Thread by @AukeHoekstra

It's unfortunate that @ADAC published the conclusions from a deeply flawed study saying natural gas is better in terms of CO2 than electric vehicles. This is wrong!

In reality break even with CNG is after 24-63k km.
With diesel after 11-40k km.

Let me show you. (thread)

https://twitter.com/ADAC/status/1165944431276695553

@ADAC irresponsibly published the conclusions before publishing the study itself but we can reverse engineer the most important assumptions using this result graph.
As you can see producing an EV (E-Auto) emits around 7 tonnes of CO2 more than a combustion car according to @ADAC.

If you realize producing a diesel or gasoline engine emits 1 tonne more than an EV drivetrain, this means for the battery production they assume 8 tonnes of CO2 is emitted. That means they assume producing a ~250kg battery emits more than producing the rest of the vehicle...

Looking at energy use of gasoline and diesel variants it seems they have taken a Golf. The eGolf has a 36 kWh battery. If that cost 8 tonnes to produce that means 8000/36= 222 kg per kWh. In reality it is by now closer to 65 kg per kwh. That's 3x less!!
sciencedirect.com/science/articl…

I have no idea where they got the 222 kg per kWh number. Maybe they ignored the combustion drivetrain difference (which is wrong) and took a 50 kWh battery (which is big for the compact class) to arrive at 140 kg/kWh but that would still combine an error with an outdated number.

The second big issue I see is emissions during the lifetime of the EV. If you once again assume an eGolf it uses around 0.18 kWh per km including charging losses (fueleconomy.gov/feg/Find.do?ac…).

Now in the graph we see the EV emits 38 tonnes of CO2 after 225000 km. Subtract the production of 12 tonnes and divide by 225000 and you get 115 gram per km. Divide that bij 0.18 kWh/km and you get an electricity mix of 640 gr/kWh.

That is wrong for two reasons. First of all it's pretty high. Even Buchal and Sinn in their misguided attempt to make the diesel green put the German mix at 550 gr/km. innovationorigins.com/no-diesel-is-n…

Secondly, electricity emits less CO2 every year so your EV gets greener as it drives longer. My estimate over the lifetime of the EV in Germany is 375 gr/kWh. innovationorigins.com/no-diesel-is-n…

Now let's look at the combustion cars. Diesel emits 39t after 225k km and costs 6t to produce. So that's 33t after 225 km or 147 gr/km. Knowing that producing and burning diesel causes 3.2kg CO2/kWh that means the diesel uses (3.2/0.147)x100 = 4.6 liter/100km.

That is another classic mistake: take the numbers from the brochure instead of energy use in the real world. spritmonitor.de puts the golf diesel at 5.8l and the EPA puts it at 7.3l. So you can quarrel about the number but 4.6l is brochureware, not reality.

For gasoline the error is similar. For CNG the error is lower but still substantial. Using spritmonitor.de (4.24l) CNG emissions would be 130 gr/km. A lot less than the diesel but still much more than the EV.

Now let's establish after how many km the EV overtakes the combustion variants.

The eGolf battery costs 65 kg/kWh x 36 kWh = 2.4t to produce. The drivetrain costs 1t less so it starts 1.4t behind.

If we average the energy use over de lifetime of the eGolf, emissions per km are 375 gr/kWh x 0.18 kWh/km = 68 gr/km.

For the Golf diesel, let's say 6l/100km leading to 192 gr/km. That's 124 gr/km more.

For CNG 62 gr/km more.

If we divide 1400 kg (the eGolf disadvantage) by 0.124 kg/km (the eGolf advantage) we would be break even with diesel after 11k km. NOT 219k km. That's 20x less!

For CNG it's 23k km. NOT more than 300k km. Still more than 10x less.

To summarize:

Outdated sources (probably) lead to 2-3x too high battery emissions.

Ignoring the electricity mix progression over the lifetime doubled the eGolf emissions per km.

Taking brochure instead of real life emissions mean diesel emissions should be 25 to 60% higher.

I don't know how to sugarcoat this so let's just say I'm disappointed in @ADAC. I hope to get the details of the study soon but I thought it was important to debunk this before everybody copied the conclusions before the study came out.

Are there not caveats from my side? Yes there are.

The eGolf has a smallish battery: you could enlarge it to 50 kWh. You could assume 100 kg CO2/kWh for battery production on pure coal. But you would still break even with diesel at less than 40k km. With CNG within 64k km.

Oh and one final thing: I'm going to bed now (busy day tomorrow) and lot's of people will be retweeting the @ADAC study in an attempt to disparage the EV.

If you see that: please attach this thread to the tweet so curious readers can see my counterargument.

Thank you!

@ADAC PS I missed the fold-out below the table (thx @WolbertusR): I could have saved myself some time. Fortunately my reverse engineering based on the graph was close.
Biggest open question: what are the sources for the exaggerated impact of battery production?

https://twitter.com/hanseric/status/1166244914096758789