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Life cycle analysis of three battery chemistries for PHEVs and BEVs; environmental impacts higher than expected

Flow diagram of the battery system, defined by the functional unit of 50 MJ stored and delivered to the powertrain. Credit: ACS, Majeau-Bettez et al. Click to enlarge.

Researchers from the Norwegian University of Science and Technology (NTNU) have performed life cycle assessments (LCA) of three batteries for plug-in hybrid (PHEV) and full performance battery electric (BEV) vehicles. They compiled a transparent life cycle inventory (LCI) in a component-wise manner for nickel metal hydride (NiMH), nickel cobalt manganese lithium-ion (NCM), and iron phosphate lithium-ion (LFP) batteries.

The battery systems were investigated with a functional unit based on energy storage, and environmental impacts were analyzed using midpoint indicators. On a per-storage basis, the team found that the NiMH technology was found to have the highest environmental impact, followed by NCM and then LFP, for all categories considered except ozone depletion potential. They also found higher life cycle global warming emissions than have been previously reported.

A paper on the study appears in the ACS journal Environmental Science & Technology.

Except for ozone depletion potential, the NiMH battery performs significantly worse than the two Li-ion batteries for all impact categories. This difference may be rationalized by the greater use phase efficiency of Li-ion relative to NiMH, and the fact that each kilogram of Li-ion battery is expected to store between 2 to 3 times more energy in the course of its lifetime. Moreover, the NCM and LFP batteries contain at least an order of magnitude less nickel and virtually no rare earth metals.

Among Li-ion batteries, our analysis points to overall environmental benefits of LFP relative to NCM, which can be explained by a greater lifetime expectancy and the use of less environmentally intensive materials. As an approximate indicator, if we assume a vehicle powertrain efficiency of 0.5 MJ·km-1, our results indicate an overall global warming impact of 35 gCO2-eq·km-1 for NiMH, 19 gCO2-eq·km-1 for NCM, and 14 gCO2-eq·km-1 for LFP.

—Majeau-Bettez et al.

Life cycle environmental impacts of storing 50 MJ of electrical energy in NiMH, NCM, and LFP traction batteries and delivering it to a PHEV or BEV powertrain. Total impacts are expressed quantitatively (left) and also normalized against the worst performance (graphically, right), with impacts broken down between the production of the battery and the electricity consumption during the use phase.

Impact Categories: global warming (GWP); fossil depletion (FDP); freshwater ecotoxicity (FETP); freshwater eutrophication (FEP); human toxicity (HTP); marine ecotoxicity (METP); marine eutrophication (MEP); metal depletion (MDP); ozone depletion (ODP); particulate matter formation (PMFP); terrestrial acidification (TAP); and terrestrial ecotoxicity (ETEP) potentials, with the suffixes “eq”, “inf”, and “100” referring to “equivalent”, infinity, and 100 years, respectively.

Abbreviations: 1,4-DCB refers to 1,4-dichlorobenzene; CFC-11 to trichlorofluoromethane; PM10 to “particulate matter less than 10 µm in diameter”; NMVOC to “non methane volatile organic carbon”.

Credit: ACS, Majeau-Bettez. Click to enlarge.

The team expressed its results for a given amount of energy (50 MJ) accumulated by the battery and then delivered to the powertrain. This approach is intuitive, representative of the purpose of the device, free of any assumption concerning the powertrain, and inclusive of the majority of battery characteristics, such as specific energy capacity, depth-of- discharge, cycle-life expectancy, and charge-discharge energy efficiency, they reasoned.

They did not define the functional unit in terms of driving distance or driving range, as such a functional unit would have been dependent on powertrain and driving cycle assumptions. As a result, they deemed any electricity consumed by the vehicle powertrain, including the energy requirements induced on the powertrain to transport the mass of the battery, beyond the system definition. This approach preserves the generality of the inventory, they argued, allowing it to be adapted to other specific systems of interest.

Among the findings from the study were:

  • For all three batteries, the manufacture energy requirements are a major cause of GWP. The production of polytetrafluoroethylene as dispersant/binder in the electrode paste is responsible for more than 97% of the ozone depletion potential of all three batteries, along with 14.15% of the GWP of the two Li-ion batteries, mostly due to the halogenated methane emissions of this value chain. The final shipping and the productions of the cell containers, module packaging, separator material, and electrolyte contribute relatively little to the environmental damage, with collectively less than 10% of any impact category.

  • While production of NiMH causes the least GWP impact per kilogram, its lower energy density makes it score worst both relative to its nominal energy capacity and our storage-based functional unit. Similarly, the GWP impacts of LFP and NCM production are roughly equal for a given mass or nominal energy capacity, but the greater life expectancy of LFP confers a net environmental advantage to this chemistry for a per-energy-delivered functional unit.

  • Differences in battery designs can lead to important variations in environmental impacts. For example, alternative materials have been used by the battery industry in lieu of polytetrafluoroethylene as binder and nickel foam as NiMH current collectors, both of which are identified in the study as especially environmentally consequential.

  • When altering the ratio of the components to optimize for either more energy or power density, a change of 25% in energy density changed the GWP impact of the life cycle of the battery by 3–10%.

  • The efficiency of the battery proves to be a crucial parameter, with an alteration of 5 percentage points (80 ± 5% for NiMH and 90 ± 5% for Li-ion) leading to 8.23% changes life cycle GWP due to changes in use phase electricity waste. A reduction of lifetime estimations by one-third increases all categories of impacts by 30–45%.

  • If average Chinese electricity mix is used for all inventoried production processes instead of average European electricity mix, the life cycle impacts of the batteries increase by 10.16% for GWP and by 10.29% for particulate matter and photochemical oxidant formation.

  • More than 70% of GWP emissions occurred in processes more than 6 tiers upstream of the use phase in the value chain.

Though associated with important uncertainties, our results point to a higher than expected level of environmental impacts for the production and use of traction batteries. This inventory and LCA provide a basis for further benchmarking and focused development policies for the industry.

—Majeau-Bettez et al.


  • Guillaume Majeau-Bettez, Troy R. Hawkins, Anders Hammer Strømman (2011) Life Cycle Environmental Assessment of Lithium-Ion and Nickel Metal Hydride Batteries for Plug-In Hybrid and Battery Electric Vehicles. Environmental Science & Technology Article ASAP doi: 10.1021/es103607c



Oh no! The environmental impacts of these batteries are - higher than expected.

Don't panic, what's important is "are they lower than the ICE alternative?"


This is based on current and past technologies.

Future technologies will have very different impacts.

China's energy mix is not the greenest.

Our 100% hydro may give very different conclusions.


"While production of NiMH causes the least GWP impact per kilogram, its lower energy density makes it score worst both relative to its nominal energy capacity"

So, we have one million HEVs with 1 kWh of NiMH batteries all getting 40% better mileage for a decade. I would say that is a good use for the batteries overall.


@ai vin:

Wrong! What's important is that the Spinach Party has foolishly claimed e vehicles to be a panacea that is far from reality.

Consequently, the Spinach Party has lost credibilty and that is good.


@ HarveyD:

"Future technologies will have very different impacts."

That's a truly profound thought. Future technologies could be better, the same, or worse.

Making engineering and manufacturing decisions around pie in the sky technology is a crap shoot.


future why worry about it, the world ends in 20 months



Why would you hate all EVs because of a couple of idiots? There are people who are extreme about everything.

They have some clear advantages today if you are a person who just commutes around town for short distances and lives in a place with lots of green electricity.

They will get better on distance and the grid will get cleaner in other areas. A few idiots don't invalidate the entire genre.



I don't know if you're kidding or one of the guys who enjoys end of the world theories.

But for those who are serious: what always amazes me is that everyone freaks out over the 2012 calendar ending. Do people realize that ours ends every year on Dec 31st! And the next day another one starts! I'm pretty sure they just planned on starting their version of Jan 1st next year, but it's a lot more fun to make movies about it and scare everyone LOL

The sad part is that some morons will have a kool-aid party and end it all rather than admit it's still going and they were wrong.

But then, I guess the gene pool needs cleaning too.


Forget the Mayan calender, the world ends next month! So sayth the great Harold Camping!




You seem to be a depressed person, get help.

There are those that think it is ending and they will act accordingly. Then there are those that know it is not ending and will plan for a long future. The future planners will win and the losers will lose, simple as that.

HarveyD can anybody make prediction for 2050 without making forward looking assumptions on technologies moving ahead. The world will not be static. Various technologies advancement will not necessarily be linear. If China can grow at 10%+/year, so can electrified vehicles, specially in China.

It took less than 50 years to go from horses/buggies and steam locomotives to ICE vehicles and diesel/electric locomotives. Changes have a tendency to materialize faster and it could happen with vehicles electrification. Over 69% of potential buyers in China want to their next vehicle to be electrified. The rest of the world may want to catch up by 2020.


When you look at nano technologies as an enabler, advances in batteries and fuel cells like this could not be done 30 years ago. This is the natural of technical surges brought about by ideas that never existed before.


So if I read this right (and I'm not sure I do) the GWP of even the highest impact battery (NiMH) is still 1/4 that of the best gasoline engines?

One thing I did not see is the expected life of the battery type, since the only batteries we currently have real extended data is the NiMH. Since they didn't seem to include end of life data, I'm not really sure of what they are trying to say, other than it takes more energy to make NiMH batteries than Lithium Ion.

Since I didn't want to spend money to download the report, all I have to go by is the article here. And all I see is the refernce to 50MJ storage. 50MJ works out to about 14KWh or about 1/2 the Leaf battery. What I didn't see mentioned is that batteries are rechargable. So am I to assume the GPW is incrementally reduced every time you recharge the battery?


ds -- So 20 months from now, be sure to turn off your gas and water to the house, and use alternate side of the street parking. LOL


How about lower cost post lithium batteries with energy density of 1000+ Wh/Kg and 5000 cycles?


@ DaveD

I have nothing against EVs. It's their cost of upwards of $30k in addition to their very limited capabilities that's the problem.


Average purchase price of a new vehicle was $28K in the US for 2009. If the range of an EV is enough for you they don't have limited capabilities. So what's the problem? They'll get better and cheaper.

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