3 ms·
They say that is a "cradle-to-gate" analysis, which means it covers the cost from gathering resources through manufacturing up to the point it leaves the factor
by tzs 3y ago
They say that is a "cradle-to-gate" analysis, which means it covers the cost from gathering resources through manufacturing up to the point it leaves the factory.
Consider an EV with a 75 kWh battery pack. Using their numbers that would be 2318 kg of CO₂ to make that battery. If the battery lasts 1000 full cycles that would be 75000 kWh of energy produced.
Amortizing that 2300 kg of CO₂ over that gives 0.0303 kg CO₂/kWh discharged.
A typical EV gets about 4 miles per kWh, so that's about 0.0076 kg of CO₂/mile driven.
A gallon of gasoline releases 8.8 kg of CO₂ when burned. Given an ICE car that gets 40 miles/gallon that's 0.22 kg CO₂/mile.
That's 29x as much CO₂ per mile as the EV.
Instead of amortizing, and assuming clean electricity, the EV costs 2318 kg CO₂ upfront for its equivalent of a gas tank but has 0 CO₂ operating cost. The ICE has negligible CO₂ cost for its gas tank up front, but costs 0.22 kg CO₂/mile operating cost.
Breakeven for the EV vs the ICE is at 10300 miles. For the average American that's about 9 months worth of driving.
PS: I took a look at non-clean electricity. Electricity from coal or petroleum burning power plants is about 1 kg CO₂/kWh. An EV gets about 4 miles/kWh so that's about 0.25 kg CO₂/mi if you charge your EV with 100% coal or petroleum based electricity. Slightly worse than a 40 mpg ICE car.
The US average is around 0.4 kg CO₂/kWh electricity, which would give 0.11 kg CO₂/mi to operate an EV. That's about 2x the cost of the 40 mpg ICE.
Note that the above is ignoring the CO₂ costs of producing the gasoline. Brief Googling suggests that is somewhere from 1.5-3 kg CO₂/gallon from well to gas pump, which would raise the cost of buring a gallon of gas from 10.3-11.8 kg CO₂/gallon, or by 17-34%.
That would make the EV slightly better than the ICE when powered from coal or petroleum plant electricity, and 2.3-2.7x better when powered by average US electricty, and 34-39x better when powered by clean electricity.
- seanmcdirmid 3y agoDoes refining oil into gas have a CO2 cost?
- tzs 3y agoAlmost certainly. A more thorough comparison would need to take that into account. It would also want to consider electricity generation because not every place has 100% clean electricity. But if all one is trying to determine is whether 30.3 kg/kWh cradle-to-gate cost of batteries is enough to bring EV cars up to anywhere near the CO₂ cost of ICE cars for a typical use case the ICE car uses way more without taking making the gas costs into account so there is no need to go farther. I've updated the original to include a look at the case of non-clean electricity and to consider the CO₂ cost of producing gasoline.
- duskwuff 3y agoAbsolutely -- both in terms of the energy cost of refining and in direct emissions from the process. Extracting crude oil, transporting it to the refinery, and transporting the resulting gasoline to the gas station all have substantial carbon costs associated with them as well.
- biomcgary 3y agoThanks for this detailed computation. I think the increase from 2.5x better (current US electric) to 35x better (clean electric) illustrates the value of providing daytime charging infrastructure that utilizes solar.
- brnt 3y agoThe preexisting term for this sort of analysis (and deeper) is well-to-wheels analyses. The aim is to account for any externality.
- jandrese 3y agoWhy do these sorts of studies always measure the cradle-to-grave CO2 output of EVs to only the CO2 released per gallon of gas in the ICE? Very rarely do you see the studies that include factors like CO2 released in extracting, shipping, and refining the oil in the first place. The CO2 released when fighting wars in foreign countries to insure access to said oil. The CO2 released in making the ICE car in the first place and all of those supply chain issues like people always bring up with EVs and renewable power systems.
- Retric 3y agoIn part because crude oil is used for many different things so it’s not as clear exactly what the gasoline specific emissions numbers are. Roughly speaking 50% is a good estimate, but it varies quite a bit based on your assumptions. Similarly the gasoline lifecycle + ICE engine, gas tank, and transmission should be compared to the battery + electric motors + electricity not just the battery vs gasoline.
- nomel 3y agoI imagine the ICE and EV body is relatively similar. The extra metals found in an ICE engine probably aren't that much greater, considering all the extra support/casing requiring for the batteries/weight. It would be interesting to see the numbers.
- deleted 3y ago[deleted]