins
Richard Smokers
Jordy Spreen
CONTACT
Dr. ir. R. T. M. (Richard) Smokers
Anna van Buerenplein 1
2595 DA Den Haag
T 088 866 86 28
E richard.smokers@tno.nl
Version: September 2017 - TNO 2017 R10952
TNO.NL
TOWARDS ZERO-EMISSION BUS TRANSPORT
8