Analysis of the Reduction of CO2 Emissions in Urban Environments by Replacing Conventional City Buses by Electric Bus Fleets: Spain Case Study

Abstract

The emissions of CO 2 gas caused by transport in urban areas are increasingly serious, and the public transport sector plays a vital role in society, especially when considering the increased demands for mobility. New energy technologies in urban mobility are being introduced, as evidenced by the electric vehicle. We evaluated the positive environmental effects in terms of CO 2 emissions that would be produced by the replacement of conventional urban transport bus fleets by electric buses. The simulation of an electric urban bus conceptual model is presented as a case study. The model is validated using the speed and height profiles of the most representative route within the city of Madrid-the C1 line. We assumed that the vehicle fleet is charged using the electric grid at night, when energy demand is low, the cost of energy is low, and energy is produced with a large provision of renewable energy, principally wind power. For the results, we considered the percentage of fleet replacement and the Spanish electricity mix. The analysis shows that by gradually replacing the current fleet of buses by electric buses over 10 years (2020 to 2030), CO 2 emissions would be reduced by up to 92.6% compared to 2018 levels.Energies 2019, 12, 525 2 of 31 EUROPEAN PARLIAMENT AND OF THE COUNCIL, on the promotion of the use of energy from renewable sources and amending and subsequently" [4], which makes reference to public transport, in particular, providing incentives for its use, the application of energy efficient technologies, and the use of renewable sources in the sector, in order to reduce the dependency on petroleum.Analysing the subject at a local level (Spain), in 2013, 239.7 MtCO 2 were emitted by all sectors, and the largest CO 2 -emitting sectors in Spain were transport (34.1%) and power generation (20.4%). Industry accounted for 16.6%, followed by other energy industries (including refining) producing 7.9%, households producing 6.6%, and the commercial sector producing 6.5% of the total [5]. The transport sector shows a similar trend at the world level, with road transport being the most representative in the contribution of CO 2 , emitting 81.08 MtCO 2 of the 86.13 MtCO 2 total. In other words, this type of transport represents 94% of all the emissions of the sector.The main cause of these high CO 2 emissions in the transport sector is the excessive use of energy vectors from non-renewable sources, especially gasoline and diesel. The problem of energy dependency is crucial in countries such as Spain that lack these resources, and are forced to import them. Therefore, it is essential to look for alternative sources and methods in order to reduce the demand for this type of resource.Public transport via urban buses plays a fundamental role in society, as it is an efficient means to move a considerable number of people throughout a city. With the current occupation rate in relation to cars, a standard full urban bus could remove more than 40 cars from the city [7], which would considerably improve traffic problems, re...

Replacing Diesel Buses with Electric Buses for Sustainable Public Transportation and Reduction of CO₂ Emissions

“…Grijalva et al [14] expressed the values of CO 2 emissions for diesel buses based on the well-to-wheels (WTW) and life cycle analysis (LCA) concepts, which examine the impact of CO 2 emitted into the atmosphere on the environment for all phases in the flow of power from extraction (oil well), refining, fuel transport, distribution, feed pump, tank, combustion process, power distribution to the propulsion system, and consumption on the wheels (Fig. 9).…”

“…For a proper delimitation of the CO 2 emissions value, which can be used for both buses (diesel and electric), it was considered that the CO 2 emissions for WTW concept is formed by CO 2 emissions from the well-totank (WTT) section -the stages corresponding to the processes of extraction, transport and distribution of the fuel ( (kgCO 2 eq/1) [14,35]) and the tankto-wheels (TTW) section -the stages corresponding to the processes of the fuel supply and the fuel conversion ( (kgCO 2 eq/1)) [36], according to Equation (3):…”

“…WTW concept for electric buses. the considered period, only CO 2 emissions are considered in the WTT section, whose values are given in Table 9 [14,[40][41][42]. The electric buses with zero local pollution are much more efficient also from the point of view of energy efficiency, having much lower energy consumption.…”

“…European Commission (EC) Regulation 443/2009 [9], which refers to the M1 vehicle category, aims to reduce emissions from new vehicles and imposes limits on CO 2 emissions to a value of 95 g CO 2 /km by 2020, compared to the current standard of 130 g CO 2 /km. European Union (EU) Regulation 2400/2017 [10], which implements EC Regulation 595/2009 [11] and amends Directive 2007/46/EC [12] and EU Regulation 582/2011 [13], indicates that emissions from trucks, coaches, and buses are currently about 25% of the total CO 2 emissions from road transport, and are expected to increase further in the future [14]. Reducing CO 2 emissions from heavyduty vehicles and buses requires the implementation of effective measures to achieve the 60% reduction target by 2050.…”

Analysis of the Electric Bus Autonomy Depending on the Atmospheric Conditions

“…In [2], Grijalva et al noted that a bus used at the nominal occupancy level could replace up to 40 personal cars from urban traffic.…”