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Targets, constraints and rules for hybrid management in a series hybrid bus intended for commercial introduction
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
KTH, School of Electrical Engineering (EES), Automatic Control.
Scania, Bus Development.
2008 (English)In: Society of Automotive Engineers, Technical Papers, no 2008-01-1563Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2008. no 2008-01-1563
National Category
Vehicle Engineering Chemical Engineering
URN: urn:nbn:se:kth:diva-8325DOI: 10.4271/2008-01-1563ScopusID: 2-s2.0-84877496617OAI: diva2:13616
QC 20100722Available from: 2008-05-05 Created: 2008-05-05 Last updated: 2010-07-22Bibliographically approved
In thesis
1. Towards sustainable urban transportation: Test, demonstration and development of fuel cell and hybrid-electric buses
Open this publication in new window or tab >>Towards sustainable urban transportation: Test, demonstration and development of fuel cell and hybrid-electric buses
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.
Trita-CHE-Report, ISSN 1654-1081 ; 2008:30
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, 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
urn:nbn:se:kth:diva-4721 (URN)978-91-7178-940-2 (ISBN)
Public defence
2008-05-23, F3, Lindstedtsvägen 26, Stockholm, 13:00
QC 20100722Available from: 2008-05-05 Created: 2008-05-05 Last updated: 2010-07-22Bibliographically approved

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