Resultados C40 en Latinoamérica

In
partnership
with:

Hybrid – Electric Bus Test
Program in Latin America
Final Report
ISSRC
January 2013
Prepared by:
International Sustainable Systems Research Center - ISSRC
605 South Palm Street, Suite C, La Habra, CA 90631, USA
www.issrc.org

In
partnership
with:

Project Name: Hybrid Electric Bus Test Program in Latin America (HEBTP-LA)
Implementing Agency: C40 - Clinton Climate Initiative (CCI)
Tests performed by: International Sustainable Systems Research Center (ISSRC)
This Report: Santiago Report (ISSRC-HEBTP-08)
C40-CCI Contact Person: Manuel Olivera, LATAM Hybrid bus test program & City
Director, Santiago D.C.: molivera@clintonfoundation.org
ISSRC Contact Person: Mauricio Osses, maosses@issrc.org

TABLE OF CONTENTS
1
INTRODUCTION....................................................................................................................1

1.1
GENERAL BACKGROUND ....................................................................................................1

1.2
ORGANIZATION OF THIS REPORT ........................................................................................1

1.3
GENERAL METHODOLOGY..................................................................................................1

1.4
ABOUT HYBRID & ELECTRIC BUS TECHNOLOGIES ............................................................4

2
ENERGY PERFORMANCE AND DRIVING CYCLES ....................................................6

2.1
FUEL AND ENERGY CONSUMPTION.....................................................................................6

2.1.1
Rio de Janeiro .............................................................................................................7

2.1.2
Sao Paulo ....................................................................................................................7

2.1.3
Bogota .........................................................................................................................8

2.1.4
Santiago.......................................................................................................................9

2.2
DRIVING CYCLES ..............................................................................................................10

2.2.1
Rio de Janeiro ...........................................................................................................11

2.2.2
Sao Paulo ..................................................................................................................11

2.2.3
Bogota .......................................................................................................................12

2.2.4
Santiago.....................................................................................................................13

3
EXHAUST EMISSIONS AND ENERGY CONSUMPTION............................................15

3.1
OVERALL RAW EMISSIONS RESULTS .................................................................................15

3.1.1
Rio de Janeiro ...........................................................................................................16

3.1.2
Sao Paulo ..................................................................................................................17

3.1.3
Bogota .......................................................................................................................19

3.1.4
Santiago.....................................................................................................................20

3.2
EMISSIONS BY ENERGY DEMAND SITUATIONS PER CITY.................................................22

3.2.1
Rio de Janeiro ...........................................................................................................22

3.2.2
Sao Paulo ..................................................................................................................25

3.2.3
Bogota .......................................................................................................................28

3.2.4
Santiago.....................................................................................................................31

3.3
NORMALIZED EMISSIONS RESULTS ..................................................................................34

3.3.1
Rio de Janeiro ...........................................................................................................34

3.3.2
Sao Paulo ..................................................................................................................36

3.3.3
Bogota .......................................................................................................................37

3.3.4
Santiago.....................................................................................................................39

4
DISCUSSION AND CONCLUSIONS .................................................................................41

4.1
EXHAUST EMISSIONS ........................................................................................................41

4.2
ENERGY AND FUEL EFFICIENCY .......................................................................................42

4.3
KEY FINDINGS AND RECOMMENDATIONS ........................................................................44

4.3.1
Key findings and recommendations for stakeholders................................................45

4.3.2
Key recommendations ...............................................................................................45

LIST OF TABLES
Table 2.1 Bus acronym and description .......................................................................................................... 6

Table 2.2 Drive cycle characteristics for HB2-S in Rio de Janeiro............................................................... 11

Table 2.3 Drive cycle characteristics for Sao Paulo...................................................................................... 11

Table 2.4 Drive cycle characteristics for Bogota .......................................................................................... 12

Table 2.5 Drive cycle characteristics for Santiago........................................................................................ 13

Table 3.1 Bus acronym and description ........................................................................................................ 16

Table 3.2 Raw results of emissions and fuel consumption, Rio de Janeiro .................................................. 16

Table 3.3 Raw results of emissions and fuel consumption, Sao Paulo ......................................................... 17

Table 3.4 Raw results of emissions and fuel consumption, Bogota.............................................................. 19

Table 3.5 Raw results of emissions and fuel consumption, Santiago ........................................................... 20

Table 3.6 Normalized results of emissions and fuel consumption, Rio de Janeiro....................................... 35

Table 3.7 Normalized results of emissions and fuel consumption, Sao Paulo.............................................. 36

Table 3.8 Normalized results of emissions and fuel consumption, Bogota .................................................. 37

Table 3.9 Normalized results of emissions and fuel consumption, Santiago................................................ 39

In
partnership
with:

LIST OF FIGURES
Figure 1.1 Testing methodology for exhaust emissions and fuel consumption .............................................. 3

Figure 2.1 Fuel consumption test results in Rio de Janeiro ............................................................................ 7

Figure 2.2 Fuel consumption test results in Sao Paulo.................................................................................... 8

Figure 2.3 Fuel consumption test results in Bogota ........................................................................................ 9

Figure 2.4 Fuel consumption test results in Santiago.................................................................................... 10

Figure 2.5 Drive Cycle for HB1-P in Rio de Janeiro .................................................................................... 11

Figure 2.6 Common Drive Cycle for Sao Paulo............................................................................................ 12

Figure 2.7 Common Drive Cycle for Bogota ................................................................................................ 13

Figure 2.8 Common Drive Cycle for Santiago.............................................................................................. 14

Figure 3.1 Raw results normalized in comparison with DB1-R in Rio de Janeiro ....................................... 17

Figure 3.2 Raw results normalized in terms of DB-R in Sao Paulo.............................................................. 19

Figure 3.3 Raw results normalized in terms of DB1-R in Bogota ................................................................ 20

Figure 3.4 Raw results normalized in terms of DB1-R in Santiago.............................................................. 21

Figure 3.5. CO2 per VSP-Bin Rio de Janeiro ................................................................................................ 23

Figure 3.6. NOx per VSP-Bin Rio de Janeiro ............................................................................................... 24

Figure 3.7. PM1.5 per VSP-Bin Rio de Janeiro ............................................................................................ 25

Figure 3.8. CO2 per VSP-Bin Sao Paulo ....................................................................................................... 26

Figure 3.9. NOx per VSP-Bin Sao Paulo ...................................................................................................... 27

Figure 3.10. PM1.5 per VSP-Bin Sao Paulo ................................................................................................. 28

Figure 3.11. CO2 per VSP-Bin Bogotá.......................................................................................................... 29

Figure 3.12. NOx per VSP-Bin Bogotá......................................................................................................... 30

Figure 3.13. PM1.5 per VSP-Bin Bogotá...................................................................................................... 31

Figure 3.14. CO2 per VSP-Bin Santiago ....................................................................................................... 32

Figure 3.15. NOx per VSP-Bin Santiago ...................................................................................................... 33

Figure 3.16. PM1.5 per VSP-Bin Santiago ................................................................................................... 34

Figure 3.17 Normalized results normalized in terms of DB-R in Rio de Janeiro ......................................... 36

Figure 3.18 Normalized results normalized in terms of DB-R in Sao Paulo ................................................ 37

Figure 3.19 Normalized results normalized in terms of DB-R in Bogota..................................................... 39

Figure 3.20 Normalized results normalized in terms of DB-R in Santiago .................................................. 40

Figure 4.1 Emissions reductions for carbon dioxide and criteria pollutants ................................................. 42

Figure 4.2Fuel and energy consumption results............................................................................................ 43

Figure 4.3 Fuel and energy consumption results per passenger.................................................................... 44

LIST OF ACRONYMS
CCI Clinton Climate Initiative
HEBTP Hybrid-Electric Buses Test Program
GHG Green House Gas
BRT Bus Rapid Transit
HB Hybrid Bus
DB Diesel Bus
HB1-P Hybrid Bus 1 - Parallel configuration, running on conventional diesel and electricity
HB1-S Hybrid Bus 1 - Serial configuration, running on conventional diesel and electricity
EB1 Electric Bus 1 running on electricity only
DB1-R Diesel Bus 1 – Reference, running on conventional diesel
DB2-F Diesel Bus 2 – Filter, running on conventional diesel and fitted with DPF
DB2-N Diesel Bus 2 – New, running on conventional diesel, new technology
DB2-A Diesel Bus 2 – Articulated, running on conventional diesel, 18 mt long
VSP Vehicle Specific Power
SCR Selective Catalytic Reduction for NOx control
FE Fuel Efficiency in kilometers per liter
FC Fuel Consumption in liters per 100 kilometers
GPS Global Positioning System
FE fm Fuel Efficiency flowmeter
DPF Diesel Particulate Filter
DOC Diesel Oxidation Catalyst
LATAM Latin America
SOC State of Charge of the battery pack

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1 INTRODUCTION
1.1 General Background
The Hybrid and Electric Bus Test Program (the “Program”) was conceived by C40-CCI,
and has been actively supported by the IDB with a financial contribution of $1.49
million. C40-CCI as the implementing agency was responsible for gathering
contributions from multiple stakeholders, and especially those involved in the testing of
hybrid and electric buses and, for comparison purposes, conventional diesel vehicles.
The Program aims to help cities to make sound decisions regarding test bus technology
performance in city-specific driving conditions and duty cycles, with special attention to
bus operating costs and to local emissions of air pollutants and emissions of GHG. The
Program establishes the case for investment in hybrid and electric buses by bus
technology companies, cities, and local transport operators; compiles and shares results
within a network of participants, interested parties and cities in Latin American countries;
and is designed ultimately to lead to the deployment of up to 9,000 hybrid and electric
buses across Latin American cities in the period up to 2018, resulting in a steady-state
reduction of 475,000 tons of carbon dioxide (CO2) emissions annually.
Local governments, bus suppliers and operators in Bogota, Sao Paulo, Rio de Janeiro and
Santiago implemented the Program. The results of testing and economic analysis have
contributed to building a database that has been shared among cities and is helping to
speed up decisions related to the incorporation of efficient, low emissions bus
technologies.
Reduction of GHG emissions will be demonstrated by verifying that performance of
various hybrid bus technologies is superior to conventional public transport vehicles.
Performance will be evaluated in different geographical altitudes and driving cycles. Test
results will enable manufacturers to make appropriate adjustments to bus design or
operation while guiding cities in the purchase of new or replacement fleets for existing,
new Bus Rapid Transit (BRT) or conventional systems.
1.2 Organization of this Report
1.3 General Methodology
Vehicle emissions determination is a complex science; the most important challenge is to
obtain representative results of a given technology under real operating conditions. In
addition, it is particularly challenging to measure direct exhaust emissions from heavy-

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duty vehicles (trucks or buses), mainly because laboratory equipment required to test
these vehicles is almost inexistent in Latin America and most developing countries.
A new methodology has been internationally developed to overcome these challenges;
this methodology is called On Road Testing and to put it in practice Portable Emissions
Measurement Systems (PEMS) are required.
On the research performed on this Program, On Road Testing and PEMS have been
applied to measure 17 buses in 4 cities of South America (Bogota, Sao Paulo, Santiago
and Rio de Janeiro). Basically, the methodology used in this Program is dealing with the
following challenges:
• Testing buses with different technologies, in 4 Latin American cities using a
common and robust methodology
• Measure exhaust emissions and energy performance from real buses performing
under real operating conditions
• Being able to report comparative results between technologies and cities
In order to tackle the above challenges, ISSRC has performed a rigorous protocol in each
city participating in the Program, applying its IVE1
methodology for measuring tailpipe
emissions, driving cycles and energy use, and combining all these results through the
Vehicle Specific Power (VSP) binning methodology.
Testing protocol comprises two phases, as shown in Figure 1.1. Phase 1 uses PEMS
equipment for measuring direct raw emissions from the exhaust tailpipe of each bus
burning diesel fuel (diesel and hybrid technologies). Phase 2 measures energy use and
driving characteristics while buses are running under representative operating conditions
in each city (diesel, hybrid and electric technologies).
After both phases have been performed, following a protocol of 10 repetitions for Phase 1
and 50 repetitions for Phase 2, all results follow a normalization procedure in order to
compare results. On one hand, exhaust emissions are statistically binned according to the
energy required to move the bus, following the vehicle specific power delivered and the
amount of pollutants emitted per second for each bus. This procedure is repeated for CO,
HC, NOx, PM1.5 and CO2 and provides a matrix of VSP Emissions.
On the other hand, driving cycles from all diesel-burning buses are combined into a
single cycle per city. Driving dynamics of this single cycle are also binned according to
vehicle’s specific power, producing a set of driving conditions linked to levels of energy
required to operate the bus along the designated route on each city. It is important to note
that Phase 1 and Phase 2 do not necessarily share the same route. This procedure
generates a VSP Driving matrix, which is associated to an energy efficiency measured
under the same conditions.
1
International
Vehicle
Emissions
Model,
IVE,
available
at
www.issrc.org/ive

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Crossing both matrices, VSP-Emissions and VSP-Driving, produces a set of normalized
emissions where all pollutants are estimated assuming the same driving characteristics.
These emissions results are compared with fuel consumption and a validation process
through carbon balance takes place closing the circuit.
Using the VSP Binning Methodology both emissions and driving cycle can be classified
under different energy demand situations. The advantage of this methodology relays on
its versatility, combining VSP Emissions and VSP Driving allows evaluations of
emissions under different routes for these buses or technologies.
Figure 1.1 Testing methodology for exhaust emissions and fuel consumption
Phase 1 has been designed to obtain emissions under all possible energy demand
situations of a bus, defined as Emissions divided by Vehicle Specific Power (VSP Bin).
This phase allows the evaluation of different Driving Pattern or Driving Cycles for the
bus on the city, even future cycles developed by the city.

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Phase 2 has been designed to measure energy efficiency and to determine driving cycles
under real world situations, basically under an existing bus route. In order to obtain
representative results each bus ran this route for at least 25 hours. Energy consumption
was recorded using an external tank with a fuel flowmeter for diesel and with electronic
equipment for hybrid and electric buses.
In addition, each bus was equipped with a high resolution GPS which recorded bus
position each second. This data frequency allows for fine energy demand analysis making
possible the precise calculation of VSP binning.
1.4 About Hybrid & Electric Bus Technologies
Hybrid and electric bus technologies are recognized as low carbon technologies. Hybrid
buses combine a conventional internal combustion engine propulsion system with an
electric propulsion system. These types of buses normally use a diesel-electric power-
train and are also described as hybrid diesel-electric buses. The electric power-train is
intended to achieve better fuel economy than in a conventional vehicle. Modern hybrid
diesel-electric buses make use of efficiency-improving technologies such as regenerative
braking, which converts the vehicle's kinetic energy into electric energy to charge the
battery rather than it being dissipated as heat energy whenever the vehicle slows down.
In general, hybrid electric vehicles can be classified according to how the power is
supplied to the drive-train: in parallel or in series. In parallel hybrids, both the internal
combustion engine and the electric motor are connected to the mechanical transmission
and can simultaneously transmit power to drive the wheels, usually through a
conventional transmission. In series hybrids, only the electric motor drives the drive-
train, and the internal combustion engine works as a generator to power the electric motor
or to recharge the batteries. Series hybrids usually have smaller combustion engines and
larger battery pack compared to parallel hybrids. Parallel hybrids have smaller engines
compared to the equivalent diesel bus.
Hybrid buses do not require incremental investments in infrastructure. The hybrid system
consumes less fuel and correspondingly reduces CO2, nitrogen oxides, and particulate
matter emissions.
Electric buses are powered by electricity and propelled by electric motors. They can be
connected by wires or run on batteries that need to be plugged into an electricity source
and recharged over several hours. Battery-based vehicles run on chemical energy stored
in rechargeable battery packs and do not have an internal combustion engine. These
battery electric vehicles (BEV) or electric buses are dependent on the battery being
plugged in at a charging station. Battery electric buses are propelled by motor controllers
and electric motors instead of internal combustion engines. The motor controller
regulates the power to the motor, which can be either a central electrical motor or, more
recently, an in-wheel motor system. The wheel hub motor is an electric motor that is
incorporated into the wheel hub which it drives directly, conferring additional savings by

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eliminating the need for a transmission, differential, and related mechanical parts. This
reduces both the overall weight of the bus and energy losses due to friction.
Tail pipe emissions generated by an electric bus can be close to zero if the electricity used
to charge it comes from low-carbon generating sources such as hydroelectricity. Vehicle
GHG savings depend also on how the electricity is generated.
A fleet of electric buses requires charging stations in bus terminals, a combination
between quick-charging and slow-overnight charging schemes or multiple recharging per
day at bus stops, which requires changes to the street infrastructure.
The Program shows the better performance of hybrid and electric buses compared to
conventional diesel buses in relation to exhaust emissions and energy efficiency.
In Latin American countries the adoption of new low carbon technologies is subject to
various policy scenarios regarding regulation and tax systems. For example, current
subsidies for diesel tip the balance towards investing in conventional diesel technology,
and import barriers in the form of duties favor continuation of local established
production of diesel buses. Life-cycle costs are also a factor in long-term evaluations of
operating costs. In analyzing different possible market scenarios, provision of technical
assistance, and a secondary market at the end of the life cycle can be important.
Although the economic life cycle of a hybrid or electric bus is shorter than that of a diesel
bus, over a 10-year period the case should not be argued on economic grounds only. The
bottom line in economic terms is a higher initial cost and a competitive operating cost,
plus very low maintenance costs for electric buses. Their greatest advantages are the
environmental, health, and social benefits of this technology. Decisions to adopt low
carbon technologies could drive policy and market conditions and make these
technologies more competitive and more convenient than traditional ones.

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2 Energy Performance and Driving Cycles
2.1 Fuel and Energy consumption
The Program tested fuel consumption for diesel-only and hybrid diesel-electric buses, as
well as energy performance for full electric buses. Results varied by city, as showed in
Figures 5 to 8, but in all cases energy efficiency of parallel-hybrid and full-electric buses
was better than traditional diesel buses. Two electric vehicles, seven hybrid technologies
and six diesel-only buses were tested in the four cities participating in the Program. In
terms of fuel consumption, parallel-hybrid technologies reported an average of 31%
reduction in fuel use compared to diesel buses. For electric buses an equivalent amount of
diesel fuel was determined (eq-fuel), based on local electricity costs per kWh and diesel
value per liter. Under these assumptions, electric technologies showed 76% eq-fuel
consumption reduction comparing between buses, as an average for Santiago and Bogota.
This reduction gets down to 59% if eq-fuel consumption per passenger is calculated, due
to a lower carrying capacity when comparing electric and diesel-only vehicles. 2
Fuel consumption results per city are described below, where diesel buses are
denominated as DB1 and DB2, hybrid buses are denominated as HB1 and HB2 and
electric buses are EB1-1 and EB1-2. As well as before, it is important to note that these
acronyms are not necessarily referred to the same buses or technologies when moving
from city to city. The analysis included comparisons of fuel consumption by bus (FC) and
by passenger (FC/pax), using the corresponding reference DB1 in each city.
Different bus technologies were tested for fuel and energy consumption measurement and
their designation for the analysis below are the following:
Table 2.1 Bus acronym and description
ID BUS DESCRIPTION
DB1-R Diesel Bus Reference tested in each city
DB2-F Diesel Bus with particulate Filter tested only in Santiago
DB2-A Diesel Bus Articulated tested only in Sao Paulo
HB1-P
HB2-P
Hybrid Bus Parallel configurations
TB1-S Hybrid Bus Serial configuration
EB1-C Electric Bus - equivalent fuel consumption based in energy Costs
EB1-E Electric Bus - equivalent fuel consumption based in Energy content
2
Diesel
buses
have
a
greater
passenger
capacity
given
their
comparatively
lighter
weight.
Hybrid

buses
have
20-‐30%
less
capacity
than
diesel
buses
and
electric
buses
40-‐50%
less.

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Data for consumption for electric buses was compared to the base line per monetary
value and per unit of energy used. EB1-C estimates equivalent FC converting kWh into
liters of fuel using local prices for each type of energy source, thus including local
subsidies and/or taxes in the analysis. EB1-E estimates FC converting kWh and liters into
kcal of energy, thus avoiding distortions or fluctuations from local energy market prices.
2.1.1 Rio de Janeiro
Four buses were tested in Rio de Janeiro: a diesel reference bus (DB1), a newer Euro 4
diesel bus (DB2), a parallel-hybrid bus (HB1) and a serial-hybrid bus (HB2). Similarly to
the case for emissions, strong differences between the two hybrid technologies were
found for fuel use. The serial-hybrid (HB2) has considerably higher FC than DB1, while
the parallel vehicle (HB1) was consistently lower. Hybrid Bus 1 (HB1) reported the best
fuel performance, with 32% less FC than DB1. Hybrid Bus 2 reported the worst fuel
consumption, with 3% higher FC than DB1.
Figure 2.1 Fuel consumption test results in Rio de Janeiro
2.1.2 Sao Paulo
Figure 2.2 shows results for Sao Paulo, where four buses were tested: a 12-meter diesel
reference bus (DB1), an 18-meter diesel articulated bus (DB2), a 12-meter parallel-hybrid
bus (HB1) and a 12-meter serial-hybrid bus (HB2). In general hybrid technologies had
less fuel consumption than diesel standard technology. There was 42% reduction in fuel
consumption (FC) for HB1 and 22% for HB2. This reduction goes up to 47% for HB1
when fuel consumption per passenger (FC/pax) is estimated and gets down to 14% for
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HB2, due to its lower capacity. DB2 shows 16% higher FC than DB1, but due to its
larger capacity FC/pax is 19% lower (comparable to HB2).
Figure 2.2 Fuel consumption test results in Sao Paulo
2.1.3 Bogota
Figure 2.3 shows two hybrid-parallel technologies and one full-electric bus compared
with one reference diesel bus in Bogota. Hybrid and electric technologies had less fuel
consumption than diesel standard technology, under comparable conditions. There was a
33% reduction of fuel consumption (FC) as an average for HB1 and HB2 technologies.
This reduction goes down to 31% for HB1 when fuel consumption per passenger
(FC/pax) is estimated and gets up to 43% for HB2, due to its higher capacity.
There was one electric bus in Bogota, and its equivalent fuel consumption has been
estimated using the two approaches explained above. For EB1-1, equivalent fuel
consumption per bus was 72% lower for the electric bus in Bogota, compared with DB1,
or 52% lower for equivalent FC/pax. For EB1-2 the same above savings were 81% and
71% respectively.3
3
Costs
of
energy
in
Bogota
were,
at
the
time
of
analysis,
0.17
U$/kW
and
1.21
U$/liter
of
fuel

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Figure 2.3 Fuel consumption test results in Bogota
2.1.4 Santiago
Testing in Santiago comprised four buses for energy performance analysis. A diesel bus
used as reference (DB1), a second diesel bus fitted with particle filter and oxidation
catalyst (DB2), a parallel-hybrid bus (HB1) and a full-electric bus (EB1). There was 40%
reduction of fuel consumption (FC) for HB1. This reduction goes down to 25% for HB1
when fuel consumption per passenger (FC/pax) is estimated, due to its lower capacity.
There was one electric bus in Santiago and, as well as in Bogota, its equivalent fuel
consumption has been estimated using two approaches. EB1-1 estimates equivalent FC
converting kWh into liters of fuel using local prices for each type of energy source. EB1-
2 estimates FC converting kWh and liters into kcal of energy. For EB1-1, equivalent fuel
consumption per bus was 79% lower, compared with DB1, or 60% lower for equivalent
FC/pax. For EB1-2 the same above savings were 73% and 50% respectively. Electricity
costs per kWh are lower in Santiago than in Bogota, while diesel cost per liter is similar
in both cities. This distortion makes electricity more attractive in Santiago.4
4
Costs
of
energy
in
Santiago
were,
at
the
time
of
analysis,
0.086
U$/kW
and
1.155
U$/liter
of
fuel

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Figure 2.4 Fuel consumption test results in Santiago
2.2 Driving Cycles
According to the methodology, each city participating in the Program selected one or two
bus routes for conducting this testing. Each bus ran along the designated route during 10
hours for Phase 1 and 25 hours for Phase 2. Phase 1 provided emissions in grams per
kilometer and also emissions per VSP bins. Phase 2 provided energy consumption and
also driving dynamics recorded along the route.
Several drive cycles have been created using GPS data collected in Phase 2. Each driving
cycle has two sections with the same duration, the first one corresponding to low speed
conditions and the second one representing high speed operation. There is one cycle for
each bus participating in the program and, even the buses used the same route, there are
differences in their driving behavior due to several factors such as vehicle technology,
driver habits, variations in traffic conditions, and weather conditions.
In order to generate emissions results that are comparable, a common driving cycle has
been produced combining cycles from all buses using diesel fuel (thus conventional
diesel and hybrid buses). A VSP-Driving matrix is generated from this cycle, applying
VSP binning methodology. Combining VSP-Emissions and VSP-Driving matrices, a set
of Normalized Emissions is calculated, where all buses share the same operating
conditions.
Next, a summary of driving cycles for each bus and the common driving cycle used to
normalize emissions is shown.
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Four buses were tested in Rio de Janeiro: a reference diesel (DB1-R), a new diesel model
with modern technology (DB2-N), a parallel hybrid bus (HB1-P) and a serial hybrid bus
(HB2-S).
Table 2.2 Drive cycle characteristics for HB2-S in Rio de Janeiro
Variable
Low
Speed
High Speed
Cycle length [s] 600 600
Idle [%] 52 14
Operation [%] 48 86
Average Speed [km/h] 3.39 22.68
Average Acceleration [m/s2
] 0.452 0.49
Average Deceleration [m/s2
] -0.34 -0.543
Maximum Speed [km/h] 25.308 54.396
Maximum Acceleration [m/s2
] 2.33 5.03
Maximum Deceleration [m/s2
] -2.37 -3.04
Figure 2.5 Drive Cycle for HB1-P in Rio de Janeiro
2.2.2 Sao Paulo
Four buses were tested in Sao Paulo: a reference diesel (DB1-R), a parallel hybrid bus
(HB1-P), a serial hybrid bus (HB2-S) and a conventional trolley bus (TB1).
Combining driving characteristics from the above buses (one reference diesel and two
hybrid vehicles) a common driving cycle has been created, which is described below.
Table 2.3 Drive cycle characteristics for Sao Paulo

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Variable
Low
Speed
High Speed
Idle [%] 46.25 15.42
Operation [%] 53.75 84.58
] 0.585 0.402
] -0.717 -0.479
] 1.63 3.97
] -1.86 -4.19
Figure 2.6 Common Drive Cycle for Sao Paulo
2.2.3 Bogota
Four buses were tested in Bogota: a reference diesel (DB1-R), two parallel hybrid buses
(HB1-P and HB2-P) and a full electric bus (EB1).
Combining driving characteristics from the above buses (one reference diesel and two
hybrid vehicles) a common driving cycle has been created, which is described below.
Table 2.4 Drive cycle characteristics for Bogota
Variable
Low
Speed
High Speed
Idle [%] 31.25 15.417
Operation [%] 68.75 84.583
] 0.323 0.387

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] -0.483 -0.586
] 0.93 2.28
] -1.7 -1.75
Figure 2.7 Common Drive Cycle for Bogota
2.2.4 Santiago
Four buses were tested in Santiago: a reference diesel (DB1-R), a diesel model fitted with
diesel particle filter (DB2-F), a parallel hybrid bus (HB1-P) and a full electric bus (EB1).
Combining driving characteristics from the above buses (two diesel and one hybrid
vehicle) a common driving cycle has been created, which is described below.
Table 2.5 Drive cycle characteristics for Santiago
Variable
Low
Speed
High Speed
Idle [%] 44.583 18.333
Operation [%] 55.417 81.667
] 0.617 0.572
] -0.649 -0.849
] 1.36 1.2
] -2.02 -2.43

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Figure 2.8 Common Drive Cycle for Santiago

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3 Exhaust Emissions and Energy Consumption
This chapter describes exhaust emissions and energy consumption results, based on the
methodology used in this project. As a first step for measuring emissions, each bus was
tested for around 10 hours with Portable Emissions Measurement Systems (PEMS). This
stage is defined as Phase 1 and two important results were obtained from here: 1) Raw
Average Emissions (Section 3.1) and 2) Emissions by Energy Demand or Vehicle
Specific Power (Section 3.2).
Raw Average Emissions correspond to a direct result of exhaust emissions in grams per
kilometre, but since the bus is under certain operational restrictions due to the equipment
installed in the interior, these emissions are not totally representative of the same bus in
normal operations. To overcome this issue, emissions are recorded at 1Hz frequency,
allowing the correlation of driving behaviour with instant emissions (second by second).
This frequency for measuring and collecting data allows the calculation of emissions by
vehicle energy demand.
Thus, emissions in terms of Energy Demand or by Vehicle Specific Power (VSP) are
obtained in grams per second according to different energy bins. With this binning
distribution analysis, emissions can be matched to specific situations such as idling,
braking or accelerating. In addition, this methodology allows estimating emissions for
any driving pattern of the city. Thus, emissions can be modelled in different routes from
their representative driving patterns.
Simultaneously, in Phase 2 each bus was tested in real traffic conditions, for 25 hours for
one week. This Phase has two main products: 1) Fuel Efficiency and 2) Driving Cycle
Development. Both results are obtained under real world conditions on a representative
route defined by a local team in each city.
Adding all driving results for all buses in each city, a common cycle was developed. This
cycle has the distinction of representing a normalized driving behaviour. Each overall
cycle included data recorded from 75 to 100 hours (270,000 to 360,000 seconds) of real
conditions on a representative route.
Finally, emissions by VSP and the common cycle of each city are processed together to
obtain Normalized Emissions (Section 3.3). These emissions are comparable considering
that each bus emissions are evaluated under the same driving pattern or driving
behaviour.
3.1 Overall raw emissions results
The following section describes exhaust tailpipe emissions and fuel consumption
performed by each bus tested in Rio de Janeiro, Sao Paulo, Bogota and Santiago. These
results are directly taken from Phase 1 and are considered raw results.

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Different bus technologies were tested for emissions measurement and their designation
for the analysis below are the following:
Table 3.1 Bus acronym and description
ID BUS DESCRIPTION
DB1-R Diesel Bus Reference tested in each city
DB2-F
Diesel Bus with particulate Filter tested
only in Santiago
DB2-A
Diesel Bus Articulated tested only in Sao
Paulo
HB1-P
HB2-P
Hybrid Bus Parallel configuration
HB2-S Hybrid Bus Serial configuration
Regarding fuel consumption (FC), raw results are included in accordance with the testing
phase where they were obtained. Fuel consumption measurements under emissions
testing methodology (Phase 1) are designed as FC Ph1.
The first city were tests were performed was Rio de Janeiro. Table 3.2 shows raw results
performed by buses in Rio de Janeiro for emissions and fuel consumption.
Table 3.2 Raw results of emissions and fuel consumption, Rio de Janeiro
ID BUS
THC
(g/km)
CO
(g/km)
NOx
(g/km)
CO2
(g/km)
PM1.5
(g/km)
FC Ph1
[L/100km]
DB1-R 0.12 5.46 10.07 1,073.4 0.10 39.37
HB1-P 0.04 1.06 5.19 891.6 0.03 32.79
HB2-S - 6.39 12.52 1,776.2 0.22 58.82
In general, HB1-P performed with lower emissions rates (g/km) than DB1-R an average
emission reduction was 58%, considering all pollutants measured. The greatest emission
reduction result was for CO with 81%.
Regarding NOx and PM1.5 in HB1-P, emission rates reached 5.19 (g/km) and 0.03
(g/km), which is equivalent to a reduction of 48% for NOx and 74% for PM1.5.
CO2 emissions were 1,073 (g/km) and 891.6 (g/km) for DB1-R and HB1-P, respectively,
and equivalent HB1-P emission reduction was 17% with respect to DB1-R. Results for

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fuel consumption (L/100km) in HB1-P running under Phase 1 methodology were 17%
lower than DB-R.
In case of HB2-S tested in Rio de Janeiro, in general, it performed with higher emissions
rates (g/km) than DB1-R and average emission increase was 57%, considering all
pollutants measured.
Figure 3.1 shows the difference between diesel reference bus (DB1-R) and hybrid buses
tested in Rio de Janeiro, where raw results have been compared in terms of DB1-R
emissions and fuel consumption results (DB1-R is 1).
Figure 3.1 Raw results normalized in comparison with DB1-R in Rio de Janeiro
3.1.2 Sao Paulo
Following Rio de Janeiro, the second city where tests were performed was Sao Paulo. In
addition to the buses tested during the first campaign, a serial hybrid bus was measured
during the second campaign. Table 3.3 shows raw results performed by all buses tested in
Sao Paulo for emissions and fuel consumption.
Table 3.3 Raw results of emissions and fuel consumption, Sao Paulo
ID BUS
THC
(g/km)
CO
(g/km)
NOx
(g/km)
CO2
(g/km)
PM1.5
(g/km)
FC Ph1
[L/100km]
DB1-R 0.19 8.83 13.52 1,442.1 0.32 53.45
DB2-A 5.85 13.76 1,655.8 0.18 61.21
HB1-P 0.08 1.02 7.38 995.3 0.10 35.88
HB2-S 1.86 7.19 1,265.2 47.44
0.00
0.50
1.00
1.50
2.00
2.50
THC CO NOx CO2 PM1.5 FC-Ph1
RawEmissions
DB1-R HB1-P HB2-S

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Hybrid buses, both parallel and serial configuration, performed with lower emissions
rates (g/km) than DB1-R. Average emission reductions were, 58% and 46% for HB1-P
and HB2-S5
, respectively. The greatest emission reduction results were in CO with 88%
for HB1-P and 79% for HB-S.
Regarding NOx in hybrid technology, HB1-P and HB2-S emissions rates reached 7.38
(g/km) and 7.19 (g/km), which is equivalent to 45% and 47% emission reduction with
respect to DB1-R bus, respectively.
In case of HB1-P, emissions reduction for PM1.5 was 70% lower than DB1-R bus and
absolute values were 0.10 (g/km) for HB1-P and 0.32 (g/km) for DB1-R.
CO2 emissions were 1,442 (g/km), 995.3 (g/km) and 1,265 (g/km) for DB1-R, HB1-P and
HB2-S, respectively, and equivalent HB1-P and HB2-S emission reductions were 31%
and 12% with respect to DB1-R.
Results for fuel consumption (L/100km) in HB1-P and HB2-S running under Phase 1
methodology were 33% and 11% lower than DB1-R bus, respectively.
An articulated diesel bus DB2-A was tested in Sao Paulo which performed with higher
NOx and CO2 emissions rates than DB1-R with 2% and 15% of increment, respectively.
On the other hand, DB2-A results for CO and PM1.5 emissions were lower than DB1-R
bus with 34% and 44% reductions, respectively.
Figure 3.2 shows differences between diesel reference bus (DB1-R), hybrid buses and the
articulated diesel bus (DB2-A) tested in Sao Paulo, where raw results have been
normalized in terms of DB1-R emissions and fuel consumption results.
5
There
are
no
THC
and
PM1.5
measurements
for
HB1-‐S
in
Sao
Paulo

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Figure 3.2 Raw results normalized in terms of DB-R in Sao Paulo
3.1.3 Bogota
The third campaign of the Program was performed in Bogotá, Colombia. Four buses were
tested, a reference diesel bus, 2 hybrid buses and 1 full electric bus. Only results for the
buses with an internal combustion engine are analysed in this subsection. Table 3.4 shows
raw results performed by buses in Bogota for emissions and fuel consumption.
Table 3.4 Raw results of emissions and fuel consumption, Bogota
ID BUS
THC
(g/km)
CO
(g/km)
NOx
(g/km)
CO2
(g/km)
PM1.5
(g/km)
FC Ph1
[L/100km]
DB1-R 0.53 6.40 12.19 1,011.0 0.066 37.66
HB1-P 0.03 2.64 1.70 796.6 0.021 29.94
HB2-P 0.03 3.95 6.07 890.7 0.019 33.58
In general, both HB-P buses performed with lower emissions rates (g/km) than DB1-R
and average emission reduction was 59%, considering all pollutants measured in both
hybrid buses: HB1-P and HB2-P. The greatest emission reduction results were in THC
with 94% for HB1-P and 95% for HB2-P.
Regarding NOx in hybrid technology, HB1-P and HB2-P emissions rates reached 1.70
(g/km) and 6.07 (g/km), which is equivalent to 86% and 50% emission reduction with
respect to DB-R, respectively.
Emissions reductions for PM1.5 were 68% (HB1-P) and 71% (HB2-P) in comparison with
DB1-R and absolute values were 0.021 (g/km) for HB1-P, 0.019 (g/km) for HB2-P and
0.066 (g/km) for DB1-R.
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
RawEmissions
DB1-R DB2-A HB1-P HB2-S

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CO2 emissions were 1,011 (g/km), 796.6 (g/km) and 890.7 (g/km) for DB1-R, HB1-P and
HB2-P, respectively, and equivalent HB1-P bus and HB2-P emission reductions were
21% and 12% with respect to DB-R bus.
Results for fuel consumption (L/100km) in HB1-P and HB2-P running under Phase 1
methodology were 20% and 11% lower than DB1-R, respectively.
Figure 3.3 shows difference between diesel reference bus (DB1-R) and hybrid buses
tested in Bogota, where raw results have been normalized in terms of DB1-R emissions
and fuel consumption results.
Figure 3.3 Raw results normalized in terms of DB1-R in Bogota
3.1.4 Santiago
The last city where tests were performed was Santiago, Chile. In Santiago, 4 buses were
tested. Once again only the internal combustion engines buses are analysed in this sub
section. In Santiago, a diesel bus equipped with a particle filter was tested and compared
against the hybrid bus, Table 3.5 shows raw results performed by bus in Santiago for
emissions and fuel consumption.
Table 3.5 Raw results of emissions and fuel consumption, Santiago
ID BUS
THC
(g/km)
CO
(g/km)
NOx
(g/km)
CO2
(g/km)
PM1.5
(g/km)
FC Ph1
[L/100km]
DB1-R 0.10 13.32 12.76 1,030.6 0.029 38.92
DB2-F 0.02 1.84 15.44 956.9 0.001 36.00
HB1-P 0.03 0.37 2.55 667.4 0.007 25.21
0.00
0.20
0.40
0.60
0.80
1.00
1.20
RawEmissions
DB1-R HB1-P HB2-P

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In general, HB1-P produced lower emissions rates (g/km) than DB1-R and average
emission reduction was 72%, considering all pollutants measured. The greatest emission
reduction result was in CO with 97%.
Regarding NOx and PM1.5, HB1-P, emissions rates reached 2.55 (g/km) and 0.007
(g/km), which is equivalent to 80% and 76% emission reduction with respect to the DB1-
R bus, respectively.
CO2 emissions were 1,030 (g/km) and 667.4 (g/km) for DB1-R and HB1-P, respectively,
and the equivalent HB1-P bus emission reduction was 35% with respect to DB1-R.
Results for fuel consumption (L/100km) in HB1-P running under Phase 1 methodology
were 35% lower than DB-R bus.
DB2-F, a diesel bus equipped with a Diesel Particle Filter was tested in Santiago, which
operates with lower emissions rates than DB1-R bus in all pollutants with exception of
NOx. PM1.5 emission reduction was 97% and reached 0.001 (g/km). However, NOx
emissions increased 21% and reached 15.44 (g/km). Regarding CO2 emissions, DB2-F
reduced 7% with respect to DB1-R, equivalent to 956.9 (g/km).
Figure 3.1 shows differences between diesel reference bus (DB1-R) and hybrid buses
tested in Santiago, where raw results have been normalized in terms of DB1-R emissions
Figure 3.4 Raw results normalized in terms of DB1-R in Santiago
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
RawEmissions
DB1-R DB2-F HB1-P

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3.2 Emissions by Energy Demand Situations per City
As previously mentioned in this report, important sets of results from this study are
emissions per unit energy demand. These types of results are only possible using high
frequency reading equipment on a real world testing procedure. The importance of this
approach is based on the versatility to use it in future applications, allowing comparisons
of technology behavior under different energy demand situations and the possibility to
give recommendations on how to optimize engines or even drivers during bus operation.
Emissions by energy demand or by Vehicle Specific Power (VSP) are widely used in the
USEPA to make comparisons between technologies. On the appendix of each city report
VSP methodology is explained in detail and should be reviewed to better understand the
following results. In this case the VSP methodology used is according to the IVE model
methodology (www.issrc.org/ive).
In the following subsections, emissions by VSP per city are compared and analyzed.
In Rio de Janeiro, the first field campaign, four buses were tested: a diesel reference bus
(DB1-R), a new diesel euro 3 bus (not included in the analysis because it lacks the testing
minimum time) and two hybrid buses, a parallel hybrid (HB1-P) and a serial hybrid
(HB2-S).
On the following graphs, emissions results by Vehicle Specific Power Bins (9 to 14) for 3
buses are shown. Each Bin represents a comparable energy demand situation. Bins 9 to
10 represent decelerating conditions, Bin 11 near idling conditions and Bin 12 to 14
accelerating conditions.
On the first graph, CO2 emissions are compared for DB1-R and HB1-P. CO2 emissions
are comparable for almost every VSP Bin, a noticeable difference appears in Bin 12
where HB1-P shows a 13% reduction against DB1-R. Bin 12 is the first energy situation
after idling, and normally a high percentage of the driving is made under this situation,
this difference explains a possible overall CO2 emissions reduction.
Since HB2-S is a serial hybrid6
, it shows a totally different emissions pattern. Basically,
under any energy situation emissions stay constant. For VSP Bins 9 to 11 emissions are
more than double DB1-R emissions. This result explains high overall CO2 for this bus,
considering that most of the driving is made under VSP Bin 11.
6
In
serial
configurations
the
internal
combustion
engine
is
used
at
constant
rpm
as
a
generator
to

charge
the
batteries

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Figure 3.5. CO2 per VSP-Bin Rio de Janeiro
For NOX emissions, VSP analysis shows the difference between technologies. DB1-R
and HB1-P follow the same pattern, increasing emissions by increasing VSP Bin with a
very different rate. HB1-P reaches its maximum value on Bin 13 at 0,05 g/sec, DB1-R
reaches its maximum in Bin 14 at 0,18 [g/sec], on Bin 14 HB1-P NOX emission
reductions is 87% versus DB1-R. In general terms, HB2-S shows the same behaviour as
expected, with almost the same emissions for every VSP Bin, even though emissions on
Bins 9 to 11 are still higher than DB1-R.
0
5
10
15
20
25
BIN 9 BIN 10 BIN 11 BIN 12 BIN 13 BIN 14
CO2[g/s]
DB1-R
HB1-P
HB2-S

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Figure 3.6. NOx per VSP-Bin Rio de Janeiro
Average PM1.5 emissions have a different tendency than other pollutants; HB1-P
emissions are the lowest for every VSP Bin, with a maximum of 77% reduction over
DB1-R in Bin 11.
HB2-S reported the highest emissions; on average for all Bins HB2-S is 33% higher than
DB1-R. The VSP Bin with the highest difference is Bin 11 with 117% more PM1.5
emissions than DB1-R, normally this VSP Bin is the one with most time percentage in
urban driving.
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
NOx[g/s]
DB1-R
HB1-P
HB2-S

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Figure 3.7. PM1.5 per VSP-Bin Rio de Janeiro
3.2.2 Sao Paulo
The second city where the tests were performed was Sao Paulo. Four buses were tested in
two rounds: a reference diesel bus (DB1-R), an articulated diesel bus (DB2-A) and two
hybrids, a parallel hybrid bus (HB1-P) and a serial hybrid bus (HB2-S). The next graphs
show emissions in grams per second by energy demand (VSP Bins), this methodology is
used according to the International Vehicle Emission (IVE) model, as mention previously
in this report: Bin 11 represents energy demand near idling, Bin 9 and 10 represent
energy demand when the vehicle is decelerating and Bin 12 to 14 represent energy
demand when the vehicle is accelerating.
In the case of CO2 emissions, there is an increase for all buses when the energy demand
increases as expected, from Bin 9 to 11 all buses show comparable results, except for
HB2-S showing high emissions for lower VSP Bins, this high emissions on lower energy
situations are related with the HB2-S configuration, this bus is a series hybrid which
means that the internal combustion engine is always running, normally charging batteries.
This can result in high emissions when the bus is idling or decelerating.
From Bin 11 differences appear between buses. For HB1-P emissions are 25% lower and
for HB2-S are 5% higher. In Bin 12 HB1-P shows a 31% reduction and HB2-S shows a
27% reduction for the same energy situation. For Bin 13 HB1-P shows a reduction of
16% and for Bin 14 it shows no reduction against DB1-R, HB2-S shows 53% reduction
for Bin 13 and 52% for Bin 14.
0
0.0002
0.0004
0.0006
0.0008
0.001
0.0012
0.0014
0.0016
PM1.5[g/s]
DB1-R
HB1-P
HB2-S

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DB2-A emissions are almost the same that DB1-R for Bins 9 to 11, while for VSP-Bins
12 and 13 emissions are 21% and 18% higher than DB1-R respectively.
Figure 3.8. CO2 per VSP-Bin Sao Paulo
With respect to NOx emissions, energy demand analysis shows that the difference
between technologies, DB1-R, HB1-P and HB2-S, follow the same pattern, increasing
emissions by increasing VSP Bin number, however the rates are different. It is noticeable
that HB2-S being a series hybrid is showing a similar pattern, this is possible considering
that the bus regulating RPM of the engines under load conditions.
While HB1-P reaches its maximum value on Bin 14 at 0.13 g/sec, DB1-R reaches its
maximum also in Bin 14 at 0.18 [g/sec]; this means a reduction of 31% for NOx
emissions at the maximum level. HB2-S is below both results, reaching a maximum of
0.07 g/sec on Bin 14, which indicates a 59% emissions reduction against DB1-R for the
maximum level.
Interesting enough, DB2-A NOX emissions are lower than DB1-R emissions, for Bins 12
and 13, and for the rest of the Bins DB2-A emissions are very comparable between each
other.
0
5
10
15
20
25
30
CO2[g/s]
DB1-R
DB2-A
HB1-P
HB2-S

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Figure 3.9. NOx per VSP-Bin Sao Paulo
PM1.5 emissions per VSP-Bin show important differences between DB1-R, DB2-A and
HB1-P7
, DB1-R is the dirtiest one for almost every energy demand situation while HB1-P
is the lowest. In average, PM1.5 emissions reductions are 68% for all VSP Bin, in BIN 13
the main gap appears with a difference of 72% between DB1 and HB1-P. DB2-A shows a
28% average PM1.5 reduction for all VSP Bins in comparison with DB1-R, although
DB1-R is a smaller bus, this fact is explained due to DB2-A electronic which is more
advance than DB1-R.
7
HB2-‐S
PM1.5
emissions
were
not
measure
due
to
PM
equipment
problems.

0
0.05
0.1
0.15
0.2
0.25
NOX[g/s]
DB1-R
DB2-A
HB1-P
HB2-S

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Figure 3.10. PM1.5 per VSP-Bin Sao Paulo
3.2.3 Bogota
In Bogota, Colombia, once again four buses were tested, a diesel reference bus (DB1-R),
two Parallel hybrids buses (HB1-P and HB2-P) and a Full Electric Bus (EB1).
The following graphs show emissions in grams per second divided by energy demand
(VSP Bins), this methodology is used according to the IVE model and is highly
recommended to read the Annex related with this methodology on the report to better
understand this section results. Basically, Bin 11 represents energy demand near idling,
Bin 9 and 10 represent energy demand when the vehicle is slowing down and Bin 12 to
14 represent energy demand when the vehicle is accelerating.
With respect to CO2 emissions, it is interesting how for all buses there is a similar trend
when energy demand increases as expected, from Bin 9 to 10 all buses show very
comparable results. From Bin 11 differences appear between buses, for HB1-P emissions
are 35% lower and for HB2-P the reduction is 11% in comparison with HB2-P. In Bin 12
HB1-P shows a 19% reduction and HB2 shows a 31% reduction for the same energy
situation, once again respect DB1-R. For Bin 13 and 14 HB1-P shows little or non
reduction against DB1-P, HB2 shows 20% reduction for Bin 13 and 11% for Bin 14.
Normally, the most of the time for urban conditions is spent in Bin 11; this is why HB1-P
still may have an advantage over HB2-P although on the rest of the energy situations CO2
emissions are higher.
0
0.0005
0.001
0.0015
0.002
0.0025
0.003
0.0035
0.004
0.0045
PM1.5[g/s]
DB1-R
DB2-A
HB1-P

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Figure 3.11. CO2 per VSP-Bin Bogotá
For NOx emissions, energy demand analysis shows the difference between technologies
once again in Bogota’s altitude (2600 mt). Emissions from DB1-R, HB1-P and HB2-P
follow the same pattern, increasing by increasing Bin number and once again rates are
very different. While HB1-P reaches its maximum value in Bin 14 at 0.026 g/sec, DB1
reaches its maximum in Bin 14 at 0.23 [g/sec], meaning there is a reduction of 93% in
NOx emissions at the maximum level. On average, NOx reductions for all VSP Bins are
78% for HB1-P compared with DB1-R.
HB2-P is in between both results, reaching a maximum of 0.095 g/sec on Bin 14, which
indicates a 58% emissions reduction against DB1 for the maximum level. On average,
NOx reduction for all VSP Bins is 37% for HB2-P compared with DB1-R.
0
5
10
15
20
25
CO2[g/s]
DB1-R
HB1-P
HB2-P

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Figure 3.12. NOx per VSP-Bin Bogotá
PM emissions per Bin show important differences between the standard bus and hybrids
buses, DB1-R is dirtier for almost every energy demand situation than both hybrids
buses. On Bin 14 the main gap appears with a difference of 86% between DB1 and HB1.
HB2 shows a difference of 83%, both hybrids shows very comparable results. In average,
reduction from both hybrids is 64% compared with DB1-R.
0
0.05
0.1
0.15
0.2
0.25
NOx[g/s]
DB1-R
HB1-P
HB2

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Figure 3.13. PM1.5 per VSP-Bin Bogotá
3.2.4 Santiago
The last campaign was performed in Santiago, Chile, once again four buses were tested, a
reference diesel bus (DB1-R), a diesel equipped with diesel particle filter (DB2-F), a
hybrid bus (HB1-P) and a Full Electric Bus (EB1). This last bus was not reported in this
section due to obvious reasons.
The next images show emissions in grams per second classified by energy demand
(Bins), as in rest of the program this methodology is used according to the IVE model8
. In
terms of driving dynamic Bin 11 represents energy demand near idling, Bin 9 and 10
represent energy demand when the vehicle is decelerating and Bin 12 to 14 represent
energy demand when the vehicle is accelerating.
Analyzing CO2 emissions, the increase for all buses when the energy demand increases is
consistent with other cities. From Bin 9 to 11 results show higher emissions for DB2-F
and important differences appear from Bin 12 where DB1 shows higher emissions.
Comparing DB1-R against DB2-F, CO2 emissions results are close as expected. For Bin
11 and Bin 14 DB2-F is higher by 7% and 11%. DB2 shows lower emissions on Bins 12
and 13 by 11% and 12%.
Comparing HB1-P against DB1-R emissions for HB1 emissions are lower for all energy
situations, from 68% on Bin 10 to 20% on Bin 14%. In average emissions reduction from
HB1-P to DB1-R is 45%.
8
www.issrc.org

0
0.0005
0.001
0.0015
0.002
0.0025
0.003
0.0035
PM1.5[g/s]
DB1-R
HB1-P
HB2-P

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Figure 3.14. CO2 per VSP-Bin Santiago
In the case of NOX emissions, energy demand analysis explain the differences between
technologies, DB1-R, DB2-F and HB1-P follow the same pattern, increasing emissions
by increasing Bin number, and as seen during the entire program rates are different once
again.
HB1-P emissions reaches its maximum value in Bin 14 at 0.049 g/sec, in the same Bin
DB1-R reaches its maximum at 0.29 [g/sec] and DB2-F reaches its maximum in Bin 14 at
0.31 [g/sec] meaning there is a reduction of 83% for NOX emissions at the maximum
level from DB1-R compared to HB1-P. In averaged, there is 59% reduction for all Bins
when comparing HB1-P to DB1-R.
DB2-F shows an increase of NOx emissions against DB1-R of 21% from Bin 11 to Bin
14, this can be explained by the effect of the Diesel Particle Filter (DPF) counter-pressure
on the engine. In fact, looking at average results, NOx emissions are the only pollutant
where DB2-F show higher emissions compare with the reference bus (DB1-R).
0
5
10
15
20
25
30
35
CO2[g/s]
DB1-R
DB2-F
HB1-P

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Figure 3.15. NOx per VSP-Bin Santiago
Santiago’s PM1.5 emissions per Bin provide an important technology comparison to the
program: a diesel bus equipped with a diesel particle filter (DB2-F). In addition, Santiago
has the cleaner diesel in the program, less than 50 ppm of sulfur.
As expected, DB1-R is dirtier for every energy demand situation. HB1-P shows an
emissions reduction of 72% in average for all Bins compared to DB1-R, main difference
appear in Bin 10 with 85% reduction.
The cleanest bus is DB2-F showing the lowest PM1.5 emissions, in average emissions
reduction for all Bin situations reaches a 96% with emissions reductions from 91% on
Bin 14 to 98% on Bin 10. This results show the high efficiency of diesel particle filters.
0.00
0.05
0.10
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0.20
0.25
0.30
0.35
NOx[g/s]
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DB2-F
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Figure 3.16. PM1.5 per VSP-Bin Santiago
3.3 Normalized Emissions Results
Finally, to directly compare average emissions results under the same driving pattern or
driving behavior, normalized emissions are calculated. These emissions are calculated
combining Phase 1 results with Phase 2 driving behavior results through vehicle specific
power binning methodology, to evaluate every bus of each city under the same driving
pattern represented by the over all driving cycle of a given city.
In summary, with the GPS data collected in Phase 2 a representative driving cycle was
developed for each city (see Chapter 3), this driving cycle include driving behavior, buses
dynamics and traffics factor conditions that allows to normalized emissions by city.
On the following sections normalized emissions are compared.
As mentioned previously in this report, Rio de Janeiro was the first city to be tested;
Table 3.2 shows raw results performed by bus in Rio de Janeiro for emissions and fuel
consumption.
0
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
PM1.5[g/s]
DB1-R
DB2-F
HB1-P

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Table 3.6 Normalized results of emissions and fuel consumption, Rio de Janeiro
ID BUS
THC
(g/km)
CO
(g/km)
NOx
(g/km)
CO2
(g/km)
PM1.5
(g/km)
FC Ph1
[L/100km]
FC Ph2
[L/100km]
DB1-R 0.13 6.23 11.32 1,230 0.13 46.67 33.33
HB1-P 0.07 1.47 5.89 1,243 0.06 47.14 30.03
HB2-S - 5.79 11.50 1,693 0.21 64.24 50.25
In summary, HB1-P performed with lower normalized emissions rates (g/km) than DB-R
and average emission reduction was 46%, considering all pollutants measured. The
greatest emission reduction result was in CO with 76%. In general, normalized emissions
increase unitary emissions for most of the pollutants in HB1-P.
Regarding NOx and PM1.5 in HB1-P, emissions normalized rates reached 5.89 (g/km) and
0.06 (g/km), which is equivalent to 48% and 56% emission reduction with respect to
DB1-R bus, respectively.
Normalized CO2 emissions were 1,230 (g/km) and 1,243 (g/km) for DB1-R bus and
HB1-P bus, respectively; these results correspond to no reduction between HB1-P with
respect to DB1-R bus. Results for fuel consumption (L/100km) in HB-P running under
Phase 2 was 10% lower than DB-R bus.
In the case of HB-S bus tested in Rio de Janeiro, in general, it performed with higher
normalized emissions rates (g/km) than DB1-R bus and average emission increment was
24%, considering all pollutants9
measured. This result is better than raw emissions where
the difference was 57% on average increase emissions over DB1-R.
Figure 3.1 shows difference between diesel reference bus (DB-R) and hybrid buses tested
in Rio de Janeiro, where raw results have been normalized in terms of DB-R emissions
9
There
is
no
THC
measurement
for
HB-‐S
in
Rio
de
Janeiro

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Figure 3.17 Normalized results normalized in terms of DB-R in Rio de Janeiro
3.3.2 Sao Paulo
As mention before in this chapter, the second city were the tests were performed was Sao
Paulo; in a second campaign, emissions from a serial hybrid bus were added to the
campaign analysis. Table 3.3 shows raw results performed by buses in Sao Paulo for
Table 3.7 Normalized results of emissions and fuel consumption, Sao Paulo
ID BUS
THC
(g/km)
CO
(g/km)
NOx
(g/km)
CO2
(g/km)
PM1.5
(g/km)
FC Ph1
[L/100km]
FC Ph2
[L/100km]
DB1-R 0.174 7.91 12.33 1,363 0.28 51.73 65.23
DB2-A 0.156 6.16 12.77 1,584 0.10 60.09 75.43
HB1-P 0.082 1.06 7.12 1,063 0.09 40.34 37.92
HB2-S - 1.74 6.45 1,112 - 42.19 51.03
Hybrid buses, both parallel and serial configuration, produce lower normalized emissions
rates (g/km) than DB1-R and average emission reductions were, considering all
pollutants measured, 54% and 48% for HB1-P and HB2-S10
, respectively. The greatest
emission reduction results were in CO with 87% for HB1-P and 78% for HB2-S.
Regarding NOX in hybrid technology, HB1-P and HB2-S normalized emissions rates
reached 7.12 (g/km) and 6.45 (g/km), which is equivalent to 42% and 48% emission
reduction with respect to DB1-R, respectively.
In case of HB1-P, emissions reduction for PM1.5 was 67% lower than DB1-R bus and
absolute values were 0.09 (g/km) for HB1-P bus and 0.28 (g/km) for DB1-R bus.
10
There
are
no
THC
and
PM1.5
measurements
for
HB-‐S
in
Sao
Paulo

0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
THC CO NOx CO2 PM1.5 FC-Ph1 FC-Ph2
NormalizedEmissions
DB1-R HB1-P HB2-S

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Normalized CO2 emissions were 1,363 (g/km), 1,063 (g/km) and 1,112 (g/km) for DB1-R
bus, HB1-P bus and HB2-S bus, respectively, and equivalent HB1-P bus and HB2-S
emission reductions were 22% and 18% with respect to DB1-R bus.
Results for fuel consumption (L/100km) in Phase 2, HB1-P and HB1-S results were 42%
and 22% lower than DB1-R bus.
An articulated diesel bus DB2-A was tested in Sao Paulo, which produces higher NOx
and CO2, normalized emissions rates than DB1-R bus with 4% and 16% of increment,
respectively. On the other hand, DB2-A normalized results for CO and PM1.5 emissions
were lower than DB1-R bus with 22% and 62% of reduction, respectively
Figure 3.2 shows difference between diesel reference bus (DB1-R), hybrid buses (HB1-P
and HB2-S) and articulated diesel bus (DB2-A) tested in Sao Paulo, where raw results
have been normalized in terms of DB1-R emissions and fuel consumption results.
Figure 3.18 Normalized results normalized in terms of DB-R in Sao Paulo
3.3.3 Bogota
As mentioned before, the first campaign after Brazil was performed in Bogotá, Colombia,
4 buses were tested, a reference diesel bus (DB1-R), 2 hybrid buses (HB1-P and HB2-P)
and 1 full electric bus (EB). Table 3.8 shows raw results performed by bus in Bogota for
Table 3.8 Normalized results of emissions and fuel consumption, Bogota
ID BUS
THC
(g/km)
CO
(g/km)
NOx
(g/km)
CO2
(g/km)
PM1.5
(g/km)
FC Ph1
[L/100km]
FC Ph2
[L/100km]
DB1-R 0.64 7.74 14.80 1,212 0.075 45.98 50.49
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
NormalizedEmissions
DB1-R DB2-A HB1-P HB2-S

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HB1-P 0.04 3.34 2.05 967 0.027 36.69 33.57
HB2-P 0.02 3.90 5.96 907 0.020 34.39 34.46
As in previous cities, HB1-P buses produces lower normalized emissions rates (g/km)
than DB1-R bus and average emission reduction was 63%, considering all pollutants
measured in both hybrid buses: HB1-P and HB2-P. The greatest emission reduction
results were in THC with 94% for HB1-P and 97% for HB2-P.
Regarding normalized NOX in hybrid technology, HB1-P and HB2-P emissions rates
reduction with respect to DB1-R bus, respectively.
Normalized emissions reductions for PM1.5 were 64% (HB1-P) and 73% (HB2-P) lower
than DB-R bus and absolute values were 0.027 (g/km) for HB1-P, 0.020 (g/km) for HB2-
P and 0.075 (g/km) for DB1-R.
CO2 normalized emissions were 1,212 (g/km), 967 (g/km) and 907 (g/km) for DB1-R
bus, HB1-P bus and HB2-P bus, respectively, and equivalent HB1-P bus and HB2-P
emission reductions were 20% and 25% with respect to the DB1-R bus. This result is one
of the unique results where normalized emissions show increased reductions. In this case,
HB2-P increases its reduction by 13% (it was only 12% in the case of raw emissions)
over raw results. This is possible considering that emissions per VSP Bin (Section 3.2.3)
for HB2-P are lower than HB1-S for VSP-Bin 12 and 13. The normalized cycle is
expending more time under this situation than the raw driving pattern.
Results for fuel consumption (L/100km) in HB1-P and HB2-P results for Phase 2 were
34% and 32% lower than DB1-R bus.
Figure 3.3 shows differences between diesel reference bus (DB1-R) and hybrid buses
tested in Bogota, where raw results have been normalized in terms of DB1-R emissions

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Figure 3.19 Normalized results normalized in terms of DB-R in Bogota
3.3.4 Santiago
As mention before in this report, Santiago, Chile was the last city where tests were
performed. In Santiago 4 buses were tested, once again only the buses with internal
combustion engines are analysed in this sub section. In Santiago, a diesel bus equipped
with a Diesel Particle Filter was tested and compared with the Hybrid bus. Table 3.9
shows raw results performed by bus in Santiago for emissions and fuel consumption.
Table 3.9 Normalized results of emissions and fuel consumption, Santiago
ID BUS
THC
(g/km)
CO
(g/km)
NOx
(g/km)
CO2
(g/km)
PM1.5
(g/km)
FC Ph1
[L/100km]
FC Ph2
[L/100km]
DB1-R 0.19 22.03 22.03 1,756 0.056 66.61 55.95
DB2-F 0.04 3.56 26.67 1,659 0.001 62.94 59.06
HB1-P 0.05 0.60 4.14 1,128 0.013 42.80 33.56
Once again, HB1-P normalized emissions rates (g/km) were lower than DB1-R
normalized emissions rates. The average emission reduction was 73%, considering all
pollutants measured. The greatest emission reduction result was for CO with a 97%
reduction.
With respect to normalized NOx and PM1.5 emissions for HB1-P, emissions rates
reduction with respect to DB1-R, respectively.
Normalized CO2 emissions were 1,756 (g/km) and 1,128 (g/km) for DB1-R bus and
HB1-P bus, respectively, and equivalent HB1-P bus emission reduction was 36% with
0.00
0.20
0.40
0.60
0.80
1.00
1.20
NormalizedEmissions
DB1-R HB1-P HB2-P

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respect to DB1-R bus. Results for fuel consumption (L/100km) in HB1-P running under
Phase 1 methodology were 35% lower than DB1-R bus. Analogue HB1-P result for
Phase 2 was 40% lower than DB1-R bus.
A diesel bus with particulate filter DB-R was tested in Santiago, which produces less
emission rates than DB1-R bus in all pollutants with exception of NOX. PM1.5 emission
reduction was 98% and reached 0.001 (g/km). However, NOX emissions increased 21%
and reached 26.67 (g/km). Regarding CO2 emissions, DB1-F reduced 6% with respect to
DB-R, equivalent to 1,659 (g/km).
Figure 3.1 shows difference between diesel reference bus (DB-R) and hybrid buses tested
in Rio de Janeiro, where raw results have been normalized in terms of DB-R emissions
Figure 3.20 Normalized results normalized in terms of DB-R in Santiago
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
NormalizedEmissions
DB1-R DB2-F HB1-P

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4 DISCUSSION AND CONCLUSIONS
The Program involved 16 buses undergoing 30 hours of testing under real-world driving
conditions, for emissions and energy consumption, running along bus routes defined by
each participating city’s local authority and transport operators. Pioneering bus
manufacturers, made buses available to the C40-CCI team for testing. Bus testing
comprised different hybrid (diesel/electric) and full electric vehicles, compared against a
diesel bus (reference case). Following detailed planning, ISSRC group took on the testing
in each city.
Three main testing components were measured to assess bus performance:
i. Direct exhaust emissions
ii. Fuel and energy consumption
iii. Role of drivers, routes, topography and altitude
The Program received the support of local bus operators and representatives in each city.
Bus routes were identified by common agreement among the relevant representatives,
and based on criteria such as specific local policies, normal operating conditions for
public transport services, topography and maximum coverage of the main urban area.
Tests were carried out under normal operating conditions at maximum loading capacity
using simulated weights.
The results from the technical phase of the Program show that adoption of hybrid buses
could reduce CO2 emissions by up to 35% (26% on average) compared to the reference
diesel buses. Average reductions in local emissions of between 60-80% were achieved,
alongside a 30% reduction in fuel consumption. Electric buses emit almost no local
emissions and offer up to 77% reduction in energy consumption based on electricity
compared with diesel.
4.1 Exhaust Emissions
The Program tested several emissions components for diesel-only and hybrid diesel-
electric buses (full electric buses are not included in this analysis since this technology
has zero direct exhaust pipe emissions). Results varied by city, as described below, but in
all cases emissions performance was higher for parallel hybrid buses than traditional
diesel buses. Several hybrid technologies and diesel-only buses were tested in the four
cities participating in the Program. Both Brazilian cities presented two hybrid
technologies, a serial and a parallel bus; Bogota participated with two parallel hybrid
technologies; Santiago had one parallel hybrid bus. In Bogota and Santiago electric buses
were tested and a trolley was evaluated in Sao Paulo.
Figure 1 compares CO2 and criteria pollutant reduction emissions for parallel-hybrid
technologies and the respective reference diesel bus, for the four cities participating in the
Program. On average, parallel-hybrid bus technologies registered 25% lower CO2
emissions than the standard diesel technology, under comparable weights, routes and

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traffic conditions (all results have been normalized using a common driving cycle). For
criteria pollutants, when comparing parallel-hybrid versus diesel-only technologies,
average reductions were 61% for nitrogen oxides, 72% for fine particle matter, 72% for
unburnt hydrocarbons and 79% for carbon monoxide.
Figure 4.1 Emissions reductions for carbon dioxide and criteria pollutants
One bus manufacturer made available its parallel-hybrid technology in all four cities; the
grey bars indicate how the technology improved over time. In Bogota there were two
parallel-hybrid technology vehicles being tested within the Program; they show relatively
similar reductions compared with the reference diesel bus. Thus, the values for Bogota
shown above are the averages of the two bus providers; for the other three cities the bus
manufacturer was the same.
Emission reductions for gases and fine particle matter were always greater than 50% for
all parallel and improved-serial hybrid technologies, with increased performance of over
70% reduction in all criteria pollutants analyzed. The results for PM1.5 are particularly
interesting, showing an almost constant 72% reduction for all cities. These improvements
would have important impact on local air quality, resulting in major health benefits (the
combined population of the four cities is around 50 million). Introducing economic
valuations based on health impact analysis, and assuming fleet turnovers in favor of
hybrid technologies, should be considered part of an assessment framework.
4.2 Energy and Fuel Efficiency
The Program tested fuel consumption for diesel-only and hybrid diesel-electric buses, as
well as electric energy consumption for full electric buses and a trolleybus. The analysis
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includes comparisons of fuel consumption by bus (FC) and by passenger (FC/pax), using
a corresponding reference diesel bus in each city. Electric energy consumption is
converted into equivalent liters of diesel fuel, as explained below.
Four reference diesel, seven hybrid and three full electric vehicles were tested in the four
cities participating in the Program. Reference diesel buses are denominated DB-R; hybrid
buses are denominated HB-P and HB-S for parallel and serial technologies respectively;
full-electric vehicles are EB whose equivalent fuel consumption is estimated by
converting kWh and liters into kcal of energy to avoid distortions to or fluctuations in
local energy market prices. Note that these acronyms do not necessarily refer to the same
vehicles between cities. As already explained, the hybrid buses were provided by three
different manufacturers, one serial (HB-S) and two parallel (HB-P) configurations, and in
relation to the full-electric vehicles (EB), Sao Paulo provided a conventional in-use
trolleybus, and in Bogota and Santiago brand new full-electric buses were tested, in the
form of a single bus from a different manufacturer in each city. A representative diesel
bus (DB-R) was identified at each location.
Figure 4.2Fuel and energy consumption results
Figure 2 shows that results vary by city, but in all cases energy efficiency from parallel-
hybrid and full-electric buses was higher than for the traditional diesel bus. Average fuel
consumption was 31% less for the parallel-hybrid technologies compared to the diesel
bus. This increases to 38% if the value for Rio de Janeiro is excluded; it is assumed that
the bus manufacturer providing this technology learned and improved during the Program
following experience in Rio.
Electric technologies showed differences between cities and vehicle types. An average
77% better fuel consumption was achieved in the two cities testing brand new electric
buses (81% for Bogota and 73% for Santiago). Fuel consumption for the in-use trolleybus
tested in Sao Paulo was 56% lower than for the diesel bus.
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Similar to the results for exhaust emissions, the fuel consumption results for the serial
hybrid bus were poor compared to diesel in Rio de Janeiro (+51%) but improved and
were better than diesel in Sao Paulo (-22%). This improvement could be due to a learning
process triggered by this Program, which might be ongoing and could produce better
results.
The values reported above change when calculated as consumption per passenger due to
the smaller passenger capacity of electric compared to diesel-only vehicles. Diesel buses
have a larger passenger capacity given their comparatively lighter weight. Hybrid buses
have a 10-20% smaller capacity than diesel buses, and electric buses can accommodate
40-50% fewer passengers, due mainly to the extra load of the huge battery packs. Figure
3 shows fuel and equivalent energy consumption per passenger.
Figure 4.3 Fuel and energy consumption results per passenger
The serial hybrid technologies maintain their benefits, with 29% average reduction
compared with the diesel buses. Electric buses lose some of their advantage over the
reference diesel bus, going from 77% average reduction to 61% taking account of load
carrying capacity. Local operators were concerned about the smaller passenger capacity
of the new and cleaner technologies, not only because of the reduced benefit in energy
savings but also on operational logistical grounds. This is a problem that low carbon
technology bus manufacturers are tackling.
4.3 Key Findings and Recommendations
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Santiago
Report
for
C40-‐CCI-‐IDB
Hybrid
Electric
Bus
Test
Program
in
Latin
America

International
Sustainable
Systems
Research
Center
45

4.3.1 Key findings and recommendations for stakeholders
The Program has demonstrated the significant effects of hybrid and electric buses
compared with conventional diesel vehicles:
i) Reductions in GHG and emissions of criteria pollutants including especially
PM1.5,which shows reductions of 75% on average;
ii) Reductions in CO2 emissions of 26% on average;
iii) More efficient fuel consumption based on reductions of between 31% and
40% depending on altitude in the case of hybrid-electric buses, and up to 77%
in the case of full electric battery powered buses (equivalent fuel
consumption).
The Program found also that:
i) Driving patterns, driver competence, and steepness of the terrain affect the
performance of low carbon buses;
ii) Ten-year life-cycle analysis of hybrid and electric buses results in lower net
present value compared to conventional diesel buses, for several scenarios;
This is evidence that these technologies can compete with conventional buses with some
initial incentives, financing arrangements, and creative business models for the electric
vehicle components.
4.3.2 Key recommendations
Bus manufacturers should be encouraged to pay attention to current regulation and work
to adapt their products to the Latin American market directives especially regarding
vehicle weights, which can have a negative effect on economic evaluations of bus
operations. Suppliers should be invited to participate in the development of financial
solutions to facilitate the acquisition of these new vehicles by city bus operators.
Cities and national governments should be encouraged to introduce and maintain certain
incentives, such as low or zero VAT, import duty, and local taxes, in order to facilitate
the initial uptake of low carbon vehicles.
Given the positive effect of the new technologies on population health and health sector
costs, governments should contribute to the initial capital costs, for example, through
direct subsidies or by allowing marginal increases to fares. Diesel prices should be
corrected to reflect the real price of the fuel and pollution taxes should be imposed on this
energy source.
Cities in Latin America are responsible for the renewal of their bus fleets, representing
purchase of some 9,000 buses by 2020. Old vehicles should be scrapped and replaced by
low carbon technologies. Governments should develop, implement, and enforce strict fuel
performance regulations for buses to encourage the building of clean public

Santiago
Report
for
C40-‐CCI-‐IDB
Hybrid
Electric
Bus
Test
Program
in
Latin
America

International
Sustainable
Systems
Research
Center

46

transportation. The data provided by the Program are strong and persuasive. They
propose firm benchmarks that cities can apply with confidence when setting regulation.
In summary, Latin American cities have a great opportunity to drive the markets for low
carbon transport technologies, and particularly hybrid and electric buses. The economic
effort required will be far outweighed by the large environmental and health benefits that
will accrue. Both the IDB and C40-CCI have a deep commitment to helping lead cities to
move their transport sectors to the frontier in low carbon sustainable mobility.

Resultados C40 en Latinoamérica

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