Debunking the Caterpillar meme

Have you seen this meme?

Let’s start with what is true: this indeed IS a Caterpillar 994-series excavator used in the mining industry.

Before we start dissecting the many falsehoods included in this short meme, let’s take what it says at face value and follow through.

Burning 1 liter of diesel fuel produces 2.7 kg of CO2 (source), so in 12 hours of work our “toy” excavator spews 2,7 tons of CO2 to dig enough Lithium for one battery.

How long will such a battery run? Well, the battery of my electric car is guaranteed for 160.000 km, which is a typical value, so we can assume (unless OEMs are suicidal) that this is the bare minimum mileage a battery is expected to last. During these 160.000 km an average diesel car would produce at least 24 tons of CO2 (assuming 150 g/km, which is rather conservative and certainly not characteristic of a car which can make nought-to-one-hundred in less than 5 seconds), while the electric car would consume around 27.000 kWh causing emissions which vary from country to country, but taking the EU average of 300 g/kWh (source) we can calculate another 8 tons of CO2.

To sum up:

  • the ICE will produce 160,000 * 150 = 24 tons of CO2
  • the electric car will produce 27,000 * 300 = 8,1 + 2.7 = 10,8 tons of CO2 per year

Whoever thought up the meme, therefore, didn’t think it through carefully, because it actually demonstrates that the electric car EVEN WITH THE MEME’S DATA, cuts emissions by 55%.

But wait, it gets better

However – as I hinted before – there is plenty of false information in the meme, so let’s run the numbers again, this time using real data.

First of all, a Cat994 24hr tank contains a whopping 5,700 liters of diesel fuel (source), so we can assume its consumption for 12 hrs to be around half that, producing 7.7 tons of CO2.

Now, how much Lithium is actually needed for a battery? As you can see, regardless of the chemistry of the cathode, we need about 1 kg of Lithium for every 10 kWh of capacity. Again let’s take the worst case, i.e. the biggest battery in the Tesla range (100 kWh), for which therefore we’ll need 10 kg of Lithium.

Mind you, Lithium hard rock extraction happens essentially only in Australia, as everywhere else it is extracted from natural brines, a much gentler process that does not require excavators AT ALL. Moreover “spent” batteries can be completely and economically recycled, but we’ll not bother with such minutiæ.

The ore containing Lithium is called Spodumene and in the Australian mines, it carries a waste-to-ore ratio ranging from 6:1 to 10:1 to obtain ore whose Lithium content is about 6% (source).

So, to obtain the 10 kg of Lithium needed for our battery we will have to move 10 * 10 / 6% = 1.7 tons of rock.

The bucket of the Cat994 has an average capacity of 40 tons, depending on the options (source), so if each round trip lasts, say, 20 mins, in the 12 hours we are considering, this monster moves 1,440 tons of rock, or enough material to build 1,440 / 1.7 = 847 of the biggest Tesla batteries, bringing the Lithium mining-related emissions of a single battery to 7.7 / 847 = 9 kg of CO2.

To sum up again, this time with the correct numbers:

  • the ICE will still produce 160,000 * 150 = 24 tons of CO2
  • the electric car will produce 27,000 * 300 = 8,1 + 0,009 = 8,01 tons of CO2 or, if you prefer, 67% less!

These memes are not the work of stupid haters, but come straight from a campaign whose objective is to discredit the electric car; your guess is as good as mine as to who the authors of the campaign could be.

If there is little we can do to stop misinformation, we can avoid helping it, by double checking what we share.

2 thoughts on “Debunking the Caterpillar meme

  1. In your calculations, I am wondering if there is not some mixing between the various kind of lithium (Li, Li2O, LCE…).
    Would be helpful to clarify this point!

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