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You are right. But one misconception I often read is that everyone focuses on batteries. It would make more sense in general to talk about energy storage inste

by Ringz 2y ago

You are right. But one misconception I often read is that everyone focuses on batteries. It would make more sense in general to talk about energy storage instead of just batteries. Like Kinetic, chemical, thermal and so on. Batteries cannot be solely responsible for back-up. You need different types of storage: short term, medium term and long term storage. There are different concepts for each application. Batteries, compressed air storage, pumped storage, kinetic, thermal storage as well as power-to-X systems are able to absorb the increasing summer power and provide the energy again in the medium term or seasonally shifted. https://doi.org/10.3929/ethz-b-000445597 https://doi.org/10.3929/ethz-b-000445597

bryanlarsen 2y ago
There are only three energy storage forms that are relevant for the next decade. All the others looked promising, but the learning curve on batteries has rendered them irrelevant. Your link is from 2020, it is out of date. The best energy storage form is "final form". Some energy products can be stored. For example if you are using the energy to create heat, you can store heat for use in the future. Heat storage sucks as a way to store energy destined for electricity, but is a great way to store energy destined for use as heat. The utility of batteries for daily storage is obvious and well proven. Thirdly, the best annual storage is pumped hydro. It's the cheapest and it can be used pretty much everywhere -- all you need is water at one end of an elevation change and a way to build storage at the other end. All the other forms that you'd think would fit in between the two are being quickly subsumed by the rapid price drops in battery pricing. The cutover points are rapidly shifting -- batteries are now cheapest for biweekly-ish. And the primary sources are getting so cheap that overbuilding is an alternative to storage. Rather than storing for the reduced amount of daylight in the winter, just overbuild. More overbuilding and a few days of storage will let you handle a stretch of cloudy, windless days in January. No annual storage required.
- Ringz 2y ago
  Don’t get me wrong—I’d be all for batteries ruling the world if they were both affordable and technically advanced enough to meet various demands. That means they shouldn’t degrade too quickly, for example, when capturing and releasing wind energy in milliseconds. Or they shouldn’t lose too much energy over time due to self-discharge. Or they should be able to supply large amounts of energy instantly. Overbuilding is also a valid approach, especially in connection with a smart grid spanning multiple countries. All of that is fine. However, the point of the study is different, and that makes it still relevant today: The barrier to expanding energy storage isn’t a technical one—it’s a political one. The study also shows that there is a great deal of variability, and the often-used argument that there’s not enough lithium or rare earth elements doesn’t hold up. More recent studies validate different storage technologies depending on their specific use case, showing that they can complement batteries in a meaningful way—also from a financial perspective. Another perspective is that we still have a long way to go before full electrification. Right now, batteries are used in suitable scenarios, but many other areas haven’t been electrified or optimized at all. Other storage technologies might still become relevant. Building a house around a 20,000-liter tank to store energy for heating in Alaska over six months might already be financially and technically viable. But whether the logistical challenges of such solutions will ever make them truly feasible—that’s something I neither want nor can predict.
- pfdietz 2y ago
  > Thirdly, the best annual storage is pumped hydro. I strongly dispute this. E-fuels like hydrogen would be much superior to PHES for annual storage. https://x.com/iain_staffell/status/1722544993179504965 https://x.com/iain_staffell/status/1722544993179504965
  - Ringz 2y ago
    Only if we have more than enough renewable energy to spend making hydrogen. Hydrogen storage has a round-trip efficiency of 40%-50%, leading to significant energy losses. Partly by: Electrolysis requires 50-55 kWh to produce 1 kg of hydrogen, which only contains about 40 kWh, resulting in a 20%-30% energy loss upfront. It’s low energy density requires high-pressure or cryogenic storage, increasing costs and energy use, while leakage further reduces efficiency. Limited pipelines and refueling stations make hydrogen adoption costly and complex. Highly flammable hydrogen demands a lot of safety measures adding even more cost and complexity.
    - pfdietz 2y ago
      At the current exponential growth rate, PV will reach the point of supplying the entire world primary energy demand in a decade and a half. Yes, hydrogen has low round trip efficiency. But it comes out cheaper than PHES. The "cost of inefficiency" is proportional to the number of charge/discharge cycles. For annual storage, efficiency is 365x less impactful than it is for diurnal storage. What matters for annual storage is capex of storage capacity.
      - bryanlarsen 2y ago
        > What matters for annual storage is capex of storage capacity. Which is exactly why PHES wins the cost comparison for annual storage. Open air water storage is ridiculously cheap compared to hydrogen storage.
        pfdietz 2y ago
        I dispute this as well. From what I see, the very best case per kWh cost of just the reservoirs and waterways for PHES is about $10/kWh. Hydrogen stored as compressed gas in solution mined salt caverns would be an order of magnitude cheaper. For storage of liquid e-fuels in tanks, tank capex would be another order of magnitude cheaper still. This assessment is consistent with the link I posted earlier. If you want something that may compete with hydrogen for annual storage, consider bulk thermal storage (using artificially injected heat, not naturally occurring heat). The thermal time constant of a very large object increases quadratically with radius, if everything is scaled proportionally, and can easily reach many years. This is why geothermal works at all -- there's plenty of heat stored in the near crust ready to be mined.
- derriz 2y ago
  > Thirdly, the best annual storage is pumped hydro. It's the cheapest and it can be used pretty much everywhere -- all you need is water at one end of an elevation change and a way to build storage at the other end. Pumped hydro is primarily used for short term storage. The vast majority of pumped hydro installations around the world operate on an intra-day cycle. For storage systems generally (not just electricity), profitability is a linear function of capacity, the possible price arbitrage AND how frequently you charge and discharge. Nobody is going to build a pumped hydro storage facility with the intension of operating a single charge/discharge cycle per year. Nor are pumped hydro facilities cheap to build and certainly cannot be deployed everywhere as they require particular geographic and geologic conditions and mostly locations suitable for pumped hydro are few and far between and those locations that are suitable are generally far away from population centers where the demand for electricity is. Batteries are often cheaper than pumped hydro, they can be located near demand, they scaled down as well as up and can be distributed around the grid to provide "virtual transmission". They are quick to deploy and require little maintenance or staffing. The solution for "long term" storage will be massive over-provision of wind and solar and more grid interconnections. Batteries will take care of everything else.
pjc50 2y ago
I think this is going to turn out like the exotic panel chemistries: batteries are simple and have powerful continual improvement in performance and price, while the others turn out to be more complicated. In particular solid state wins over mechanical anything almost every time.
- Ringz 2y ago
  I am on you side (but not all are more complicated and there are mechanical variations that are better than batteries for some scenarios) but the takeaway of that study is described here: https://news.ycombinator.com/item?id=43425560 https://news.ycombinator.com/item?id=43425560

by Ringz 2y ago

bryanlarsen 2y ago

There are only three energy storage forms that are relevant for the next decade. All the others looked promising, but the learning curve on batteries has rendered them irrelevant. Your link is from 2020, it is out of date. The best energy storage form is "final form". Some energy products can be stored. For example if you are using the energy to create heat, you can store heat for use in the future. Heat storage sucks as a way to store energy destined for electricity, but is a great way to store energy destined for use as heat. The utility of batteries for daily storage is obvious and well proven. Thirdly, the best annual storage is pumped hydro. It's the cheapest and it can be used pretty much everywhere -- all you need is water at one end of an elevation change and a way to build storage at the other end. All the other forms that you'd think would fit in between the two are being quickly subsumed by the rapid price drops in battery pricing. The cutover points are rapidly shifting -- batteries are now cheapest for biweekly-ish. And the primary sources are getting so cheap that overbuilding is an alternative to storage. Rather than storing for the reduced amount of daylight in the winter, just overbuild. More overbuilding and a few days of storage will let you handle a stretch of cloudy, windless days in January. No annual storage required.

Ringz 2y ago
Don’t get me wrong—I’d be all for batteries ruling the world if they were both affordable and technically advanced enough to meet various demands. That means they shouldn’t degrade too quickly, for example, when capturing and releasing wind energy in milliseconds. Or they shouldn’t lose too much energy over time due to self-discharge. Or they should be able to supply large amounts of energy instantly. Overbuilding is also a valid approach, especially in connection with a smart grid spanning multiple countries. All of that is fine. However, the point of the study is different, and that makes it still relevant today: The barrier to expanding energy storage isn’t a technical one—it’s a political one. The study also shows that there is a great deal of variability, and the often-used argument that there’s not enough lithium or rare earth elements doesn’t hold up. More recent studies validate different storage technologies depending on their specific use case, showing that they can complement batteries in a meaningful way—also from a financial perspective. Another perspective is that we still have a long way to go before full electrification. Right now, batteries are used in suitable scenarios, but many other areas haven’t been electrified or optimized at all. Other storage technologies might still become relevant. Building a house around a 20,000-liter tank to store energy for heating in Alaska over six months might already be financially and technically viable. But whether the logistical challenges of such solutions will ever make them truly feasible—that’s something I neither want nor can predict.
pfdietz 2y ago
> Thirdly, the best annual storage is pumped hydro. I strongly dispute this. E-fuels like hydrogen would be much superior to PHES for annual storage. https://x.com/iain_staffell/status/1722544993179504965 https://x.com/iain_staffell/status/1722544993179504965
- Ringz 2y ago
  Only if we have more than enough renewable energy to spend making hydrogen. Hydrogen storage has a round-trip efficiency of 40%-50%, leading to significant energy losses. Partly by: Electrolysis requires 50-55 kWh to produce 1 kg of hydrogen, which only contains about 40 kWh, resulting in a 20%-30% energy loss upfront. It’s low energy density requires high-pressure or cryogenic storage, increasing costs and energy use, while leakage further reduces efficiency. Limited pipelines and refueling stations make hydrogen adoption costly and complex. Highly flammable hydrogen demands a lot of safety measures adding even more cost and complexity.
  - pfdietz 2y ago
    At the current exponential growth rate, PV will reach the point of supplying the entire world primary energy demand in a decade and a half. Yes, hydrogen has low round trip efficiency. But it comes out cheaper than PHES. The "cost of inefficiency" is proportional to the number of charge/discharge cycles. For annual storage, efficiency is 365x less impactful than it is for diurnal storage. What matters for annual storage is capex of storage capacity.
    - bryanlarsen 2y ago
      > What matters for annual storage is capex of storage capacity. Which is exactly why PHES wins the cost comparison for annual storage. Open air water storage is ridiculously cheap compared to hydrogen storage.
      - pfdietz 2y ago
        I dispute this as well. From what I see, the very best case per kWh cost of just the reservoirs and waterways for PHES is about $10/kWh. Hydrogen stored as compressed gas in solution mined salt caverns would be an order of magnitude cheaper. For storage of liquid e-fuels in tanks, tank capex would be another order of magnitude cheaper still. This assessment is consistent with the link I posted earlier. If you want something that may compete with hydrogen for annual storage, consider bulk thermal storage (using artificially injected heat, not naturally occurring heat). The thermal time constant of a very large object increases quadratically with radius, if everything is scaled proportionally, and can easily reach many years. This is why geothermal works at all -- there's plenty of heat stored in the near crust ready to be mined.
derriz 2y ago
> Thirdly, the best annual storage is pumped hydro. It's the cheapest and it can be used pretty much everywhere -- all you need is water at one end of an elevation change and a way to build storage at the other end. Pumped hydro is primarily used for short term storage. The vast majority of pumped hydro installations around the world operate on an intra-day cycle. For storage systems generally (not just electricity), profitability is a linear function of capacity, the possible price arbitrage AND how frequently you charge and discharge. Nobody is going to build a pumped hydro storage facility with the intension of operating a single charge/discharge cycle per year. Nor are pumped hydro facilities cheap to build and certainly cannot be deployed everywhere as they require particular geographic and geologic conditions and mostly locations suitable for pumped hydro are few and far between and those locations that are suitable are generally far away from population centers where the demand for electricity is. Batteries are often cheaper than pumped hydro, they can be located near demand, they scaled down as well as up and can be distributed around the grid to provide "virtual transmission". They are quick to deploy and require little maintenance or staffing. The solution for "long term" storage will be massive over-provision of wind and solar and more grid interconnections. Batteries will take care of everything else.

pjc50 2y ago

I think this is going to turn out like the exotic panel chemistries: batteries are simple and have powerful continual improvement in performance and price, while the others turn out to be more complicated. In particular solid state wins over mechanical anything almost every time.

Ringz 2y ago
I am on you side (but not all are more complicated and there are mechanical variations that are better than batteries for some scenarios) but the takeaway of that study is described here: https://news.ycombinator.com/item?id=43425560 https://news.ycombinator.com/item?id=43425560