Environmental assessment of 9 European public bus transportation systems

Urban passenger transport energy saving and emission reduction potential: A case study for Tianjin, China

Today both the economic growth and expansion of urbanization have increased community access to private cars. Thus, the urban transportation has become a critical part of energy consumption and greenhouse gas emissions. The excessive dependence of urban transportation on high-emission fuels is the main obstacle to develop a low-carbon transport. Meanwhile, natural gas is a bridge fuel to develop a low-emission transport. To the best of our knowledge, there has been little attention towards the association between the development of natural gas-fueled vehicles and the CO2 emission. Therefore, the problem we studied is the role of compressed natural gas (CNG) vehicles in replacing high-emission fuels. In this study, we aimed to study this association by selecting the system dynamics approach due to the complexities of the social-economic system of transportation. In this modeling, different subsystems of the transport fleet were employed including CNG vehicles and urban transportation subsystems. Iran has used CNG as an alternative fuel in the transportation sector, making it one of the three leading countries in the use of natural gas in the urban transportation system. Our case study is focused on Tehran, which is the capital and the largest city of Iran. In this paper, we considered several scenarios to replace the gasoline fuel in the private car sector and taxis and diesel fuel in the bus fleet with natural CNG fuel. The results show that the replacement of CNG fuel with high-emission fuels can have a significant effect on reducing CO2 emissions. In the synthetic scenario, CO2 emission will be decreased by 11.42% in 2030, as compared to the business as usual (BAU) scenario in this year. According to Iran’s commitment to the Paris Agreement, the emission of CO2 in Iran should normally be reduced by 4% in 2030, as compared to its amount in the BAU scenario. Therefore, Iran can easily fulfill its obligations in the urban transport sector only by replacing gasoline and diesel fuel with CNG.

Driving a sustainable road transportation transformation

Energy Consumption and Transportation in Developing Countries: Need for Local Scenario-Based Energy Efficiency Plans

The coronavirus pandemic has severely impacted our day-to-day activities and brought about significant change in all major sectors, especially surface passenger transport. Lockdowns and stay-at-home restrictions have significantly reduced energy demand and consequently CO2 emissions of surface passenger transport. The change in CO2 emissions is calculated from near-real-time activity change data as a function of 3 confinement levels. The activity change and related emission trends reflect changes in the mode of transport during different waves, this can be used to understand mobility trends and patterns when stringent measures are imposed. Consequently, constructive use of this data can help prepare and develop the transport sector in case of another epidemic outbreak or other unprecedented calamities and to build a resilient transport infrastructure post-COVID-19. This study estimates and analyzes the changes in CO2 emissions associated with the public (bus and rail) and private surface passenger transport from March 1st, 2020 to Jan 31st, 2021 in 21 countries. The research period covers the 1st and the 2nd waves of COVID-19 in these countries. A higher activity reduction and consequently CO2 emission reduction is displayed during the 1st wave compared to the 2nd for most countries despite implementing stringent measures during both waves. This is in line with countries adapting to the ‘new normal’ and restarting socio-economic activities. Similarly, public transport recovery is slower than private transport recovery, making it essential to focus on reinforcement and adaptation of public transport infrastructure for the future. The results show that a cumulative 510 Mt CO2 has been reduced over 11 months in 21 countries, compared to pre-pandemic levels. This reduction brings about a 6% drop in transport CO2 emissions and a 1.5% drop in global CO2 emissions. This analysis sheds light on mobility trends and travel behavior of surface passenger transport modes and related CO2 emissions in different countries which can be used to exemplify the path to recovery based on near-real-time data.

The COVID pandemic has caused a major exodus of passengers who chose urban and suburban transport. In many countries, especially in the European Union, there is a tendency to choose individual means of transport, causing damage to the environment and contributing significantly to greenhouse gas emissions. One method to promote urban transport is replacing bus fleets with newer ones, thus making public transport more attractive and reducing the emission of harmful exhaust fume components into the atmosphere. The aim of this study was to show a methodology for calculating CO2e for bus fleets. When determining CO2e, the principal greenhouse gases, such as CO2, CH4, and N2O, are usually considered. However, CO emissions also have indirect effects on climate through enhanced levels of tropospheric O3 and increased lifetime of CH4; therefore, CO2, CH4, N2O, and CO emissions were determined for CO2e emission calculations. Two bus fleet variant scenarios were analysed; the first non-investment variant assumed passenger transport using the old fleet without any P&R parking zones. The second scenario was based on the current state, which includes the purchase of new low-emission buses and the construction of P&R infrastructure. The calculations were performed using the COPERT emission model with real data from 52 buses running on 13 lines. For the analysed case study of the Rzeszow agglomeration and neighbouring communes, implementing the urban and suburban transport modernisation project resulted in a reduction in estimated CO2e emissions of about 450 t. The methodology presented, which also considers the impact of CO emissions on the greenhouse effect, is a new element of the study that has not been presented in previous works and may serve as a model for other areas in the field of greenhouse gas emission analyses. The future research scope includes investigation of other fuels and powertrain supplies, such as hydrogen and hybrid vehicles.

Energy-related activities are a major contributor of greenhouse gas (GHG) emissions. A growing body of knowledge clearly depicts the links between human activities and climate change. Over the last century the burning of fossil fuels such as coal and oil and other human activities has released carbon dioxide (CO2) emissions and other heat-trapping GHG emissions into the atmosphere and thus increased the concentration of atmospheric CO2 emissions. The main human activities that emit CO2 emissions are (1) the combustion of fossil fuels to generate electricity, accounting for about 37% of total U.S. CO2 emissions and 31% of total U.S. GHG emissions in 2013, (2) the combustion of fossil fuels such as gasoline and diesel to transport people and goods, accounting for about 31% of total U.S. CO2 emissions and 26% of total U.S. GHG emissions in 2013, and (3) industrial processes such as the production and consumption of minerals and chemicals, accounting for about 15% of total U.S. CO2 emissions and 12% of total ...

Current international discussions on the increasingly critical levels of carbon emissions from the transportation sector commonly attribute the causality chain to urban sprawl growth–private car use–carbon emission. An often assumed development context of this causality chain is that common of developed country urbanization. However, in the particular context of developing country urbanization, urban sprawl and associated workplace–home distanciation may lead to more intensive use by the urban workforce of public mass transportation system, instead of higher dependence on private vehicle travel. Thus, the source of the rise in carbon emission may actually be the public transportation system. Utilizing mixed methods, combining quantitative (origin–destination matrices) and qualitative data gathering and analysis, the authors present a case study in Metro Manila which has been experiencing sprawl and increasing costs and unaffordability of land and housing in the workforce’s vicinity of employment. This, in turn, causes greater distances of daily travel between home and workplace using public transportation system. When the latter is characterized by fuel-inefficient small vehicles with second-hand engines, higher carbon emission results. We argue that the convergence of multiple interacting factors such as urban sprawl, lack of affordability of housing near the centres of employment, high dependence of commuters on public transports, longer distance travel by commuters, and low fuel efficiency of the public utility vehicles primarily causes the increase in CO2 emission from the transport sector. Implications of this case to policy scoping of immediate and long-term state responses for carbon emission mitigation in transportation sector are discussed.

The U.S. transportation sector is the second largest energy consumer in 2020 with about a 35% usage rate. However, the sector accounted for the largest proportion (29%) of the total greenhouse gas emissions in 2019. Compared with the use of personal automobiles, public transportation is believed to be cost-effective and provides low emissions, which tends to reduce the need to travel long distances and lower the carbon footprints of transit operations. This study examined the impact of alternative fuels (various blends of biodiesel, hydrogen, methanol, and ethanol) versus conventional fuels on greenhouse gas emissions in the U.S. public transit system. The research was anchored by three regression models to analyze the joint and individual impact of both conventional fuel and alternative fuel. Secondary data were extracted from the American Public Transit Association 2021 Fact Book, the U.S. Bureau of Transportation Statistics, and the Inventory of U.S. Greenhouse Gas Emissions and Sinks 1999-2019 (EPA 2021). The descriptive statistics, correlation, and stationarity tests were established on the variables, and the regression models were estimated using ordinary least squares. The findings revealed that while conventional fuel expands the flow of carbon emissions, alternative fuel is a drag on the total emissions from public transportation. However, it was concluded that the utilization of alternative fuels in the U.S. transportation industry is still very low, thus there is a need to put all machinery in motion to embrace this fuel type to reverse climate change issues, especially in the public transit system.

This study presents a California-focused comprehensive GHG emissions analysis, at an individual level and within the context of the transportation sector, by comparing public and shared means of transportation with private transportation. The main objective is to identify the threshold in which the number of passengers in a public mode of transportation, such as bus or rail, results in a lower GHG emissions per person than private transportation users. Since the number of emissions varies by location depending on multiple factors, such as population size, economic, industrial activity, etc., this study delineated the state of California as the area to be observed. Also, by using GHG emissions per person while using private transportation over one year, the corresponding thresholds in which public transportation becomes more efficient, in terms of fewer emissions, can be found. Generally, there’s always the perception that public transportation, in general, can result in lower GHG emissions. However, following the data analysis, this study has concluded that, for a bus ride to have a better GHG emissions than a passenger car, the minimum number of passengers needs to be, at least, six. For rail transportation, in turn, the minimum amount needs to be 13 passengers per ride. In this scenario, a person using a bus emits 43% less GHGs than a person using a car, and rail users emit 61% less than car drivers.

Energy demand and greenhouse gas emissions of urban passenger transport in the Internet era: A case study of Beijing

In recent years, the issue of climate change has gained significant attention and become a focal point of discussion in various sectors of civil society. Governments, individuals, and scientists worldwide are increasingly concerned about the observed changes in climate patterns, often attributed to the rising levels of greenhouse gases. In this context, the main objective of this study is to assess the greenhouse gas emissions associated with the railway system in the state of Pernambuco, Brazil, and compare them with other national case studies, aiming to obtain greenhouse gas emission parameters specific to the railway system and propose mitigation models to address this environmental impact in the air. To achieve this goal, a comprehensive life cycle assessment (LCA) methodology was employed to examine the life cycle of the Pernambuco Metro. This involved conducting an inventory of resource inputs and emissions using actual observed data. Additionally, a comparative analysis of greenhouse gas emissions across different urban rail transport systems is presented to provide valuable contextual insights. The study findings reveal that the total greenhouse gas emissions from the Pernambuco rail system amount to 6170.54 t CO2e. Considering a projected total service life of 50 years, the estimated greenhouse gas emissions for the entire life cycle of the system’s operation and maintenance reach 308,550 t CO2e. The interdisciplinary nature of this research highlights the significance of studying the atmospheric effects of the Pernambuco railway system as a crucial parameter for designing strategies and technologies aimed at reducing air pollution within the region. Through quantifying and analyzing the greenhouse gas emissions of the Pernambuco rail system, this study provides valuable insights that contribute to addressing concerns related to climate change and promoting sustainable practices. It underscores the importance of developing effective strategies to mitigate air pollution and facilitates informed decision-making for the future of urban transportation systems.

This paper compares the energy consumption, CO2 emissions and public policies of two mega-cities, Sao Paulo (SP) and Shanghai (SH), in order to identify their GHG emissions mitigation policies. Both cities have experienced rapid growth of the automotive sectors resulting in sizable pollution and CO2 emission challenges. SP has successfully implemented the ethanol and encouraged the growth of the fleet of light-duty vehicles. SH has coal-based power generation and restricted the ownership of the vehicles in an attempt to reduce GHG emissions, invested in public transportation and electric mobility. Tabular analysis of secondary data was adopted in this study, revealing also that SP has considerably expanded individual transportation. Despite investments in ethanol, the city could not contain the increase in CO2 emissions from road transportation. SH invested in public transportation and inhibited individual transportation, but also failed to contain CO2 emissions. Mitigation policies and measures taken were not sufficient to prevent growth of CO2 emissions in both cities. To reduce CO2 emissions in transportation, SP and SH should focus on public policies to encourage public and clean transportation and limit the burning of fossil fuels.

Air pollution caused by CO2 emissions has become a global issue of vital importance, posing irreversible risks to health and life when concentration of CO2 becomes too high. This study aims to estimate the CO2 emissions and carbon footprint of the public transport bus fleet in Bucharest, with a comparative analysis of greenhouse gas (GHG) emissions generated by diesel and electric buses of the Bucharest Public Transport Company (STB S.A.) in the period 2021–2024, after the modernization of the fleet through the introduction of 130 hybrid buses and 58 electric buses. In 2024, the introduction of electric buses and the reduction in diesel bus mileage reduced GHG emissions by almost 13% compared to 2023, saving over 11 kilotons of CO2e. There was also a 2.68% reduction in the specific carbon footprint compared to the previous year, which is clear evidence of the potential of electric vehicles in achieving decarbonization targets. We have also developed two strategies, one for 2025 and one for the period 2025–2030, replacing the aging fleet with electric vehicles. This demonstrates the relevance of electric transport integrated into the sustainable development strategy for urban mobility systems and alignment with European standards, including improving air quality and living standards.

The broad expanse of the urban metropolitan area of São Paulo (MASP) has made buses, the predominant public transport mode for commuters in the city. In 2016, the bus fleet in the MASP reached 56,354 buses and it was responsible for more than 12 million daily trips. Here, we evaluate for the first time, the emission profile of gaseous and particulate pollutants from buses running on 7% biodiesel + 93% petroleum diesel and their spatial distribution in the MASP. This novel study, based on four bus terminal experiments, provides an extensive analysis of atmospheric pollutants of interest to public health and climate changes, such as CO2, CO, NOx, VOCs, PM10, PM2.5 and their constituents (black carbon (BC) and elements). Our results suggest that the renovation of the bus fleet from Euro II to Euro V and the incorporation of electric buses had a noticeable impact (by a factor of up to three) on the CO2 emissions and caused a decrease in NO emissions, by a factor of four to five. In addition, a comparison with previous Brazilian studies, shows that the newer bus fleet in the MASP emits fewer particles. Emissions from the public transport sector have implications for public health and air quality, not only by introducing reactive pollutants into the atmosphere but also by exposing the commuters to harmful concentrations. Our findings make a relevant contribution to the understanding of emissions from diesel-powered buses and about the impact of these new vehicular technologies on the air quality in the MASP.