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The main problem with replacing a fossil fuel plant with renewable + batteries is finding a battery system that can hold energy over a sufficiently long period

The main problem with replacing a fossil fuel plant with renewable + batteries is finding a battery system that can hold energy over a sufficiently long period of time and has enough capacity to replace solar/wind when it is dark and calm. In the studies I've seen the time shift required is on the order of seasons and the capacity required is cost prohibitive. It may be that the weather patterns in Hawaii are sufficiently stable that it makes it possible to remove the companion base load generation capacity. The article seems to hint at the fact that the total capacity of the coal plant was much higher than the storage capacity of the battery system: > With 565 megawatt-hours of storage, the battery can’t directly replace the coal plant’s energy production ... So it isn't clear how much capacity has been lost in this switch. They may also be other changes in the generation portfolio that aren't discussed in the article.

gumby 3y ago
DoE has a development program called “Long Term Storage”. IIRC “long term” is anything more than 12 hours. Seasonal sounds implausible to my, but it’s not my area and I haven’t worked in storage for over a decade.
- ceejayoz 3y ago
  Seasonal is possible, but I'd imagine scaling it is tough. https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community https://www.planete-energies.com/en/media/article/how-does-long-term-thermal-energy-storage-work https://www.planete-energies.com/en/media/article/how-does-l...
  - gumby 3y ago
    My problem with seasonal isn't the duration itself (though that's a challenge too). But if you're trying to shift seasonally you need not just storage duration but volume-duration too. That is, let's hypothesize a house uses 24 kWh per day, roughly the magnitude in California, 365 days/year (AC in summer, heating in winter). Power is from solar and wind. If you look at "duck curve" demand, you need a bit extra in the afternoon / early evening when there is higher A/C demand -- you can scavenge a bit more power in the morning (say 5 AM to noon) and discharge it in the afternoon (when the solar flux is high BTW), then do the same trick tomorrow. Call it 5 kWh. That's all the storage you need: a relatively small amount for a few hours. Could you hold that 5 kWh for four months? Maybe. Maybe you need to store 7 kWh to get 5 out four months later. Only it's not just 5 kWh for four months: that's 120 days of needing your storage, to produce 600 kWh...on a battery you then don't use much until next season. And that's just for one house. I don't see how seasonal long term storage works, except in a few weird corner cases. Maybe you store it as something else than protons, like methanol. But if you can build a better grid I suspect it's still better to export power from the Mojave to Bangor and the Mahgreb to Helsinki. I am glad someone is thinking about this though!
    - ceejayoz 3y ago
      I think seasonal underground thermal storage is most interesting for somewhere like a remote community up near the Arctic Circle; away from grids, high seasonal variability in generation, etc. I don't think it's ever gonna be how you, say, run the whole European grid; there, a large geographic range of interconnected grid is more likely to be the answer. Cloudy in Germany? Spain's fine.
      - jacquesm 3y ago
        Thermal storage is hamburger, hard to re-use, hard to transport. You need electrons.
    - jacquesm 3y ago
      > That is, let's hypothesize a house uses 24 kWh per day We're at approximately half that and it still isn't a tractable problem just for a single day, for the 1st week of January we used 88 Kwh and made 18.7 Kwh in solar, about 7.5 of which went to the grid (so would have been available to charge a battery). We'd need 4 times as much solar to get through the days and even then there would be days when there wouldn't be enough to go around. Making that work for a week would require 70 KWh of storage and a nameplate installed solar capacity of about 60 Kw, well into fantasy territory, it would never make sense from an economics perspective to set that up. You're looking at 150 to 200 panels depending on type, massive power infrastructure (your normal hookup will not even be close to enough for this) and a formidable array of batteries for storage. It won't happen locally for that reason, much as I would like to. The only thing we can do is to try to conserve even further but we're already close to what you can do with four people in one house, approximately 3 KWh / person / day, especially in the winter. Transporting that power from the excess in the summer would be an even more impressive feat. We still have 11 months of netmetering and then that's over.
      - gumby 3y ago
        I don’t think any meaningful storage makes sense for a home, but for a grid-attached solar plant. The surface area is large but I think the cap ex (and naturally the op ex) are naturally much lower. Even if the solar plant doesn’t generate enough in the middle of summer when demand is high, its grid connection means the batteries could be charging from surplus wind at night. Not that this addresses my time-volume issue, just saying it’s not worth considering from the single home perspective except in unusual cases.
soperj 3y ago
> when it is dark and calm. When is that in Hawaii?
- dylan604 3y ago
  What's the geothermal power potential in Hawaii? Seems like it would be a good source for it to me.
  - auspiv 3y ago
    Equally important: how much would said geothermal cost?
    - senectus1 3y ago
      The Hellisheidi Geothermal Power Plant, which is the largest geothermal power plant in Iceland cost approximately €380 million to build. However a smaller geothermal plant such as the Svartsengi Geothermal Power Plant cost only around €100 million to build
      - pfdietz 3y ago
        We'll see if it survives, since there's a large magma intrusion occurring just about under it. The recent eruption there (east of the plant) fortunately flowed away, and they've built a berm to deflect nearer eruptions, but an eruption directly under the plant, inside the berm, would destroy it.
        senectus1 3y ago
        yeah that is interesting. but then that issue is universal for places like iceland and Hawaii isnt it?
  - sosborn 3y ago
    The only island with active geothermal activity is an island without many people (compared to Oahu). https://en.wikipedia.org/wiki/Puna_Geothermal_Venture https://en.wikipedia.org/wiki/Puna_Geothermal_Venture
itishappy 3y ago
There also is no upper bound on the maximum time, just a lower and lower probability. Like with flooding, there's a recurrence interval. An hour long blackout may happen once a week. A day long blackout may happen once a year. A week long blackout may happen once a decade. (Numbers have been made up to illustrate the point.) https://en.wikipedia.org/wiki/100-year_flood https://en.wikipedia.org/wiki/100-year_flood
- littlestymaar 3y ago
  The problem is that is non-tropical regions, in winter you get less sun and long periods (3 weeks is routine in European winter) with no winds so you need to be able to supply enough power for a very big amount of time.
  - bryanlarsen 3y ago
    There has never been a 3 week wind drought recorded on the North Sea. Wind droughts on cloudy days are even more rare.
    - eldaisfish 3y ago
      not three, but 2022 saw a two week period of wind drought in the north sea. This was well documented.
    - littlestymaar 3y ago
      You don't need to have complete wind drought to have issues (three weeks with only occasional spikes topping at 50% available power is the kind of behavior I'm referring to, and this is routine). And most wind turbines aren't located in the middle of the North sea either.
- gpm 3y ago
  The same is true of other types of energy production... like when France lost 50% of it's nuclear simultaneously... https://www.france24.com/en/france/20220902-france-to-restart-all-nuclear-reactors-by-winter-amid-energy-crunch https://www.france24.com/en/france/20220902-france-to-restar... Ultimately every technology has some unplanned downtime, and there will always be a risk of too much not generating simultaneously.
littlestymaar 3y ago
> In the studies I've seen the time shift required is on the order of seasons and the capacity required is cost prohibitive. Another option is too build some kind of overcapacity with the renewable so that you can avoid using the battery and recharge it even when the whether is not optimal. It doesn't work if the weather isn't stable enough[1], but for Hawaii I would be too surprised if it was viable. [1]: that's why solar + wind in northern Europe is a dead end like what we're seeing with Germany: in winter here we have very little sun and weeks long periods with practically no wind, so you'd need to have something like 10x solar if you wanted the overcapacity strategy to work, which also make things prohibitively expensive.
- actionfromafar 3y ago
  We don't know if 10x will be prohibitively expensive going forward. It can also enable new kinds of uses of electricity we don't have today, offsetting the cost of build-out.
  - littlestymaar 3y ago
    I never said it will be 10x more expensive: if the unit cost is twice as low, then having a 10x overcapacity is “only” 5x more expensive, but that's still too expensive.
- pfdietz 3y ago
  Germany can do it with a combination of wind, solar, batteries, and hydrogen. The green hydrogen is crucial, to deal with Dunkelflauten and to some extent seasonality. Germany has ample salt formations for cheap hydrogen storage. At the site I linked elsewhere in these comments, the solution for 24/7 power from RE is nearly doubled in Germany if green hydrogen is omitted. Germany is suffering now from the decision to pay for the 2009-2012 solar builds using long term high rates. When that ends (2032?) the costs should come down a lot. Building out solar now should be much less expensive.
- nicoburns 3y ago
  > so you'd need to have something like 10x solar if you wanted the overcapacity strategy to work, which also make things prohibitively expensive. In the short-term, gas backup for such scenarios (which are relatively rare, and during which renewables will still operate at some non-100% fraction of the required energy) seems like it might be a reasonable option: we could probably get to (pulling numbers out of thin air) 95% renewable generation or something that way. Longer term, we'll definitely need some kind of long-term storage though. Perhaps synthetic fuel driven by overcapacity renewables during peak generation times might be an option here?
DamonHD 3y ago
Storage is useful at all sorts of scales, from microseconds to years. Interseasonal or even a dunkleflaute's worth is hard at the moment, though we manage it with heat and with (eg) methane already in places. It's happening. Plus we are getting better at moving demand to when energy is available.
- Slava_Propanei 3y ago
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audunw 3y ago
Do you have any links to those studies? Because the ones I've seen indicate the exact opposite. You only need 2-3 days of storage or so at most. Tony Seba has some presentations on this topic. His argument is that renewables is getting so cheap that you can build so much that the minimum production covers all days with few exceptions. I guess that might assume some reasonable grid upgrades as well. Marc Z Jacobsen has some fairly detailed studies for going 100% renewables. He doesn't generally assume any improvements in technology, so his estimates are conservative. I don't remember seeing anything about seasonal storage. You may ask about colder regions. Seems like the solution there will be 1. Trash burning (getting common in Scandinavia.. you could even do it with CO2 capture as a power plant in Oslo, Norway is developing), with district heating 2. Geothermal for district heating 3. Nuclear for a bit of extra baseload (UK, Sweden and Finland are all building nuclear) Also keep in mind that to go zero-carbon, we need to make a hell of a lot of hydrogen, ammonia, e-fuels, biofuel/oil/coal (I just read news about a Danish company starting commercial operation of a giant microwave reactor that can efficiently make bio-oil/coal from sewer sludge). All these solutions will imply a lot of storage capacity. If you're making enormous quantities of hydrogen you're going to have buffers at both the production and consumption side. Production can probably be throttled if needed. I'm guessing that the hydrogen power plants we already have will also be kept around to serve as backup. There's some pretty serious talk about switching the natural gas pipelines from Norway to Europe from gas to hydrogen. First making hydrogen with carbon capture and storage, then green hydrogen made with off-shore wind. And off-shore wind is another thing that's getting more common. If you build really big off-shore wind turbines the production is very reliable.
- chmars 3y ago
  It’s about 12 weeks in Germany: https://iopscience.iop.org/article/10.1088/1748-9326/ac4dc8 https://iopscience.iop.org/article/10.1088/1748-9326/ac4dc8
  - akvadrako 3y ago
    It also depends how much one overbuilds the supply, since the batteries need to be fully charged at the beginning of that 12 week drought. Based on a quick reading it seems they are assuming the average supply is 130% of the average load over the year.
pfdietz 3y ago
To get a handle on this, I point people to this fun site https://model.energy https://model.energy which allows you to use historical weather data, various cost assumptions, and optimize for the cheapest combination of wind, solar, batteries, and hydrogen to get steady 24/7 power (which would be a drop-in replacement for a nuclear power plant, essentially.) By disabling the hydrogen you can get a handle on the cost bump for handling the storage with just batteries. In some places, that cost increase would be considerable (for example, Germany); in others, negligible (India). If you don't like the cost assumptions (they cite sources) you can tweak them and see how the optimum solutions change.
- martinald 3y ago
  This is really interesting but I am not seeing how it gets to end price. It's saying around 54eur/mwh in the UK with the 2020 technology assumption. I can see that cost for the solar/wind itself but seems very low for the masses of hydrogen (and associated round trip losses) that it's suggesting. I have read some estimates that it could at least double the price?
  - pfdietz 3y ago
    If there is otherwise curtailed wind/solar, the RTE doesn't matter very much, since the energy is otherwise thrown away.
    - martinald 3y ago
      I know, but the model above suggests massively overbuilding solar and wind to convert it to hydrogen for storage. That overbuild isn't "free" and I can't see how you can get to €50eur/MWh at the moment for baseload esque power.
      - Turskarama 3y ago
        The overbuild isn't free but the cost of (renewable) generation is so cheap compared to storage that it's most often cheaper to just build too much.
beders 3y ago
Who paid for these studies? "order of seasons" - that can't be right.
- gwright 3y ago
  Why do you think that can't be right? Solar and wind generation themselves are seasonal and don't match the seasonal patterns of demand. So you need to time shift across seasons if you don't have the instantaneous (base load) capacity available all the time. You might say, well, just build more windmills or solar farms. Doesn't help when it is dark and calm. Your "overbuild" is useless in that situation. So you need storage (or other base load generation, fossil or nuclear). In this study, it is estimated that Germany and California both need about 25TWh of storage to time shift energy supplied by intermittent sources to other parts of the year. The study claims $5 trillion to purchase batteries to store that much energy. http://euanmearns.com/the-cost-of-wind-solar-power-batteries-included/ http://euanmearns.com/the-cost-of-wind-solar-power-batteries...
  - mikeyouse 3y ago
    You're kind of making OPs point though - that post was written by a retired 80yr oil engineer who just blogs into the aether because he hates solar and wind.. the $5 trillion estimate was him literally just making up numbers. To critique this more specifically - in that post he assumed we would spend $5 trillion on batteries, and they would still cost the same $200/kwh that they cost in back in 2018. Even if his other assumptions on the capacity required were valid (they aren't), costs have already fallen below $100/kwh since learning curves exist - so his scary $5 trillion number is already below $2.5 trillion. Add in the additional cost savings and amortize that investment over a decade and you're talking about maybe 3.5% of the Federal budget?
  - oezi 3y ago
    No, you just need peaker plants which can run for the 1-3 weeks per year when there is no wind in the winter. Battery capacity will never be built to exceed 1-3 days of demand.
jltsiren 3y ago
This is not a new problem, and there is no silver bullet that will solve it. Just a long sequence of incremental improvements that will make the difference over decades. In the Nordics, the solution is primarily hydro + wind + nuclear, with cogeneration from district heating and industrial processes. Old-style power plants that generate electricity by burning fuels are largely obsolete, and the cogeneration plants are also phasing out fossil fuels. The solution is within reach, but it took decades to get there. Other regions will need other solutions.
standardUser 3y ago
> So it isn't clear how much capacity has been lost in this switch. They may also be other changes in the generation portfolio that aren't discussed in the article. I understand why people are so quick to argue against batteries as a power supply when they are unproven in a given scenario. I think it's a narrow way of thinking that ignores everything we know about the progression of technology and devalues the skilled professionals actually doing this work, but I understand. What I don't understand is what compels a person to grasp at straws and pose speculative "what ifs" after a project is successfully in operation. What more do you need? Does it need to run fifty years before you're convinced?
- gwright 3y ago
  Well in terms of the various capabilities the article highlighted * dark starting * capacity * grid stabilization it sounds like the battery plant is successful. But the article itself says that the plant does not replace the "energy" component of the old coal power plant, which is why I asked the questions I asked. And it is the energy component that is critical for really retiring base load capacity provided by fossil fuel plants at grid level. Without the ability to retire the base load capacity you aren't really solving the problem. Costs rise dramatically (you now have two energy systems) and/or you have to accept less reliability (running out of power when wind/solar/hydro/battery are inadequate). I think you are mis-interpreting my comment and being unfair in characterizing what I'm saying as "narrow minded" or "grasping at straws". > The old coal generator provided three key values to Oahu, Keefe explained: energy (the bulk volume of electricity), capacity (the instantaneous delivery of power on command), and grid services (stabilizing functions for the grid, wonky but vital to keeping the lights on). > The battery directly replaces the latter two: It matches the coal plant’s maximum power output (or “nameplate capacity,” in industry parlance), and it is programmed to deliver the necessary grid services that keep the grid operating in the right parameters.
  - standardUser 3y ago
    Yes, I was talking more about an attitude than your specific concern. Though your framing still contorts the issue in a way that makes a coal plant appear like the proper, ideal solution while this new "problem" method is some shady, questionable alternative that must have hidden flaws. And you continue to list more speculative flaws in this comment as well. What do you think of the idea that, given proper experience and technology, we can have a grid system that does not suffer from inadequate wind/solar/hydro/battery? That is the mindset we need to shift our framing to as these technologies continue to expand and prove themselves on larger and larger scales. I have no doubt people had to shift their framing around the entire idea a reliable coal-based electricity production once upon a time as well.
Kon5ole 3y ago
>The main problem with replacing a fossil fuel plant with renewable + batteries is finding a battery system that can hold energy over a sufficiently long period of time and has enough capacity to replace solar/wind when it is dark and calm. Synthesizing gas seems like a good solution. With electricity prices often dipping into the negatives thanks to all the renewable fluctuations, synthesized gas should be able to compete with any other base source on price. Generate gas when electricity is cheap enough and use it to generate electricity when it's expensive enough. Basically a profit-pump once the initial investment is paid off.
weebull 3y ago
It's Hawaii. They're literally sitting on an infinite energy supply and have almost continuous sun (apart from nights).
itslennysfault 3y ago
I'd think for long term storage pumped hydro would be a better solution. Pump water up a hill and just leave it sitting up there until you need to let it fall to generate some power.

gumby 3y ago

DoE has a development program called “Long Term Storage”. IIRC “long term” is anything more than 12 hours. Seasonal sounds implausible to my, but it’s not my area and I haven’t worked in storage for over a decade.

ceejayoz 3y ago
Seasonal is possible, but I'd imagine scaling it is tough. https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community https://www.planete-energies.com/en/media/article/how-does-long-term-thermal-energy-storage-work https://www.planete-energies.com/en/media/article/how-does-l...
- gumby 3y ago
  My problem with seasonal isn't the duration itself (though that's a challenge too). But if you're trying to shift seasonally you need not just storage duration but volume-duration too. That is, let's hypothesize a house uses 24 kWh per day, roughly the magnitude in California, 365 days/year (AC in summer, heating in winter). Power is from solar and wind. If you look at "duck curve" demand, you need a bit extra in the afternoon / early evening when there is higher A/C demand -- you can scavenge a bit more power in the morning (say 5 AM to noon) and discharge it in the afternoon (when the solar flux is high BTW), then do the same trick tomorrow. Call it 5 kWh. That's all the storage you need: a relatively small amount for a few hours. Could you hold that 5 kWh for four months? Maybe. Maybe you need to store 7 kWh to get 5 out four months later. Only it's not just 5 kWh for four months: that's 120 days of needing your storage, to produce 600 kWh...on a battery you then don't use much until next season. And that's just for one house. I don't see how seasonal long term storage works, except in a few weird corner cases. Maybe you store it as something else than protons, like methanol. But if you can build a better grid I suspect it's still better to export power from the Mojave to Bangor and the Mahgreb to Helsinki. I am glad someone is thinking about this though!
  - ceejayoz 3y ago
    I think seasonal underground thermal storage is most interesting for somewhere like a remote community up near the Arctic Circle; away from grids, high seasonal variability in generation, etc. I don't think it's ever gonna be how you, say, run the whole European grid; there, a large geographic range of interconnected grid is more likely to be the answer. Cloudy in Germany? Spain's fine.
    - jacquesm 3y ago
      Thermal storage is hamburger, hard to re-use, hard to transport. You need electrons.
  - jacquesm 3y ago
    > That is, let's hypothesize a house uses 24 kWh per day We're at approximately half that and it still isn't a tractable problem just for a single day, for the 1st week of January we used 88 Kwh and made 18.7 Kwh in solar, about 7.5 of which went to the grid (so would have been available to charge a battery). We'd need 4 times as much solar to get through the days and even then there would be days when there wouldn't be enough to go around. Making that work for a week would require 70 KWh of storage and a nameplate installed solar capacity of about 60 Kw, well into fantasy territory, it would never make sense from an economics perspective to set that up. You're looking at 150 to 200 panels depending on type, massive power infrastructure (your normal hookup will not even be close to enough for this) and a formidable array of batteries for storage. It won't happen locally for that reason, much as I would like to. The only thing we can do is to try to conserve even further but we're already close to what you can do with four people in one house, approximately 3 KWh / person / day, especially in the winter. Transporting that power from the excess in the summer would be an even more impressive feat. We still have 11 months of netmetering and then that's over.
    - gumby 3y ago
      I don’t think any meaningful storage makes sense for a home, but for a grid-attached solar plant. The surface area is large but I think the cap ex (and naturally the op ex) are naturally much lower. Even if the solar plant doesn’t generate enough in the middle of summer when demand is high, its grid connection means the batteries could be charging from surplus wind at night. Not that this addresses my time-volume issue, just saying it’s not worth considering from the single home perspective except in unusual cases.

soperj 3y ago

> when it is dark and calm. When is that in Hawaii?

dylan604 3y ago
What's the geothermal power potential in Hawaii? Seems like it would be a good source for it to me.
- auspiv 3y ago
  Equally important: how much would said geothermal cost?
  - senectus1 3y ago
    The Hellisheidi Geothermal Power Plant, which is the largest geothermal power plant in Iceland cost approximately €380 million to build. However a smaller geothermal plant such as the Svartsengi Geothermal Power Plant cost only around €100 million to build
    - pfdietz 3y ago
      We'll see if it survives, since there's a large magma intrusion occurring just about under it. The recent eruption there (east of the plant) fortunately flowed away, and they've built a berm to deflect nearer eruptions, but an eruption directly under the plant, inside the berm, would destroy it.
      - senectus1 3y ago
        yeah that is interesting. but then that issue is universal for places like iceland and Hawaii isnt it?
- sosborn 3y ago
  The only island with active geothermal activity is an island without many people (compared to Oahu). https://en.wikipedia.org/wiki/Puna_Geothermal_Venture https://en.wikipedia.org/wiki/Puna_Geothermal_Venture

itishappy 3y ago

There also is no upper bound on the maximum time, just a lower and lower probability. Like with flooding, there's a recurrence interval. An hour long blackout may happen once a week. A day long blackout may happen once a year. A week long blackout may happen once a decade. (Numbers have been made up to illustrate the point.) https://en.wikipedia.org/wiki/100-year_flood https://en.wikipedia.org/wiki/100-year_flood

littlestymaar 3y ago
The problem is that is non-tropical regions, in winter you get less sun and long periods (3 weeks is routine in European winter) with no winds so you need to be able to supply enough power for a very big amount of time.
- bryanlarsen 3y ago
  There has never been a 3 week wind drought recorded on the North Sea. Wind droughts on cloudy days are even more rare.
  - eldaisfish 3y ago
    not three, but 2022 saw a two week period of wind drought in the north sea. This was well documented.
  - littlestymaar 3y ago
    You don't need to have complete wind drought to have issues (three weeks with only occasional spikes topping at 50% available power is the kind of behavior I'm referring to, and this is routine). And most wind turbines aren't located in the middle of the North sea either.
gpm 3y ago
The same is true of other types of energy production... like when France lost 50% of it's nuclear simultaneously... https://www.france24.com/en/france/20220902-france-to-restart-all-nuclear-reactors-by-winter-amid-energy-crunch https://www.france24.com/en/france/20220902-france-to-restar... Ultimately every technology has some unplanned downtime, and there will always be a risk of too much not generating simultaneously.

littlestymaar 3y ago

> In the studies I've seen the time shift required is on the order of seasons and the capacity required is cost prohibitive. Another option is too build some kind of overcapacity with the renewable so that you can avoid using the battery and recharge it even when the whether is not optimal. It doesn't work if the weather isn't stable enough[1], but for Hawaii I would be too surprised if it was viable. [1]: that's why solar + wind in northern Europe is a dead end like what we're seeing with Germany: in winter here we have very little sun and weeks long periods with practically no wind, so you'd need to have something like 10x solar if you wanted the overcapacity strategy to work, which also make things prohibitively expensive.

actionfromafar 3y ago
We don't know if 10x will be prohibitively expensive going forward. It can also enable new kinds of uses of electricity we don't have today, offsetting the cost of build-out.
- littlestymaar 3y ago
  I never said it will be 10x more expensive: if the unit cost is twice as low, then having a 10x overcapacity is “only” 5x more expensive, but that's still too expensive.
pfdietz 3y ago
Germany can do it with a combination of wind, solar, batteries, and hydrogen. The green hydrogen is crucial, to deal with Dunkelflauten and to some extent seasonality. Germany has ample salt formations for cheap hydrogen storage. At the site I linked elsewhere in these comments, the solution for 24/7 power from RE is nearly doubled in Germany if green hydrogen is omitted. Germany is suffering now from the decision to pay for the 2009-2012 solar builds using long term high rates. When that ends (2032?) the costs should come down a lot. Building out solar now should be much less expensive.
nicoburns 3y ago
> so you'd need to have something like 10x solar if you wanted the overcapacity strategy to work, which also make things prohibitively expensive. In the short-term, gas backup for such scenarios (which are relatively rare, and during which renewables will still operate at some non-100% fraction of the required energy) seems like it might be a reasonable option: we could probably get to (pulling numbers out of thin air) 95% renewable generation or something that way. Longer term, we'll definitely need some kind of long-term storage though. Perhaps synthetic fuel driven by overcapacity renewables during peak generation times might be an option here?

DamonHD 3y ago

Storage is useful at all sorts of scales, from microseconds to years. Interseasonal or even a dunkleflaute's worth is hard at the moment, though we manage it with heat and with (eg) methane already in places. It's happening. Plus we are getting better at moving demand to when energy is available.

Slava_Propanei 3y ago
[dead]

audunw 3y ago

Do you have any links to those studies? Because the ones I've seen indicate the exact opposite. You only need 2-3 days of storage or so at most. Tony Seba has some presentations on this topic. His argument is that renewables is getting so cheap that you can build so much that the minimum production covers all days with few exceptions. I guess that might assume some reasonable grid upgrades as well. Marc Z Jacobsen has some fairly detailed studies for going 100% renewables. He doesn't generally assume any improvements in technology, so his estimates are conservative. I don't remember seeing anything about seasonal storage. You may ask about colder regions. Seems like the solution there will be 1. Trash burning (getting common in Scandinavia.. you could even do it with CO2 capture as a power plant in Oslo, Norway is developing), with district heating 2. Geothermal for district heating 3. Nuclear for a bit of extra baseload (UK, Sweden and Finland are all building nuclear) Also keep in mind that to go zero-carbon, we need to make a hell of a lot of hydrogen, ammonia, e-fuels, biofuel/oil/coal (I just read news about a Danish company starting commercial operation of a giant microwave reactor that can efficiently make bio-oil/coal from sewer sludge). All these solutions will imply a lot of storage capacity. If you're making enormous quantities of hydrogen you're going to have buffers at both the production and consumption side. Production can probably be throttled if needed. I'm guessing that the hydrogen power plants we already have will also be kept around to serve as backup. There's some pretty serious talk about switching the natural gas pipelines from Norway to Europe from gas to hydrogen. First making hydrogen with carbon capture and storage, then green hydrogen made with off-shore wind. And off-shore wind is another thing that's getting more common. If you build really big off-shore wind turbines the production is very reliable.

chmars 3y ago
It’s about 12 weeks in Germany: https://iopscience.iop.org/article/10.1088/1748-9326/ac4dc8 https://iopscience.iop.org/article/10.1088/1748-9326/ac4dc8
- akvadrako 3y ago
  It also depends how much one overbuilds the supply, since the batteries need to be fully charged at the beginning of that 12 week drought. Based on a quick reading it seems they are assuming the average supply is 130% of the average load over the year.

pfdietz 3y ago

To get a handle on this, I point people to this fun site https://model.energy https://model.energy which allows you to use historical weather data, various cost assumptions, and optimize for the cheapest combination of wind, solar, batteries, and hydrogen to get steady 24/7 power (which would be a drop-in replacement for a nuclear power plant, essentially.) By disabling the hydrogen you can get a handle on the cost bump for handling the storage with just batteries. In some places, that cost increase would be considerable (for example, Germany); in others, negligible (India). If you don't like the cost assumptions (they cite sources) you can tweak them and see how the optimum solutions change.

martinald 3y ago
This is really interesting but I am not seeing how it gets to end price. It's saying around 54eur/mwh in the UK with the 2020 technology assumption. I can see that cost for the solar/wind itself but seems very low for the masses of hydrogen (and associated round trip losses) that it's suggesting. I have read some estimates that it could at least double the price?
- pfdietz 3y ago
  If there is otherwise curtailed wind/solar, the RTE doesn't matter very much, since the energy is otherwise thrown away.
  - martinald 3y ago
    I know, but the model above suggests massively overbuilding solar and wind to convert it to hydrogen for storage. That overbuild isn't "free" and I can't see how you can get to €50eur/MWh at the moment for baseload esque power.
    - Turskarama 3y ago
      The overbuild isn't free but the cost of (renewable) generation is so cheap compared to storage that it's most often cheaper to just build too much.

beders 3y ago

Who paid for these studies? "order of seasons" - that can't be right.

gwright 3y ago
Why do you think that can't be right? Solar and wind generation themselves are seasonal and don't match the seasonal patterns of demand. So you need to time shift across seasons if you don't have the instantaneous (base load) capacity available all the time. You might say, well, just build more windmills or solar farms. Doesn't help when it is dark and calm. Your "overbuild" is useless in that situation. So you need storage (or other base load generation, fossil or nuclear). In this study, it is estimated that Germany and California both need about 25TWh of storage to time shift energy supplied by intermittent sources to other parts of the year. The study claims $5 trillion to purchase batteries to store that much energy. http://euanmearns.com/the-cost-of-wind-solar-power-batteries-included/ http://euanmearns.com/the-cost-of-wind-solar-power-batteries...
- mikeyouse 3y ago
  You're kind of making OPs point though - that post was written by a retired 80yr oil engineer who just blogs into the aether because he hates solar and wind.. the $5 trillion estimate was him literally just making up numbers. To critique this more specifically - in that post he assumed we would spend $5 trillion on batteries, and they would still cost the same $200/kwh that they cost in back in 2018. Even if his other assumptions on the capacity required were valid (they aren't), costs have already fallen below $100/kwh since learning curves exist - so his scary $5 trillion number is already below $2.5 trillion. Add in the additional cost savings and amortize that investment over a decade and you're talking about maybe 3.5% of the Federal budget?
- oezi 3y ago
  No, you just need peaker plants which can run for the 1-3 weeks per year when there is no wind in the winter. Battery capacity will never be built to exceed 1-3 days of demand.

jltsiren 3y ago

This is not a new problem, and there is no silver bullet that will solve it. Just a long sequence of incremental improvements that will make the difference over decades. In the Nordics, the solution is primarily hydro + wind + nuclear, with cogeneration from district heating and industrial processes. Old-style power plants that generate electricity by burning fuels are largely obsolete, and the cogeneration plants are also phasing out fossil fuels. The solution is within reach, but it took decades to get there. Other regions will need other solutions.

standardUser 3y ago

> So it isn't clear how much capacity has been lost in this switch. They may also be other changes in the generation portfolio that aren't discussed in the article. I understand why people are so quick to argue against batteries as a power supply when they are unproven in a given scenario. I think it's a narrow way of thinking that ignores everything we know about the progression of technology and devalues the skilled professionals actually doing this work, but I understand. What I don't understand is what compels a person to grasp at straws and pose speculative "what ifs" after a project is successfully in operation. What more do you need? Does it need to run fifty years before you're convinced?

gwright 3y ago
Well in terms of the various capabilities the article highlighted * dark starting * capacity * grid stabilization it sounds like the battery plant is successful. But the article itself says that the plant does not replace the "energy" component of the old coal power plant, which is why I asked the questions I asked. And it is the energy component that is critical for really retiring base load capacity provided by fossil fuel plants at grid level. Without the ability to retire the base load capacity you aren't really solving the problem. Costs rise dramatically (you now have two energy systems) and/or you have to accept less reliability (running out of power when wind/solar/hydro/battery are inadequate). I think you are mis-interpreting my comment and being unfair in characterizing what I'm saying as "narrow minded" or "grasping at straws". > The old coal generator provided three key values to Oahu, Keefe explained: energy (the bulk volume of electricity), capacity (the instantaneous delivery of power on command), and grid services (stabilizing functions for the grid, wonky but vital to keeping the lights on). > The battery directly replaces the latter two: It matches the coal plant’s maximum power output (or “nameplate capacity,” in industry parlance), and it is programmed to deliver the necessary grid services that keep the grid operating in the right parameters.
- standardUser 3y ago
  Yes, I was talking more about an attitude than your specific concern. Though your framing still contorts the issue in a way that makes a coal plant appear like the proper, ideal solution while this new "problem" method is some shady, questionable alternative that must have hidden flaws. And you continue to list more speculative flaws in this comment as well. What do you think of the idea that, given proper experience and technology, we can have a grid system that does not suffer from inadequate wind/solar/hydro/battery? That is the mindset we need to shift our framing to as these technologies continue to expand and prove themselves on larger and larger scales. I have no doubt people had to shift their framing around the entire idea a reliable coal-based electricity production once upon a time as well.

Kon5ole 3y ago

>The main problem with replacing a fossil fuel plant with renewable + batteries is finding a battery system that can hold energy over a sufficiently long period of time and has enough capacity to replace solar/wind when it is dark and calm. Synthesizing gas seems like a good solution. With electricity prices often dipping into the negatives thanks to all the renewable fluctuations, synthesized gas should be able to compete with any other base source on price. Generate gas when electricity is cheap enough and use it to generate electricity when it's expensive enough. Basically a profit-pump once the initial investment is paid off.

weebull 3y ago

It's Hawaii. They're literally sitting on an infinite energy supply and have almost continuous sun (apart from nights).

itslennysfault 3y ago

I'd think for long term storage pumped hydro would be a better solution. Pump water up a hill and just leave it sitting up there until you need to let it fall to generate some power.