Benefits of Reducing Air Emissions: Replacing Conventional with Electric Passenger Vehicles ()
1. Introduction
Two major forces are driving the world to find alternative fuels for conventional transportation. The first is the increasing concern about local and global air emissions and their effects on areas such as human health, agricultural crops and property value. The second force is the need to reduce the world’s dependency on oil, and will not be discussed in this paper.
Gasolineand diesel-powered passenger vehicles are major contributors of many noxious emissions, on the local level, including carbon monoxide (CO), nitrogen oxides (NOx) and fine particulate matter (PM2.5) [1]. [2,3] showed that, although PM2.5 is directly related to vehicle exhaust emissions, PM10 emissions originate from nonexhaust emissions. Since our analysis is based on tankto-wheel emissions as will be described shortly, we may regard transportation as the sole contributor of PM2.5. Within urban areas, the contribution by passenger cars is particularly high [4]. The effect of traffic on urban air quality in Israel can be most accurately assessed on Yom Kippur (the Day of Atonement—the holiest day in the Jewish calendar), when the streets are practically empty of traffic for the entire day, whereas heavy industry (including power plants and oil refineries) reduces its capacity only slightly [5]. The data show that pollutant concentrations in the large urban centers are reduced nearly to zero.
Growing evidence links vehicle pollutants to severe health effects such as respiratory, cardio-pulmonary diseases and lung cancer [6]. According to the World Health Organization (WHO), car-exhaust emissions are responsible, worldwide, for more deaths than road accidents [1].
Numerous studies have shown that introduction of electric vehicles (EV) can contribute to pollution abatement, mainly CO2, from gasolineand diesel-powered vehicles (e.g., [7-10]). All these studies concluded that introduction of EVs will be beneficial, especially where the power for charging the vehicles will be generated from alternative, low emissions, sources (renewable or nuclear).
The economic benefits of improving air emissions by replacing internal combustion engine (ICE) vehicles with EVs are country-specific, as they not only depend on specific meteorology [11], synoptic patterns [12,13] and geographic variation [14]. They are also a function of population density [15,16] and of the type of vehicles replaced (for example, NOx and CO2 emissions from diesel cars are higher than from gasoline cars, therefore, one may expect that replacing diesel cars will be more beneficial than replacing gasoline cars).
These economic benefits should be assessed according to various inputs, such as the specific energy mix required to produce the electricity, the specific cost of air emissions (or benefits gained by improving it) and the population affected by the pollution.
The current study assessed the benefits of introducing EVs in Denmark, France and Israel, as these benefits have not been previously evaluated and these countries are characterized by very different fuel mixes to produce electricity and by different car fleet compositions. In addition, the study enables calculation of the benefits of improved air quality in urban areas.
It is important to note that these countries were the first to introduce the EV developed by Renault, as part of the EASYBATEU FP7 project [17]1.
2. Methodology
The study was conducted in several stages:
1) Energy mix for electricity production and related air emissions. Assessment of anticipated air emissions from the projected electricity production mix (tons pollutant/kWh) for the different countries under study, for the year 2020.
2) Passenger car stock and related emissions. According to the national assessments of passenger car stock in 2020, we estimated air emissions from ICE vehicles according to Euro 6 standards and real-world emissions, under different scenarios of EV penetration to the market.
3) Electricity needs for charging EV cars. Calculation of the electricity needs for charging EV cars and the share of the additional needs in the overall electricity consumption was analysed for every country.
4) Air emission costs. Calculation of the externalities2 resulting from the electricity production needed for charging the EV cars compared to the air emissions from the same number of ICE vehicles.
5) Life cycle differences between the proposed switchable battery (SB) and the conventional FB (fixed battery, e.g., Nissan Leaf). The only difference found was the amount of electricity needed at the battery switch stations for battery temperature control. Therefore, this electricity consumption and the related environmental externalities will be subtracted from the benefits found in the next stage.
6) Quantification of benefits from reducing emissions by replacing conventional cars with EVs. For Denmark and France, the analysis was performed according to the Extern E Methodology developed by the European Commission [16,19]. For the analysis in Israel, we used the environmental quantification produced by [20,21]. It is noteworthy that the Israeli figures were obtained using the benefit-transfer approach3.
3. Assumptions
3.1. Anticipated Energy Mix for Electricity Production
The projected fuel mixes for electricity production in Denmark, France and Israel are presented in Table 1, according to national policy papers and energy outlooks [22-24].
As much effort is invested today in reducing the specific emissions resulting from electricity production, it is reasonable to assume that by 2020, they will be lower than at present. Yet, we calculated primary air pollutants and CO2 emissions from electricity production according to present data. There fore, the use of current limits, regardless of the techniques used to achieve them, is a stringent assumption with respect to the present research. For
Table 1. Projected share of fuel mix for electricity production for 2020.
the purpose of the analyses presented in this study, we shall refer to this mix as BAU (Business As Usual).
Given the BAU energy mix in Table 1 and each country’s anticipated emission limits, we calculated the total emissions from 1 kWh of electricity produced. The figures are provided in Table 2.
3.2. Anticipated Passenger Car Stock and Emissions from ICE Vehicles
The projected car fleet composition in the countries under study is presented in Table 3, calculated according to [25-27].
[28] sets two emission standards for the registration and sale of new passenger vehicles, vans and commercial vehicles intended for the transport of passengers or goods (Euro 5 standard came into force on January 1st 2011 and Euro 6 standard will come into force on the January 1st 2015). Vehicles that do not comply with the limits set in the Euro 5 and 6 standards must be refused registration in the member state [28]. Actions targeting the reduction of CO2 emissions in the transport sector have been discussed since the early 1990s. In 2007, a new objective target for emissions was proposed at a level of 120 g CO2/km by 2012. Later, however, this target was set to a level of 130 g/km [29].
This study considers Euro 6 emissions for ICE vehicles which, according to different penetration scenarios, will be replaced by EV.
Nevertheless, several studies have indicated that, in particular, on-road (real-world) NOx emissions from lightduty diesel vehicles might substantially exceed the emission levels identified during emissions testing in the laboratory. [30] showed that Portable Emission Measurement Systems indicate that average NOx emissions of Euro 5 diesel vehicles are 0.62 ± 0.19 g/km (grams NOx per kilometer), which substantially exceed the Euro emission limits.
On-road NOx emissions of gasoline vehicles, as well as CO and THC (total hydrocarbon) emissions of both diesel and gasoline vehicles generally stay within Euro emission limits.
During on-road testing, the average emissions from light-duty diesel and gasoline vehicles are 189 ± 51 g CO2/km and 162 ± 29 g CO2/km, respectively, thereby exceeding the CO2 emissions as specified during laboratory testing by 21% ± 9%. The magnitude of on-road emissions varies depending on vehicle type, operation mode, route characteristics and ambient conditions; the higher the emission from ICE vehicles, the greater the benefits from replacing these vehicles. To conduct a conservative analysis in this study, we used the following real-world emissions: NOx emissions from diesel cars— 0.6 g/km instead of 0.08 g/km [28] and CO2 emissions— 160 g/km instead of 130 g/km for both gasolineand diesel-powered vehicles [28]. In all other parameters and with respect to gasoline cars, we used the Euro 6 standards.
Table 4 presents the emission limits of Euro 6 and real-world emissions used in this study.