Comment by gjm11 | Hacker News Reader

Comment by gjm11 | Hacker News Reader

To rephrase the story a little: Instead of making solar panels out of silicon, with 20-25% efficiency, we could make them out of perovskite, which contains lead and yields a little below 20% efficiency. Because then we could reuse lead from car batteries instead of putting them in landfill.

It seems to me that by the time the car batteries are in the recycling system, ready for use to make perovskite solar panels, the lead-pollution problem is already solved. So then the question is: You have a stash of car batteries that you can reuse if you want to. Do you want to make solar panels out of silicon or out of perovskite?

It looks to me as if the answer is clearly "silicon". Can it really be harder to dispose of the lead batteries safely than it is to make perovskite solar panels out of them?

It had better not be, given that the amount of lead needed by one solar panel installation is about 1/30 the amount in one car battery. There are a lot more car batteries made per year than 1/30 the number of solar panel installations.

um, it is not easy to dispose of lead batteries "safely". In fact, there is no method currently to do so. Do you have a suggestion for how to do so?

There's a reason it is illegal in most (all?) states to throw out a car battery[1]. Currently, over 98% of battery lead is recycled into new batteries[2]. This is about affording us the flexibility to put battery lead to other uses while still having it be largely recoverable.

As for silicon vs. perovskite, did you miss the fact that a solar cell should be able to have both and show higher output than silicon alone?

[1] http://c.ymcdn.com/sites/batterycouncil.org/resource/resmgr/... [2] http://batterycouncil.org/?page=Battery_Recycling

My guess is that as lead acid car batteries are phased out, then the lead acid recycling industry will migrate to supplying stationary batteries. By that I mean e.g. residential photovoltaics storage, grid load smoothing, battery banks for rapid charging electric cars. Situations where the weight/bulk doesn't matter, but low cost does matter.

If there are no other economic uses for the lead then those applications should become nice and cheap. However this is just the opinion of an armchair energy wonk, so take it with a big grain of salt.

I think the underlying assumption here is that there is a problem with lead recycling. AFAIK, nearly all lead batteries are recycled.

We are many, many years from the inflection point where electric cars will start displacing internal combustion.

Where are you seeing 20-25% effi PV modules? The physics of silicon's bandgap prevents getting much above 18% without (expensive) multiple junction layers (of different material) or concentrators, which tend to reduce module lifecycle time.

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