Sustainable Cities and Society 28 (2017) 42–52 Contents lists available at ScienceDirect Sustainable Cities and Society journal homepage: www.elsevier.com/locate/scs Environmental assessment of 9 European public bus transportation systems E.A. Nanaki a,∗ , C.J. Koroneos a , J. Roset b , T. Susca c , T.H. Christensen d , S. De Gregorio Hurtado e , A. Rybka f , J. Kopitovic (Head of Department) g , O. Heidrich (Senior Researcher) h , P. Amparo López-Jiménez i a University of Western Macedonia, Department of Mechanical Engineering, Bakola and Sialvera, 50100 Kozani, Greece b Departament de Física Aplicada, ETS Arquitectura Barcelona Universitat Politecnica de Catalunya Avda, Diagonal, 649 08028 Barcelona, Spain c Bundesanstalt für Materialforschung und –prüfung (BAM), Division 7.1 – Building Materials, Unter den Eichen, 87, 12205 Berlin, Germany d Danish Building Research Institute, Aalborg University, A. C. Meyers Vænge 15, 2450 Copenhagen SV, Denmark e CEDEX, Ministerio de Fomento C, Alfonso XII, 3 y 528014 Madrid, Spain f Faculty of Civil and Environmental Engineering, Department of Town Planning and Architecture, Rzeszow University of Technology, Poland g Software Engineering Transport and Telecommunication, Lomonosova Street 1, Riga, Latvia h School of Civil Engineering & Geosciences, Research Fellow with the Tyndall Centre for Climate Change Research, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK i Hydraulic and Environmental Engineering Department, Universitat Politècnica de València, Camino de Vera s/n, 46022, Valencia, Spain a r t i c l e i n f o Article history: Received 2 June 2016 Received in revised form 11 August 2016 Accepted 25 August 2016 Available online 29 August 2016 Keywords: Urban buses Air pollution Urban transportation a b s t r a c t The transportation sector is one of the largest sources of EU’s greenhouse gas emissions. In 2011, trans- portation represented approximately 25 percent of total EU’s greenhouse gas emissions. Urban mobility accounts for 40% of all CO 2 emissions of road transport and up to 70% of other pollutants from transport. As, transportation and mobility play a crucial part both in urban economics and the quality of life, it is of great significance to ensure a low carbon transportation sector, so as to deal with the threat that climate change poses to urban areas. This study examines the factors that affect the production of carbon dioxide (CO 2 ) as well as of air pollutants, in 9 major European cities, aiming to provide a comprehensive overview of the actual knowledge on the atmospheric pollution from public transportation systems. CO 2 emissions as well as air pollutants, such as CO, HC, PM, NOx are calculated for the diesel and CNG bus fleets of the European cities under study. Finally the environmental benefits, in terms of CO 2 and CO, HC, PM, NOx emissions reductions, from the penetration of different biodiesel blends (from B10 to B100) to the bus fleets are estimated. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction In 2009, CO 2 emissions, from the transportation sector increased, with over 50% of those emissions coming from passenger vehicles (OECD/IEA, 2005). Since 1990, greenhouse gas emissions (GHG) from the transport sector in the EU have grown consid- erably and they are projected to continue increasing (European Environment Agency (EEA), 2009). Public transportation systems ∗ Corresponding author. E-mail addresses: evananaki@gmail.com (E.A. Nanaki), koroneos@aix.meng.auth.gr (C.J. Koroneos), Jaime.roset@upc.edu (J. Roset), tiziana.susca@gmail.com (T. Susca), thc@sbi.aau.dk (T.H. Christensen), sdegregorio@mailpersonal.com (S. De Gregorio Hurtado), akbyr@prz.edu.pl (A. Rybka), kopitovs.j@tsi.lv (J. Kopitovic), Oliver.heidrich@ncl.ac.uk (O. Heidrich), palopez@upv.es (P.A. López-Jiménez). play a crucial role to cities, as they are responsible for the mobility and access to most activities; nonetheless the transition to a low carbon public transportation system is challenging. In this context, cities lay out the path for CO 2 mitigation, showing the way to a low carbon public transportation system. Especially in the case of Euro- pean cities that encounter problems originated from transport and traffic, the challenge is to improve mobility whilst at the same time reducing the use of fossil fuels, traffic congestion and air pollution. Alone in the UK some 30000 deaths were linked to air pollution in 2008 − with 4000 in London alone (House of Commons (HOC), 2011). As per National Strategic Reference Frameworks, which was submitted by EU Member States, the sustainable urban transport is a key area to be examined (Green Paper, 2007). The upgrading of public transport services in conjunction with affordable transporta- tion fares seems to be a cost-effective measure for fuel savings and http://dx.doi.org/10.1016/j.scs.2016.08.025 2210-6707/© 2016 Elsevier Ltd. All rights reserved.