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> Cheap batteries from earth-abundant materials change that completely. Not really. Batteries need to be about 100 times cheaper than current ones to make a di

> Cheap batteries from earth-abundant materials change that completely. Not really. Batteries need to be about 100 times cheaper than current ones to make a difference. The way to think is this: how many cycles do you need to recoup the cost of the battery? Let's say you get electricity in the summer for roughly zero cents per kWh, and sell in the winter at 50 cents, and you incur zero losses. Current battery prices are above $100 per kWh, so you need at least 200 cycles to break even. At one cycle per year, that's 200 years. If, however, you charge during the day and sell at night, you can break even fairly quickly, even if the profit per cycle is just a few cents per kWh. So, current batteries are ok for daily charge-discharge cycles. But not for yearly ones, and no battery will be for the foreseeable future, because the cost needs to go down by a factor of 100, at least.

dash2 2y ago
How many years did it take for them to drop by the previous factor of 100?
- bsder 2y ago
  Erm, never a factor of 100. Lithium battery prices dropped from about $700-ish per kWH to about $140 or so. About 1/5 in 10 years and most of the drop was early (about a factor of 1/3 from 2013 to 2016). Lithium battery prices will continue to drop, but the big gains are over. It's now going to be a slow industrial production decrease over time.
  - DennisP 2y ago
    But the history of lithium-ion is thirty years long, and over that period, their price did drop by 99%: https://rmi.org/the-rise-of-batteries-in-six-charts-and-not-too-many-numbers https://rmi.org/the-rise-of-batteries-in-six-charts-and-not-... The drop has been a fairly steady exponential, so if you look at the last decade, of course most of the drop was early, since that's how exponentials work. As far as anyone can tell, the trend shows no sign of stopping anytime soon.
DennisP 2y ago
Absolutely, I don't see batteries being helpful for annual cycles, just for daily. Hence my mention of getting through windless nights. The article I referenced was mainly about that too, suggesting we'd need about a week of battery storage. For annual cycles, the easier method is simply to overbuild your generation. If you have half as much solar input during the winter, then build twice as much solar. Here's an article covering a study based on US data, suggesting that four days of storage and a 2X overbuild is roughly optimal there: https://caseyhandmer.wordpress.com/2023/07/12/grid-storage-batteries-will-win/ https://caseyhandmer.wordpress.com/2023/07/12/grid-storage-b...
- credit_guy 2y ago
  > For annual cycles, the easier method is simply to overbuild your generation. If you have half as much solar input during the winter, then build twice as much solar. At latitudes such as of New York or London the solar input during the winter is 5 times lower than in the summer, or more. That's because there are three effects that all go in the same direction: shorter day, lower inclination and thicker atmosphere for the rays to cross (because they come more slanted). If you build five times more solar than you need during the summer, it means you have to idle 80% of the capacity at that time. Long before this will happen the marginal profit of building a new solar plant will become negative for the investors, and long before that happens the profit will be positive, but the risk too high for the investors to secure financing.
  - DennisP 2y ago
    Sure, if you're Canada, you probably need to go ahead and build nuclear. Even if solar keeps getting exponentially cheaper, it'd be nice to be reasonably efficient with land use. What has surprised me is that a solar/wind/battery grid is starting to look feasible anywhere, even if not everywhere. It could probably handle a decent portion of the US now.
PaulKeeble 2y ago
This is why this isn't the plan. Instead there will be some amount of over capacity at abundant times such as summer for solar which means power will be very cheap or free during some months of the year and batteries will simply be used to match power usage through the day and across a few days. If batteries were very much cheaper than having just enough power across the year would be the right strategy but we don't so it's not and in a lot of countries the overproduction is only +50% and the much cheaper option.

dash2 2y ago

How many years did it take for them to drop by the previous factor of 100?

bsder 2y ago
Erm, never a factor of 100. Lithium battery prices dropped from about $700-ish per kWH to about $140 or so. About 1/5 in 10 years and most of the drop was early (about a factor of 1/3 from 2013 to 2016). Lithium battery prices will continue to drop, but the big gains are over. It's now going to be a slow industrial production decrease over time.
- DennisP 2y ago
  But the history of lithium-ion is thirty years long, and over that period, their price did drop by 99%: https://rmi.org/the-rise-of-batteries-in-six-charts-and-not-too-many-numbers https://rmi.org/the-rise-of-batteries-in-six-charts-and-not-... The drop has been a fairly steady exponential, so if you look at the last decade, of course most of the drop was early, since that's how exponentials work. As far as anyone can tell, the trend shows no sign of stopping anytime soon.

DennisP 2y ago

Absolutely, I don't see batteries being helpful for annual cycles, just for daily. Hence my mention of getting through windless nights. The article I referenced was mainly about that too, suggesting we'd need about a week of battery storage. For annual cycles, the easier method is simply to overbuild your generation. If you have half as much solar input during the winter, then build twice as much solar. Here's an article covering a study based on US data, suggesting that four days of storage and a 2X overbuild is roughly optimal there: https://caseyhandmer.wordpress.com/2023/07/12/grid-storage-batteries-will-win/ https://caseyhandmer.wordpress.com/2023/07/12/grid-storage-b...

credit_guy 2y ago
> For annual cycles, the easier method is simply to overbuild your generation. If you have half as much solar input during the winter, then build twice as much solar. At latitudes such as of New York or London the solar input during the winter is 5 times lower than in the summer, or more. That's because there are three effects that all go in the same direction: shorter day, lower inclination and thicker atmosphere for the rays to cross (because they come more slanted). If you build five times more solar than you need during the summer, it means you have to idle 80% of the capacity at that time. Long before this will happen the marginal profit of building a new solar plant will become negative for the investors, and long before that happens the profit will be positive, but the risk too high for the investors to secure financing.
- DennisP 2y ago
  Sure, if you're Canada, you probably need to go ahead and build nuclear. Even if solar keeps getting exponentially cheaper, it'd be nice to be reasonably efficient with land use. What has surprised me is that a solar/wind/battery grid is starting to look feasible anywhere, even if not everywhere. It could probably handle a decent portion of the US now.

PaulKeeble 2y ago

This is why this isn't the plan. Instead there will be some amount of over capacity at abundant times such as summer for solar which means power will be very cheap or free during some months of the year and batteries will simply be used to match power usage through the day and across a few days. If batteries were very much cheaper than having just enough power across the year would be the right strategy but we don't so it's not and in a lot of countries the overproduction is only +50% and the much cheaper option.