- Email: [email protected]
Novel technologies and strategies for clean transport systems
Applied Energy 157 (2015) 563–566
Contents lists available at ScienceDirect
Applied Energy journal homepage: www.elsevier.com/locate/apenergy
Editorial
Novel technologies and strategies for clean transport systems q
1. Introduction The ambition of this special issue of Applied Energy is to introduce cutting-edge research that addresses the technical challenges in reducing the environmental impact of all modes of transport. The focus is on technologies and strategies relevant to power and propulsion systems, optimisation and improved efficiency, and the use of alternative fuels and renewable resources in the context of sustainable transport systems. The role of policy, environmental assessment and economic analysis are also addressed.
of the problem and set tight targets to significantly reduce the impact of transport to provide clean mobility across modes and environments e.g. urban, interurban, and maritime. For instance, the European Commission published the Transport White Paper in 2011 setting an ambitious target of reducing 60% of transportrelated emissions by 2050 relative to 1990 [7]. Similar targets have been introduced in other parts of the world. This provides the backdrop that has accelerated the need to develop viable technologies and strategies to make clean transport a reality. 2.1. Road transport
2. Background Transport systems have been described as the blood system of society [1]. Together with energy, transport is a key driver of our economy and way of life. There is increasing emphasis in adopting more sustainable and clean mobility solutions that would allow us to continue on our path of growth and prosperity. This is particularly relevant in urban conurbations where the highest proportion of the population and economic activity takes place. Greenhouse gas (GHG) emissions from the transport sector have more than doubled since 1970; increasing at a rate faster than any other energy end-use sector [2] and projected to double between 2010 and 2050 [3]. Carbon dioxide (CO2) forms the vast majority of the GHG emissions generated by transport, representing 23% and 30% of overall CO2 emissions from fossil fuel combustion globally and in OECD1 countries respectively [4]. From surface passenger transport alone, CO2 emissions are expected to rise by a factor of between 1.2 and 2.3 by 2050 [5]. The outlook for freight transport is similar if more challenging. For instance, port volumes and associated emissions from shipping are expected to increase fourfold by 2050, with particulate matter (PM) a major concern as this is linked to a significant number of health risks [5]. Demand for travel is strong and the trend is to continue on an upward trajectory for the foreseeable future. While curbing mobility would reduce its impact, many parties are understandably opposed to this due to its strong historic link to economic growth [6]. The Kyoto Protocol set global targets for the reduction of total anthropogenic GHGs emissions. Since then, governments and inter-governmental panels have continued to highlight the scale
q This paper is included in the Special Issue of Clean Transport edited by Prof. Anthony Roskilly, Dr. Roberto Palacin and Prof. Yan. 1 The Organisation for Economic Co-operation and Development (OECD) has currently 34 member States including most of Europe, the US, Australia, Japan and emerging economies such as Mexico and Turkey.
http://dx.doi.org/10.1016/j.apenergy.2015.09.051 0306-2619/Ó 2015 Published by Elsevier Ltd.
The largest contributor to transport GHG emissions by a significant margin is road transport. In Europe, it is responsible for approximately 72% of the total transport emissions [8]. In other parts of the world the situation is similar. The sector has embarked on a journey to reduce their impact on the environment in the past few decades. Innovative technologies, driven via clear policy and regulatory frameworks, have been developed. In-engine developments, after-treatment systems and the use of sophisticated control strategies have resulted in significant advances towards a cleaner road transport. Some of these developments include
common rail fuel injection systems, exhaust gas recirculation (EGR) systems, advanced turbochargers, improved combustion chamber design, engine control and variable valve actuation, waste heat recovery, and electrification of engine-driven accessories and auxiliaries.
In addition, the advent of hybridisation of powertrains and auxiliaries, as well as the use of electric drives (e.g. plug-in electric vehicles), is set to play a significant role in cleaning road transport emissions. 2.2. Rail transport Railways make a small contribution to GHG emissions and energy consumption when compared to other transport modes. The core of its advantage is the extremely low rolling resistance, which allows operating at higher speeds using less energy by comparison. Unlike other modes, railways use non-autonomous (e.g. electrified) propulsion systems as well as autonomous systems (e.g. diesel). This influences their environmental impact as it becomes dependent of the energy mix of a given country. The
564
Editorial / Applied Energy 157 (2015) 563–566
majority of recent advances to reduce energy consumption in railway systems have focused on the traction system itself, primarily by using regenerative braking, applying energy-efficient driving strategies, or improving the propulsion chain efficiency [9]. Another significant aspect differentiating railways is the comparatively longer life of its vehicles, which are expected to operate in excess of 30 years, leading to slower market penetration of new technologies and design advances. Legislation restricting CO2, nitrogen oxides (NOx) and PM emissions has been adopted in recent years both in Europe and North America, with the former being the most significant case given the market size in Europe. The application of the Non-Road Mobile Machinery (NRMM) European Directive to rail diesel vehicles in the form of the stage IIIB legislation (which imposes emission limits) has raised key challenges including vehicle design, reliability and life cycle costs [10]. The introduction of such legislation has implied that the emission levels can no longer be met only through improving in-engine design and control strategies. The use of after-treatment systems, e.g. EGR, selective catalytic reduction (SCR) and diesel particulate filters (DPF), is required, regardless of the implications on complexity of design, weight and space aspects. The use of energy storage systems (ESSs) is an area of increasing attention for rail-related research [11]. The predictable nature of railway operations with clearly defined control strategies (e.g. timetables) represents a clear opportunity to explore the uptake of ESSs to optimise energy use. 2.3. Maritime transport In 2007, it was estimated that shipping accounted for 3.3% of global CO2 emissions. The second International Maritime Organisation (IMO) GHG study [12] predicted that shipping contribution to CO2 global emissions might grow by a factor of between 2 and 3 by 2050 if no action was taken. The study also highlighted the likelihood of achieving significant potential for GHG reduction on a 25– 75% scale through technical and operational measures. These include
novel hull and superstructure design, advances in power and propulsion system, use of low-carbon fuels and renewable energy, energy management improvement, and operational optimisation.
The attempt to curb emissions by the shipping sector has led to the setting up of a regulatory framework to catalyse technological and strategic development. Regulations set up by the IMO, including the International Convention for the Prevention of Marine Pollution from Ships (MARPOL), has primarily focused on the reduction of NOx and sulphur oxides (SOx). Similar to that of rail transport, the penetration rate of novel technologies through replacement is also significantly affected by the 30-year minimum lifespan of the vast majority of marine propulsion and auxiliary plants. 2.4. Air transport Previously, the environmental impact caused by aircraft emissions was considered insignificant. The rapid growth in aircraft emissions and its possible effects were only fully realised in the early 1990s [13]. Consequently, the Intergovernmental Panel on Climate Change (IPCC) commissioned a seminal report in 1999 to investigate the effects of aviation on the global atmosphere [14]. This report has been subsequently updated every 6–7 years. The latest update [2] indicates that (i) the amount of CO2 emissions
from aviation is expected to grow approximately 3–4% per year; and (ii) improved fuel efficiency has the potential to offer a medium-term mitigation for CO2 emissions. Aircraft are main source of air transport emissions, however unlike other modes, ground operations also play a major role in the overall environmental impact of air transport. The prospect of reducing emissions by these additional services may be greater [15]. The main fuel currently used in civil aviation is kerosene and most of its emissions arise from modern gas turbine engines [16]. Compatible alternative fuels, more efficient engines and aircraft structural design (e.g. lightweighting) are areas of clear potential towards cleaner aviation. 3. Research included in this special issue The papers in this special issue cover a range of issues revolving around clean transport research. These include electrification of powertrains, the role of novel fuels, the impact of innovative technologies, strategies for the improvement of existing internal combustion engines (ICEs), life cycle assessment (LCA) and life cycle costing (LCC). These areas are addressed from the perspectives of technology, market and user uptake, durability and sustainability, which are suitable for automotive, maritime and rail applications. In addition, a system approach to air transport is explored assessing the sustainability effects and gains of using a multi-objective integrated optimisation framework for airport ground operations [17]. The papers are organised as follows: (i) hybridisation of powertrains; (ii) electric vehicles (EVs); (iii) advances in ICEs; and (iv) LCA, LCC and strategies. 3.1. Hybridisation of powertrains The use of ESSs for the hybridisation of urban buses is explored using conventional battery technology and a diesel ICE [18] as well as a combination of double-layer capacitors and compressed natural gas (CNG) [19]. The suitability of using on-board ESSs for the hybridisation of railway vehicles is described in [20,21]. These include the use of flywheels in locomotives [20] and the analysis of hybrid architecture design and system integration aspects of using ESSs based on various combinations of either battery technology, double-layer capacitors and hydrostatic accumulators [21]. 3.2. Electric vehicles (EVs) A model for optimal sizing electric bus components and the potential role of ESSs in reducing the investment scale and network connectivity requirements of fast charging networks is described [22]. A comprehensive critical review on fuel cell durability and performance degradation challenges faced in the scaling-up process from laboratory testing to full scale real application is presented [23]. Simulation results of a multi-objective optimisation using a Pareto optimal approach to determine the balance between fuel economy and system durability applied to a fuel cell city bus using a typical duty cycle in China is described [24]. The charging behaviour of EV drivers in Italian cities has been assessed [25] to determine GHG emissions based on the national energy mix. Real-world data describing EV charging profiles and residential smart metre load demand have been analysed [26] using a probabilistic method to explore the impact on distribution networks, and ways to roll out extensive charging infrastructure has been suggested. An agent-based model is described to simulate the impact of low, medium and high EV uptake in the UK distribution network where a case study in south-east England is presented [27]. A similar approach is followed to assess the fuel consumption of hybrid EVs, plug-in hybrid electric vehicles (PHEVs) and EVs compared to conventional ICE vehicles for real-
Editorial / Applied Energy 157 (2015) 563–566
world driving conditions in Beijing [28]. By comparing the results with data from the US, conclusions are drawn in terms of vehicles characteristics and data relevance when the potential impact of EVs is evaluated. US data of drivers using EVs on a daily basis is used to study the suitability of existing domestic charging infrastructure [29]. 3.3. Advances in internal combustion engines (ICEs) Various aspects related to waste heat recovery [30–32] and engine efficiency [33–35] are described. A design methodology for applying a mobile organic Rankine cycle for waste heat recovery is presented [30] and a novel split cycle ICE integrating waste heat recovery is proposed [31]. The effects of powertrain design on effective waste heat recovery are analysed for both conventional and hybridised vehicles [32]. Computational drive cycle simulations are used to assess fuel economy and engine emissions for conventional and high efficiency ICEs and a number of areas for design improvement are made [33]. Thermal stratification using a quasi-dimensional model for convective heat transfer correlation is applied to improve the efficiency of spark ignition engines [34] and a genetic optimisation algorithm is employed to enhance the power performance and reduce fuel consumption [35]. Experimental results for the starting process of a free piston engine generator are presented and results related to misfire, linear electric machine mode switch and control strategy are described [36,37]. The use of EGR to reduce such emissions on two-stroke marine diesel engines [38] and the outcomes of a study on the characteristics of spray used in SCR [39] are presented. The characteristics and role of novel fuels are investigated [40,41] and an empirical study characterising the effects of post-injection timing on power production, exhaust temperature and exhaust gas composition applied to conventional and alternative fuels is presented [42]. 3.4. Life cycle assessment (LCA), life cycle costing (LCC) and strategies The implications of LCA and LCC on various aspects related to clean transport initiatives and technologies are addressed. An LCA is applied [43] to evaluate the environmental performance of present and future middle-sized passenger vehicles covering a range of scenarios based on technology progression from conventional ICEs to hybrid EVs and fuel cells. A life cycle impact assessment is used to assess the production and end-of-life of fuel cell systems for automotive application [44]. A comprehensive appraisal and evaluation of energy management strategies and technical LCC of rail-specific hybridisation architectures is presented [45]. Diverse aspects related to the overall transport contribution to GHG emissions are also studied. A model is used to perform a range of scenarios to analyse the cost and CO2 emission impact of replacing current vehicle drivetrains with alternative ones in China during the 2010–50 period [46]. A historic quantitative measurement of the upward fuel efficiency trend associated with technology use in US automotive development is evaluated [47]. A Bayesian methodology is described to quantify new car fuel consumption in a more realistic fashion highlighting that the projected consumption of an average car in the UK is expected to exceed the targets set by policy [48]. Downsized turbocharged engines, novel transmissions and hybrids are considered the most promising new technologies for the highly relevant compact and medium sized car market in the US following a benefit-cost assessment are presented [49]. A strategy based on the outcomes of a simplified systems dynamic model is described to evaluate social, economic and environmental aspects affecting urban transport systems measured as their potential in reducing energy and CO2
565
emissions [50] and the effects of tyre characteristics on CO2 emissions are explored [51]. Acknowledgements The guest editors would like to express their gratitude to the Elsevier publication team for their support in the production of this special issue. Our gratitude extends to the authors for sharing their research and the expert reviewers for their constructive contribution and suggestions to ensure the high quality of the papers published. It is hoped that the extensive and wide-ranging nature of the research presented in this special issue will constitute a significant reference for the research community. Last but not least, many special thanks go to Mrs Janie Ling-Chin and Dr Keerthi Rajendran for their invaluable support in compiling this special issue. References [1] Givoni M, Banister D. The need for integration in transport policy and practice. Integ Transp: From Policy Practice 2010:1–11. [2] Sims R. Schaffer R, Creutzig F, Cruz-Núñez X, D’Agosto M, Dimitriu D, et al. Transport. In: Edenhofer O, Pichs-Madruga R, Sokona Y, Farahani E, Kadner S, Seyboth K, et al., editors. Climate change 2014: mitigation of climate change. Contribution of working group III to the fifth assessment report of the intergovernmental panel on climate change; 2014. [3] OECD. Environmental outlook to 2050: climate change chapter; 2011. [4] (ITF) ITF. Reducing transport greenhouse gas emissions: trends & data; 2010. [5] (ITF) ITF. Transport outlook 2015; 2015. [6] Batty P, Palacin R, González-Gil A. Challenges and opportunities in developing urban modal shift. Travel Behav Soc 2015;2:109–23. [7] Commission of the European C. White Paper—roadmap to a single European transport area—towards a competitive and resource efficient transport system. Belgium: Commission of the European Communities Brussels; 2011. [8] Comission E. EU transport in figures: statistical pocketbook; 2014. [9] Powell JP, González-Gil A, Palacin R. Experimental assessment of the energy consumption of urban rail vehicles during stabling hours: influence of ambient temperature. Int J Appl Therm Eng 2014;66:541–7. [10] Beatrice C, Rispoli N, Di Blasio G, Patrianakos G, Kostoglou M, Konstandopoulos A, et al. Emission reduction technologies for the future low emission rail diesel engines: EGR vs SCR. SAE technical papers. 2013;6. [11] González-Gil A, Palacin R, Batty P, Powell JP. A systems approach to reduce urban rail energy consumption. Int J Energy Convers Manage 2014;80:509–24. [12] Buhaug Ø, Corbett JJ, Endresen Ø, Eyring V, Faber J, Hanayama S, et al. Second IMO GHG study; 2009. [13] Price T, Probert D. Environmental impacts of air traffic. Int J Appl Energy 1995;50:133–62. [14] (IPCC) IPoCC. Aviation and the global atmosphere. In: Penner JE, Lister DH, Griggs DJ, Griggs DJ, Dokken DJ, McFarland M, editors.; 1999. [15] Daley B. Air transport and the environment; 2010. [16] Lee DS, Pitari G, Grewe V, Gierens K, Penner JE, Petzold A, et al. Transport impacts on atmosphere and climate: aviation. Atmos Environ 2010;44: 4678–734. [17] Weiszer M, Chen J, Locatelli G. An integrated optimisation approach to airport ground operations to foster sustainability in the aviation sector. Appl Energy 2015;157:567–82. [18] Millo F, Rolando L, Fuso R, Zhao J. Development of a new hybrid bus for urban public transportation. Appl Energy 2015;157:583–94. [19] Ouyang M, Zhang W, Wang E, Yang F, Li J, Li Z, et al. Performance analysis of a novel coaxial power-split hybrid powertrain using a CNG engine and supercapacitors. Appl Energy 2015;157:595–606. [20] Spiryagin M, Wolfs P, Szanto F, Sun YQ, Cole C, Nielsen D. Application of flywheel energy storage for heavy haul locomotives. Appl Energy 2015;157:607–18. [21] Meinert M, Prenleloup P, Schmid S, Palacin R. Energy storage technologies and hybrid architectures for specific diesel-driven rail duty cycles: Design and system integration aspects. Appl Energy 2015;157:619–29. [22] Ding H, Hu Z, Song Y. Value of the energy storage system in an electric bus fast charging station. Appl Energy 2015;157:630–9. [23] Wang J. Theory and practice of flow field designs for fuel cell scaling-up: a critical review. Appl Energy 2015;157:640–63. [24] Xu L, Mueller CD, Li J, Ouyang M, Hu Z. Multi-objective component sizing based on optimal energy management strategy of fuel cell electric vehicles. Appl Energy 2015;157:664–74. [25] Donateo T, Licci F, D’Elia A, Colangelo G, Laforgia D, Ciancarelli F. Evaluation of emissions of CO2 and air pollutants from electric vehicles in Italian cities. Appl Energy 2015;157:675–87.
566
Editorial / Applied Energy 157 (2015) 563–566
[26] Neaimeh M, Wardle R, Jenkins AM, Yi J, Hill G, Lyons PF, et al. A probabilistic approach to combining smart meter and electric vehicle charging data to investigate distribution network impacts. Appl Energy 2015;157:688–98. [27] Poghosyan A, Greetham DV, Haben S, Lee T. Long term individual load forecast under different electrical vehicles uptake scenarios. Appl Energy 2015;157:699–709. [28] Wang H, Zhang X, Ouyang M. Energy consumption of electric vehicles based on real-world driving patterns: a case study of Beijing. Appl Energy 2015;157:710–9. [29] Saxena S, MacDonald J, Moura S. Charging ahead on the transition to electric vehicles with standard 120 V wall outlets. Appl Energy 2015;157:720–8. [30] Costall AW. Gonzalez Hernandez A, Newton PJ, Martinez-Botas RF. Design methodology for radial turbo expanders in mobile organic Rankine cycle applications. Appl Energy 2015;157:729–43. [31] Dong G, Morgan R, Heikal M. A novel split cycle internal combustion engine with integral waste heat recovery. Appl Energy 2015;157:744–53. [32] Shabashevich A, Richards N, Hwang J, Erickson PA. Analysis of powertrain design on effective waste heat recovery from conventional and hybrid electric vehicles. Appl Energy 2015;157:754–61. [33] Gao Z, Curran SJ, Parks Ii JE, Smith DE, Wagner RM, Daw CS, et al. Drive cycle simulation of high efficiency combustions on fuel economy and exhaust properties in light-duty vehicles. Appl Energy 2015;157:762–76. [34] Irimescu A, Merola SS, Tornatore C, Valentino G. Development of a semi-empirical convective heat transfer correlation based on thermodynamic and optical measurements in a spark ignition engine. Appl Energy 2015;157:777–88. [35] Zhu Z, Zhang F, Li C, Wu T, Han K, Lv J, et al. Genetic algorithm optimization applied to the fuel supply parameters of diesel engines working at plateau. Appl Energy 2015;157:789–97. [36] Jia B, Tian G, Feng H, Zuo Z, Roskilly AP. An experimental investigation into the starting process of free-piston engine generator. Appl Energy 2015;157:798–804. [37] Zhang S, Zhao C, Zhao Z. Stability analysis of hydraulic free piston engine. Appl Energy 2015;157:805–13. [38] Raptotasios SI, Sakellaridis NF, Papagiannakis RG, Hountalas DT. Application of a multi-zone combustion model to investigate the NOx reduction potential of two-stroke marine diesel engines using EGR. Appl Energy 2015;157:814–23. [39] Varna A, Spiteri AC, Wright YM. Dimopoulos Eggenschwiler P, Boulouchos K. Experimental and numerical assessment of impingement and mixing of urea– water sprays for nitric oxide reduction in diesel exhaust. Appl Energy 2015;157:824–37. [40] Asad U, Kumar R, Zheng M, Tjong J. Ethanol-fueled low temperature combustion: a pathway to clean and efficient diesel engine cycles. Appl Energy 2015;157:838–50.
[41] Chen Q, Rao A, Samuelsen S. Coproduction of transportation fuels in advanced IGCCs via coal and biomass mixtures. Appl Energy 2015;157:851–60. [42] Jeftic´ M, Zheng M. A study of the effect of post injection on combustion and emissions with premixing enhanced fueling strategies. Appl Energy 2015;157:861–70. [43] Bauer C, Hofer J, Althaus H-J, Del Duce A, Simons A. The environmental performance of current and future passenger vehicles: life cycle assessment based on a novel scenario analysis framework. Appl Energy 2015;157: 871–83. [44] Simons A, Bauer C. A life-cycle perspective on automotive fuel cells. Appl Energy 2015;157:884–96. [45] Meinert M, Melzer M, Kamburow C, Palacin R, Leska M, Aschemann H. Benefits of hybridisation of diesel driven rail vehicles: energy management strategies and lifecycle costs appraisal. Appl Energy 2015;157:897–904. [46] Gambhir A, Tse LKC, Tong D, Martinez-Botas R. Reducing China’s road transport sector CO2 emissions to 2050: technologies, costs and decomposition analysis. Appl Energy 2015;157:905–17. [47] MacKenzie D, Heywood JB. Quantifying efficiency technology improvements in U.S. cars from 1975–2009. Appl Energy 2015;157:918–28. [48] Martin NPD, Bishop JDK, Choudhary R, Boies AM. Can UK passenger vehicles be designed to meet 2020 emissions targets? A novel methodology to forecast fuel consumption with uncertainty analysis. Appl Energy 2015;157:929–39. [49] Simmons RA, Shaver GM, Tyner WE, Garimella SV. A benefit-cost assessment of new vehicle technologies and fuel economy in the U.S. market. Appl Energy 2015;157:940–952. [50] Cheng Y-H, Chang Y-H, Lu IJ. Urban transportation energy and carbon dioxide emission reduction strategies. Appl Energy 2015;157:953–73. [51] Sina N, Nasiri S, Karkhaneh V. Effects of resistive loads and tire inflation pressure on tire power losses and CO2 emissions in real-world conditions. Appl Energy 2015;157:974–83.
Prof. A.P. Roskilly Managing Editor Director of Sir Joseph Swan Centre for Energy Research, Newcastle University, UK E-mail address: [email protected] R. Palacin Senior Research Associate Newcastle University, UK E-mail address: [email protected] Prof. J. Yan Editor-in-Chief of Applied Energy Royal Institute of Technology (KTH) and Malardalen University (MDU), Sweden E-mail address: [email protected]
Contents lists available at ScienceDirect
Applied Energy journal homepage: www.elsevier.com/locate/apenergy
Editorial
Novel technologies and strategies for clean transport systems q
1. Introduction The ambition of this special issue of Applied Energy is to introduce cutting-edge research that addresses the technical challenges in reducing the environmental impact of all modes of transport. The focus is on technologies and strategies relevant to power and propulsion systems, optimisation and improved efficiency, and the use of alternative fuels and renewable resources in the context of sustainable transport systems. The role of policy, environmental assessment and economic analysis are also addressed.
of the problem and set tight targets to significantly reduce the impact of transport to provide clean mobility across modes and environments e.g. urban, interurban, and maritime. For instance, the European Commission published the Transport White Paper in 2011 setting an ambitious target of reducing 60% of transportrelated emissions by 2050 relative to 1990 [7]. Similar targets have been introduced in other parts of the world. This provides the backdrop that has accelerated the need to develop viable technologies and strategies to make clean transport a reality. 2.1. Road transport
2. Background Transport systems have been described as the blood system of society [1]. Together with energy, transport is a key driver of our economy and way of life. There is increasing emphasis in adopting more sustainable and clean mobility solutions that would allow us to continue on our path of growth and prosperity. This is particularly relevant in urban conurbations where the highest proportion of the population and economic activity takes place. Greenhouse gas (GHG) emissions from the transport sector have more than doubled since 1970; increasing at a rate faster than any other energy end-use sector [2] and projected to double between 2010 and 2050 [3]. Carbon dioxide (CO2) forms the vast majority of the GHG emissions generated by transport, representing 23% and 30% of overall CO2 emissions from fossil fuel combustion globally and in OECD1 countries respectively [4]. From surface passenger transport alone, CO2 emissions are expected to rise by a factor of between 1.2 and 2.3 by 2050 [5]. The outlook for freight transport is similar if more challenging. For instance, port volumes and associated emissions from shipping are expected to increase fourfold by 2050, with particulate matter (PM) a major concern as this is linked to a significant number of health risks [5]. Demand for travel is strong and the trend is to continue on an upward trajectory for the foreseeable future. While curbing mobility would reduce its impact, many parties are understandably opposed to this due to its strong historic link to economic growth [6]. The Kyoto Protocol set global targets for the reduction of total anthropogenic GHGs emissions. Since then, governments and inter-governmental panels have continued to highlight the scale
q This paper is included in the Special Issue of Clean Transport edited by Prof. Anthony Roskilly, Dr. Roberto Palacin and Prof. Yan. 1 The Organisation for Economic Co-operation and Development (OECD) has currently 34 member States including most of Europe, the US, Australia, Japan and emerging economies such as Mexico and Turkey.
http://dx.doi.org/10.1016/j.apenergy.2015.09.051 0306-2619/Ó 2015 Published by Elsevier Ltd.
The largest contributor to transport GHG emissions by a significant margin is road transport. In Europe, it is responsible for approximately 72% of the total transport emissions [8]. In other parts of the world the situation is similar. The sector has embarked on a journey to reduce their impact on the environment in the past few decades. Innovative technologies, driven via clear policy and regulatory frameworks, have been developed. In-engine developments, after-treatment systems and the use of sophisticated control strategies have resulted in significant advances towards a cleaner road transport. Some of these developments include
common rail fuel injection systems, exhaust gas recirculation (EGR) systems, advanced turbochargers, improved combustion chamber design, engine control and variable valve actuation, waste heat recovery, and electrification of engine-driven accessories and auxiliaries.
In addition, the advent of hybridisation of powertrains and auxiliaries, as well as the use of electric drives (e.g. plug-in electric vehicles), is set to play a significant role in cleaning road transport emissions. 2.2. Rail transport Railways make a small contribution to GHG emissions and energy consumption when compared to other transport modes. The core of its advantage is the extremely low rolling resistance, which allows operating at higher speeds using less energy by comparison. Unlike other modes, railways use non-autonomous (e.g. electrified) propulsion systems as well as autonomous systems (e.g. diesel). This influences their environmental impact as it becomes dependent of the energy mix of a given country. The
564
Editorial / Applied Energy 157 (2015) 563–566
majority of recent advances to reduce energy consumption in railway systems have focused on the traction system itself, primarily by using regenerative braking, applying energy-efficient driving strategies, or improving the propulsion chain efficiency [9]. Another significant aspect differentiating railways is the comparatively longer life of its vehicles, which are expected to operate in excess of 30 years, leading to slower market penetration of new technologies and design advances. Legislation restricting CO2, nitrogen oxides (NOx) and PM emissions has been adopted in recent years both in Europe and North America, with the former being the most significant case given the market size in Europe. The application of the Non-Road Mobile Machinery (NRMM) European Directive to rail diesel vehicles in the form of the stage IIIB legislation (which imposes emission limits) has raised key challenges including vehicle design, reliability and life cycle costs [10]. The introduction of such legislation has implied that the emission levels can no longer be met only through improving in-engine design and control strategies. The use of after-treatment systems, e.g. EGR, selective catalytic reduction (SCR) and diesel particulate filters (DPF), is required, regardless of the implications on complexity of design, weight and space aspects. The use of energy storage systems (ESSs) is an area of increasing attention for rail-related research [11]. The predictable nature of railway operations with clearly defined control strategies (e.g. timetables) represents a clear opportunity to explore the uptake of ESSs to optimise energy use. 2.3. Maritime transport In 2007, it was estimated that shipping accounted for 3.3% of global CO2 emissions. The second International Maritime Organisation (IMO) GHG study [12] predicted that shipping contribution to CO2 global emissions might grow by a factor of between 2 and 3 by 2050 if no action was taken. The study also highlighted the likelihood of achieving significant potential for GHG reduction on a 25– 75% scale through technical and operational measures. These include
novel hull and superstructure design, advances in power and propulsion system, use of low-carbon fuels and renewable energy, energy management improvement, and operational optimisation.
The attempt to curb emissions by the shipping sector has led to the setting up of a regulatory framework to catalyse technological and strategic development. Regulations set up by the IMO, including the International Convention for the Prevention of Marine Pollution from Ships (MARPOL), has primarily focused on the reduction of NOx and sulphur oxides (SOx). Similar to that of rail transport, the penetration rate of novel technologies through replacement is also significantly affected by the 30-year minimum lifespan of the vast majority of marine propulsion and auxiliary plants. 2.4. Air transport Previously, the environmental impact caused by aircraft emissions was considered insignificant. The rapid growth in aircraft emissions and its possible effects were only fully realised in the early 1990s [13]. Consequently, the Intergovernmental Panel on Climate Change (IPCC) commissioned a seminal report in 1999 to investigate the effects of aviation on the global atmosphere [14]. This report has been subsequently updated every 6–7 years. The latest update [2] indicates that (i) the amount of CO2 emissions
from aviation is expected to grow approximately 3–4% per year; and (ii) improved fuel efficiency has the potential to offer a medium-term mitigation for CO2 emissions. Aircraft are main source of air transport emissions, however unlike other modes, ground operations also play a major role in the overall environmental impact of air transport. The prospect of reducing emissions by these additional services may be greater [15]. The main fuel currently used in civil aviation is kerosene and most of its emissions arise from modern gas turbine engines [16]. Compatible alternative fuels, more efficient engines and aircraft structural design (e.g. lightweighting) are areas of clear potential towards cleaner aviation. 3. Research included in this special issue The papers in this special issue cover a range of issues revolving around clean transport research. These include electrification of powertrains, the role of novel fuels, the impact of innovative technologies, strategies for the improvement of existing internal combustion engines (ICEs), life cycle assessment (LCA) and life cycle costing (LCC). These areas are addressed from the perspectives of technology, market and user uptake, durability and sustainability, which are suitable for automotive, maritime and rail applications. In addition, a system approach to air transport is explored assessing the sustainability effects and gains of using a multi-objective integrated optimisation framework for airport ground operations [17]. The papers are organised as follows: (i) hybridisation of powertrains; (ii) electric vehicles (EVs); (iii) advances in ICEs; and (iv) LCA, LCC and strategies. 3.1. Hybridisation of powertrains The use of ESSs for the hybridisation of urban buses is explored using conventional battery technology and a diesel ICE [18] as well as a combination of double-layer capacitors and compressed natural gas (CNG) [19]. The suitability of using on-board ESSs for the hybridisation of railway vehicles is described in [20,21]. These include the use of flywheels in locomotives [20] and the analysis of hybrid architecture design and system integration aspects of using ESSs based on various combinations of either battery technology, double-layer capacitors and hydrostatic accumulators [21]. 3.2. Electric vehicles (EVs) A model for optimal sizing electric bus components and the potential role of ESSs in reducing the investment scale and network connectivity requirements of fast charging networks is described [22]. A comprehensive critical review on fuel cell durability and performance degradation challenges faced in the scaling-up process from laboratory testing to full scale real application is presented [23]. Simulation results of a multi-objective optimisation using a Pareto optimal approach to determine the balance between fuel economy and system durability applied to a fuel cell city bus using a typical duty cycle in China is described [24]. The charging behaviour of EV drivers in Italian cities has been assessed [25] to determine GHG emissions based on the national energy mix. Real-world data describing EV charging profiles and residential smart metre load demand have been analysed [26] using a probabilistic method to explore the impact on distribution networks, and ways to roll out extensive charging infrastructure has been suggested. An agent-based model is described to simulate the impact of low, medium and high EV uptake in the UK distribution network where a case study in south-east England is presented [27]. A similar approach is followed to assess the fuel consumption of hybrid EVs, plug-in hybrid electric vehicles (PHEVs) and EVs compared to conventional ICE vehicles for real-
Editorial / Applied Energy 157 (2015) 563–566
world driving conditions in Beijing [28]. By comparing the results with data from the US, conclusions are drawn in terms of vehicles characteristics and data relevance when the potential impact of EVs is evaluated. US data of drivers using EVs on a daily basis is used to study the suitability of existing domestic charging infrastructure [29]. 3.3. Advances in internal combustion engines (ICEs) Various aspects related to waste heat recovery [30–32] and engine efficiency [33–35] are described. A design methodology for applying a mobile organic Rankine cycle for waste heat recovery is presented [30] and a novel split cycle ICE integrating waste heat recovery is proposed [31]. The effects of powertrain design on effective waste heat recovery are analysed for both conventional and hybridised vehicles [32]. Computational drive cycle simulations are used to assess fuel economy and engine emissions for conventional and high efficiency ICEs and a number of areas for design improvement are made [33]. Thermal stratification using a quasi-dimensional model for convective heat transfer correlation is applied to improve the efficiency of spark ignition engines [34] and a genetic optimisation algorithm is employed to enhance the power performance and reduce fuel consumption [35]. Experimental results for the starting process of a free piston engine generator are presented and results related to misfire, linear electric machine mode switch and control strategy are described [36,37]. The use of EGR to reduce such emissions on two-stroke marine diesel engines [38] and the outcomes of a study on the characteristics of spray used in SCR [39] are presented. The characteristics and role of novel fuels are investigated [40,41] and an empirical study characterising the effects of post-injection timing on power production, exhaust temperature and exhaust gas composition applied to conventional and alternative fuels is presented [42]. 3.4. Life cycle assessment (LCA), life cycle costing (LCC) and strategies The implications of LCA and LCC on various aspects related to clean transport initiatives and technologies are addressed. An LCA is applied [43] to evaluate the environmental performance of present and future middle-sized passenger vehicles covering a range of scenarios based on technology progression from conventional ICEs to hybrid EVs and fuel cells. A life cycle impact assessment is used to assess the production and end-of-life of fuel cell systems for automotive application [44]. A comprehensive appraisal and evaluation of energy management strategies and technical LCC of rail-specific hybridisation architectures is presented [45]. Diverse aspects related to the overall transport contribution to GHG emissions are also studied. A model is used to perform a range of scenarios to analyse the cost and CO2 emission impact of replacing current vehicle drivetrains with alternative ones in China during the 2010–50 period [46]. A historic quantitative measurement of the upward fuel efficiency trend associated with technology use in US automotive development is evaluated [47]. A Bayesian methodology is described to quantify new car fuel consumption in a more realistic fashion highlighting that the projected consumption of an average car in the UK is expected to exceed the targets set by policy [48]. Downsized turbocharged engines, novel transmissions and hybrids are considered the most promising new technologies for the highly relevant compact and medium sized car market in the US following a benefit-cost assessment are presented [49]. A strategy based on the outcomes of a simplified systems dynamic model is described to evaluate social, economic and environmental aspects affecting urban transport systems measured as their potential in reducing energy and CO2
565
emissions [50] and the effects of tyre characteristics on CO2 emissions are explored [51]. Acknowledgements The guest editors would like to express their gratitude to the Elsevier publication team for their support in the production of this special issue. Our gratitude extends to the authors for sharing their research and the expert reviewers for their constructive contribution and suggestions to ensure the high quality of the papers published. It is hoped that the extensive and wide-ranging nature of the research presented in this special issue will constitute a significant reference for the research community. Last but not least, many special thanks go to Mrs Janie Ling-Chin and Dr Keerthi Rajendran for their invaluable support in compiling this special issue. References [1] Givoni M, Banister D. The need for integration in transport policy and practice. Integ Transp: From Policy Practice 2010:1–11. [2] Sims R. Schaffer R, Creutzig F, Cruz-Núñez X, D’Agosto M, Dimitriu D, et al. Transport. In: Edenhofer O, Pichs-Madruga R, Sokona Y, Farahani E, Kadner S, Seyboth K, et al., editors. Climate change 2014: mitigation of climate change. Contribution of working group III to the fifth assessment report of the intergovernmental panel on climate change; 2014. [3] OECD. Environmental outlook to 2050: climate change chapter; 2011. [4] (ITF) ITF. Reducing transport greenhouse gas emissions: trends & data; 2010. [5] (ITF) ITF. Transport outlook 2015; 2015. [6] Batty P, Palacin R, González-Gil A. Challenges and opportunities in developing urban modal shift. Travel Behav Soc 2015;2:109–23. [7] Commission of the European C. White Paper—roadmap to a single European transport area—towards a competitive and resource efficient transport system. Belgium: Commission of the European Communities Brussels; 2011. [8] Comission E. EU transport in figures: statistical pocketbook; 2014. [9] Powell JP, González-Gil A, Palacin R. Experimental assessment of the energy consumption of urban rail vehicles during stabling hours: influence of ambient temperature. Int J Appl Therm Eng 2014;66:541–7. [10] Beatrice C, Rispoli N, Di Blasio G, Patrianakos G, Kostoglou M, Konstandopoulos A, et al. Emission reduction technologies for the future low emission rail diesel engines: EGR vs SCR. SAE technical papers. 2013;6. [11] González-Gil A, Palacin R, Batty P, Powell JP. A systems approach to reduce urban rail energy consumption. Int J Energy Convers Manage 2014;80:509–24. [12] Buhaug Ø, Corbett JJ, Endresen Ø, Eyring V, Faber J, Hanayama S, et al. Second IMO GHG study; 2009. [13] Price T, Probert D. Environmental impacts of air traffic. Int J Appl Energy 1995;50:133–62. [14] (IPCC) IPoCC. Aviation and the global atmosphere. In: Penner JE, Lister DH, Griggs DJ, Griggs DJ, Dokken DJ, McFarland M, editors.; 1999. [15] Daley B. Air transport and the environment; 2010. [16] Lee DS, Pitari G, Grewe V, Gierens K, Penner JE, Petzold A, et al. Transport impacts on atmosphere and climate: aviation. Atmos Environ 2010;44: 4678–734. [17] Weiszer M, Chen J, Locatelli G. An integrated optimisation approach to airport ground operations to foster sustainability in the aviation sector. Appl Energy 2015;157:567–82. [18] Millo F, Rolando L, Fuso R, Zhao J. Development of a new hybrid bus for urban public transportation. Appl Energy 2015;157:583–94. [19] Ouyang M, Zhang W, Wang E, Yang F, Li J, Li Z, et al. Performance analysis of a novel coaxial power-split hybrid powertrain using a CNG engine and supercapacitors. Appl Energy 2015;157:595–606. [20] Spiryagin M, Wolfs P, Szanto F, Sun YQ, Cole C, Nielsen D. Application of flywheel energy storage for heavy haul locomotives. Appl Energy 2015;157:607–18. [21] Meinert M, Prenleloup P, Schmid S, Palacin R. Energy storage technologies and hybrid architectures for specific diesel-driven rail duty cycles: Design and system integration aspects. Appl Energy 2015;157:619–29. [22] Ding H, Hu Z, Song Y. Value of the energy storage system in an electric bus fast charging station. Appl Energy 2015;157:630–9. [23] Wang J. Theory and practice of flow field designs for fuel cell scaling-up: a critical review. Appl Energy 2015;157:640–63. [24] Xu L, Mueller CD, Li J, Ouyang M, Hu Z. Multi-objective component sizing based on optimal energy management strategy of fuel cell electric vehicles. Appl Energy 2015;157:664–74. [25] Donateo T, Licci F, D’Elia A, Colangelo G, Laforgia D, Ciancarelli F. Evaluation of emissions of CO2 and air pollutants from electric vehicles in Italian cities. Appl Energy 2015;157:675–87.
566
Editorial / Applied Energy 157 (2015) 563–566
[26] Neaimeh M, Wardle R, Jenkins AM, Yi J, Hill G, Lyons PF, et al. A probabilistic approach to combining smart meter and electric vehicle charging data to investigate distribution network impacts. Appl Energy 2015;157:688–98. [27] Poghosyan A, Greetham DV, Haben S, Lee T. Long term individual load forecast under different electrical vehicles uptake scenarios. Appl Energy 2015;157:699–709. [28] Wang H, Zhang X, Ouyang M. Energy consumption of electric vehicles based on real-world driving patterns: a case study of Beijing. Appl Energy 2015;157:710–9. [29] Saxena S, MacDonald J, Moura S. Charging ahead on the transition to electric vehicles with standard 120 V wall outlets. Appl Energy 2015;157:720–8. [30] Costall AW. Gonzalez Hernandez A, Newton PJ, Martinez-Botas RF. Design methodology for radial turbo expanders in mobile organic Rankine cycle applications. Appl Energy 2015;157:729–43. [31] Dong G, Morgan R, Heikal M. A novel split cycle internal combustion engine with integral waste heat recovery. Appl Energy 2015;157:744–53. [32] Shabashevich A, Richards N, Hwang J, Erickson PA. Analysis of powertrain design on effective waste heat recovery from conventional and hybrid electric vehicles. Appl Energy 2015;157:754–61. [33] Gao Z, Curran SJ, Parks Ii JE, Smith DE, Wagner RM, Daw CS, et al. Drive cycle simulation of high efficiency combustions on fuel economy and exhaust properties in light-duty vehicles. Appl Energy 2015;157:762–76. [34] Irimescu A, Merola SS, Tornatore C, Valentino G. Development of a semi-empirical convective heat transfer correlation based on thermodynamic and optical measurements in a spark ignition engine. Appl Energy 2015;157:777–88. [35] Zhu Z, Zhang F, Li C, Wu T, Han K, Lv J, et al. Genetic algorithm optimization applied to the fuel supply parameters of diesel engines working at plateau. Appl Energy 2015;157:789–97. [36] Jia B, Tian G, Feng H, Zuo Z, Roskilly AP. An experimental investigation into the starting process of free-piston engine generator. Appl Energy 2015;157:798–804. [37] Zhang S, Zhao C, Zhao Z. Stability analysis of hydraulic free piston engine. Appl Energy 2015;157:805–13. [38] Raptotasios SI, Sakellaridis NF, Papagiannakis RG, Hountalas DT. Application of a multi-zone combustion model to investigate the NOx reduction potential of two-stroke marine diesel engines using EGR. Appl Energy 2015;157:814–23. [39] Varna A, Spiteri AC, Wright YM. Dimopoulos Eggenschwiler P, Boulouchos K. Experimental and numerical assessment of impingement and mixing of urea– water sprays for nitric oxide reduction in diesel exhaust. Appl Energy 2015;157:824–37. [40] Asad U, Kumar R, Zheng M, Tjong J. Ethanol-fueled low temperature combustion: a pathway to clean and efficient diesel engine cycles. Appl Energy 2015;157:838–50.
[41] Chen Q, Rao A, Samuelsen S. Coproduction of transportation fuels in advanced IGCCs via coal and biomass mixtures. Appl Energy 2015;157:851–60. [42] Jeftic´ M, Zheng M. A study of the effect of post injection on combustion and emissions with premixing enhanced fueling strategies. Appl Energy 2015;157:861–70. [43] Bauer C, Hofer J, Althaus H-J, Del Duce A, Simons A. The environmental performance of current and future passenger vehicles: life cycle assessment based on a novel scenario analysis framework. Appl Energy 2015;157: 871–83. [44] Simons A, Bauer C. A life-cycle perspective on automotive fuel cells. Appl Energy 2015;157:884–96. [45] Meinert M, Melzer M, Kamburow C, Palacin R, Leska M, Aschemann H. Benefits of hybridisation of diesel driven rail vehicles: energy management strategies and lifecycle costs appraisal. Appl Energy 2015;157:897–904. [46] Gambhir A, Tse LKC, Tong D, Martinez-Botas R. Reducing China’s road transport sector CO2 emissions to 2050: technologies, costs and decomposition analysis. Appl Energy 2015;157:905–17. [47] MacKenzie D, Heywood JB. Quantifying efficiency technology improvements in U.S. cars from 1975–2009. Appl Energy 2015;157:918–28. [48] Martin NPD, Bishop JDK, Choudhary R, Boies AM. Can UK passenger vehicles be designed to meet 2020 emissions targets? A novel methodology to forecast fuel consumption with uncertainty analysis. Appl Energy 2015;157:929–39. [49] Simmons RA, Shaver GM, Tyner WE, Garimella SV. A benefit-cost assessment of new vehicle technologies and fuel economy in the U.S. market. Appl Energy 2015;157:940–952. [50] Cheng Y-H, Chang Y-H, Lu IJ. Urban transportation energy and carbon dioxide emission reduction strategies. Appl Energy 2015;157:953–73. [51] Sina N, Nasiri S, Karkhaneh V. Effects of resistive loads and tire inflation pressure on tire power losses and CO2 emissions in real-world conditions. Appl Energy 2015;157:974–83.
Prof. A.P. Roskilly Managing Editor Director of Sir Joseph Swan Centre for Energy Research, Newcastle University, UK E-mail address: [email protected] R. Palacin Senior Research Associate Newcastle University, UK E-mail address: [email protected] Prof. J. Yan Editor-in-Chief of Applied Energy Royal Institute of Technology (KTH) and Malardalen University (MDU), Sweden E-mail address: [email protected]