Do electric cars emit half the CO2 as diesel from a life-cycle perspective?

Question

From The Guardian:

"On average, electric vehicles will emit half the CO2 emissions of a diesel car by 2030, including the manufacturing emissions,” said Yoann Le Petit, a spokesman for the T&E think tank, which commissioned the study.

-"Electric cars emit 50% less greenhouse gas than diesel, study finds" (2017-10-25)

Is it true that electric cars pollute 50% less than diesel from a life-cycle perspective?

Answer 1

Summary: I found numbers from University of Cologne (2010) which together with production-related emission numbers spread out over a number of German newspaper articles are in agreement with the claim.

There is large uncertainty caused by uncertainty about the development of renewable energies in relation to increasing e-mobility and also somewhat on conditions for battery production, though.

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Sorry: all but the book chapter link go to German language sites

http://www.zeit.de/mobilitaet/2014-01/elektroauto-energiebilanz compares a VW Golf (gasoline, 169 g CO2/km*) with a Nissan Leaf (e-vehicle, 2014 German e-mix 106g CO2/km; both taking numbers from real-world gasoline tanking/charging data collections) saying that production of battery takes about 125 kg CO2/kWh, for the Leaf about 3t CO2 for battery production. OTOH, the rest of the car needs less, so production of the car incl. battery 2,74 t CO2 more for the e-car. That is, after 28000 km they are about equal in their CO2 emission. Unfortunately no absolute values for the production of the whole cars are given (only the difference).

However, lifetime of an e-car battery is cited as 80000 / 100 000 - 160 000 km So we may say: in addition to the 106g CO2/km for electricity we have another 19 - 38 g CO2/km (18 - 36 %) for battery production.**

So with these numbers, the current (2014ish) state is the Leaf producing 74 - 85% of the CO2 emissions of the gasoline car according to the numbers from the Zeit, with the CO2 emissions from the fuel consumption collections below, e-vehicle and diesel car cause about the same CO2 emission.

(The Geo article refers to a "Swiss study" (no further details given) saying that assuming a lifetime of 150.000 km, a maximum of 15 % of the total environmental pollution for an e-vehicle (production, use, dismantling) is for the battery.)

Richter & Lindenberger: Elektromobilität als CO2-Vermeidungsoption - Ergebnisse einer aktuellen EWI-Studie, e|m|w 4, 2010, p. 20-22 (pdf available at University of Cologne) which refers to this book chapter(which I don't have access to) give current e-vehicle as emitting 75 % of the CO2 compared to a similar diesel (2010). And give a graph of projected development which for 2030 projects the diesel to emit ca. 10 % less CO2, and the e-vehicle improving by about 50 %, leading to in 2030 the e-vehicle having emissions in the range of 40 - 50 % of those of the diesel - which even if battery production needs to be added would be rougly around half of the diesel's CO2 emissions. I note though, that their explanation of well-to-wheel calculation does neither list production of the vehicle nor the battery for the e-vehicle.

An important point in their discussion is that depending on how the electricity market, the CO2 emission certificate market and electricity production develop, there may be no CO2 savings at all or any CO2 not emitted by conventional cars is truly saved. After all, if you have enough renewable energy, you can use that also for battery production - note that a former Tesla manager is about to build a battery factory in Sweden where comparably low amounts of fossil fuel are used - while LG Chem is building another battery factory in Poland who at the moment have coal being 80 % of primary energy production.

This recent newspaper article says the projections for battery production are particularly difficult as the CO2 balance depends largely on a lot of factors such as

• where and how the raw materials and battery are produced
• battery size and lifetime
• possible secondary use as stationary buffer for photovoltaics and recycling

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* https://www.verbrauchsrechner.de/ (https://www.spritmonitor.de) list Golf VI gasoline with an average of 6,93 (7.22) l/100 km (161 - 168 g CO2/km) and diesel with 5,19 (5,55) l/100 km (137 - 147 g CO2).

Note also that for combustion engines, the fuel consumption varies easily by more than a factor 2 depending on driving style and type of route. E-vehicles have different behaviour in terms of acceleration/deceleration, so that these influences have different effect on energy consumption compared to combustion engines. E.g. e-vehicles can be much better in start-and-stop situations, but also there recuperation depends on driving style.

This puts natural limitations on conclusions - though less on a car-to-car comparison than on projections including population behaviour (which are needed for the CO2 emission for energy mix and renewable energy projections).

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** These numbers do not account for possible savings due to recycling. And they cannot, as they are guesstimates (according to the Zeit article, by IFEU not numbers by battery producers) for the current state of the art in battery production. AFAIK, currently no medium- or large-scale recycling facilities for e-vehicle batteries are in operation, so real-world numbers for current state of the art are not available. I found only some older newspaper articles referring to a pilot plant for e-vehicle battery recycling that was to be built by last year IIRC. However, I did not find news relating to an operational pilot plant. The FAZ article linked above says that there's currently too much uncertainty in use and recycling scenarios to get useful (reliable) predictions. There's a number of things that can and may be done, but already what would be sensible (as possibly opposed to what is actually done) seems to depend rather sensitively on technical circumstances (for the whole e-vehicle concepts).

E.g. (my thoughts/questions)

• Would it be better to have easily exchangeable car batteries, allowing
  • super-fast "recharging" by exchange for a full battery, and thus
  • be able to charge most car batteries on surplus renewable energy when that is available?
  • (on a per-household basis or at "battery stations" like we do it when buying gas bottles)
  • That would also allow e-vehicles with usually comparably low battery capacity (50 or 100 km for typical daily commute use etc.) that for long distance drives plug in a high-capacity battery and exchange it say, every 300+ km - or charge it on a e-highway), i.e. from a macro-economic perspective, less total battery capacity may be sufficient and/or better surplus renewable charging may be achieved.
  • While that sounds appealing, does it make sense given the cost (also energy-wise and raw material-wise) of producing more batteries?
• There are concepts under discussion to "downgrade" old car batteries (< 70 % of original capacity) and use them as stationary buffers for a while before recycling the batteries.
  But that's probably going to be a competing technology to the battery exchange concept above.