We all know Auke Hoekstra from his relentless struggle for correct, verified data about electric driving. He often writes about it at Innovation Origins. Recently he had a fierce discussion with Belgian professor Damien Ernst, who claimed that an electric car only becomes ‘greener’ than a petrol car after 700,000 kilometres. Nonsense, Hoekstra demonstrates. That turning point comes after only 20 to 40,000 kilometres – and in the near future even after only 7,000 kilometres. He neatly recapitulates the facts in a long blog post. Here’s the summary for Tomorrow is Good.
I show how in Europe, an electric vehicle becomes greener after 20 to 40 thousand kilometres of driving, not 700 thousand as a famous Belgian professor calculated on television recently. He has corrected his calculation in a new blog post but in such a confusing way that I feel the need to explain. I also show that in science facts are still facts and Damien Ernst and I actually agree about them: we don’t live in a post-truth world!
At the core of this discussion is the following problem: electric vehicles emit less CO2 while driving, but they need a battery and producing that battery emits more CO2. How bad is this battery compared to the driving advantage? Two weeks ago the famous and impressive prof. Damien Ernst (Blondel Medal winner, working on supergrids that help to solve the energy transition) calculated – on Television – it would take more than the lifetime of the electric vehicle (697,612 km to be precise) for the electric car to compensate for the global warming caused by battery production.
How bad is battery production?
CO2 emitted during battery production causes global warming. Ernst first claimed 312 kg CO2 was emitted for every kWh of battery produced. He now estimates 127 kg. Industry experts put it at 65 kg and it will become less when batteries are produced using renewable energy.
How dirty is electricity?
CO2 emitted during electricity production causes global warming too. For reasons unexplained, Ernst first assumed Belgian electric vehicles drive on German electricity (550 grams/kWh). He now takes the EU mix over the coming ten years that he pegs at 317 grams per kWh. I can explain why he actually means 289 grams.
Don’t forget the production of gasoline
In his first calculation, Ernst forgot to include the CO2 emissions caused by the production of gasoline. He now includes this and it increases gasoline car emissions by 40%.
How much energy do electric and gasoline vehicles use?
For reasons not explained, Ernst decided to compare a large electric vehicle with a small gasoline car. Ernst takes an electric vehicle that outputs 0.23 kWh/km and compares it with a gasoline car using 6 liter per 100 km. I have made a little comparison of the energy use of different vehicles on the site of the American Environmental Protection Agency to show how strange this is. (I use American numbers because the official numbers in Europe are wrong because of the car lobby.)
As you can see 0.23 kWh/km equates to a Tesla Model X: a large SUV. A direct comparison would be a Porsche Cayenne: a bit smaller and slower but close. So a comparable gasoline vehicle would use 11.28 liters per 100 km.
Instead, Ernst compares to a car using 6 liter per 100 km. That’s less than a VW Golf with a small motor and manual transmission.
Ernst’s new conclusion is hard to find
Drawing a conclusion from all this is straightforward. But Ernst is apparently confusing many readers if I see what they say on Twitter and in newspapers. They think the answer to his calculations can be found under the heading: “And now the calculation!” But at that point in his post, the Belgian/European cars still drive on the coal-heavy German electricity mix (?) while the production of gasoline is still excluded (?). It is not clear to me why you would display the results of these faulty assumptions so prominently.
He says that an electric vehicle with a battery of 80 kWh would begin to have a lower carbon footprint than a petrol-driven vehicle somewhere between 67,226 km and 151,259 km travelled. What Ernst is saying in the lower number is: if I correct my mistake of forgetting gasoline production, if battery production is close to my corrected source, if I assume the European electricity mix is not getting cleaner and if I compare a very big EV to a small gasoline car, then the EV is greener after 67,226 km. The higher number says the same but assumes battery production emits 225 kg CO2/kWh without naming any source.
If you find this confusing: I was confused too.
Using Ernst’s corrected numbers, a large EV becomes greener than a small gasoline car after 81 thousand km. If you compare like with like the EV becomes greener after about 35 thousand km. Using the best information I have available, I would put it at 19 thousand now and 7 thousand in the future.
It’s not rocket science. Let me show you.
If we multiply 127 kg CO2/kWh and 80 kWh we get (and I quote Ernst): “10,153 kg for the manufacture of an 80 kWh battery.” I round Ernst to 10,160 kg of CO2 for the production of the battery.
EV emissions while driving
0.23 kWh/km multiplied by 289 grams/kWh means 66 grams of CO2 per km for the EV.
Gasoline car emissions while driving6 liter/100km multiplied by 3.192 kg of CO2 per liter means 192 gr CO2/km for the gasoline car.
The EV emits 192 – 66 = 125 gr CO2/km less than the gasoline car. 10,160/0.125 = 81,248 km.
So after 81,248 km, a Tesla Model X is gaining on a small gasoline car using Ernst’s assumption
That was scenario 1 in the table below. But we can also make some other interesting scenarios.
Scenario 2. We could compare the Tesla Model X with a car his own size. Then the Model X is greener than his counterpart (we took the Porsche Cayenne) after 35 thousand km.
Scenario 3. We could compare an electric VW Golf with a gasoline VW Golf using the assumptions of Ernst to get electric is greener after 41 thousand km.
Scenario 4. Again comparing eGolf against gasoline Golf using Ernst his new assumptions but battery production according to the best official sources. This gives 35 thousand km.
Scenario 5. These are my best guess assumptions: battery production based on industry estimates of someone I trust and CO2 emissions over the lifetime of the EV based on mainstream assumptions. Then I get about 19 thousand km before the EV is greener.
Scenario 6. This is the future I’m doing it all for. Mining and production of batteries will use renewable electricity and electric cars will drive on renewable electricity. When that happens they will become greener after 7 thousand km and less than that if the battery was recycled.
Electric cars are really much better for the climate than gasoline or diesel cars, even according to the new calculations from prof. Damien Ernst and certainly according to the most up-to-date information.
PS: I hope everyone understands that video conferencing, electric bikes and trains are better for the environment than large cars, whether electric or not.
About this column:
In a weekly column, alternately written by Maarten Steinbuch, Mary Fiers, Carlo van de Weijer, Lucien Engelen, Tessie Hartjes and Auke Hoekstra, Innovation Origins tries to find out what the future will look like. The six columnists, occasionally supplemented with guest bloggers, are all working in their own way on solutions for the problems of our time. So tomorrow will be good. Here are all the previous episodes.
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