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Indirect emissions from electric vehicles: Emissions from electricity generation


Abstract and Figures

Carbon dioxide (CO2) emissions from passenger cars represent an important and growing contributor to climate change. Increasing the proportion of electric vehicles (EVs) in passenger car fleets could help to reduce these emissions, but their ability to do this depends on the fuel mix used in generating the electricity that energises EVs. This study analyzes the indirect well-to-wheels CO2 emissions from EVs when run in the US, the UK, and France and compares these to well-to-wheels emission data for a selection of internal combustion engine vehicles (ICEVs) and hybrid electric vehicles (HEVs). The study also compares the well-to-wheels emissions of the existing passenger car fleet in each country to a hypothetical EV fleet with the average electricity generation requirements of the three EVs considered in this analysis.
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Carbon dioxide (CO2) emissions
from passenger cars represent an
important and growing contributor
to climate change. Increasing the
proportion of electric vehicles
(EVs) in passenger car fleets could
help to reduce these emissions,
but their ability to do this depends
on the fuel mix used in generating
the electricity that energises EVs.
This study analyzes the indirect
well-to-wheels CO2 emissions
from EVs when run in the US, the
UK, and France and compares
these to well-to-wheels emissions
data for a selection of internal
combustion engine vehicles
(ICEVs) and hybrid electric
vehicles (HEVs). The study also
compares the well-to-wheels
emissions of the existing
passenger car fleet in each
country to a hypothetical EV fleet
with the average electricity
generation requirements of the
three EVs considered in this
Indirect Emissions from Electric Vehicles:
Emissions from Electricity Generation
by Aaron Holdway, Alex Williams, Oliver Inderwildi and Sir David King
Policy Brief
Tr an sp or t is o ne o f th e la rg es t a nd
fastest-growing contributors to
increased greenhouse gas
concentrations and the associated
climate change 1, 2. Globally, passenger
cars alone emit more than 6 percent of
anthropogenic carbon dioxide (CO2) 2,
the most abundant anthropogenic
greenhouse gas 3. Electric vehicles (EVs)
– vehicles which have onboard batteries
that are charged with grid electricity and
which have no tailpipe emissions – have
received significant attention in the past
two decades as a means of helping to
further reduce localised vehicle
emissions and mitigate the associated
health concerns. Consequently, policies
to increase the number of EVs on the
roads have become increasingly
common in industrialised countries in
recent years 4-6.
!Upstream emissions from power
plants that energise EVs, however, are
often neglected, and only recently
studies by Jacobson 7 and Arar 8 have
addressed this issue. These studies
conclude that an instantaneous
conversion of the US vehicle fleet to
battery power could bring a CO2
emission reduction of up to 58 percent,
and even greater reductions are
possible if electricity generated entirely
from renewable sources such as hydro,
solar, wind, or nuclear power is used 9.
The potential of EVs to reduce
greenhouse gas emissions depends on
the fuel mix used in the electricity
generation that charges the vehicles’
batteries, which can vary widely from
country to country, and within countries.
Consequently, the emissions from
electricity generation, and thus the
indirect CO2 emissions from EV use,
also vary widely across and within
!This study focuses on CO
2, the most
important contributor to anthropogenic
climate change 3. It examines these
indirect emissions from electric car
usage from well to wheels, comparing
across three major industrialised
countries in which the national
electricity grid is fed by different mixes
of renewable and fossil fuel sources:
the US, where coal has the largest share;
the UK, where natural gas has a share
nearly equal to coal; and France, where
nuclear power predominates. The
paper calculates the amount of
electricity required to run electric cars
and the CO2 emissions that result from
generating this electricity in the US, the
UK, and France in order to establish a
sensitivity analysis of indirect emissions
and electricity carbon footprint.
Moreover, this study compares these
indirect emissions to the well-to-wheels
CO2 emissions of some of the most
efficient ICEVs and HEVs – that is,
emissions from primary fuel extraction
to delivery to the vehicle fuel tank (well-
to-tank) and emissions from combustion
of the fuel (tank-to-wheels).
!The study also considers the increase
in net electricity consumption that could
occur if the entire passenger car* fleet in
each country was replaced with EVs.
Smith School of Enterprise
and the Environment
University of Oxford
Hayes House
75 George Street
United Kingdom
Dr Oliver Inderwildi
DOI: 10.4210/ssee.pbs.2010.003
* “Passenger cars” does not include light-duty
trucks: SUVs, pickup trucks, and minivans with a
gross weight of up to 8500 pounds (3.9 metric
tons) in the US and 3.5 tons in the UK and France
(refs. 13, 25, 28). This study omits light-duty
trucks as there were, at the time of writing (April
2010), no commercially-available battery electric
Electric power generators do not operate at full capacity all
the time. The average capacity factor, or plant load factor,
of electricity generation – that is, the ratio of net electricity
generation in a given period to the amount of electricity that
would be generated in that period if operating at full
nameplate capacity – is 48 percent in the US 10, 11, 52
percent in the UK 11, 12, and 55 percent in France 11, 13, 14.
Net electricity generation is less than the nominal capacity
of the grid – in the US and UK it is about 70 percent of
annual peak demand 10, 12 – because power stations must
be shut down periodically for maintenance and because
electricity demand is not constant over the course of a day
or year. The effect a large-scale introduction of EVs might
have on net electricity consumption, and the ability of the
grid to supply this, is considered below.
!A number of recent studies have looked at emissions
associated with plug-in hybrid-electric vehicles (PHEVs)
15-17. Most studies on the potential of EVs to reduce
greenhouse gas emissions compared to conventional
vehicle technologies are at least a decade old 18-21. As
previously mentioned, two exceptions are Jacobson 7 and
Arar 8. In a review of options for powering EVs and fuel cell
vehicles, Jacobson states that “The US could theoretically
replace all 2007 on-road vehicles with BEVs (battery
electric vehicles) powered by 73 000-144 000 5-MW wind
turbines, less than the 300 000 airplanes the US produced
during World War II,” resulting in a 33 percent reduction in
US CO2 emissions. Jacobson assumes that wind-
generated electricity is over 99 percent carbon-free and
that the plug-to-wheels efficiency of BEVs (75-86 percent)
is much greater than the average tank-to-wheels efficiency
of fossil-fuel vehicles (17 percent). Arar, using 2006 figures,
finds that an instantaneous conversion of the US fleet of
passenger cars and light-duty trucks to battery power
could bring a CO2 emission reduction of 58 percent. Arar
also attempts to estimate fleet emissions for 2020
assuming a 10 percent uptake in EVs per year from 2011
to 2020 but using the present fuel mix. He finds that the
2020 fleet would emit 36 percent less CO2 than if the
conversion to EVs had not taken place.
!The present study looks specifically at the electricity
usage and associated well-to-wheels CO2 emissions for
three battery EVs which, at the time of writing (April 2010),
were the only multi-passenger EVs available for sale in
more than a single country: the Tesla Roadster; the TH!NK
City; and the REVAi (marketed in the UK as the G-Wiz i).
The Tesla Roadster, from Tesla Motors of San Carlos,
California, has been available for purchase in the US since
2008 and from stores in Europe and Canada since 2009 .
The TH!NK City, from Think of Aurskog, Norway, has been
available in Norway since 2008, with plans for sales
elsewhere in Europe in 2009 and in the US from 2010 .
The REVAi, from REVA Electric Car Company of Bangalore,
India, has been available since 2008 in India and several
European countries §. Unlike previous US-focused studies
7, 8, the present study focuses on the US, the UK, and
France. Moreover, by calculating indirect emissions from
electricity generation in France, a country with relatively
low-carbon grid electricity, the study explores the potential
for emissions reduction through decarbonisation of the
electricity sector.
Here we elaborate on the methodology used in the
calculations. Data used are given in the text.
"The average CO
2 emissions from electricity generation in
each country (Table 3) were calculated as follows:
Net electricity generation is defined here as electricity
generated by major power producers – that is, companies
whose main business is electricity generation – since
national CO2 emissions figures for electricity generation
refer only to major power producers. The US Energy
Information Administration’s Annual Energy Review
expressly excludes plants with a generator nameplate
capacity less than 1 MW 10.
!The well-to-wheels CO
2 emissions for the three EVs
considered in this study were calculated by summing well-
to-power-plant emissions and power-plant-to-wheels
emissions. Well-to-power-pla nt CO 2 emissions –
analogous to well-to-tank for ICEVs – are defined here as
emissions from primary fuel extraction (e.g., coal, oil, gas)
to delivery to the power plant for use in electricity
generation, including all intermediate steps (detailed in
Ta b le 6 ). Well-to-power-plant emissions fo r eac h EV in each
country were calculated from fuel efficiency data (Table 2),
the breakdown of total net electricity generation (Table 4),
and the well-to-power-plant emissions for each type of fuel
used in electricity generation (Table 6).
!Power-plant-to-wheels CO
2 emissions – analogous to
tank-to-wheels for ICEVs – are defined as emissions from
generation of electricity at the power plant to delivery to the
EV’s battery. Power-plant-to-wheels emissions for each EV
in each country were calculated from the fuel efficiency for
each EV (Table 2) and the average direct CO2 emissions
from electricity generation (Table 3).
"The sum of the well-to-power-plant (WtPP) and the
power-plant-to-wheels (PPtW) CO2 emissions for each EV
in each country (C) is the well-to-wheels (WtW) CO2
emissions (Table 5):
2 April 9, 2008, and
March 3, 2009. All websites in this paper were accessed August 1, 2009. March 12, March 18,
and May 6, 2009
!Analogously, well-to-wheels CO
2 emissions for the ICEVs
and HEVs (Table 9) are the sum of well-to-tank emissions,
defined as emissions from primary fuel extraction to
delivery to vehicle fuel tank, and tank-to-wheels emissions,
defined as emissions from combustion of the fuel. The
tank-to-wheels data are from the UK Government’s Vehicle
Certification Agency (VCA); the well-to-tank figures were
calculated from fuel efficiency figures from the VCA and
the literature value for oil in Table 6, taken to be the same
for well-to-tank as for well-to-power plant. The well-to-tank
emissions (75 g/kWh) are comparable to those from Silva
et al. 22, who report 51.1 g/kWh for well-to-tank
greenhouse gas emissions for diesel.
"The well-to-wheels CO
2 emissions of the hypothetical EV
fleet in each country is the average of each row in Table 5.
The average well-to-wheels CO2 emissions for the existing
passenger car fleets in each country were calculated from
the net calorific value of fuel consumed by the fleet, the
number of vehicle kilometres driven, the literature value for
oil in Table 6, and fleet tailpipe CO2 emissions.
Results and Discussion
Ta b le 1 c o m pa r es k ey c ha r a c te r i st i c s o f e a c h o f t h e t h r ee
EVs included in this study (see Tables and Figures). The
amount of electricity generation required to run each of the
three EVs in each of the three countries considered in this
analysis is shown in Table 2 .
Ta bl e 2. Amount of electricity required to run EVs (kWh/km) a
Tesla Roadster
TH!NK City
US 10
UK 12
France 14
!All vehicle data are from,, and, except a personal communication from M. Boxwell
(REVA G-Wiz [REVAi] Owners’ Club) stating that the REVAi’s loss due to
charging inefficiency is 13 percent.
The figures are inclusive of electricity transmission and
distribution losses and battery charging inefficiency.
"The average CO
2 emissions from electricity generation in
the same countries are shown in Table 3 (see Methods for
details on calculations).
Ta bl e 3. Average CO2 emissions from electricity generation
(g CO2/kWh)
Average Emissions
US 10, 36
UK 12, 37
France 14, 38
These figures can be interpreted in part through the share
of electricity in each country that is generated from fossil
fuels: 71 percent in the US, 77 percent in the UK, and just
10 percent in France 10, 12, 14. The carbon intensity of the
UK’s electricity generation is less than that of the US
despite the UK having a greater share of its electricity
generation coming from fossil fuels. This is because, as
shown in Table 4, the US has a greater share of coal in its
fuel mix, while the UK has a greater share of natural gas.
Coal produces approximately twice as much CO2 per kWh
as natural gas 12.
Ta bl e 4. Breakdown of total net electricity generation
(GWh / percent of net electricity generation)
Other a
Net Elec.
Gen. b
US 10
1 990 900
64 400
813 000
409 500
4 065 000
UK 12, c
136 173
2 727
122 232
9 903
339 283
14, c
21 302
5 005
19 494
72 673
541 327
!“RES” refers to renewable energy sources; “Other” fuel includes other
gases and non-renewable waste, amounting to less than 2 percent of net
electricity generation in each country.
b"Percentages may not add to totals due to rounding.
"Gross figures have been converted to net by removing electricity used
in pumping for pumped storage.
"The well-to-wheels CO
2 emissions for the three EVs
considered in this study are shown in Table 5.
Ta bl e 5. Average well-to-wheels CO2 emissions for EVs
(g CO2/km) (Tables 2, 3, 4, 5)
Tesla Roadster
TH!NK City
As this table demonstrates, the fuel mix in the national
electricity grid is the overwhelming factor in determining the
indirect well-to-wheels CO2 emissions from electric
vehicles (see Figure 1).
All data in this study are for 2006, the last year for which all data were
Fig. 1. Average well-to-wheels CO2 emissions for EVs (g CO2/km)
plotted from the data in Table 5
TH!NK City!
Tes l a R o a d s t e r !
g CO2/km!
In the US and the UK, the emissions for the TH!NK City and
the Tesla Roadster are not appreciably lower than those of
the most efficient small diesel cars, as shown below.
France, however, with 78 percent of its electricity coming
from nuclear (Table 4), would find substantial emissions
reductions from passenger cars if it were to replace a large
part of its fleet with EVs. The well-to-power-plant CO2
emissions associated with nuclear power generation are
less than half the average of coal, oil, and natural gas (Table
6), and the generation of electricity from nuclear fission
produces no CO2 emissions.
Ta bl e 6. Well-to-power-plant CO2 emissions by type of fuel used
in electricity generation (g CO2/kWh) a
Coal 39, b
Oil 40,c
Gas 39, d
Nuclear 7,e
Mean f
"The well-to-power-plant CO2 emissions for hydro power (1.9 g CO2/
kWh) 41 are negligible and have been excluded. This figure does not
include methane emissions, which may occur in a flooded reservoir from
the anaerobic decomposition of biomass 40.
b"For coal, this includes mining and transport.
"For oil, this includes exploration, extraction, transportation, and
d"For natural gas, this includes gas processing, venting wells, pipeline
operation (mainly compression), and system leakage in transportation and
handling 40.
"For nuclear, this consists of fuel conversion, enrichment, and
fabrication. Enrichment produces up to 95 percent of the CO2 emissions
from nuclear fuel processing. Emissions can vary greatly depending on
the specific enrichment process employed.
f"Used in all calculations
ICEVs and HEVs
The figures from Table 5 can be compared to well-to-
wheels CO2 emissions data for a selection of ICEVs and
HEVs, as shown in the overall comparison, Table 9 (EV data
are shaded; ICEV and HEV data are unshaded).
!Table 9 underlines the importance of comparing the
vehicles on a well-to-wheels basis. By simply looking at
tank-to-wheels or the analogous power-plant-to-wheels,
the lowest-emitting car besides the EVs running in France
and the REVAi running in the UK, would be the Smart
fortwo cdi at 88 g CO2/km . The next six ICEVs and HEVs
in Table 9 would all come ahead of the Tesla Roadster
running in the US. A well-to-wheels analysis, however,
demonstrates that EVs generally produce less CO2
emissions than comparable ICEVs or HEVs. The Tesla
Roadster fares well against comparable ICEVs such as the
Lotus Elise and the Porsche Boxster, both of which have
well-to-wheels emissions approximately double those of
the Tesla Roadster in the US.
!The well-to-tank CO
2 emissions for the ICEVs and HEVs
in Table 9 range from 25 to 64 g/km. The analogous well-
to-power-plant emissions for the three EVs ranges from just
6 to 17 g/km, due to their superior fuel efficiency. Even
though the average efficiency of electricity generation and
supply to end users in the US, the UK, and France is only
30 percent, 34 percent, and 37 percent, respectively 10, 12, 23
– about the same as an efficient diesel engine 24 – these
EVs’ lower use of fuel means their emissions are lower
than comparable ICEVs or HEVs. The next section
examines a hypothetical move to replace the current ICEV
fleet in each country with EVs.
The three EVs under analysis differ in size and power, and
the average of their emissions can be used to represent
those of a hypothetical EV fleet. If all passenger cars in
each country** were replaced with EVs with the average
electricity generation requirements of the Tesla Roadster,
TH!NK City, and REVAi (the three EVs considered in this
analysis), the fleet well-to-wheels CO2 emissions for each
country would be as found in Table 7. (The results are
based on the average CO2 emissions from electricity
generation from Table 3, which may change by the time
electric vehicles reach significant fleet penetration.)
Ta bl e 7. Average well-to-wheels CO2 emissions for hypothetical
EV fleets (Table 5) and existing passenger car fleets (g CO2/km).
Hypothethical EV fleet a
Existing fleet b
10, 27-29, 40
12, 25, 37, 40
12, 13, 38, 40, 42
"The figures for the hypothetical EV fleets are the average of the well-to-
wheels CO2 emissions of the Tesla Roadster, TH!NK City, and REVAi.
b"Existing fleet figures are calculated from the net calorific value of fuel
consumed by the fleet, the number of vehicle kilometres driven, the
literature value for oil in Table 6, and fleet tailpipe CO2 emissions.
4 (UK Government’s Vehicle Certification
** That is, the number of passenger cars registered in each country in
2006, the last year for which all study data were available.
"Table 7 also shows the average well-to-wheels CO
emissions for the existing passenger car fleets in each
country. Compared to the existing fleets, the hypothetical
EV fleets would produce 59 percent less CO2 emissions in
the US, 49 percent less in the UK, and 90 percent less in
France. The UK and French fleet figures are lower than that
of the US in part because of their greater use of diesel
vehicles, whose engines are more efficient than petrol
engines; the higher use of manual transmissions compared
to automatic; the smaller average car size; and the
traditionally stricter fuel efficiency standards 13, 25, 26. Even
considering the 2006 model year only, the US well-to-
wheels CO2 emissions would still be higher, at 234 g/km,
than those of the entire fleets in the UK and France 10, 27-29.
The difference would be even more marked if light-duty
trucks were included. Light-duty trucks, many of which are
used as passenger cars and include SUVs, pickup trucks,
and minivans, make up 42 percent of all light-duty vehicles
in the US, while accounting for only 10 percent in the UK
and 16 percent in France 13, 25, 28.
"Moving a large part of the ICEV fleet to EVs would require
a number of considerations. First, it may be difficult to get
consumers to move to smaller cars such as the TH!NK City,
and REVAi, particularly in the US, where, as mentioned
above, SUVs, pickup trucks, and minivans make up two-
fifths of the light-duty vehicle fleet. Second, EVs are still
more expensive than comparable ICEVs, despite tax
credits and other incentives (Table 1). Third, the average
vehicle lifetime in the US (for example) is about 15 years 30,
meaning that major fleet penetration, under the best
circumstances, would take many years 8. Fourth, emissions
reductions from taking ICEVs off the roads would be
partially offset by increased emissions from power plants,
although controlling emissions from a few thousand power
plants may be easier than controlling emissions from
millions of tailpipes. Fifth, a charging infrastructure and
concomitant government policies would be required.
Finally, if the entire fleet in each country (see footnote **)
were replaced with EVs with the average electricity demand
of the Tesla Roadster, TH!NK City, and REVAi, the increase
in net electricity consumption that would occur in each
country would be 12 percent in the US 10, 28, 20 percent in
the UK 12, 25, and 15 percent in France 13, 14. However, since
EVs are usually charged at night when demand is lower,
and most EVs would not have to be charged, or charged
fully, every night for average daily usage, the increase in
demand could potentially be met in part by maintaining
daytime electricity production levels overnight. In the UK,
for example, where charging the hypothetical EV fleet
would see a greater relative increase in electricity demand
than in the US or France, half of the additional demand
could potentially be met in this way, as shown in Figure 2,
without the need for additional electricity generation
Fig. 2. Average electricity demand in the UK in 2006
(, with half the demand
the full hypothetical UK EV fleet would bring.
!Furthermore, charging EVs in large numbers in this way,
in off-peak hours, could lead to improved load shapes,
reducing daily variability in electricity demand 15, 31. The
extent of this improvement may increase with the flexibility
offered by intelligent electricity grids 32 and the introduction
of EV batteries with shorter charging times. EVs could also
potentially return to the grid excess electricity stored in their
batteries during times of peak load and replace it with
electricity in off-peak hours 33. Under the status quo,
meeting the demand of the full hypothetical EV fleet along
with existing demand would require using approximately 66
percent of installed capacity 11, 12, 25,†† instead of the current
52 percent 11, 12. But an increase in demand for charging
EVs, if it happens, would come gradually, over many years,
and extra capacity could be added over time.
Overall comparison
The well-to-wheels CO2 emissions for EVs, a selection of
ICEVs and HEVs, and the hypothetical EV and existing
national fleets are compared in Table 9. This table
demonstrates that EVs generally emit less CO2 than
comparable ICEVs. The data also underline the importance
of the fuel mix in the electricity grid: the more electricity
generation from nuclear and renewable sources, the lower
the CO2 emissions associated with EV use.
!The data hide regional differences within each country,
however. In the US, for example, in twelve states more than
70 percent of in-state electricity generation comes from the
combustion of coal, while in four states more than 70
percent comes from nuclear and renewable sources ‡‡,¶¶.
At one extreme is North Dakota, where 94 percent of in-
¶¶ These figures are indicative only, as electricity in much of the US is
generated and transmitted on a regional basis, in regions that may span
several states and may not follow state boundaries.
state electricity generation comes from coal, and where
emissions from in-state electricity generation average 1012
g CO2/kWh §§. At the other extreme are states like Idaho,
which generates 84 percent of its in-state electricity from
hydroelectric, resulting in in-state electricity generation
emissions of just 65 g CO2/kWh 2§§. In the UK, 96 percent
of electricity generated by major power producers in
Northern Ireland comes from fossil fuels, while 37 percent
in Scotland is from nuclear and renewable sources 12. In
France, 99 percent of electricity generation in the region of
Île de France is from conventional thermal combustion,
while in eight other regions more than 95 percent of
generation is from nuclear and renewable sources 14.
"If the EVs in this study were to run in states or regions
where one fuel predominates, the results would be similar
to Table 8, which shows CO2 emissions for the three EVs if
running on just one fuel.
Ta bl e 8. Average well-to-wheels CO2 emissions for EVs (g CO2/
km) if using electricity generated from a single fuel (Tables 2, 4, 5), a
TH!NK City
EV fleet
Natural gas
"Using CO2 emissions estimates for electricity generation in the UK 12:
912 g/kWh for coal, 670 g/kWh for oil, and 412 g/kWh for natural gas.
These figures compare to well-to-wheels CO2 emissions of
234 g/km for passenger cars from the 2006 model year in
the US (see above, under Fleets). Thus, even though the
EVs may be running on electricity generated entirely from
coal, and even though the efficiency of electricity
generation and supply to end users in the US, the UK, and
France averages only 34 percent (see above), the EVs’
superior efficiency means they have lower well-to-wheels
emissions than the average ICEV. The EVs considered here
require 37 to 55 percent less energy per kilometre than the
most efficient ICEV or HEV in Table 9.
!Obtaining maximum environmental benefits from EVs,
however, requires decarbonising the electricity sector.
Changing the fuel mix is difficult due to long lead times
from planning to operation, combined with plant lifetimes of
up to 50 years. Jacobson suggests that nuclear, tidal,
wave, and hydroelectric may not be the best options
because their long lead times produce “opportunity cost
emissions” compared to technologies with the least delay:
solar-photovoltaics, concentrated solar, and wind, closely
followed by geothermal 7.
"Despite the environmental advantages mentioned above,
the number of EVs on the road remains small, most likely
due to cost and limited vehicle range. As of 2007, there
were approximately 4200 battery electric passenger cars
running in the US 34 and 1200 in the UK (P. Syron, UK
Department for Transport, personal communication).
Vehicle cost remains high at these low production volumes,
although those who cannot yet afford an EV would do well
to drive a fuel-efficient ICEV or HEV like those shown in
Ta bl e 9 . C o nt i n ue d im p ro v e m en t in I CE V te c h no l o gy i s
essential, as ICEVs will continue to dominate vehicle sales
for the foreseeable future.
Analyzing the indirect well-to-wheels CO2 emissions from
three production EVs has shown that EVs can reduce well-
to-wheels CO2 emissions over the existing fleet by more
than 90 percent. This suggests that EVs should be
particularly promoted where electricity generation is the
least carbon-intensive – as has been done, for example, in
California and France 4 – as the potential for EVs to reduce
CO2 emissions depends on the fuel mix used in generating
the electricity that powers them. The electricity grid must be
decarbonised if EVs’ full potential to reduce CO2 emissions
is to be realised: Decarbonisation of electricity production
should go hand-in-hand with the introduction of EVs.
Decisions on building new electricity generation capacity in
the coming years will affect the carbon intensity level of the
grid for decades to come and affect the potential for EVs to
greatly reduce CO2 emissions. In order to create a
comprehensive picture of the environmental benefits of
different vehicles and drivetrains, however, the cradle-to-
grave emissions of the vehicles themselves have to be
taken into account. The authors’ research group is currently
investigating these embedded emissions.
This work is part of the Future of Mobility project,
conducted at the Smith School of Enterprise and the
Environment, University of Oxford, and funded by Shell
International Petroleum Co. Ltd. We are grateful to Jack
Jacometti, Vice President, Future Fuels & CO2; Stewart
Kempsell, GM Business Development, Future Fuels & CO2;
Steve Skippon, Scientist, Shell Global Solutions (UK); and
Sylvia Williams, Business Development Manager, Global
XTL Development, for fruitful discussions, as well as our
Smith School colleague, Dr. Xiaoyu Yan.
Notes and references
a!Low-Carbon Mobility Centre, Smith School of Enterprise
and the Environment, University of Oxford, Hayes House, 75
George Street, Oxford, OX1 2BQ. Fax: +44 (0)1865 614960;
Te l: + 4 4 ( 0 )1 8 6 5 6 1 49 4 2 ; E - ma i l :
§§ and
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Ta bl e s an d fi g u re s
Ta bl e 1. EV characteristics a
Te sl a Ro a d st e r
TH!NK City
Driving range, combined
"city/highway (km)
80 (city only)
To p s p ee d (k m / h )
Peak power (kW)
Battery type
Lithium-ion or sodium
Lead acid
Battery capacity (kWh)
Battery charging time (h),
"0-100% state of charge
3.5-48 b
Battery weight (kg)
To ta l cu r b w e i g ht ( kg )
650 c
Base price (US$) d
"All data are from,, and, except where noted.
b!The charging time is 3.5 hours using Tesla’s High Power Connector; 8 hours using its 240-V Mobile Connector, the highest-
power portable charging option; and 37-48 hours using its 120-V Mobile Connector.
"The REVAi is classified as a quadricyle rather than a passenger car under European Parliament and Council Directive 2002/24/EC
d!Base price in the US (Tesla Roadster), Norway (TH!NK City: NOK 212 500), and the UK (REVAi: £8495;
store/pick_new [UK REVA retailer]); converted to US dollars on August 1, 2009, at
EV Modelb
Smart fortwo (diesel)
EV Fleet
To yo t a P r i us T 3
TH!NK City
Seat Ibiza
Volks wagen P olo
To yo t a i Q
Te sl a Ro a d st e r
Smart fortwo (gasoline)
Honda Civic Hybrid
Mini Cooper Clubman
Lotus Elise
Existing Fleet
Porsche Boxster
TH!NK City
EV Fleetd
Te sl a Ro a d st e r
Smart fortwo (diesel)e
To yo t a P r i us T 3 d
Seat Ibizae
Volks wagen P oloe
To yo t a i Q f
Smart fortwo (gasoline)f
Honda Civic Hybridd
Mini Cooper Clubmanf
Lotus Elisef
Existing Fleet
Porsche Boxsterf
Smart fortwo (diesel)
To yo t a P r i us T 3
TH!NK City
EV Fleet
Seat Ibiza
Volks wagen P olo
To yo t a i Q
Smart fortwo (gasoline)
Honda Civic Hybrid
Te sl a Ro a d st e r
Mini Cooper Clubman
Lotus Elise
Porsche Boxster
Existing Fleet
Ta bl e 9 . Comparison of well-to-wheels CO2 emissions for EVs, hypothetical EV and existing fleets by country, and a
selection of current ICEVs and HEVs a.
a. (UK Government’s Vehicle Certification Agency)
b. The 2009 model year is used for all. Except where noted, the fuel is gasoline and the gearbox is automatic.
c. The figure for the hypothetical EV fleets is the average of the fuel efficiency figures of the Tesla Roadster, TH!NK city, and REVAi.
d. HEV
e. ICEV Diesel
f. ICEV Gasoline
An abbreviated version of this Policy Brief will be published in Energy and Environmental Science, 2010
... EVs provide a convenient way to shift the emissions from the tailpipe to the power plants although such power plants might use non-renewable sources that still cause emissions. These are often termed as indirect emissions and with an increasingly diversifying energy mix across the world with a growing contribution from the renewable energy systems, these indirect emissions will also fall (Holdway et al., 2010;Wolfram et al., 2021;Sher et al., 2021). Since most nations across the world are now moving towards using renewables and clean energy, governments everywhere acknowledge electric vehicles as a clean alternative to mobility (Kuehr, 2007). ...
... Indirect emissions are emissions that are associated with the mobility but have its origin in the way they are powered. The term gained popularity when EVs were initially claimed to be emission-free and the claim was moderated by pointing out that there were emissions associated with the nature of the electricity that was used to power it (Holdway et al., 2010). However it is largely ignored that, by this rationale, it is the case that internal combustion engines also have associated emissions if the emissions that arise from the refineries that produce and transport the fuels are accounted for (Griffiths et al., 2022). ...
With the passing of every second we get closer to a society that is more cognizant of the effect carbon dioxide emissions are having on our planet, and that is more willing to take part in sustainable efforts to combat this and ever more interested in investing in cleaner technologies like electric vehicles (EVs). EVs are marching strongly into a market that is currently dominated by internal combustion engine vehicles, the current main fuel of which is a known contributor to most of the emission related climate problems that we now find ourselves in. Moving ahead, it is important that any move from internal combustion engines to more nascent technologies like EVs is sustainable and not detrimental to the environment. There is an ongoing debate between proponents of so-called e-fuels (being synthetic fuels made from atmospheric carbon dioxide, water, and renewable energy) and EVs wherein e-fuels are largely accused of being a half-measure while EVs are thought to contribute more in terms of brake and tire emissions than the ICE vehicles. This raises the question of whether there should even be a complete replacement of the combustion engine vehicle fleet or that should there be a 'mobility mix' similar to how we currently refer to an energy mix with power grids. This article offers some perspectives by critically analyzing and diving deeper into these pressing concerns to answer some of these questions.
... Many studies focused on the fuel consumption and emissions of ICEVs/HEVs/PHEVs/BEVs from the perspective of the life cycle method under different time and space conditions, and the research results significantly vary globally due to differences in the basic data, modeling process and scenarios [26][27][28][29][30][31][32][33][34][35][36][37][38]. Holdway et al. studied the indirect emissions from EVs and compared with the CO2 emissions from EVs in America [26]. ...
... Many studies focused on the fuel consumption and emissions of ICEVs/HEVs/PHEVs/BEVs from the perspective of the life cycle method under different time and space conditions, and the research results significantly vary globally due to differences in the basic data, modeling process and scenarios [26][27][28][29][30][31][32][33][34][35][36][37][38]. Holdway et al. studied the indirect emissions from EVs and compared with the CO2 emissions from EVs in America [26]. Wu, Huo and Ou developed the research on life cycle analysis of energy consumption and GHG emissions for HEVs/PHEVs/BEVs in China and other significant regions [27][28][29]. ...
Full-text available
In order to fulfill the commitment of China to achieve carbon peak by 2030 and carbon neutrality by 2060, all industries have been taking their respective carbon reduction actions. The transportation industry accounts for 11% of CO2 emission of the whole society, and its energy conservation and carbon reduction benefit is of great significance to the national carbon reduction process. New energy vehicles are undoubtedly one of the most important means of carbon emission reduction in the transportation sector. However, electric vehicles still have CO2 emissions, as the fossil fuel use comes from upstream power. To systematically and comprehensively evaluate the CO2 emissions of HEV, PHEV and BEV in the whole process, this study introduces the life-cycle method to research on the past and current situations, and predict future scenarios for ICEV and EV light-duty vehicles at the national and regional levels, by deeply analyzing the generation mix and generating efficiency from the WTT stage, and fuel economy from the TTW stage. The study shows that compared with ICEV, HEV and PHEV could reduce around 30% of CO2 emissions. Currently, BEV could reduce 37% of CO2 emission in the region where the proportion of coal-fired power is high, and 90% of CO2 emission in the region where the proportion of hydro power is high. This study discusses the impact of the proportion of renewable energy application on the carbon emissions from electric vehicles, analyzes the environmental benefits of promoting electric vehicles in different regions, and lays a foundation for the promotion strategy of electric vehicles for different regions in the future.
... Aaron et al. [7] conducted an LCA to assess the CO 2 emissions of real-world ICEVs, HEVs, and BEVs. The study reported a 90% reduction in well-to-wheels (WTW) lifecycle CO 2 emissions in BEVs, in comparison to conventional ICEVs. ...
Full-text available
Demand for sustainable transportation with a reduced environmental impact has led to the widespread adoption of electrified powertrains. Hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) produce lower greenhouse gas (GHG) emissions during the use phase of their lifecycle, compared to conventional internal combustion engine vehicles (ICEVs). However, a full understanding of their total environmental impact, from resource extraction to end-of-life (EOL), of a contemporary, real-world HEV and PHEV remains broadly elusive in the scientific literature. In this work, for the first time, a systematic cradle-to-grave lifecycle analysis (LCA) of a Toyota Prius XW50, as a HEV and PHEV, was used to comprehensively assess its environmental impact throughout its entire lifecycle using established lifecycle inventory databases. The LCA revealed that the gasoline fuel cycle (extraction, refinement, and transportation) is a major environmental impact “hotspot”. The more electrified PHEV model consumes 3.2% more energy and emits 5.6% more GHG emissions within the vehicle’s lifecycle, primarily owed to the manufacturing and recycling of larger traction batteries. However, when factoring in the fuel cycle, the PHEV model exhibits a 29.6% reduction in overall cradle-to-grave life energy consumption, and a 17.5% reduction in GHG emissions, in comparison to the less-electrified HEV. This suggests that the higher-electrified PHEV has a lower environmental impact than the HEV throughout the whole lifecycle. The presented cradle-to-grave LCA study can be a valuable benchmark for future research in comparing other HEVs and PHEVs or different powertrains for similarly sized passenger vehicles.
... Moreover, we do not intend to delve into the problem of the economic evaluation, or life cycle assessment of EVs, and on the comparison of EVs with ICEVs are growing as in Mersky et al. (2016); Holdway et al. (2010); Samaras and Meisterling (2008). Our focus is rather on the outcomes of the strategic actions of the governments and the producers in a context in which the prices of the cars differ according to the income of the people, and the perceived disutility of pollution emitted. ...
Full-text available
We consider a model in which local firms produce differentiated vehicles: Electric Vehicles, Hybrid Vehicles, and Internal Combustion Engine Vehicles. The government chooses the level of public policy (tax) imposed on pollution to maximize welfare. The model is set on a two-stage game. At the first stage, the government determines the tax level on pollution taking the firms’ output levels as given. At the second stage, firms, competing in an oligopolistic market, choose their output and emission levels observing the tax level set by the government. It is found that a high perception of pollution damage encourages the setting of a pollution tax despite the fall in the consumer surplus and the profits of Internal Combustion Engine Vehicles producers; this policy encourages the production of Electric Vehicles and Hybrid Vehicles. Otherwise, the government is not willing to set a severe pollution policy.
... They will generate even lower emissions when generating electricity from renewable energy sources such as wind power. A plug-in hybrid electric vehicle (PHEV) combines of fossil fuel and electricity, equipped with a battery, electric motor, fuel tank, and IC engine (The U.S. EPA, 2022;Holdway et al., 2010). The International Energy Agency (The IEA, 2021a) reported that 6.85 million EVs were sold in 2020, increasing to 30 million by 2025 and 45 million by 2030. ...
This study aims to develop a mathematical model to encourage electric trucks and charging stations by providing tax incentives and subsidies in Indonesia. This study contributes to research on tax incentives and subsidies due to the need for more research on optimizing the optimal number of electric trucks and charging stations based on cost trade-offs for diesel and electric trucks. We consider carbon emission caps to limit the number of diesel trucks. This study examines the types of electric and diesel trucks consisting of multiple brands with these types of trucks. Total cost is formulated as the total investment cost of the electric truck and charging stations, the cost of operating and maintenance, diesel truck investment cost, carbon cost, and operation cost of charging stations. A numerical example and sensitivity analysis are illustrated to verify the proposed model and provide managerial insight for government and industry. The results show that a tax incentive of 36.0% without subsidies will not attract to purchase of electric trucks. In contrast, when incentives reach 36.5% to 40.0% and various subsidies ($1,000 to $25,000), then electric truck skyrocket. In the year 2030, it is expected that about 477 trucks will be on the road in Indonesia and requiring the addition of 360 and 103 regular and fast charging stations, respectively.
... Although emissions from traffic are high, and reforestation does not always absorb all the greenhouse gases emitted, reforestation and good road design are currently the best tools for reducing and offsetting emissions related to this sector (Ying et al. 2019). Another excellent option for reducing traffic emissions is to promote the use of electric vehicles, provided that energy is produced from renewable sources, to avoid burning fossil fuels, which would indirectly affect global emissions (Holdway et al. 2010). In urban areas, as in this case, it could also be of value to calculate what the buildings could absorb (Li et al. 2021) if green roofs were used as a standard urban planning practice in the area. ...
Full-text available
Carbon dioxide emissions linked to the transport sector are of particular relevance on islands. In the case of the Canary Islands, there is a high level of tourism, with tourists who generally travel in rented vehicles upon arrival in the archipelago. In addition, mobility of the local population in the islands is also always growing. Thus, transport is one of the sectors that emits the greatest amount of greenhouse gases. In this sense, the net carbon balance becomes a pioneering study in the framework of management of high‐capacity road transport routes and will help plan new strategies which pursue the neutrality and climate resilience of the road network. It will therefore be possible to design different future scenarios, according to traffic intensities detected, to mitigate their local effects by increasing green areas which will contribute to greater absorption. This study calculated the carbon footprint linked to vehicles on the three high‐capacity roads on the island of Tenerife, as well as the carbon footprint of the public lighting attached to these roads. The absorption of carbon by vegetation planted by the Road Service and the soil located on the margins of the road have also been calculated, in order to explore the possibility of modifying the vegetation, using other types of local shrubs and trees that have a higher absorption factor. The results show that conifers have the highest absorption factor, the Canary Island pine being the best option in this case. However, it is not always possible to locate trees on the roadside, and it is necessary to resort to smaller species. This study concludes that better mobility planning, an increase in electric vehicles, improved energy production from renewable sources, and the promotion and enhancement of absorption capacity of carbon sinks are key in the face of climate change. Key Points This study is a pioneering one in the Canary Islands, as it attempts to determine the emissions from the main roads on the island of Tenerife, which is the most populated and largest island in the Canary Islands archipelago. This article is protected by copyright. All rights reserved. Integr Environ Assess Manag 2022;00:0–0.
... Reducing carbon dioxide emission is necessary to stop the increase of the Green House Effect. Using electric mobility might be a promising way to reach this goal ( Holdway et al., 2010 ). To support the acceptance of ecological transportation solutions, it is essential to investigate the relevant psychological predictors for sustainable behavior and the precursors of behavioral change, such as attitudes, intentions, and trait mindfulness. ...
Full-text available
In these times of intense political debate about climate change, it is more important than ever to understand which factors are central to adopting environmentally friendly behavior, like buying an electric car instead of a conventional one. The stage model of self-regulated behavioral change (SSBC) offers a promising explanatory approach in which explicit attitudes, which are connected to factors such as mindfulness, play an essential role. So far, the role of implicit attitudes regarding environmental behavior was neglected in this model. Accordingly, the present study investigated if the (goal) intention to buy an electric car can be predicted by established variables like explicit attitudes, personal and social norms, and the perceived usefulness of electric vehicles and implicit attitudes. Besides, it was investigated if attitudes depend on socio-demographic variables and mindfulness aspects. For this purpose, 168 participants completed questionnaires and performed an explicit rating and an implicit affective priming task with pictures of electric vs. conventional cars. The results showed that while explicitly, electric cars were rated more positively, implicitly, this difference could not be shown. Furthermore, mindfulness was not significantly associated with attitudes or goal intention. However, goal intention was significantly predicted by explicit and implicit attitudes, personal norms, and perceived usefulness, while explicit attitudes mediated the last two variables. Accordingly, we concluded that implicit attitudes should be integrated into existing models of behavioral change and further predictors need to be identified.
Full-text available
Transportation plays a significant role in the global economy and society and takes part in a lot of different processes such as mass transportation and the supply chain. Therefore, it is crucial to introduce modern technologies in this area of the economy in the context of Industry 4.0. The main scope of this study is to develop a model that supports analyzing last-mile logistics modern solutions using the latest technologies such as road autonomous delivery robots (RADRs), civil drones, or smart bikes, and compare them to conventional solutions (delivery vehicles). Multi-criteria decision analysis (MCDA) was applied to build a formal comparison model that scores the solutions and weights different criteria according to decision-makers and placeholders, to rank the solutions from the most crucial option to the weakest in a predetermined scenario with set parameters and conditions (three varied scenarios were included in the present investigation). The results of the model were in favor of using civil drones or smart bicycles to perform light deliveries in small urban areas (these key findings support the assumptions that are often manifested in speech in the context of the use of new technologies). The modern solutions scored almost 40–80% higher in total in the conglomeration of assessment criteria (such as safety, economy, laws and regulations, operation time for the delivery, environment, and payload) than the conventional solution, which indicates the importance of studying the implementation of such technologies. An interesting result of the study is the operational cost reduction by ca. 60–74% in favor of autonomous delivery robots, 89–93% in favor of civil delivery drones, and 87–90% in favor of smart bikes vs. conventional delivery trucks/vans. Yet, it should be underlined that the results may vary with different assumptions within the MCDA method.
Full-text available
The United States faces energy shortages and increasing energy prices within the next few decades (Duncan, 2001). Coal, petroleum, natural gas, and other mined fuels provide 75% of U.S. electricity and 93% of other U.S. energy needs (USBC, 2001). On average, every year each American uses about 93,000 kWh, equivalent to 8000 L of oil, for all purposes, including transportation, heating, and cooling (USBC, 2001). About 12 kWh (1 L of gasoline) costs as much as $0.50, and this cost is projected to increase signifi cantly in the next decade (Schumer, 2001).
All advanced industrialized societies face the problem of air pollution produced by motor vehicles. In spite of striking improvements in internal combustion engine technology, air pollution in most urban areas is still measured at levels determined to be harmful to human health. Throughout the 1990s and beyond, California and France both chose to improve air quality by means of technological innovation, adopting legislation that promoted clean vehicles, prominently among them, electric vehicles (EVs). In California, policymakers chose a technology-forcing approach, setting ambitious goals (e.g., zero emission vehicles), establishing strict deadlines and issuing penalties for non-compliance. The policy process in California called for substantial participation from the public, the media, the academic community and the interest groups affected by the regulation. The automobile and oil industries bitterly contested the regulation, in public and in the courts. In contrast, in France the policy process was non-adversarial, with minimal public participation and negligible debate in academic circles. We argue that California's stringent regulation spurred the development of innovative hybrid and fuel cell vehicles more effectively than the French approach. However, in spite of the differences, both California and France have been unable to put a substantial number of EVs on the road. Our comparison offers some broad lessons about how policy developments within a culture influence both the development of technology and the impact of humans on the environment.
The transportation industry is a major contributor to greenhouse gas and pollutant emissions. Of particular significance is the fleet of private vehicles powered by internal combustion engines utilizing petroleum-based fuels. The subject project was initiated to develop methodology to assess the impact of vehicle fleet electrification on electric power generation and global environmental change. While vehicle electrification will reduce vehicle emissions, the recharging energy will be generated at utility generation sites where emissions will increase. The project included a case study for Alabama. The vehicle emissions fleet model is based on the EPA software mobile5a and employs Alabama Department of Transportation data as inputs to the case study. Electric vehicle penetration effects on vehicle emissions are computed by linear scaling of the base-case emissions. Power plant quarterly emission data from the EPA were employed in the case study for the State of Alabama. Values for feedstock and fuel emissions were taken from greet1.5 to complete the fuel cycle calculations. In the 10% EV penetration Alabama case study, all light-duty vehicle emissions are reduced by 10%, and the total (light-duty vehicle and utility) emissions for the principle greenhouse gas CO2 were altered by −1.79%. Emissions for NOx and SO2 were altered by −4.37%, and +1.44%, respectively.
The paper provides an overview and comparison of Greenhouse Gas Emissions associated with fossil, nuclear and renewable energy systems. In this context both the direct technology-specific emissions and the contributions from full energy chains within the Life Cycle Assessment framework are considered. Examples illustrating the differences between countries and regional electricity mixes are also provided. Core results presented here are based on the work performed at PSI, and by partners within the Swiss Centre for Life-Cycle Inventories.
Conference Paper
The emissions of logically competing mid-1990 gasoline vehicles (GVs) and electric vehicles (EVs) are estimated as if the vehicles were driven in the same pattern of driving. Six different driving cycles are evaluated, ranging in speed from 7 to 49 miles per hour (mph). These steps are repeated using specifics of fuel composition, electric power mix, and environmental conditions applicable to Chicago, Denver, Los Angeles, and New York in the month of July. The year 2000 emissions differences for each of four regulated pollutants - HC, CO, NO[sub x,] SO[sub x] - are estimated. CO[sub 2] emissions are also estimated. With use of EVs, HC and CO emissions are consistently lowered by 98% or more. CO[sub 2] emissions reductions are uniformly large at low speed, but variable at high speed. It is found that initially introduced EVs could achieve 100% emission reductions in Chicago by using off-peak power from nuclear power plants for EV electricity generation. Emissions reductions occur for all combinations in Los Angeles, and for most combinations in New York, excepting SO[sub x]. NO[sub x] emissions are reduced in all four cities. An avoided cost'' value for each regulated pollutant is estimated for each of the cities. The values for each city depend on severity of air quality violations. It is estimated that the emissions reduction value of EVs driven an average of one and one half hours per day in Los Angeles ranges from $1050 to $3,900; $590 to $2100 in New York; $270 to $1200 in Chicago, and $330 to $1250 in Denver (1989$). Assuming a range of about 100 miles in congested conditions with speeds of 10 mph or less, the estimates range from $3600 to $13300 for Los Angeles; $2004 to $7200 for New York; $930 to $2930 for Chicago; and $1120 to $4290 for Denver. Low estimates are obtained using EPA's draft Mobile5 model for GV emissions, high values by using California's EMFAC7EP-SCF1 model. The dollar value benefit estimates include no economic value.
A number of recent studies have examined the greenhouse gas emissions of various light duty vehicle alternatives in some detail. These studies have highlighted the extreme range of predicted net greenhouse gas emissions depending on scenarios for fuel types, vehicle and power generation efficiencies, the relative greenhouse contributions of emitted gases and a number of uncertainties in fuel chain efficiencies. Despite the potential range of results, most studies have confirmed that electric vehicles generally have significant potential for reducing greenhouse gas emissions relative to gasoline and most alternative fuels under consideration. This report summarizes the results of a study which builds on previous efforts with a particular emphasis on: (1) A detailed analysis of ICEV, FCV, and EV vehicle technology and electric power generation technology. Most previous transportation greenhouse studies have focused on characterization of fuel chains that have relatively high efficiency (65--85%) when compared with power generation (30--40%) and vehicle driveline (13--16%) efficiencies. (2) A direct comparison of EVs, FCVs with gasoline and dedicated alternative fuel, ICEVs using equivalent vehicle technology assumptions with careful attention to likely technology improvements in both types of vehicles. (3) Consideration of fuel cell vehicles and associated hydrogen infrastructure. (4) Extension of analyses for several decades to assess the prospects for EVs with a longer term prospective.
This article summarizes a report to the California Institute for Energy Efficiency on The Impact of Electric Vehicles on the Southern California Edison System. It begins with a review of previous studies of electric vehicles and their impact on the electric utility. It then describes the assumptions adopted for eight scenarios with large scale use of electric vehicles in southern California. The article then explains the likely impacts of these vehicles on Edison's electric loads, its system operation, its total revenue requirements and its average electric rate. The study confirms that electric vehicles can lead to improved load shapes, improved efficiency of operations, and a possible reduction in the average electric rate. But there are unexpected results as well. First, the Edison's resource plan could accommodate an unusually large number of electric vehicles if the vehicles are powered by advanced batteries and their charging is subject to smart control. And second, the rate benefits of electric vehicles can be partially erased by an increase in Edison's payments to private cogenerators who sell power on marginal cost contracts. The article concludes with an analysis of the reduction in tail pipe emissions if electric vehicles were to displace conventional vehicles in southern California.