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Transportation Research Part A
journal homepage: www.elsevier.com/locate/tra
Who will bell the cat? On the environmental and sustainability
risks of electric vehicles
Francisco J. Bahamonde-Birke
Sociale Geografie en Planologie, Universiteit Utrecht, Netherlands
I have been confronted recently with many papers considering the triggers and obstacles favoring and/or hampering the adoption
of electric vehicles (EVs). The large majority of these papers include claims such as … “Compared with traditional gasoline vehicles, EVs
have several societal and environmental benefits such as reduce carbon emissions, enhance energy security and promote the usage of renewable
and clean energy” (Wang et al., 2018) or … “These policies are in essence aiming to change the societal norm of fossil fuel based internal
combustion vehicles into a new norm of fuel efficient EVs via a number of push and/or pull measures.” (Nordlund et al., 2018) or … “Plug-in
electric vehicles are seen as a promising option to reduce oil dependency, greenhouse gas emissions, particulate matter pollution, nitrogen oxide
emissions and noise caused by individual road transportation” (Ensslen et al., 2018), just to mention some published in this journal
during in the past year. However, the number of similar cases in the transportation literature is countless.
While I certainly do not want to criticize the quality of the work on adoption of new powertrain technologies that is the actual
content of these papers, I want to raise awareness about the suitability of electric vehicles to actually contribute to sustainability.
Nowadays, and in line with the expectations of the press, politicians and the general public, many researchers take as God-given
that the switch from conventional vehicles to new powertrain technologies, such as EVs, constitutes a big step towards the dec-
arbonization and sustainability of transport systems. Nevertheless, and in spite of its broad acceptance, this is not necessarily true. It
is not even necessarily true when the electrical grid includes a large share of renewable energies; the impact of EVs must be analyzed
on case by case basis.
In countries such as Norway, Iceland or Costa Rica, where almost 100% of the electricity is generated from renewable sources
with a substantial reservoir capacity (i.e. the electric generation can easily follow the demand; Kroposki et al., 2017), EVs are almost
carbon neutral. In any other case, however, it is necessary to consider the impact of an additional vehicle-kilometer on the total
amount of CO
2
emissions associated with the electric grid.
1
The German case constitutes a good example of this phenomenon: Germany is a pioneer of the energy transition (German
Energiewende) and its electric grid exhibits a large amount of renewable sources. However, the electric grid has high volatility (which
arises mostly from wind and solar energy) and cannot easily adapt to follow demand. Hence, the electric generation exhibits large
fluctuations and while at some point the entire demand can be satisfied with wind and solar energy only, at many points every
additional kWh is being generated using lignite (a very CO
2
-intensive energy source). Therefore, charging EVs during those time
periods necessarily implies that the total amount of energy being generated using lignite in the system has to be increased in the same
amount of the energy demanded by the EVs, with disregard of the average amount of renewable sources in the mix (Jochem et al.,
2015).
Consequentially, depending on the time when EVs are being charged, a vehicle like a Chevrolet Volt can be associated with only
37 g CO
2
/km, when electricity is generated from renewable sources only (way below conventional vehicles,
2
Plötz et al., 2018) or as
https://doi.org/10.1016/j.tra.2019.12.001
Received 17 July 2019; Received in revised form 6 November 2019; Accepted 2 December 2019
E-mail addresses: bahamondebirke@gmail.com,f.j.bahamondebirke@uu.nl.
1
Note that an adequate assessment requires the analysis of the entire life cycle of vehicles (LCA), but it largely escapes the scope of this research
note focused on the impact of electricity generation on the ecological performance of EVs. The reader is referred to Messagie (2014),Manzetti and
Mariasiu (2015), and Holmberg and Erdemir (2019) for a detailed review on LCA.
2
For comparison purposes, comparable vehicles (average C-segment) are associated with 139 g CO
2
/km for Diesel vehicles and 151 g CO
2
/km for
Petrol vehicles (KBA, 2019).
Transportation Research Part A 133 (2020) 79–81
Available online 29 January 2020
0965-8564/ © 2020 The Author. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/BY-NC-ND/4.0/).
T
much as 190 g CO
2
/km, when electricity is generated from lignite (way above conventional vehicles
2
,Plötz et al., 2018). Fur-
thermore, given the charging patterns of EVs, the large majority of the electric charge occurs during the evenings (Anderson et al.,
2018).
3
During those time periods, the contribution of renewable energies is low and the electric demand is high (Schill and
Gerbaulet, 2015), meaning that the electricity being generated to satisfy the demand mostly comes from lignite (i.e. 190 g CO
2
/km);
in fact, Schill and Gerbaulet (2015) show that replacing conventional vehicles by electric vehicles increases the CO
2
emissions
throughout the country. Helveston et al. (2015) and Jenn et al. (2019) report similar results for China and the US.
It is also important to note that it is not adequate to associate the use of EVs with the average CO
2
emissions of the grid, as it does
not reflect the emissions associated with the generation of the energy actually used by the vehicle (which is obviously equal or larger
than the average given that the marginal emissions are increasing). Or in other words, associating EVs with the average CO
2
emissions of the grid implies assuming that the same electricity mix can be used to generate additional energy (for EVs), which is
obviously not possible when no further renewable sources are available (and every additional kWh would have to be generated using
less environmentally friendly sources). Consequentially, doing so incorrectly associate EVs with lower CO
2
emissions than the amount
actually being required to generate the electricity (which is reflected by the marginal emissions).
Similarly, it is also incorrect to state that EVs exhibit a better ecological performance than conventional vehicles when CO
2
emissions cap-mechanisms - like the European Union’s emissions trading system (EU ETS) - are set in place. Under these circum-
stances, the analyst would rather be capturing the effect of imperfect regulation (which may or may not be improved in the short/
medium term – note that is perfectly possible to include conventional vehicles into systems like EU ETS via fuel taxes) and not an
actual difference in the ecological performance of EVs relative to their conventional counterparts. Hence, ceteris paribus (and con-
sidering equal regulation on greenhouse pollutants for all alternatives) it would still be more efficient to rely upon vehicles with less
marginal emissions (e.g. compensating the CO
2
emissions of conventional vehicles via carbon credits produces the same results as
replacing the conventional vehicles by EV at a lesser cost). Along these lines, it must also be pointed out that the reach of mechanisms
like the EU ETS and the possibilities of compensating CO
2
emissions are also not unlimited and a large increase in CO
2
emissions
would put a lot of pressure on the system, as steep increases in the price of emissions permits have been observed every time the EU
ETS has expanded (Hintermann, 2017). In fact, the transport sector currently represents 25% of the total CO
2
emissions in the area
covered by the EU ETS (Eurostat, 2019) and the EU ETS covers 42% of those emissions (Hintermann, 2017); hence, including the
transport sector would result in an increase of ca. 60% of the emissions to be accommodated under the cap, and this figure will be
much larger if conventional vehicles are replaced by vehicles with higher marginal emissions.
The purpose of this note, however, is not to hamper the transition towards electromobility. I acknowledge the benefits of EVs in
countries like Norway or Iceland; I also acknowledge the benefits of EVs in terms of local emissions (which may prove highly
important in overly polluted cities), and also eventual benefits of EVs to balance the grid by taking advantage of their batteries when
surplus in the generation occurs. This, however, does not change the fact that, under current conditions and with flat energy prices, a
substantial increase in the number of EVs in many countries would necessarily result in an increase of CO
2
emissions. Luckily, many
European countries are not going to meet their goals regarding the number of EVs on the street by 2020, as their current electric grids
and regulation (e.g. lack of incentives to charge vehicles during generation surpluses) are not prepared. Hence, it would result either
in an important increase in greenhouse gas emissions or in prohibitively high CO
2
permit prices, compromising mechanisms such as
the EU ETS.
4
The actual purpose of this note is to raise awareness among authors and reviewers regarding the risks associated with replacing
conventional vehicles - especially those highly efficient in terms of CO
2
emissions, such as Diesel or LPG vehicles - by electric vehicles
(especially if not appropriate incentives to take advantages of generation surpluses are set in place). Despite the fact that the evidence
I am summarizing is not new (and most of it has been published in this very journal), a large proportion of the scientific community
seems to be daunted by the hype around the benefits of EVs and are unwittingly neglecting their risks. It is our duty as scientific
community to raise awareness about these issues and not let ourselves go with the hype.
Appendix A. Supplementary material
Supplementary data to this article can be found online at https://doi.org/10.1016/j.tra.2019.12.001.
References
Anderson, J.E., Steck, F., Kuhnimhof, T., 2018. Can renewable energy sources meet electric vehicle charging demand today and in the future? A microscopic time-
specific travel demand analysis for Germany. Transportation Research Board 97th Annual Meeting, 7–11. January 2018, Washington, D.C., USA.
Ensslen, A., Gnann, T., Jochem, P., Plötz, P., Dütschke, E., Fichtner, W., 2018. Can product service systems support electric vehicle adoption? Transp. Res. Part A: Pol.
Pract. https://doi.org/10.1016/j.tra.2018.04.028.
3
Actually, Anderson et al. (2018) show that the amount of renewable sources is enough to satisfy the electricity demand for a fleet of 6 million EVs
in 2030 regardless of the time of the day (accounting for the electricity grid energy composition in 2030). However, if the renewable sources are not
enough to satisfy the entire electric demand in the system (i.e. not just the transportation sector), the additional demand associated with EVs would
necessarily have to be satisfied by increasing the total generation using fossil sources (i.e. lignite).
4
Note that this stands even when countries aim at greener electricity grids in the long-term. If so, there will be an optimal time window for a large-
scale transition towards EVs (from a CO
2
emissions perspective and taking incentives schemes to charge EVs during generation surpluses into
account). This will not hamper the development of the technology as a large-scale introduction of EVs is already reasonable in other countries.
F.J. Bahamonde-Birke Transportation Research Part A 133 (2020) 79–81
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