Electric Vehicle Emissions vs Diesel

A look at whether or not our family buying an EV would be good or bad for the environment.

• 18 min read

In the following post I take a look at the claim that greenhouse gas emissions from the manufacture of electric vehicle (EV) batteries negates any significant environmental benefit EVs have over diesel. I do this by applying it to our family's use of cars and discover that the claim is false and there is in fact a large emissions reduction with EVs over diesel for our situation.

I've heard grumblings about EVs in the same way I've heard grumblings about renewable energy generators like wind and solar. Australia's Prime Minister Scott Morrison declared before the election last year that the opposition party's EV policy would "end the weekend" for Australians:

"it’s not going to tow your trailer. It’s not going to tow your boat. It’s not going to get you out to your favourite camping spot with your family". — Scott Morrison on EVs, 7 April 2019

Well, I don't own a trailer or boat or go camping Scotty, so there!

I'm not writing this to examine those claims by the Prime Minister, they've been debunked in many articles at the time and are obviously false. It does however highlight that opposition to EVs is not restricted to your local right-wing news outlet and indeed the Australian government is publicly anti-EV.

The saddest commentary on the Prime Minister's statement was this one a couple of weeks ago:

The weekend is only ruined if you hate looking at dead animals and plants.

There are plenty of "aren't environmentalists dumb memes" related to EVs such as:

Coal fired electric cars. Helping liberals pretend they're solving a make believe crisis.
But I was planning to only use organic activated-(char)coal electrons ethically sourced from free-range mines!

Even Australian federal MPs including unbelievably* the Minister for Emissions Reduction get in on it:

(*it's not that unbelievable if you're even vaguely aware of Australian politics)

It's funny because the driver parked on the wrong side of the bowser.

Or sticking with the charge-by-diesel theme:

EVs running on black gold, Texas tea, just the way Al Gore intended.

This particular charging point is in the middle of the Nullarbor between Perth and Adelaide. It's nowhere near as ridiculous as you might expect.

That's all fun but what I'd like to do is examine the following claim which I saw as a Facebook post from a family member a week or two ago. It's from the United Kingdom's Daily Mail (5 February 2020):

Old bangers can be greener than electric cars, says JOHN NAISH
Wireless electric car charging network will be installed in Britain from 2020. Connected Kerb will be the future of cars and driving in the UK, with electric charging stations and solar panels on every street to support the climate - while driving.
EVs are bad, mmmmkay?

One of the conclusions from the article's author is that it's not environmentally sensible to purchase an EV over an internal combustion engine (ICE) today in 2020 and will still be an environmental failure relative to ICEs in 2033 (just before the recently moved-forward ban on ICE passenger vehicles in the UK in 2035). The primary cause is said to be the emissions of the battery during manufacturing, something a comparable ICE vehicle does not have.

"The situation is even worse with electric cars. A Swedish-government report says that making the battery alone releases as much CO2 as eight years' worth of driving a petrol vehicle."

Similar claims about embodied emissions are made all the time against solar and wind, and I know they're a load of crap, but this I wasn't sure about.

Why do environmentalists hate the environment?
Well weird green philosophy dino, it's because I'm a low-intelligence smug asshole, obviously.

There is nothing particularly special about this opinion piece, it's just the one that popped up in my Facebook feed. There are numerous articles and commentators making similar claims, all seem to be based off the same sources, or similar scenarios.

The Daily Mail opinion piece appears to be based around this study published in 2019. There have been other studies with similar EVs are worse than ICEs conclusions, and even car makers like Mazda have arrived at a similar answer on their own. The German study which I've linked to has triggered the production of lots of material online like this:

Driving a Tesla results in more CO2 emissions than a Mercedes diesel car. New German study proves electric cards don't reduce carbon dioxide emissions at all!
Are we the baddies?

I find these types of images particularly worrying. They spread with ease on social networks, the message is conveyed quickly and reinforces biases. It takes posts like this one filled with charts and technical terms requiring 15 minutes of reading to explain why a single image is wrong. Just including these memes here could easily do more harm than good. But it's also worse than that.

Several cognitive processes can cause people to unconsciously process information in a biased way. For those who are strongly fixed in their views, being confronted with counter-arguments can cause their views to be strengthened. — Debunking Handbook

Thanks to the Worldview Backfire Effect this post in attempting to show why the claim is false could equally do more harm than good.

There are plenty of reasons to favour an EV over an ICE that are unrelated to the environment such as performance, handling, driving costs, maintenance costs, reduced noise, less pollution and simple things like leaving home "with a full tank". I'm going to ignore those and focus on a single aspect, greenhouse gas emissions, specifically carbon dioxide.

As an "inner-city raving lunatic leftie greenie" is it reasonable in 2020 for our family to buy an EV with the intention to lower emissions?

One of our two diesel cars is 12 years old and is nearing end-of-life therefore an EV purchase might be on the cards in the next few years. The claim that EVs are worse is vaguely plausible at first glance and is a far more serious claim than "an EV cannot tow your boat" which can be disproved with a simple real-world demonstration. Is it true that EVs are worse for emissions than an ICE vehicle? As I said, I didn't know the answer when this popped up in my Facebook feed so I've decided to calculate the answer for my own situation.

The studies linked above have a common structure of comparing high-emission electricity grids, battery manufacturing in high-emission environments, a short lifetime for the battery and the availability of very low-emission diesel ICEs, all which favour the diesel.

There are a lot of variables that go into determining the emissions cost of running an EV vs ICE but for this I'm focussing on the variables that apply to our family. I'm not an expert in this field and I only started researching a week ago so it's a crude analysis and ignores a number of factors but I think it's still valid and answers the question I'm asking.

Tesla Model 3
Tesla Model 3

I suspect that if we purchased an EV today it would probably be a Tesla Model 3, although the price is still a bit high for my liking. The analysis presumes we purchase a Model 3 Long Range, or carry on with a similar efficiency diesel.

Our average driving distance per year over the last decade is around 17000 to 25000km. I'm picking 25000km as our annual driving distance. It's the new normal where we now live - 20000km is the low value based on work travel alone.

We live in the state of Queensland in Australia which is a high-emissions electricity grid, primarily powered by black coal. Emissions over the last 15 years averaged 812gCO2/kWh, which is quite bad.

Queensland Energy Production by Source with Emissions Intensity
Queensland Energy Production by Source with Emissions Intensity

Our current primary diesel car uses around 7-8L/100km with highway driving and significantly more in non-highway driving. If we use either the diesel or EV for 10 years what exactly are our emissions?

For all subsequent charts I'm using the following:

  • I'm using 8L/100km as the consumption for diesel, with emissions of 211.18gCO2/km driven.
  • Lifetime is defined as 10 years
  • Distance driven per year is 25000km

The EV is definitely lower on emissions per kilometre, even when powered by a high-emissions grid, however this ignores the manufacturing emissions of the battery which is the complaint of the study and one of the complaints of the article.

The IVL study puts the EV battery manufacturing embodied emissions at somewhere between 150 and 250kgCO2eq/kWh of battery capacity. There is a lot of criticism of these values as high, e.g.:

Some put the figure closer to 65kgCO2eq/kWh (and falling with economies of scale and use of renewable energy sources during manufacturing). To start with in this analysis I've been very generous towards the diesel and used the mean of the IVL study, so 200kgCO2eq/kWh. I've also not included any emissions cost for the production and transport of diesel.

The Model 3 I picked has a 75kWh battery. Let's take a look now:

It's a lot closer now, and you could start to see why the claim could be made that EVs are higher emissions than diesel. Assign a high manufacturing emissions level, lower the distance per year, reduce the lifetime, ignore the production emissions of diesel, increase the efficiency of the ICE or power from higher emission intensity electricity and you're probably looking at higher emissions on the EV column.

Not all regions have high-emission electricity grids like Queensland. For example here is Tasmania, Australia

Tasmania Energy Production by Source with Emissions Intensity
Tasmania Energy Production by Source with Emissions Intensity

Over the last 15 years the average emissions intensity for Tasmania is 25gCO2eq/kWh, that's pretty good.

Let's take the last graph which compares an EV including battery manufacturing emissions and add in low-emission electricity for charging the EV in Tasmania and charging it entirely from renewables (like our rooftop solar).

Increasing renewables as a source for the EV significantly improves the outcome in favour of EVs and in all cases the EV pulls ahead within the 10 year lifetime. As a reminder these figures for the EV include the battery manufacturing emissions of 200kgCO2eq/kWh of battery capacity. If we use the lower and likely more accurate estimate for this (65kgCO2eq/kWh of capacity) we end up with:

There are significant differences emerging between the EV and diesel. For a look at the break-even points for "paying off" the embodied emissions of the battery (in the 200kgCO2eq/kWh of capacity scenario) we have the following:

And for the 65kgCO2eq/kWh of capacity scenario we have:

That's not 8 years. When large manufacturing emissions are assumed and the electricity grid is high-emissions it does get closer, but we should neither expect not tolerate the electricity grid to remain high-emissions over the next decade. Victoria (another state in Australia) had an average emissions intensity of 1028gCO2eq/kWh over the last 15 years, however over the last 12 months that is down to 830gCO2eq/kWh due to increasing renewable generation and the retirement of brown coal generators.

Victoria Energy Production by Source with Emissions Intensity
Victoria Energy Production by Source with Emissions Intensity

South Australia has been transitioning away from fossil fuels at an even faster rate as you can see below.

South Australia Energy Production by Source with Emissions Intensity
South Australia Energy Production by Source with Emissions Intensity

The lifetime emission figures for EVs also ignore that EV batteries are likely to be recycled or reused in a different context after the EV end-of-life (e.g. home batteries), therefore even in the high-emission grids the payback need not be limited to the lifetime of vehicle.

For my situation it's not 8 years, it's ~1 year to payback the embodied emissions of the battery manufacturing (with the 65kgCO2eq/kWh of battery capacity scenario) and over 10 years approximately 27 metric tons lower on emissions vs diesel.

Even if you take the article as factual, 8 years is a long time only if you've been led to believe EV lifetime is limited by its battery and that limit is around 10 years. There is mounting evidence to suggest this is a low estimate.

The data clearly shows that for the first 50,000 miles (100,000 km), most Tesla battery packs will lose about 5% of their capacity, but after the 50,000-mile mark, the capacity levels off and it looks like it could be difficult to make a pack degrade by another 5%.
Chart showing battery capacity vs distance driven with average line starting at 100% at 0km and ending at 90% at 275000lm
But my phone battery only lasts a year?

Tesla suggest you can expect 1500 cycles on the battery. For the Model 3 Long Range that's around 830000km of range at 90% capacity for the entire lifespan. Tesla also suggest the body of the Model 3 is designed to last around 1.6 million kilometres.

In a few weeks from now Tesla has a Battery and Powertrain Investor Day event where it is expected significant improvements to battery lifespans will be announced.

“The new battery pack that is probably going to production next year is designed explicitly for 1 million miles of operation.” — Elon Musk, April 2019

Body, drive unit and battery all rated for 1.6 million kilometres. Even if these numbers are off by a lot EV lifespans are going to be quite different to ICE vehicles.

Another ancillary claim of the article was that charging the EV at home will "destroy" the grid. I've seen this claim before and have also seen it criticised in a few places. The average daily consumption by an EV for our use is 8kWh and our home solar system has 19.8kW of panels on a 15kW inverter (without export limiting). This daily consumption equates to around 40 minutes of solar generation at peak (our yearly average daily generation is 100kWh, peaking at 135kWh).

This level of consumption is hardly an imposition and certainly less than a single Tesla Powerwall 2's capacity. 8kWh is approximately 30% of typical household energy usage where we live (4 person household with a pool - figures from here). For another comparison, 8kWh is equivalent to 1.3 hours of my home's air conditioner running.

I was discussing today with my wife what our charging routine would be if we owned an EV. We concluded it would likely be a larger charge on Saturday during the day rather than small increments at night after driving to/from work. With a maximum power draw of 11kW with the Tesla home charger, we're not going to be importing from the grid for the bulk of our charging.

What I hope will happen, and it seems certain that it will, is allowing EVs to act as a battery backup for your home, with EVs to exporting to the grid during times of peak usage to smooth out demand and charging when the grid has excessive renewable generation capacity. EVs are already starting to support this type of behaviour but they also need a government and electricity sector willing to support it.

Another claim made is that diesel ICEs will be more efficient in 2033 further negating any possible benefit of EVs. Will diesel be a better choice after mythical efficiency improvements in 2033? Highly doubtful. Engines would need to be nearly 8-10 times more efficient than today, so ~0.8L/km to match an EV in Tasmania, or infinitely better to match being powered from my roof (and we also decarbonise the production/transport of diesel).

Back here in the present, it's possible I've been overly generous to diesel in the emissions figure of 211.18gCO2/km as there is some evidence that well-to-tank emissions of diesel are higher than previously recognised and total emissions are actually around 3310gCO2/L (264.8gCO2/km at our 8L/km usage) once WTT is taken into account. If we plug this into the 10 year charts we have:

And now we're down to ~9 months to payback the battery manufacturing emissions vs diesel.

So in summary, it depends on where you live, how much you drive and how accurate the emissions calculations are but the premise of the article is almost certainly false for both low and high-emission grids and absolutely false where the EV is powered from renewables. It takes using a high-range estimate for battery manufacturing cost, a generously efficient diesel and a high-emissions grid to favour the diesel over the EV.

I'm sure there are issues with my calculations and I'm not taking into account many things like losses during charging. I doubt there is anything missing that is significant enough to alter the outcome. If you do notice something though, let me know.

If you're just getting the EV to reduce emissions and haven't put solar panels on your roof then you're likely making the wrong decision by a wide margin, at least when you live in a part of the world that is well suited to solar power. Our rooftop PV system over 10 years offsets approximately 282 metric tons of CO2 (presuming the grid emissions do not decrease). This is in comparison to the 27 metric tons reduction from choosing an EV instead of a diesel over the same timeframe. If you've already filled your roof/hit distributor limits then go ahead and get an EV when you planned to replace your current car, today in 2020 let alone 2033.

Are we buying an EV now? No. As much as I'd like to have one, our secondary car hasn't stopped working and it's fine for now. In a couple of years I hope to see the price of EVs reduce further after which we will consider getting one, be it a Model 3 or something else.