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We are advised by our various governments that the most environmentally-friendly way to dispose of a battery is to give it in to a designated battery recycling plant.

But could the process of doing all that (due to the many resources needed to perform such an intensive task - even if it outputs resources from the batter for re-use - such as the resources (other consumable materials) and energy (power) consumed to mechanise the process, and also emission contribution to long-term ecological strain), make it actually less sustainable than simply tossing it in the trash and letting it be taken to the designated local tip, where it will, assumedly underground, in time, break down there anyway?

Or maybe there's a third more sustainable method, such as burying it yourself (as far underground as possible, away from water sources or aquifers and with the assumption that eventually, microbes in the earth will break down its toxins and heavy metal compounds, even if that might take a long time)?

So in other words, which alternative, when pros and cons of battery materials reusability, and resources consumption of each alternative are weighed up, is the most sustainable?

Perhaps it depends on how efficient the battery recycling operation is, and requires consideration of scalability when comparing the methods (whereby if done in large numbers it does end up being the winner, but certainly not on smaller scales)?

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    This question is somewhat hypothetical. For example, how exactly are you going to bury it? Do you assume this is always safe, or should possible answers take into account the possibility of leakage and polluting groundwater?
    – THelper
    Sep 4, 2014 at 9:38
  • Thanks. I guess it can be difficult to tackle such important sustainability questions, with such successful scientific accuracy and method. I hope here we can develop something that helps enough in the middle. I'll specify such parameters in the question in a forthcoming edit :).
    – user487
    Sep 4, 2014 at 20:08
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    This is one of those times that we need to examine what "sustainable" means. I think you are mostly using it to mean "less polluting" - but for example, if you don't recycle it then the materials aren't available for future use, which is probably less sustainable. I suspect a clear answer will require more clarity as to what exact thing you want to optimise for.
    – Flyto
    Sep 7, 2014 at 8:08
  • Pollution (if not stopped in terms of making a contribution to it) results in unsustainability though, which is not just about material resources but large-scale and long-term ecological strain too. However you're right about the 'benefit' of re-using the extracted materials into the equation, so I'll add that in to make that clear, concluding that a weigh-up of these factors (including whether the usage of other resources by the factory just to extract and make available the ones from the battery reduce its benefit anyway), and others that haven't been stated yet!
    – user487
    Sep 7, 2014 at 20:51
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    No matter where the answers lead you, a small improvement of sustainability is using up the battery completely, say, through a project like Vampire Flashlight. Batteries too drained to run most common appliances still have quite a bit of power in them.
    – SF.
    Sep 8, 2014 at 21:35

2 Answers 2

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Burying it is a bad idea particularly for lead acid batteries. The case will eventually break down, then the solutions will leach downward into the water table.

Here we have to put down a $10 deposit on a car battery. The deposit is waived if we bring a battery with us.

The current limit for Pb in water is 5 ppb. And there is some discussion that this is too high. A battery is about 80% lead. So 40 lbs of lead -- 20 kg roughly -- is enough to contaminate 4 billion liters of water. That's 4 million cubic meters of water. 1600 Olympic pools.

Let's look at recycling costs. A battery weighs about 50 lbs. A semi can haul about 20 tons. That's about 800 batteries.

Running a semi cross country is a few thousand dollars. $4/battery.

But it doesn't work that way. More typically most large cities have various metal salvage firms.

What happens is this: Canadian Tire sells you a new battery and takes the old one in on trade. Their trucks are deadheading back for another load of store goods, so the battery's trip back to the distribution point is free.

At the distribution point in some major city, they will take them to the recycler. There they will drain the acid, precipitate the lead out, probably as PbS. The drained case then is broken, the lead plates, and lead oxide precipitates are separated. Lead plates may be melted down to smaller ingots. Oxide is either drummed or binned. Cases are washed, rinsed, and recycled as poly-ethylene (I think...) Wash water is added to the acid.

Periodically the acid is loaded into a tank car, reprocessed into new battery acid (you don't care if there is still some Pb in it.)

The lead goes back to the battery plant to make new batteries.

Commidity lead today is $0.83/lb. So the lead in the battery is worth thirty some bucks. In bulk this is cheaper than mining new lead.

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  • You could apply similar arguments to small batteries (certainly the Cd in NiCd) as well.
    – Chris H
    Feb 18, 2016 at 16:50
  • I could. But car batteries are a vastly larger threat: Much of the lead is in soluble form, while the contents of smaller batteries is a paste; the strength of the case is small compared to the weight; Both cadmium and mercury in the reducing conditions of a landfill will tend to form CdS and HgS, which are both insoluble. Well made landfills have a leachate collection system to prevent stuff from getting into the water table. That said, our used batteries go into a jar until we have enough to take to the recycle centre.
    – Sherwood Botsford
    Feb 19, 2016 at 15:12
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Buy rechargeable batteries instead, if you're talking about single-use alkaline AA cells. If you're talking about car batteries, then you should recycle them, as about 99% of the lead in them can be recycled. Also, lead is extremely toxic and shouldn't go into landfills for any reason.

Lithium-ion batteries from your laptop or phone can also be recycled, but they're far less hazardous than Lead or NiCd batteries.

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