A holistic analysis of passenger travel energy and greenhouse gas intensities

Transportation is a major energy consumer and emitter of greenhouse gases (GHGs). Exploring the opportunities for energy savings and GHG emissions reductions requires understanding transportation energy or GHG intensity, which is defined as energy use or GHG emissions per unit activity, here passenger-kilometres travelled. This aggregate indicator quantifies the amount of energy required or GHGs emitted to provide a generic transportation service. We show that the range of observed energy and GHG intensities of major transportation modes is remarkably similar and that occupancy explains about 70–90% of the variation around the mean; only the remaining 10–30% is explained by differences in trip distances and other factors such as technology and operating conditions. Whereas average occupancy levels differ vastly, they translate into roughly similar levels of energy and GHG intensity for nearly all major transportation modes.

Link to the paper: https://www.nature.com/articles/s41893-020-0514-9

About the speaker

Dr. Sonia Yeh is Professor in Transport and Energy Systems in the Department of Space, Earth and Environment. Her expertise is in energy economics and energy system modeling, alternative transportation fuels, sustainability standards, technological change, and consumer behavior and urban mobility. Her role as Professor in Transport and Energy Systems is building ties with faculty, researchers and students whose research interests lie in the distinct disciplines of energy, system modeling, sustainability, and information and communication technology (ICT), and bring them together in an emerging space of system modeling for the sustainability of integrated mobility. Throughout her work, she has advised and worked broadly with U.S. state and international advisers, policymakers, a wide range of stakeholder groups and academic researchers in developing climate policies toward reducing the environmental impacts and GHG emissions from transport. She served as Fulbright Distinguished Chair Professor in Alternative Energy Technology in 2016-2017 and was awarded Håkan Frisinger Award by Volvo Research and Educational Foundations in 2019. She is an adjunct professor at the Department of Engineering and Public Policy, Carnegie Mellon University and an Associate Editor for Energy Policy journal since 2018. She is a contributing author of the Intergovernmental Panel on Climate Change (IPCC) 2020 Assessment Report AR6.

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