Plug in Prius - Most Environmentally Friendly Vehicle in Study

Keep in mind automotive battery packs can still be used after the end of their automotive usefulness.
It looks like Tesla may be using theirs as grid level storage at some of their supercharger stations.
GM is trying out a program to make use of old Volt packs as home backup batteries.

The manufacturing cost of the batteries should be spread out over the lifespan of the batteries, not just the time it is used in the EV.

As for Tesla's warrantee, mine will end up covering about 160,000 miles at my current driving patterns.

 

El

Elon Musk is a man of his word and will stand behind the warranty. He has the financial reserves to back him up.

DBCassidy

 

Makes me wonder if anyone has ever tried this with a Prius battery.

 

The LEAF uses the same or slightly more power at highway speed than the Volt but is more efficient at stop/start city driving due to lower weight.

As for comparing the Volt to a regular Prius, the 7-11 Volt/Prius results showed at 79% EV I was emitting 21 pounds CO2e per 100 miles using PG&E's average emissions per kWh and GREET gasoline emissions. A PiP on the same commute at the maximum EV I could manage (31%) was 30 pounds. A regular Prius would probably be around 41 pounds at 60 mpg with my driving style.

Assuming my 21 in the Volt and the 41 pounds per 100 miles in a regular Prius on my commute I would be able to pay back the Volt's nominal battery CO2 manufacturing debt of 7,677 pounds within 40,000 miles. Obviously, I will do better at the 85-90% EV I'm now targetting with my new workplace charging. Even better when PG&E lets me sign up soon for their new 100% renewable power plan at home.

I've just started to look at this report but one thing I noticed right away was that they think the LEAF has a Lithium NMC battery. It actually has a Lithium Manganese ("M") battery with some Nickel sprinkled in for energy density. Manganese is common (it's the basic element in regular Alkaline batteries) and is presumably easy and cheap to mine. Nickel is harder to mine (I think) and especially Cobalt. I wonder how much this inflated their estimate of the LEAF CO2 debt, if any?

It's even worse for the Volt since they think the Volt has a Lithium Iron Phosphate battery (lower energy density) and so they appear to erroneously assign the Volt battery an extra 26% CO2 penalty. A footnote says a 24 kWh Iron Phosphate battery would take 14,488 pounds CO2 to manufacture vs. 11,516 pounds for the 24 kWh LEAF battery (see printed page 25 or 29 in PDF). Actually, the Volt battery is roughly similar to the LEAF battery chemically (Lithium Manganese with some Nickel and Cobalt pixie dust). That's a substantial and rather embarrassing mistake. One wonders what harder tasks they screwed up.

 

I like him. And he's fully behind Tesla. But, if/when the company sells LOTS of cars and if there were a major problem with massive recall costs I doubt he'd voluntarily go personally bankrupt before the company went under. And I wouldn't expect him too. And I doubt it will ever happen. Tesla is a public company...I wouldn't expect him to pitch in extra money any more than any other shareholder. And they have insurance for this kind of thing, I would suspect.

Mike

 

Okay, I have a real job and I need to get back to doing it, but here are a few more things I noticed about this study beyond all of the good points made by others earlier:

Look at Table 9 on page 25. They break out several large components of the car and account for the CO2 by scaling them against chosen "standard" car values. The Electric Car uses values from the 2013 LEAF.



They appear to assess an overall CO2 manufacturing debt based on the total curb weight of the vehicle. Presumably this accounts for the structural steel of the body etc. However, they calculate this against the full weight even though they separately break-out and account for the engine, motor, and battery pack. Since much of the weight in an EV-centric car comes from the large battery pack I think this means they are double-counting the carbon debt of the batteries.

They account for the carbon debt of the gas engine by scaling based on HP relative to a conventional gas engine. This undercounts the carbon debt for a Prius-like hybrid because they are using the Atkinson cycle HP of the engine which is lower. For the example of the Prius in Table 9 they use 98 HP but the Otto-cycle version of the Prius engine is rated at 134 HP and almost certainly has an identical carbon manufacturing impact.

They account for the carbon debt of manufacturing the electric motor but for Prius-like hybrids they are counting only the larger of the two similar motors. They count 107 HP for the LEAF but only 80 HP for the Prius when it also has a smaller 35-40 HP MG. The Prius motor should be counted for carbon debt purposes as around 120 HP.

The Prius entry in Table 9 estimates a curiously smaller value for "other Powertrain". Why would this value be so much smaller than either the LEAF or a conventional gas car?

The biggest problem, however, is battery manufacturing accounting. It's a big mess. Let's count the ways:

1. They think Lithium Iron Phosphate batteries are 26% higher in carbon debt per kWh. The primary study they depend on says Iron Phosphate batteries are about 5% higher (Hawkins, et al. page 5) and other studies say Lithium Iron Phosphate might be a bit lower carbon intensity.

2. They wrongly think the Chevrolet Volt uses Lithium Iron Phosphate cells.

3. They base their battery carbon debt on a study of Lithium NMC cells even though almost no production cars today use real NMC.

3. DING! DING! DING! They fail to tell you that the underlying study they rely on (Hawkins 2012) for the battery manufacturing carbon debt uses values than are 3.6 and 2.3 times higher than other recent studies.

According to the Hawkins paper:

The Hawkins paper (and therefore the Climate Central report) uses the high estimate from Majeau-Bettez (since he is one of the authors of the Hawkins paper). The Notter study (the lowest estimate) specifically evaluated the detailed life cycle global warming carbon impact of Lithium Manganese cells which are the closest match to the actual cell chemistry used in the LEAF and Volt.

The Climate Central report should have highlighted the wide disparity in carbon debt calculations between these papers and explained why they chose to use the highest and rather outlying result. A more honest report would have acknowledged that this is a new area of study and the results have not settled in to a consensus yet. A better approach would be to use a median of the several study results like the LCAWorks synthesis below.

The next step is to redo the Table 9 calculation for the LEAF, Volt, and regular Prius with more sensible numbers based on the criticism above.

UPDATE:

See Plug in Prius - Most Environmentally Friendly Vehicle in Study | Page 6 | PriusChat.

Sources:
I managed to find an accessible copy of the Hawkins, Notter, and Samaras papers outside of the usual journal pay walls.

Dunn:
Impact of Recycling on Cradle-to-Gate Energy Consumption and Greenhouse Gas Emissions of Automotive Lithium-Ion Batteries - Environmental Science & Technology (ACS Publications)

Hawkins:
Comparative Environmental Life Cycle Assessment of Conventional and Electric Vehicles - Hawkins - 2012 - Journal of Industrial Ecology - Wiley Online Library

Samaras:
http://solar.gwu.edu/index_files/Resources_files/LCA_for_PHEVs.pdf

Notter:
http://www.evconversion.co.nz/wp-content/uploads/files/Li-ion-batteries-environment.pdf

Battery Life Cycle Analysis Synthesis
http://www.lcaworks.com/EV%20Lit%20Rev%20FINAL.pdf

Climate Central
http://assets.climatecentral.org/pdfs/ClimateFriendlyCarsReport_Final.pdf

 

Um, yes, it's deeply flawed. I declare it useless and void. It needs a do-over.

 

I would also add that while they work at coming up with all sorts of GHG for the batteries, they ignore the GHG in shipping and producing the gasoline.

 

Notice that in over half of the states shown in table 7 where the plug-in Prius is first, it is not available from a local dealer!

 

Well, they did not ignore - see first paragraph in page 23 (27 of PDF).

 

Saw this just today and thought it very timely and spot-on for this thread:
Electric Cars Are Cleaner Today and Will Only Get Cleaner Tomorrow | Max Baumhefner's Blog | Switchboard, from NRDC

 

Reading the text (page 30 of pdf) it seems they have not given a 1.26 penalty to the volt battery (or any other vehicle they though having LiFePO4 chemistry)

We scaled the battery
manufacturing emissions in Table 9 by the ratio of the
battery capacity of the car of interest divided by the
Electric Car battery capacity in Table 9.

 

Look closer... On page 29 of the PDF in the small text under Table 9 it says:

If you look at Table 9 you will see that they did, in fact, scale the Prius NiHM battery to be 1.8 times their nominal NMC number. What makes you think they didn't also do a special scaling for FePO4 which think is 1.26 times their nominal NMC cell number and which they think is used by the Volt and the BMW Active 3? Table 9 shows a 24 kWh NMC battery as being 11,516 lbs CO2e but for FePO4 they are using 14,488.

 

One more problem with the study. It says:

However, a SCE study said that 80% of EV charging in their area is done at night. It is a well known fact that peaker plants (used in the peak afternoon time) are less efficient (thus more CO2). Maybe this is just another few percentage change in the overall mix. But when you add up all the errors, they are mostly dis-favoring EV usage in this study. I admit that for each assumption they make it can make the calculations much easier. But they should estimate the possible difference for each simplifying assumption. Maybe it is 1% difference...maybe 4 or 5%.

Mike

 

I repeat myself, but I still cannot get over the 2012 coal use data. Very interesting.
We do need to ask if the study is valid or too many errors?

FWIW I have reported the data to the local environmental group.
Enviromental groups here plaster Virginia as an eco-villain, with give high praise to Maryland.
But the data show VA down to 20% coal and MD still at 43% coal. Of course, MD talks a more eco-friendly talk.

 

The LCAWorks report takes 200 kgCO2/kWh as a median of several studies. This study takes for the Leaf 218 kgCO2/kWh. Not far away...certainly not a factor of 3
Agree they had to acknowledge this is a new area of study with no consensus yet.

 

Yes, coal use study is very concerning.

DBCassidy

 

Prius already is being used as a home battery backup during power outages.

This is nothing new, using a hybrid as a emergency power source.
GM is trying to play catch up.

DBCassidy

 

Where is it flawed: is it because the Volt did not make the top 5? or is it the Prius is consistently in the top 5?

DBCassidy

 

I haven't had time to look at it carefully yet but I should be able to take a look within another day or two.