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Oh come on! No one here, other than yourself, has tried to claim that exponential cost reductions will continue indefinitely. But it is a fact, that solar exper

Oh come on! No one here, other than yourself, has tried to claim that exponential cost reductions will continue indefinitely. But it is a fact, that solar experienced that type of cost reduction for a period of 2-3 decades. It's very unlikely to continue on that trajectory, but it doesn't really matter because solar is now one of the cheapest forms of generation on the market at this point. Batteries are in a similar position as solar was a decade or two ago. The grid operators desperately need storage capabilities, and li-ion is one of the more promising solutions, but it's still too expensive. But another decade of cost reductions can change that. No one knows for certain if it's possible, but like I said in my original post, no dramatic technology changes are really needed, just better logistics and scaling could be enough.

BeeOnRope 8y ago
> Oh come on! No one here, other than yourself, has tried to claim that exponential cost reductions will continue indefinitely. The OP did, which is what I was responding to. He mentioned the current exponential decrease in battery costs, and said "I see no reason for that not to continue". They then drew a direct analogy to Moore's law to explain how such exponential gains can be sustained. I disagree. Of course, even the GP probably agrees they won't continue "indefinitely" but my claim is that they can't even continue for very long (the higher the rate of cost reduction, the shorter it can be sustained). > But it is a fact, that solar experienced that type of cost reduction for a period of 2-3 decades. Kind of, there were certainly long periods of stagnation in solar panel costs, but also periods of large drops. It also depends how your pick your starting point. One has to ask (as you did) whether today's batteries are more like the low-volume niche product of 70s solar panels, or more like today's solar panels. I'm willing to bet the latter, both because batteries have seen substantial investment to date (I'd wager much more than solar panels), and because the existing scale of battery manufacturing is already massive (c.f., gigafactory). Furthermore, there are no apparent revolutions in battery technology on the horizon. So rather than being at the start of a precipitous drop in battery prices, I think we are somewhere near the middle, and the drops from here will mostly slow down not speed up.
- qqqwerty 8y ago
  That is a fair point re existing battery scale. However I would counter, that to date, the vast majority of that development and investment has gone towards batteries for small devices (phones and laptops, basically). Compared to utility scale battery packs (and to some degree electric vehicle packs), I imagine the manufacturing challenges are very different. For comparison, the battery in my phone is about 13Wh, whereas the Tesla battery in question is about 130MWh, 8 orders of magnitude bigger. And we have only very recently started building systems like that. While a 10x reduction in cost certainly might be a stretch, I wouldn't be surprised to see at least a 50% reduction in the next 5-10 years.
  - BeeOnRope 8y ago
    You might be right about these large scale systems. Are they using significantly different technologies for the individual cells? I always found it weird that the large battery in a Tesla, for example, was just made up of thousands of 18650 cells that are probably smaller than the battery in your phone. Is the Powerwall is the same? Does it get any different at larger sizes? Obviously stuff must be different outside of the cells, even if the cells are the same.
    - qqqwerty 8y ago
      This is just based on my memory, but I think they use different battery chemistries but use the same cell size (18650). I also thought it was weird that they were using 18650's when I first found out about it, but I think the need for thermal management actually makes the smaller cell sizes ideal. Of course this is also why I think there are some cost reductions on the horizon, as current EV and grid tied batteries are basically just a bunch of laptop batteries thrown into a fancy box.
      - BeeOnRope 8y ago
        > but I think they use different battery chemistries but use the same cell size (18650) I also read something like that. I suspect it is more of a tweak than anything major. No doubt it is the same basic chemistry but perhaps with minor tweaks to the various ratios and material thicknesses and so on. The Tesla batteries are a single-application cell, so you know exactly the maximum discharge current, the maximum charge current, the temperature parameters, and so on, whereas a generic 18650 has to balance those for a "typical application" or whatever. See for example the Samsung high-discharge INR18650 cells which trade off capacity for higher max discharge current. OTOH the other hand I also heard the early Teslas were using exactly the Panasonic 18650B cell. They could both be true: maybe it was a stock cell in the early days and they tweaked the formula later in concert with Panasonic as their volumes rose. There was no big evident spike in capacity vs weight though...

BeeOnRope 8y ago

> Oh come on! No one here, other than yourself, has tried to claim that exponential cost reductions will continue indefinitely. The OP did, which is what I was responding to. He mentioned the current exponential decrease in battery costs, and said "I see no reason for that not to continue". They then drew a direct analogy to Moore's law to explain how such exponential gains can be sustained. I disagree. Of course, even the GP probably agrees they won't continue "indefinitely" but my claim is that they can't even continue for very long (the higher the rate of cost reduction, the shorter it can be sustained). > But it is a fact, that solar experienced that type of cost reduction for a period of 2-3 decades. Kind of, there were certainly long periods of stagnation in solar panel costs, but also periods of large drops. It also depends how your pick your starting point. One has to ask (as you did) whether today's batteries are more like the low-volume niche product of 70s solar panels, or more like today's solar panels. I'm willing to bet the latter, both because batteries have seen substantial investment to date (I'd wager much more than solar panels), and because the existing scale of battery manufacturing is already massive (c.f., gigafactory). Furthermore, there are no apparent revolutions in battery technology on the horizon. So rather than being at the start of a precipitous drop in battery prices, I think we are somewhere near the middle, and the drops from here will mostly slow down not speed up.

qqqwerty 8y ago
That is a fair point re existing battery scale. However I would counter, that to date, the vast majority of that development and investment has gone towards batteries for small devices (phones and laptops, basically). Compared to utility scale battery packs (and to some degree electric vehicle packs), I imagine the manufacturing challenges are very different. For comparison, the battery in my phone is about 13Wh, whereas the Tesla battery in question is about 130MWh, 8 orders of magnitude bigger. And we have only very recently started building systems like that. While a 10x reduction in cost certainly might be a stretch, I wouldn't be surprised to see at least a 50% reduction in the next 5-10 years.
- BeeOnRope 8y ago
  You might be right about these large scale systems. Are they using significantly different technologies for the individual cells? I always found it weird that the large battery in a Tesla, for example, was just made up of thousands of 18650 cells that are probably smaller than the battery in your phone. Is the Powerwall is the same? Does it get any different at larger sizes? Obviously stuff must be different outside of the cells, even if the cells are the same.
  - qqqwerty 8y ago
    This is just based on my memory, but I think they use different battery chemistries but use the same cell size (18650). I also thought it was weird that they were using 18650's when I first found out about it, but I think the need for thermal management actually makes the smaller cell sizes ideal. Of course this is also why I think there are some cost reductions on the horizon, as current EV and grid tied batteries are basically just a bunch of laptop batteries thrown into a fancy box.
    - BeeOnRope 8y ago
      > but I think they use different battery chemistries but use the same cell size (18650) I also read something like that. I suspect it is more of a tweak than anything major. No doubt it is the same basic chemistry but perhaps with minor tweaks to the various ratios and material thicknesses and so on. The Tesla batteries are a single-application cell, so you know exactly the maximum discharge current, the maximum charge current, the temperature parameters, and so on, whereas a generic 18650 has to balance those for a "typical application" or whatever. See for example the Samsung high-discharge INR18650 cells which trade off capacity for higher max discharge current. OTOH the other hand I also heard the early Teslas were using exactly the Panasonic 18650B cell. They could both be true: maybe it was a stock cell in the early days and they tweaked the formula later in concert with Panasonic as their volumes rose. There was no big evident spike in capacity vs weight though...