Cars are not compatible with reducing carbon emissions

Posted at — Mar 24, 2022

For many people, their imaginations of how the climate crisis will be resolved begin and end with Elon Musk’s Tesla. The idea is that we’ll all switch over to electric cars, eliminate the CO2 emissions associated with gas-powered cars, and as a result reduce global emissions enough to avert disaster.

Setting aside the fact that only about 16% of global CO2 emissions come from road vehicles1, it turns out that battery production is so carbon-intensive that electric vehicles do not on their own do anything about reducing emissions.

We can deduce that there are 3 options (1, 2a, 2b) for humanity.

  1. Do not reduce CO2 emissions to near zero at any point in the future.
  2. Cease operation of the vast majority of gas-powered cars and either a. Battery production will be revolutionized to emit nearly zero CO2 (down from at least about 2.4 tons of CO2 to produce a Nissan Leaf-sized battery) b. Cease almost all production of new cars.

We argue as follows.

If we never reduce CO2 emissions to near 0, we are in option 1, and so we are done. So suppose that we do in fact reduce emissions to near 0 by year Y.

The total amount of CO2 emitted by car production and usage in a given year is at least

$$ #(\text{EVs produced per year}) \cdot \text{CO2 emitted by producing avg. EV}

Therefore, if we want to avoid option 2b and maintain current levels in either production and operation of cars, we must reduce both of the quantities in the above sum to near 0. We show that the only way this can be achieved is with a dramatic revolution in battery technology. Once we have demonstrated this, it is clear that the options 2 and 3 are exhaustive (i.e., one of them will occur).

Clearly the second quantity, “CO2 emitted by existing ICE road vehicles”, can only be reduced to near zero by reducing the operation of existing gas-powered cars, so this result is present in both the 2a and 2b worlds.

The quantity “CO2 emitted by producing avg. EV” is greater than the CO2 emitted by producing just the battery, so the total emissions for EV production is at least

$$ #(\text{EVs produced per year}) \cdot \text{CO2 emitted by producing avg. EV battery} $$

According to a 2019 analysis, current lithium extraction and battery production processes result in at least 61 kg CO2 emitted per kWh, even “when the energy used from battery manufacturing comes from zero-carbon sources”.

The lowest range Nissan Leaf has a 40 kWh battery. Therefore, producing the battery for a modest electric car currently emits at least $40 \text{kWh} \cot 61 \text{kg CO2} = 2.44 \text{ metric tons CO2}$. About 67 million cars are sold per year globally.

Under the assumptions at this point in the argument, in the future world we are considering, these would all have to be electric cars. Therefore, we can estimate

$$ #(\text{EVs produced per year}) \cdot \text{CO2 emitted by producing avg. EV battery} $$

as $67 \text{ million} \cdot 2.44 \text{ metric tons CO2} =

So, we conclude that producing the average electric car battery (under current methods of production) results in at least 2.44 metric tons of CO2

a fraction

  1. See this section of the IPCC report. 23% of global emissions were due to transport and 70% of these came from road vehicles. 23% of 70% is 16.1%. ↩︎