Impact assessment of supply-side and demand-side policies on energy consumption and CO2 emissions from urban passenger transportation: The case of Istanbul

Abstract The transportation sector accounts for about a quarter of global energy consumption and energy-related carbon emissions. To design and realize sustainable urban transportation, it is vital to understand and analyze interactions between a set of dynamic factors that shape transportation patterns, behaviors, and impacts. To this end, this study aims to develop a systems dynamics (SD) model for Istanbul, Turkey to simulate its urban motorized passenger transport system for analyzing numerous policies under different scenarios and assessing their potential effects in reducing energy consumption and CO2 emissions in the upcoming years. The constructed SD model includes four subsystems: population, household disposable income, transport, and energy and CO2 emissions. Based on historical data (2000–2015) and model validation processes, the energy consumption and the associated CO2 emissions from motorized passenger transport are forecasted for the following scenarios. The first one is business as usual scenario (BAU) which is designed to show how energy use and the associated CO2 emissions would evolve over time with the current development plans. The second and third scenarios constitute supply management measures (SMM) which consider different levels of improvements in the fuel economy of the vehicle fleet and reduced carbon emission intensity in electricity generation through increased share of renewable energy use. The fourth and fifth scenarios consider travel demand management (TDM) policies that include different levels of transport cost increase, and trip length reduction. Finally, the last two scenarios include integrated scenarios that are composed of the SMM and TDM options. In detail, compared to the BAU scenario, integrated scenario considers (1) a 10% improvement in the fuel economy of the vehicles, (2) a 10% reduction in the emission intensity of electricity generation, (3) a 30% increase in the transportation cost, and (4) a 15% reduction in the trip lengths. Under the BAU scenario, the SD model shows that energy consumption per capita from passenger trips will increase from 183 L of oil equivalent in 2016 to 315 L of oil equivalent in 2025 while the associated CO2 emissions per capita will increase from 460 kg in 2016 to 807 kg in 2025. To combat this dramatic growth, the findings indicate that the ambitious integrated scenario achieves the lowest energy consumption and CO2 emissions by offering a 33.5% expected reduction in total energy consumption and a 32.8% expected reduction in total CO2 emissions.