Originally written to the 2012 National Greenhouse Emissions Factors tables and first printed in edition 120 of ReNew.
Revised and updated for ReNew edition 143 (2017) and most recently ReNew 159 (Apr-Jun 2022). Latest version reflects the 2021 National Greenhouse Emissions Factors tables.
It is now ten years since I first put together an analysis for Renew on how much greenhouse gas EVs (electric vehicles) driven in Australia cause as they drive. The initial answer was that in all the states and territories (except Victoria), EVs produced fewer greenhouse emissions than those produced by driving an equivalent petrol car. (In fact, even in Victoria it was a bit less if you only drove in the city – which the short-range EVs of the time were only likely to do!)
A big feature of that that analysis was just how much of a difference which state/territory you lived in made, as each state and territory uses very different mix of coal types and renewable sources.
I repeated the exercise five years later for edition 143 – and it became apparent then that as each grid moves towards including more renewable energy sources, the emissions from driving an EV decline faster than the improvements offered by the incremental improvements in ICE (internal combustion engine) design.
Since then, both here and around the world such analyses have been the subject of reasonable questioning (as well as a not inconsiderable amount of disinformation being put about) as to whether these results are robust. As a result, the last few years have seen many scientific papers and government reports on the topic written around the world – all backing up that EVs running on almost any grid will produce fewer emissions that an equivalent ICE vehiclea. (See also ‘further reading’ at end of this article).
For this update, I will look at three questions:
- Now it is 2022, have EV greenhouse driving emissions improved any further versus an equivalent ICE vehicle?
- Do EV the lifetime emissions of EV manufacture and use stack up against ICE vehicles?
- How do hybrids compare?
How well does an EV stack up in Australian greenhouse emissions versus an equivalent ICE vehicle?
First-up: I need to make the point that it is a mistake to directly compare new car petrol/diesel windscreen sticker CO2 emission numbers to EV electricity use emissions numbers – this is not an ‘apples-with-apples’ comparison. Petrol/diesel windscreen stickers only show the direct CO2 emissions from the fuel burnt. They do not include the emissions due to extracting, refining, transporting and delivering that fuel to the car. They also do not include the greenhouse effects of gasses other than CO2. On the other hand, EV emissions data generally includes the warming potential of all the known greenhouse gasses, plus a lot of the downstream grid emissions – meaning comparing the two is not a true ‘well-to-wheel’ comparison of EV to ICE (Internal Combustion Engine). Graph 1 does give that comparison. The data is from the Australian National Greenhouse Accounting Factors (produced annually by the department of Industry, Science, Energy and Resources) and the calculations were made using the carbon emissions accounting methodology specified in that document.
Graph 1: State/Territory CO2-e for 10,000 km. EV versus EV.
Comparison of full driving emissions for 2022 EV (Hyundai Kona electric) vs 2022 ICE (Toyota Corolla)
Excitingly, now that the Victorian grid has progressed in reducing its overall emissions I can now finally say that in ALL cases, a new EV will produce fewer greenhouse emissions that an equivalent new ICE vehicle! Plus, given that ICE vehicles have improved their emissions over the years (Graph 2), replacing an older ICE with a new EV will make an even bigger difference.
Graph 2: Full CO2-e for 10,000 km for 2012 Toyota petrol Corolla versus 2022 petrol Corolla.
The reason for this improvement in EV emissions? As can be seen in graph 3, in the last ten years all the states and territories have reduced their grid greenhouse emissions. (Although some have done better than others: Queensland being the stand-out failure with its emissions stuck at 0.92kg per kWh since 2015).
Graph 3: Full CO2-e per kWh for each state over the last 10 years (
Note: data correct as of the article dates. The department does make retrospective amendments to the NGA tables, therefore the historical data given in the 2021 tables differs slightly to this graph.
Do EV the lifetime emissions of EV manufacture and use stack up against ICE vehicles?
Having an EV produce fewer driving emissions is one thing – but does the inclusion of the emissions produced making the EV drivetrain (battery, motor and control electronics) negate that benefit?
Again – numerous studies have now come out to say this is not the case. EVs generally repay that manufacturing ‘debt’ within a fairly short period, depending on the annual distance travelled. In Europe, based on the average European electricity grid emissions, it has been calculated the payback period for the battery manufacture is two years of driving, with an overall 50% less life-cycle CO2-e produced over the first 150,000 kmb. In the US, where cars generally do higher mileages, that payback period is around six to sixteen monthsc. Graph 4 is taken from a UK study that estimated manufacturing and driving emissions as the grid moves towards being fully renewably sourcedd.
Graph 4: CO2/km for EVs using the UK grid 2010 – 2050. Source: ICCT.
How do hybrids compare?
I often get asked about whether hybrid electric vehicles (HEVs) are a good choice in the current period before BEVs (full Battery Electric Vehicles) reach affordable prices. The debate about what improvements they offer in terms of greenhouse emissions (as well as urban air pollution) is however severely hampered by the lack of clear data on their actual emissions.
Unfortunately, many of the vehicle consumption figures found for HEVs in the Australian Green Vehicle Guide still use the older NEDC test cycle that has been superseded in Europe, where it became largely discredited and replaced by the WLTP test cycle. (For more detail on this topic, see Renew edition 155).
As a result, the figures for HEVs in the Green Vehicle Guide are generally unrealistic and quite unachievable, just as the NEDC figures for EVs were. European WLTP test figures for the equivalent Corolla hybrid are more realistic, but significantly higher than NEDC. (The Green vehicle Guide figure for the Corolla HEV is 3.5L/100km, yet the WLTP figure is 5.3L/100km). This makes it hard to compare realistic figures for ICE and HEV as they are not being rated on the same system. Whilst it may be worth avoiding the mis-match and swap from the Australian figures to use overseas WLTP figures for the Kona electric, ICE Corolla and HEV Corolla, the ICE Corolla sold here is no longer sold in Europe as it does not meet the Euro 6C fuel and emission standards. (In fact, the one here only meets the much older Euro 5 standard – a good example of how the dumping of more inefficient and polluting older tech vehicles is already happening here). As a result, no apples-with-apples comparison is available.
Another confounding issue is these test cycle fuel economy figures are highly variable for HEVs, depending on how closely your trips reflect the test cycle. This is because the battery in a HEV is generally quite tiny. (For the Corolla HEV, it is only 1.4kWh!). The closer your mix of driving type and length of trip matches the test cycle, the closer you will get to the test cycle figure. The further you are from the trip defined in the test cycle, the more fuel you will use in comparison. All-in-all, HEVs have a very narrow use-case for meeting the expectations created by the test cycle figure.
However, to give some idea of whether HEVs are potentially a viable alternative, I have made a rough estimate in Graph 5 using the average WLTP figures for the HEV Corolla and Kona electric and the Green Vehicle Guide figure for the ICE Corolla. (Note, under the European WLTP test cycle, the Corolla HEV L/100km is listed as varying from a low of 4.4 to a high of 6.5).
Graph 5: Tonnes CO2-e per 10,000km for Kona on national grid average, ICE Corolla (city and combined) and HEV Corolla
As can be seen from Graph 5 – the HEV Corolla rated on the more reliable WLTP test cycle is an improvement on greenhouse emissions from the petrol version, but it is not as large as an EV already offers. This is also based on the use case for the HEV being close to the WLTP test cycle conditions. Outside of that, its greenhouse emissions figure will increase. On top of that, local air pollution from the HEV’s tailpipe is not eliminated as it is from a BEV.
References:
- Smit, Whitehead and Washington, 2018. Where are we heading with electric vehicles, Air Quality and Climate Change, V52, No.3, September 2018, 18 – 27.
- Effects of battery manufacturing on electric vehicle life-cycle greenhouse gas emissions. https://theicct.org
- Union of Concerned Scientists. 2015 report: Cleaner Cars from Cradle to Grave How Electric Cars Beat Gasoline Cars on Lifetime Global Warming Emissions http://www.ucsusa.org/sites/default/files/attach/2015/11/Cleaner-Cars-from-Cradle-to-Grave-full-report.pdf
- DRAX report. 2019. How clean is my electric car? https://www.drax.com/opinion/how-clean-is-my-electric-car/
Further reading:
Union of Concerned Scientists: Top Five Reasons to Choose an Electric Car https://www.ucsusa.org/resources/top-five-reasons-choose-electric-car
Climate Council report: Waiting for the Green Light: Transport Solutions to Climate Change. 2018. https://www.climatecouncil.org.au/resources/transport-climate-change/
Australian Vehicle Emission Standards: https://www.infrastructure.gov.au/vehicles/environment/emission/index.aspx
Electric Vehicle Council report, State of electric vehicles, August 2021:
https://electricvehiclecouncil.com.au/reports/state-of-electric-vehicles-2021/