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Towards sustainable urban transportation: Test, demonstration and development of fuel cell and hybrid-electric buses
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Several aspects make today’s transport system non-sustainable:

• Production, transport and combustion of fossil fuels lead to global and local environmental problems.

• Oil dependency in the transport sector may lead to economical and political instability.

• Air pollution, noise, congestion and land-use may jeopardise public health and quality of life, especially in urban areas.

In a sustainable urban transport system most trips are made with public transport because high convenience and comfort makes travelling with public transport attractive. In terms of emissions, including noise, the vehicles are environmentally sustainable, locally as well as globally. Vehicles are energy-efficient and the primary energy stems from renewable sources. Costs are reasonable for all involved, from passengers, bus operators and transport authorities to vehicle manufacturers. The system is thus commercially viable on its own merits.

This thesis presents the results from three projects involving different concept buses, all with different powertrains. The first two projects included technical evaluations, including tests, of two different fuel cell buses. The third project focussed on development of a series hybrid-bus with internal combustion engine intended for production around 2010. The research on the fuel cell buses included evaluations of the energy efficiency improvement potential using energy mapping and vehicle simulations. Attitudes to hydrogen fuel cell buses among passengers, bus drivers and bus operators were investigated. Safety aspects of hydrogen as a vehicle fuel were analysed and the use of hydrogen compared to electrical energy storage were also investigated.

One main conclusion is that a city bus should be considered as one energy system, because auxiliaries contribute largely to the energy use. Focussing only on the powertrain is not sufficient. The importance of mitigating losses far down an energy conversion chain is emphasised. The Scania hybrid fuel cell bus showed the long-term potential of fuel cells, advanced auxiliaries and hybrid-electric powertrains, but technologies applied in that bus are not yet viable in terms of cost or robustness over the service life of a bus. Results from the EU-project CUTE show that hydrogen fuelled fuel cell buses are viable for real-life operation. Successful operation and public acceptance show that focus on robustness and cost in vehicle design were key success factors, despite the resulting poor fuel economy. Hybrid-electric powertrains are feasible in stop-and-go city operation. Fuel consumption can be reduced, comfort improved, noise lowered and the main power source downsized and operated less dynamically. The potential for design improvements due to flexible component packaging is implemented in the Scania hybrid concept bus. This bus and the framework for its hybrid management system are discussed in this thesis.

The development of buses for a more sustainable urban transport should be made in small steps to secure technical and economical realism, which both are needed to guarantee commercialisation and volume of production. This is needed for alternative products to have a significant influence. Hybrid buses with internal combustion engines running on renewable fuel is tomorrow’s technology, which paves the way for plug-in hybrid, battery electric and fuel cell hybrid vehicles the day after tomorrow.

Place, publisher, year, edition, pages
Stockholm: KTH , 2008. , xii, 76 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2008:30
Keyword [en]
acceptance, analysis, auxiliary system, bus, Clean Urban Transport for Europe, concept, CUTE, demonstration, driver, drive cycle, duty cycle, energy flow, evaluation, fuel cell, heavy duty vehicle, hybrid management, hybrid vehicle, hydrogen, passenger, PEM, safety, Sankey diagram, series hybrid, sustainable, test, urban transport, vehicle simulation
Keyword [sv]
acceptans, analys, hjälpaggregat, buss, Clean Urban Transport for Europe, koncept, CUTE, demonstration, körcykel, förare, energiflöde, utvärdering, bränslecell, tunga fordon, hybridsystemkontroll, hybridfordon, vätgas, passagerare, PEM, säkerhet, Sankey-diagram, seriehybrid, uthållig, hållbar, test, stadstransport, fordonssimulering
National Category
Vehicle Engineering Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-4721ISBN: 978-91-7178-940-2 (print)OAI: oai:DiVA.org:kth-4721DiVA: diva2:13617
Public defence
2008-05-23, F3, Lindstedtsvägen 26, Stockholm, 13:00
Opponent
Supervisors
Note
QC 20100722Available from: 2008-05-05 Created: 2008-05-05 Last updated: 2010-07-22Bibliographically approved
List of papers
1. Real life testing of a hybrid PEM fuel cell bus
Open this publication in new window or tab >>Real life testing of a hybrid PEM fuel cell bus
Show others...
2003 (English)In: Journal of Power Sources, ISSN 0378-7753, Vol. 118, no 1-2, 349-357 p.Article in journal (Refereed) Published
Abstract [en]

Fuel cells produce low quantities of local emissions, if any, and are therefore one of the most promising alternatives to internal combustion engines as the main power source in future vehicles. It is likely that urban buses will be among the first commercial applications for fuel cells in vehicles. This is due to the fact that urban buses are highly visible for the public, they contribute significantly to air pollution in urban areas, they have small limitations in weight and volume and fuelling is handled via a centralised infrastructure.

Results and experiences from real life measurements of energy flows in a Scania Hybrid PEM Fuel Cell Concept Bus are presented in this paper. The tests consist of measurements during several standard duty cycles. The efficiency of the fuel cell system and of the complete vehicle are presented and discussed. The net efficiency of the fuel cell system was approximately 40% and the fuel consumption of the concept bus is between 42 and 48% lower compared to a standard Scania bus. Energy recovery by regenerative braking saves up 28% energy. Bus subsystems such as the pneumatic system for door opening, suspension and brakes, the hydraulic power steering, the 24 V grid, the water pump and the cooling fans consume approximately 7% of the energy in the fuel input or 17% of the net power output from the fuel cell system.

The bus was built by a number of companies in a project partly financed by the European Commission's Joule programme. The comprehensive testing is partly financed by the Swedish programme "Den Grona Bilen" (The Green Car). A 50 kW(el) fuel cell system is the power source and a high voltage battery pack works as an energy buffer and power booster. The fuel, compressed hydrogen, is stored in two high-pressure stainless steel vessels mounted on the roof of the bus. The bus has a series hybrid electric driveline with wheel hub motors with a maximum power of 100 kW.

Hybrid Fuel Cell Buses have a big potential, but there are still many issues to consider prior to full-scale commercialisation of the technology. These are related to durability, lifetime, costs, vehicle and system optimisation and subsystem design. A very important factor is to implement an automotive design policy in the design and construction of all components, both in the propulsion system as well as in the subsystems.

Keyword
PEM fuel cell system; hybrid bus; test; hydrogen
National Category
Vehicle Engineering Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-8316 (URN)10.1016/S0378-7753(03)00086-7 (DOI)000183286600047 ()
Note
QC 20100721Available from: 2008-05-05 Created: 2008-05-05 Last updated: 2012-02-09Bibliographically approved
2. Fuel Cell Buses in the Stockholm CUTE Project: First Experiences from a Climate Perspective
Open this publication in new window or tab >>Fuel Cell Buses in the Stockholm CUTE Project: First Experiences from a Climate Perspective
2005 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 145, no 2, 620-631 p.Article in journal (Refereed) Published
Abstract [en]

This paper aims to share the first experiences and results from the operation of fuel cell buses in Stockholm within the Clean Urban Transport for Europe (CUTE) project. The project encompasses implementation and evaluation of both a hydrogen fuel infrastructure and fuel cell vehicles in nine participating European cities. In total, 27 fuel cell buses, 3 in each city, are in revenue service for a period of 2 years.

The availability of the fuel cell buses has been better than expected, about 85% and initially high fuel consumption has been reduced to approximately 2.2 kg H-2/10 km corresponding to 7.51 diesel equivalents/10 km. Although no major breakdowns have occurred so far, a few cold climate-related issues did arise during the winter months in Stockholm.

Keyword
fuel cell bus; climate conditions; evaluation; auxiliary systems
National Category
Vehicle Engineering Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-4991 (URN)10.1016/j.jpowsour.2004.12.081 (DOI)000231893300066 ()2-s2.0-23844507950 (Scopus ID)
Note

QC 20100721

Available from: 2005-03-07 Created: 2005-03-07 Last updated: 2017-12-05Bibliographically approved
3. Energy system analysis of the fuel cell buses operated in the project: Clean Urban Transport for Europe
Open this publication in new window or tab >>Energy system analysis of the fuel cell buses operated in the project: Clean Urban Transport for Europe
2008 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 33, no 5, 689-711 p.Article in journal (Refereed) Published
Abstract [en]

During the project Clean Urban Transport for Europe (CUTE), which ended in May 2006, 27 fuel cell buses were operated in nine European cities. In this paper key performance parameters from the operation of the fuel cell buses in the project are reported, the energy system of the bus is analysed and drive cycle tests in five cities are presented and analysed. The focus of the paper is on fuel consumption and optimisation potential but experiences of, and recommendations for, evaluation in large demonstration projects are also presented. The results show that although the total fuel cell system efficiency was found to be high (36–41%), the fuel consumption was higher for the fuel cell buses than for diesel buses. Since the CUTE buses were a pre-commercial generation of fuel cell buses, with standard auxiliaries and extensive reliability measures, large fuel consumption reduction is possible. Suggestions on how to increase the efficiency is presented in this paper. Minimising the reliability measures would decrease fuel consumption by about 20% and lowering the weight by 2 tonnes would decrease fuel consumption by another 10%. Hybridisation in combination with using electrical auxiliaries could save an additional 5–10% or more.

Keyword
bus; CUTE; drive cycle; duty cycle; fuel cell; urban traffic
National Category
Vehicle Engineering Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-8318 (URN)10.1016/j.energy.2008.01.001 (DOI)000255316500002 ()2-s2.0-40849102347 (Scopus ID)
Note

QC 20150721

Available from: 2008-05-05 Created: 2008-05-05 Last updated: 2015-07-21Bibliographically approved
4. Study of the fuel economy improvement potential of fuel cell buses by vehicle simulation
Open this publication in new window or tab >>Study of the fuel economy improvement potential of fuel cell buses by vehicle simulation
(English)Article in journal (Other academic) Submitted
Keyword
auxiliary system; CUTE; energy efficiency; fuel cell bus; simulation; urban bus
National Category
Vehicle Engineering Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-8319 (URN)
Note
QS 20120326Available from: 2008-05-05 Created: 2008-05-05 Last updated: 2012-03-26Bibliographically approved
5. A First Report on the Attitude towards Hydrogen Fuel Cell Buses in Stockholm
Open this publication in new window or tab >>A First Report on the Attitude towards Hydrogen Fuel Cell Buses in Stockholm
2006 (English)In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 31, no 3, 317-325 p.Article in journal (Refereed) Published
Abstract [en]

Surveys of the attitude towards hydrogen fuel cell buses among passengers and bus drivers were performed in Stockholm during the autumn of 2004. Another field survey of the attitude of the fuel cell bus passengers is planned towards the end of the CUTE Stockholm project, i.e. during the autumn of 2005.

The main results from the surveys are:

People are generally positive towards fuel cell buses and feel safe with the technology.

Newspapers and bus stops are where most people get information about the buses.

The passengers, furthermost those above the age of 40, desire more information about fuel cells and hydrogen.

The drivers are generally positive to the fuel cell bus project.

Although the environment is rated as an important factor, 64% of the bus passengers were not willing to pay a higher fee if more fuel cell buses were to be used.

Keyword
fuel cell buses; attitude; acceptance; survey
National Category
Vehicle Engineering Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-4992 (URN)10.1016/j.ijhydene.2005.11.008 (DOI)000236294700001 ()2-s2.0-30944444575 (Scopus ID)
Note

QC 20100721

Available from: 2005-03-07 Created: 2005-03-07 Last updated: 2017-12-05Bibliographically approved
6. A follow-up and conclusive report on the attitude towards hydrogen fuel cell buses in the CUTE project: From passengers in Stockholm to bus operators in Europe
Open this publication in new window or tab >>A follow-up and conclusive report on the attitude towards hydrogen fuel cell buses in the CUTE project: From passengers in Stockholm to bus operators in Europe
2007 (English)In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 32, no 17, 4295-4305 p.Article in journal (Refereed) Published
Abstract [en]

This paper concerns the attitude towards the fuel cell bus and the hydrogen technology used in the CUTE project, represented by two passenger surveys performed in Stockholm, a survey performed among drivers in four cities and final statements as well as recommendations for future projects by project partners.

Main results are:

The passengers' willingness to pay for having more fuel cell buses in public transport was still low after one year of operation.

Concern about safety is not an issue among passengers or drivers.

The acceleration was rated as inferior to that of regular buses by 50% of the drivers; this differs from earlier findings in Stockholm.

The operators were pleased with the reliability of the buses and the trust in the new technology grew stronger during the project period. Main problems were lack of spare parts and insufficient information sharing due to confidentiality.

Keyword
hydrogen; fuel cell; buses; attitude; acceptance; CUTE
National Category
Vehicle Engineering Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-8321 (URN)10.1016/j.ijhydene.2007.07.050 (DOI)000251977800026 ()2-s2.0-36549011685 (Scopus ID)
Note

QC 20100721

Available from: 2008-05-05 Created: 2008-05-05 Last updated: 2016-05-18Bibliographically approved
7. Safety issues with hydrogen as a vehicle fuel
Open this publication in new window or tab >>Safety issues with hydrogen as a vehicle fuel
Show others...
2005 (English)In: Electrical Vehicle Symposium 21: Monaco, 2005, 2005Conference paper, Published paper (Refereed)
Keyword
alternative fuels; bus; hydrogen; safety
National Category
Vehicle Engineering Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-8322 (URN)
External cooperation:
Conference
Electrical Vehicle Symposium 21
Note

QC 20100722

Available from: 2008-05-05 Created: 2008-05-05 Last updated: 2016-08-31Bibliographically approved
8. Key factors in planning a sustainable energy future including hydrogen and fuel cells
Open this publication in new window or tab >>Key factors in planning a sustainable energy future including hydrogen and fuel cells
Show others...
2006 (English)In: Bulletin of Science, Technology & Society, ISSN 0270-4676, E-ISSN 1552-4183, Vol. 26, no 4, 264-277 p.Article in journal (Refereed) Published
Abstract [en]

In this article, a number of future energy visions, especiallythose basing the energy systems on hydrogen, are discussed.Some often missing comparisons between alternatives, from asustainability perspective, are identified and then performedfor energy storage, energy transportation, and energy use invehicles. It is shown that it is important to be aware of thelosses implied by production, packaging, distribution, storage,and end-use of hydrogen when suggesting a "hydrogen economy."It is also shown that for stationary electric energy storage,fuel cell electrolyzers could be feasible. Zero-tailpipeemissionvehicles are compared. The battery electric vehicle has thehighest electrical efficiency, but other requirements implythat plug-in hybrids or fuel cell hybrids might be a betteroption in some types of vehicles. Finally, a simplified exampleis applied to the overall results and used to discuss the needsand nature of an energy system based on intermittent energysources. 

Keyword
sustainability, hydrogen, storage, intermittent, fuel cells, electric vehicles
National Category
Vehicle Engineering Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-8323 (URN)10.1177/0270467606290294 (DOI)
Note

QC 20100707

Available from: 2008-05-05 Created: 2008-05-05 Last updated: 2012-10-02Bibliographically approved
9. Scania hybrid concept: with robust technology into the future
Open this publication in new window or tab >>Scania hybrid concept: with robust technology into the future
2007 (English)In: 57th UITP World Congress: Public transport: moving people, moving cities, Helsinki, 20-24 May 2007, 2007Conference paper, Published paper (Refereed)
National Category
Vehicle Engineering Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-8324 (URN)
Note
QC 20100722Available from: 2008-05-05 Created: 2008-05-05 Last updated: 2010-07-22Bibliographically approved
10. Targets, constraints and rules for hybrid management in a series hybrid bus intended for commercial introduction
Open this publication in new window or tab >>Targets, constraints and rules for hybrid management in a series hybrid bus intended for commercial introduction
2008 (English)In: SAE Technical Papers, 2008, no 2008-01-1563Conference paper, Published paper (Refereed)
National Category
Vehicle Engineering Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-8325 (URN)10.4271/2008-01-1563 (DOI)2-s2.0-84877496617 (Scopus ID)
Conference
2008 SAE International Powertrains, Fuels and Lubricants Congress; Shanghai; China; 23 June 2008 through 25 June 2008
Note

QC 20100722

Available from: 2008-05-05 Created: 2008-05-05 Last updated: 2017-04-03Bibliographically approved

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