Data Center

Are Lithium-ion Batteries “GREENER” than Lead Acid?

There are many different ways you could consider a product to be more environmentally friendly or not than another.  Li-ion batteries do not contain hazardous materials while lead-acid batteries do (i.e., lead).  Both battery types are recyclable; however, at present it is much easier in most regions of the world to recycle lead acid than larger format li-ion batteries used in UPSs and electric vehicles.  For a complete picture of environmental impact, however, consider the entire carbon footprint over the course of the battery lifecycle.  Carbon use accumulates throughout the product lifecycle:

  • Raw material extraction
  • Energy to produce and transport
  • Operating energy to keep batteries charged and cooled
  • Recyclability and impact on the earth when it is time to dispose

Previous analysis has shown that the operating losses (i.e., the energy used to keep the batteries charged) are, by far, the dominant driver of the carbon footprint of a UPS and its battery system over a 10 year life cycle. However, there is not a large difference in operating losses between the two systems.  Which one edges out the other depends on the actual use case.

Lithium-ion batteries do require less energy to keep them charged than lead acid.  The charge cycle is 90% efficient for a lithium-ion battery vs. 80-85% for a lead acid battery. Additionally, lead acid batteries self-discharge at a higher rate than Lithium-ion.  These efficiency gains, however, are offset by the need for Li-ion to have a battery management system (BMS) to protect against short circuits and overcharging.  This monitoring system consumes energy.  So the total operating losses are very similar between the two.


With the dominant factor for determining a 10-15 year carbon footprint basically a wash, one must look to the other factors.  Given that lithium-ion batteries containing landfill -safe materials are recyclable, and because their lifespan is 2-3 times longer than lead acid batteries, it can be argued that lithium-ion batteries are “greener”.

However, note that the recycling rate of lead from lead-acid batteries is 99%with over 90% of the batteries being collected (in North America…similar rates occur in Europe and Japan).  The state of recycling for lithium-ion batteries, particularly the larger format ones (such as those used in electric vehicles and data center UPSs), is much less mature, however.  Read the whitepaper I co-wrote with Martin Zacho on the “FAQs for Using Lithium-Ion Batteries with a UPS”.

7 Responses to “Are Lithium-ion Batteries “GREENER” than Lead Acid?”

  1. Jason Drage

    “.. the need for Li-ion to have a battery management system (BMS) to protect against short circuits and overcharging. ”
    — Yes a BMS is required.

    “This monitoring system consumes energy. So the total operating losses are very similar between the two”
    — Show me your figures supporting this claim.
    The monitoring of a battery pack can be done with circuitry that consumes milliwatts, and the balancing charge is just the charge required, put into the appropriate cell.

    Your dominant factor hasn’t been given the attention it deserves, perhaps because your company would rather we all keep buying lead-acid storage.

    • Patrick Donovan Patrick Donovan

      Hi Jason, Schneider Electric sells both VRLA and Lithium-ion batteries for many of its UPSs. Not all of our UPSs support the use of Lithium-ion…yet. We believe that given the strong benefits of li-ion and its declining prices, we believe larger format li-ion batteries will become the dominant energy storage choice for UPSs in the future. I think our white paper strongly supports this position.

      At least for the large format li-ion battery technology we chose, the energy consumed to power/charge the system is basically the same compared to our VRLA systems. At least for us, its just not really a significant comparison point. The BMS system is posed as a good thing…its a critical component to ensuring the battery system performs safely. The system monitors to the cell level.

  2. Robert Stevenson

    Hi Patrick,
    Thanks for an informative post.

    I’d make a couple of points:
    > The recycling of the two technologies is vastly different since 100% of the lead and very close to that percentage of the other materials in lead-acid cells are used to make new batteries at end of life. So it’s a true closed cycle. Over 96% by mass of every lead-acid battery is reused in a new battery. The remainder (the 4% including sulphates from the sulphuric acid) is used in industry and agriculture.

    > New lead-acid technologies, such as UltraBattery, have charge cycle efficiency well over 90%
    > Lifespan of this battery, at least in high-rate partial state of charge applications, is no shorter than li-ion (longer in fact in the only independent testing that has been done comparing the two, which was done by Sandia National Laboratories in 2008).
    > The end of life handling of lead-acid is not only safe but profitable… so where you must pay someone to take your li-ion system away, recyclers will pay you to come and pick up your old lead-acid system.
    > Li-ion at end of life is generally not safe to handle or sort into chemistry types.

    Hence li-ion “recycling” (last time I looked into it at least – and I would be thrilled to hear it if things have changed) often amounts to creating low-grade additives for construction materials. The more common disposal method is still incineration or landfill.

    The other question is the true safety of li-ion components in landfill.

    Numerous sources (for instance this one:
    tell us that li-ion is actually not landfill-safe.

    The source lists many of the common chemical ingredients of li-ion batteries and states:

    “Hazard identification for each of the solvents according to the Dangerous Substances Directive (67/548/EEC) and Classification, Labelling and Packaging Regulation ((EC) 1272/2008), which aligns the European Union system of classification, labelling and packaging of chemical substances and mixtures to the Globally Harmonized System (GHS), is presented in Table II. It can be seen that, in addition to being flammable, many of the solvents are toxic, harmful or irritant.”
    The list of compounds and their hazard status is here:

    There are also many highly volatile compounds in li-ion electrolytes, so the risks are not only for skin contact, but lung irritants and other airborne toxins and hazards. True the hazards of these compounds leaking into water and air sources have not been well documented – but this is not the same as saying the hazards don’t exist. And of course there is the fire risk, which is not reduced just because the cell is no longer being used.

    We should in any case be discouraging any product or technology from ending up in landfill (particularly those made of large numbers of compound including plastics) – so I’d personally hesitate before labeling anything but green waste as “landfill safe.”

  3. John Roccisano

    Hi Patrick,
    The assumptions you have made between the Lithium-Ion batteries and the Lead Acid batteries do not stack up.
    Your comments “Previous Analysis has shown” reference the following document;
    In this document Wendy Torell discusses the Lifecycle Carbon Footprint Analysis of Batteries vs. Flywheels. not Apples for Apples right there.
    Secondly under Analysis methodology. Point 3 delivery – Li-Ion Batteries have a much better Energy density per pound/kilogram so will cost much less to transport anywhere.
    Thirdly under Point 7 of the document notes that the VRLA battery has an expected life of 5 years where as the Tesla Powerwall warranties its product for 10 years of ‘daily cycling’.
    These 3 points alone show up the poor preparation and lack of research rigour for your Blog article.

    • Patrick Donovan Patrick Donovan

      Hi John R., thanks for your comments. I stand by my statement that the (by FAR) dominant factor determining the 10 yr carbon footprint of a battery system is the energy consumed over its life time to keep the batteries charged. This is why I referenced the “VRLA vs. Fly-wheel” analysis I did…it clearly shows this. The fact that we’re talking about VRLA vs. li-ion does not change this fact. The carbon released from raw material extraction, production, and shipping is MINISCULE compared to the energy losses due to charging the batteries over 10 years….unless, perhaps, you live in France where a large percentage of your energy is nuclear (the tool shows this). Yes, li-ion are much smaller/lighter and so the travel-related carbon would be less, but again, that is a tiny piece of the overall carbon footprint. My only point on this was that there was not much of a difference between the large format li-ion batts we use and the VRLA batts we use for our UPSs in terms of the energy losses to charge the batteries. But we still say li-ion batts are, in fact, greener than VRLA because there’s no lead (or other hazardous substances VRLAs have) and because their lifespan is much longer.

      As for the typical lifespan of VRLA batteries in UPS applications, 3-5 and 4-6 are the typical ranges you hear in the industry. I don’t think there’s much debate about that.


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