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Ford, LG Chem team reports 1st cradle-to-gate LCA for mass-produced battery pack in commercial BEV; cell manufacturing key GHG contributor

A team from Ford’s Research and Innovation Center and LG Chem’s Corporate R&D group has reported the first cradle-to-gate (i.e., the factory gate—before delivery to the consumer) emissions assessment for a mass-produced battery in a commercial battery electric vehicle (BEV)—the lithium-ion battery pack used in the Ford Focus BEV. Their paper is published in the ACS journal Environmental Science & Technology.

The researchers based their assessment on the bill of materials and energy and materials input data from the battery cell and pack supplier (LG). They calculated that the cradle-to-gate greenhouse gas (GHG) emissions for the 24 kWh Ford Focus lithium-ion battery are 3.4 metric tonnes of CO2-eq (140 kg CO2-eq per kWh or 11 kg CO2-eq per kg of battery). Cell manufacturing is the key contributor accounting for 45% of the GHG emissions.

Extending the system boundary to include the entire vehicle, they estimated a 39% increase in the cradle-to-gate GHG emissions of the Focus BEV compared to the Focus internal combustion engine vehicle (ICEV), which falls within the range of literature estimates of 27–63% increases for hypothetical non-production BEVs.

A number of LCAs [life cycle assessments] have been conducted to understand the benefits of electric mobility. Most studies have focused on the vehicle use phase, particularly on the grid mix that powers PHEVs and BEVs as it is a key determinant of emissions and energy use. However, it is important to also include the environmental impact of electrified vehicle (EV) powertrain production especially the traction battery which is energy intensive to produce. Energy use and greenhouse gas (GHG) emissions associated with EV battery production are not well established.

—Kim et al.

The battery pack in the Focus Electric consists of 430 cells with a nominal voltage of 3.7 V and has a specific energy of 0.08 kWh/kg. LG Chem in South Korea provides the cells, while Piston Group in Michigan manufactures the final pack.

Master.img-003
Cradle-to-gate GHG and criteria pollutant emissions per kWh of Focus BEV battery. GHG emissions associated with the use of utilities in cell manufacturing account for 45% of the GHG emissions— i.e., 64 kg CO2-eq/kWh. battery Credit: ACS, Kim et al. Click to enlarge.

The cradle-to-gate assessment covers battery materials production, cell and component manufacturing, and battery pack assembly, including transportation.

The cathode material is a mixture of LMO/NCM, which is combined with solven, binder and conductive carbon to make a cathode slurry. The anode uses an aqueous slurry system, and combines the active material graphite with a mixture of styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC). The slurry mixtures are coated and dried onto aluminum and copper current collectors.

Cathodes and anodes are assembled in stacks, separated by a ceramic coated polyolefin separator, and tabbed. The electrode stacks are packaged into laminated aluminum pouches and injected with electrolyte. Most of the electrode production and cell assembly operations are housed in a dry room with stringent air filtration requirements.

Cells are cycled and stored at different temperatures during the formation step and, after degassing and resealing processes, the formed cells are tested before being shipped out for pack manufacturing.

Pack manufacturing combines the cells and the balance of battery (electrical system including sensors, battery management system (BMS), thermal management system, and enclosure) into the final pack.

Cell materials account for 55% of the total mass; electrodes and collectors represent 73% of the cell mass. Steel used mostly for structural integrity and battery enclosure comprises 30% of the total mass. Plastics and composites (8%) are used in the enclosures and module components while nonferrous metals such as copper and aluminum alloys (3%) are used for the electrical architecture (bus bars, wiring etc.) and thermal management system. The BMS which consists of printed circuit board, electronics, and wiring harness accounts for the remaining 4% of the battery mass.

Running second to cell manufacturing as a leading contributor of GHG emissions, producing and manufacturing the cell materials and components including cathode, anode, current collectors, electrolyte, separator, and pouch materials accounted for 19% of the GHG emissions. Module and pack enclosures, electrical system wiring and components, and thermal manage- ment system account for 22% of the cradle-to-gate GHG emissions.

Similar to GHG emissions, cell manufacturing, cell components, and battery enclosure dominate criteria pollutant emissions, accounting for 82%−92% depending on pollutant.

Master.img-005
Cradle-to-gate GHG emissions for ICEVs and BEVs from different studies, including the current Ford/LG work. Credit: ACS, Kim et al. Click to enlarge.

Despite their higher cradle-to-gate GHG emissions, switching from ICEVs to BEVs potentially saves a large amount of GHG emissions during their life cycle. Published studies have estimated approximately 30−40% life cycle GHG emissions reduction for BEVs powered by the average US or European electric grid mix.

Using our GHG estimate for BEV battery production, 11 kg CO2-eq/kg battery, in place of those in the literature gives an estimate of 31−37% life cycle GHG benefits for BEVs over gasoline ICEVs. Our results confirm the potential for BEVs to curb GHG emissions from the transportation sector.

Current trends of increasing vehicle energy efficiency, decreasing burdens associated with battery production, decreasing burdens for electricity production, and increasing burdens for oil production are expected to increase the GHG emission benefits of electrification technology. We highlight the importance of further LCA studies for BEVs using real world data to capture future improvements in vehicle performance and battery materials.

— Kim et al.

Resources

  • Hyung Chul Kim, Timothy J. Wallington, Renata Arsenault, Chulheung Bae, Suckwon Ahn, and Jaeran Lee (2016) “Cradle-to-Gate Emissions from a Commercial Electric Vehicle Li-Ion Battery: A Comparative Analysis” Environmental Science & Technology doi: 10.1021/acs.est.6b00830

Comments

Davemart

'Using our GHG estimate for BEV battery production, 11 kg CO2-eq/kg battery, in place of those in the literature gives an estimate of 31−37% life cycle GHG benefits for BEVs over gasoline ICEVs.'

Presumably based on the US grid average.
Would someone who can access the original paper please confirm?

Davemart

The new higher density packs LG is making for the Bolt should do significantly better, as there seems no reason to assume that GHG rises commensurately with the kwh.

Against that, the smaller pack presumably does something close to the number of road miles as the bigger one, so the GHG per mile driven will not go down as much as the reduction per kwh implies.

Davemart

At 31-37% savings against presumably the Focus ICEV, it sounds to me as though it would run neck and neck in total lifetime emissions with a Prius - the non-PHEV version.

The only thing I could dig out for the Prius is this:

http://www.greencarcongress.com/2015/07/20150701-cmu.html#more

If anyone has better data it would help.

BEVs offer an improvement, but they are not the only game in town, for the time being anyway.

mahonj

It depends very much on your grid mix, and whether you can shift your charging to low CO2 times.
Thus, if it is mostly coal, you have a problem. If it is hydro or nuclear, not so much.
If it has a lot of wind or solar, and you can time your charging to match this, you are in business.
It strikes me that this means a larger battery pack (say 40 kwH). If the pack is too small (a "1 day" pack), you will have to recharge every night regardless of the grid status. If it is larger (a "2 day" pack) you would have enough time to decide when to charge and would be able to charge at a low CO2 time in many cases.
To do this automatically, you would need a weather forecasting and signalling system, and pricing based on CO2 levels to motivate people.

Davemart

mahonj:

Sounds pretty darn complicated to me.
I have just dug out this recent cradle to grave analysis of different drive train technologies in GHG emissions and cost terms:

http://www.greencarcongress.com/2016/06/20160609-usdrive.html

Unfortunately for GHG it does not readily separate out build and running emissions.

Davemart

In my link above it can be seen that in terms of running the car around FCEVs are pretty much on a par with BEVs at very low levels where the power source is the electrolysis of water from solar and wind and BEVs are run on equivalent sources.

What I am starting to think though is that not only is that a lot easier to do in winter and so on using hydrogen than a BEV, but that you can do it right now in some places.

So in Scandinavia everywhere and in Germany at the renewable hydrogen stations using wind and solar electrolysis you can actually do that running a car.

A BEV is much more grid dependent, and the Musk notion that solar arrays would power superchargers is not happening, nor do solar arrays at home actually power the car.
They offset, which is a different thing.

So perhaps as renewables only hydrogen stations spring up, it will be the lowest GHG way of powering your car there is, pending major upgrades to the grid.

mahonj

@Dave, it isn't really that complex, it just means you try to charge when the grid is at its "greenest".

In some countries (Ireland for instance), this is a matter of public record.
http://smartgriddashboard.eirgrid.com/

You "just" need a charger that can take a "charge" / "whatever" / "no-charge" signal from either the internet or some radio device.

So, you say, "I need X % by 7am tomorrow morning" and leave it to the charger.

I defined 3 statuses:
"Charge" means, grid is very low CO2, please charge now.
"Whatever" means grid is normal, charge if you need to.
"No-charge" means gird is overloaded, only charge if you must.

Alternately, these could be electricity prices.

The idea is to get people to do time variable things (like charging a car, washing clothes, heating water) at times when the grid is most available (or power is cheapest).

There are some things that you must do immediately, like boiling a kettle or turning on a light or watching TV, but some things can be done at other times.

Davemart

Hi Mahonj:

Yeah, TOU can work.

It is simpler though to produce something like hydrogen that you can use when you feel like it.

It depends on how much it costs for the convenience though.

HarveyD

Current Grid mix for/in Mexico and USA does not benefit BEVs. USA with 11% REs and about 19% Nuke (total = 30%) is slightly better than Mexico but far behind Canada with (total = 61%).

Leaders from the 3 countries are currently meting in Canada to find better ways to increase REs and reduce coal-NG-Oil fired power plants by 2025.

More Solar seems to be the best way out for Mexico and Southern USA.

mahonj

>>
More Solar seems to be the best way out for Mexico and Southern USA.

Absolutely, just don;t go as far as Germany.
Also, add in a fair chunk of wind, if you have it as it is not correlated with solar.

It strikes me as better to use PV or wind to charge batteries (probably via the grid) and use BEVs or PHEvs rather than generate H2 and use it in fuel cells.
Solid oxide fuel cells that do not need H2 could be a game changer, if they can be made work for the right price.

Time of day charging is really "just" a software/networking problem.

mahonj

To continue, I think you will always need the grid for load balancing, nights, dull, still days etc, but you should put a reasonable (say 30-50%) renewables onto it, backed up by some storage for load shaping.
You will always need dispatchable power to keep the grid running and currently that means fossil, nuclear hydro or storage, but the size of storage is limited, hence the others.

JMartin

Posters insist on arguing the grid mix issue diverting attention from the benefit of BEV or PHEV. The landscape is changing, and rapidly in the right direction. I find it pointless to argue against BEV's based on a current snapshot of coal use, when that is dropping at ~12% per year. We need to move forward on all fronts.

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