A question on storage. One of the big issues with solar/wind is variability of supply - hence the need for base load generation or storage. I was looking at the eye-watering estimates for the new nuclear stations and wondered how that compared with, say, enough batteries to store a week's worth of energy from a power station. I appreciate there will be loads of practical considerations as well (e.g. how big would it be??) but as a starting point how do the costs compare?
Oct 30, 2023·edited Oct 30, 2023Liked by Hannah Ritchie
Some of the comments have alluded to this. Some in a nice way and some in a not so nice way. I think this adage applies, "Just because you can, doesn't mean you should."
Because of variability both seasonal and daily for renewables, you have to overbuild. This is seen clearly in the graph on pg. 25 where the annual generation for an all renewable system is the largest. This also comes with increased cost. An important point is that this study is already a couple years old and the results would probably be different today. The point being that experts in system studies are continually reassessing the situation. However, as Dr. John Bistline wrote in an NYT op-ed concerning the U.S, we shouldn't worry so much about the final mix of technologies but we should do the things we know we need to do,
"For the coming decade, rapidly reducing coal electricity and building extensive wind, solar and storage systems are low-cost strategies in many places, regardless of how much energy might or might not eventually come from renewables."
Leaving aside MacKay's assessment (and perhaps bleak cynicism) about the monetary and political costs of the possible supply stack, surely the real killer in SEWTHA for renewable-only plans was the amount of storage needed?
MayKay's figure for the duration of wind lulls (5 windless days, which would require 1200 GWh (1.2 TWh) of storage) was taken from Irish data, and was far lower than that used by the Energy Research Partnership (in "Managing Flexibility Whilst Decarbonising the GB Electricity System") which found that windless periods can last up to 3 weeks, requiring storage of 6-8 TWh. I seem to recall a more recent study which looked not just at wind lulls but prolonged weeks-months of low wind and found the storage requirements even higher.
In trying to deal with this problem MacKay, arguably, erred on the side of optimism, wishing up a fleet of EVs with swappable batteries (like that Taiwanese electric moped company David Roberts talked about a wile back). Of course these didn't materialise and even the next best - V2G and bidirectional chargers everywhere - would seem to be decades away.
So, yes: it's interesting that we could generate all the energy we need, albeit not when we need it, but storage is still the bottleneck between theory and practice. And I'd guess that that comes down to electricity to hydrogen and back, and whether we have enough underground salt caverns or whatever to store the amount we need for several months' worth of low wind.
Hi Hannah. Among other points I might make later (interest rates, metals, geopolitics, energy duration, the fact these machines will need to be rebuilt in 20-30 years etc), I'll just point out for now, that -again - you're using the word 'energy' when you should say 'electricity'. Big difference. Electricity is only 20-21% of global energy use and 19% in case of UK (O'Callaghan states this correctly)
Which aligns with UK FIRES Absolute Zero (2019): https://ukfires.org/impact/publications/reports/ which lists electricity supply as *580 TWh/year.* Thank you for your work, we are deeply appreciative.
My experience is that it is safer to wait for the response of the expert community to policy analyses.
MacKay actually used 20% efficiency for the efficiency of PVs, price notwithstanding. He looked at all energy needs, including food, but presumably the UK will remain a net food and stuff importer for some years.
The big difference between MacKay and newer UK numbers were MacKay's estimates for floating turbines, from what I found. Current estimates are much higher.
I see a range of US numbers for wind capacity factors from official organizations, frustrating. I don't know how much of improved capacity factor for recent projects is due to improved designs or newer wind turbines are in better condition, they will age later, let alone the ubiquitous "wind is up/down in recent years".
Well before California got to 20% solar power, the wholesale price paid per kWh electricity when the sun is out (1-2¢/kWh) had fallen well below the cost of new solar (just counting rooftop and industrial solar from in-state, not that bought from out of state). This occurs with wind in windy areas, although to a lesser extent. The wholesale price of electricity in the late afternoon and evening rose, a lot.
In contrast to many of the commenters, these numbers look good to me as a first order approximation. My strongest argument is about the demand side. I think it is likely that the demand will actually be much higher than the 'high' demand assumed. Why? Four things jump out: 1) mitigating the effects of climate change already baked in. 2) Building the infrastructure to remove existing carbon from the atmosphere. 3) Powering the AIs that are going to help us figure out how to do those things and much more. 4) Stuff we don't even know about that we haven't been able to contemplate because the energy needed was never there.
Given those and only those, we might be looking at an order of magnitude more demand.
1. The lowest priced solar CfD operational is currently worth £106/MWh.
2. The idea of an offshore wind capacity factor of 50% is absurd. The fleet average has been 40% or thereabouts for 10 years now. Big wind turbines are wearing out *very* quickly.
3. Floating offshore wind is probably the most expensive way of generating electricity deployed at scale. The levelised cost of Kincardine Windfarm, for example, is around £288/MWh.
4. Do you understand that if you have supply equal to double demand, your unit costs increase? Wind power at £288/MWh into hydrogen storage comes out at £822/MWh (35% round trip efficiency). It will be more expensive still if the windfarm is curtailed half the time. Utter madness.
5. Do you understand that if you put windfarms far out at sea, the costs increase? Presenting figures as a percentage of the UK's EEZ could be construed as being highly deceptive.
6. Do you understand that as windfarms move away from highland areas onto farmland, the load factor will go down? Claiming 48% is easy, but looks absurd when the current figure is less than 30%.
Very cool Hannah, Dave McKay's book has been a big inspiration for me too and I'm eternally grateful that it was available for free online. And it's good to update those figures indeed. If I remember correctly, he did put his caveat on his big "NO" that much cheaper floaters for floating wind would be a joker. Delivering such cheap platforms is indeed one of the most exciting engineering problems of the day for northern Europe - they are not there yet, and I'm afraid prospects for those currently in the water are rather challenging.
That being said, I think this whole hullaballoo about 100% vs 70% renewables is more of an academic pastime than a real issue. The problem facing us still is going to 50% renewables, down from 80% fossil today (energy, not electricity).
Everything I have read suggests getting to 85% renewables should be very doable without addressing most of the concerns brought up over the last few %. The focus this decade should really be on building out renewable sources as fast as possible. It’s worth noting that additional renewable sources can also make future contributions to the potential for renewables. Floating solar in particular might increase the area available considerably and doesn’t seem to have been considered. Then there’s also still geothermal and tidal etc.
The interesting question isn't really can you power [insert name of country here] with wind and solar, but why would you want to? Most of the costs of electricity aren't in the generation but the grid. With nuclear you just plug it in and it works, with wind and solar you need a massive redesign and rebuild effort ... particularly with rooftop solar in places like Australia. A heavy rollout of rooftop PV and batteries is already breaking our grid in South Australia. We are going to have enough trouble opening enough mines fast enough for EV batteries, so why waste precious resources backing up environmentally destructive collectors of electricity like wind and solar? Please consider ...https://www.blog.geoffrussell.com.au/post/energy-spin-and-the-running-of-the-bull-shit
Thanks Hannah, really good blog to read. I had similar reaction to David MacKay’s work, in that it / he inspired me to go into policy facing work in the civil service, realising my background in science could be useful. Great to get this update to the figures in SEWTHA!
An idea for an extension, which I found helpful when I was working directly in the policy area, if you want to look beyond the totals at dispatchability and get a sense of scale of storage or other technologies needed was to look at the demand curve. If you plot half-hour demand on the grid for the year, ordered from high to low along the x-axis, you get something that looks a bit like a trapezium going from winter peak to a summer lull. You can plot a typical wind and solar profile against that. You’d expect this would show excess supply on the RHS, and an unmet demand in the LHS. You can then ask how much can be shifted around with say 4hrs of storage (very doable with cheaper batteries), and then what residual demand will you need to meet with another tech like gas, or demand response, or nuclear, or closed loop geothermal (which can also act as a kind of storage…). The optimal split depends on a mix of economics and politics. Appreciate this might be a bit too in the weeds though!
Hannah tries to "work out if Britain could power itself from renewables," which if I understand correctly means whether Britain could get all (or almost all) of its electricity from wind and solar.
This post unfortunately shows the limitations of the author's data-driven approach — the most important factors are left out because they can't be computed as easily as less important ones.
The post considers (1) the amount of energy Britain could get from wind and solar and (2) the cost of wind turbines and solar panels. The post concludes that there are enough resources available and that turbines and solar panels have become much cheaper, therefore yes Britain can get most of its electricity from renewables.
But these aren't remotely the main costs or constraints anymore. The main costs in adding solar and wind to a grid are related to (3) grid transmission and distribution, (4) storage and overbuilding to handle renewables intermittency, and (5) project finance.
Grid transmission and distribution — According to the chairman of Iberdrola, for every dollar invested in renewables, another dollar needs to be invested in grid transmission and distribution.
Handling intermittency — A recent report from the Royal Society explains that we'd likely need to store energy for decades because of long term trends in wind power generation:
> Wind supply can vary over time scales of decades and tens of TWhs of very long-duration storage will be needed. The scale is over 1000 times that currently provided by pumped hydro in the UK, and far more than could conceivably be provided by conventional batteries.
It calls for storing about 100 TWh. The only technology (they claim) to be viable is hydrogen storage.
However, as far as I'm aware, large scale hydrogen production, transport and storage is still in its infancy and therefore we need demonstration projects before estimating its cost with any certainty.
Finance costs — The constant drumbeat of offshore wind project cancellations reminds us that finance costs are important. Since most of the costs are incurred upfront but revenues are recognized over 20+ years, higher interest rates make projects more expensive.
Energy analyst Ira Joseph often issues the following challenge to promoters of small modular nuclear reactors: "Just build one." That is the only way to understand if they are practical and economically viable.
The same goes with any electrical grid that is powered (almost) entirely by renewables. Until one is built and we can evaluate its costs, discussions are likely to focus on some factors of the total cost but miss out more important ones.
I’m all for crunching numbers but expecting wind and solar to decarbonise the UK and provide security of supply is straight out of Ed Miliband dummies guide to energy.
The deployment of either technologies to the levels required to achieve and sustain that level indefinitely are well beyond credibility both from a material resources, manufacturing, construction and maintenance point of view.
David MacKay’s numbers and reasoning still has validity 15 years later.
A question on storage. One of the big issues with solar/wind is variability of supply - hence the need for base load generation or storage. I was looking at the eye-watering estimates for the new nuclear stations and wondered how that compared with, say, enough batteries to store a week's worth of energy from a power station. I appreciate there will be loads of practical considerations as well (e.g. how big would it be??) but as a starting point how do the costs compare?
Some of the comments have alluded to this. Some in a nice way and some in a not so nice way. I think this adage applies, "Just because you can, doesn't mean you should."
I continue to believe that questions like these are really best left to systems experts that do tradeoff studies, e.g. Net-Zero America Project. Here is a link to their summary, https://netzeroamerica.princeton.edu/img/Princeton%20NZA%20FINAL%20REPORT%20SUMMARY%20(29Oct2021).pdf .
Because of variability both seasonal and daily for renewables, you have to overbuild. This is seen clearly in the graph on pg. 25 where the annual generation for an all renewable system is the largest. This also comes with increased cost. An important point is that this study is already a couple years old and the results would probably be different today. The point being that experts in system studies are continually reassessing the situation. However, as Dr. John Bistline wrote in an NYT op-ed concerning the U.S, we shouldn't worry so much about the final mix of technologies but we should do the things we know we need to do,
"For the coming decade, rapidly reducing coal electricity and building extensive wind, solar and storage systems are low-cost strategies in many places, regardless of how much energy might or might not eventually come from renewables."
https://www.nytimes.com/2022/04/10/opinion/environment/ipcc-report-climate-change-debates.html .
Leaving aside MacKay's assessment (and perhaps bleak cynicism) about the monetary and political costs of the possible supply stack, surely the real killer in SEWTHA for renewable-only plans was the amount of storage needed?
MayKay's figure for the duration of wind lulls (5 windless days, which would require 1200 GWh (1.2 TWh) of storage) was taken from Irish data, and was far lower than that used by the Energy Research Partnership (in "Managing Flexibility Whilst Decarbonising the GB Electricity System") which found that windless periods can last up to 3 weeks, requiring storage of 6-8 TWh. I seem to recall a more recent study which looked not just at wind lulls but prolonged weeks-months of low wind and found the storage requirements even higher.
In trying to deal with this problem MacKay, arguably, erred on the side of optimism, wishing up a fleet of EVs with swappable batteries (like that Taiwanese electric moped company David Roberts talked about a wile back). Of course these didn't materialise and even the next best - V2G and bidirectional chargers everywhere - would seem to be decades away.
So, yes: it's interesting that we could generate all the energy we need, albeit not when we need it, but storage is still the bottleneck between theory and practice. And I'd guess that that comes down to electricity to hydrogen and back, and whether we have enough underground salt caverns or whatever to store the amount we need for several months' worth of low wind.
Hi Hannah. Among other points I might make later (interest rates, metals, geopolitics, energy duration, the fact these machines will need to be rebuilt in 20-30 years etc), I'll just point out for now, that -again - you're using the word 'energy' when you should say 'electricity'. Big difference. Electricity is only 20-21% of global energy use and 19% in case of UK (O'Callaghan states this correctly)
Please dig into this on hydrogen storage from the Royal Society last month; 2050 electricity supply for the UK is listed as *570 TWh/year*:
https://royalsociety.org/-/media/policy/projects/large-scale-electricity-storage/V1_Large-scale-electricity-storage-report.pdf
Which aligns with UK FIRES Absolute Zero (2019): https://ukfires.org/impact/publications/reports/ which lists electricity supply as *580 TWh/year.* Thank you for your work, we are deeply appreciative.
My experience is that it is safer to wait for the response of the expert community to policy analyses.
MacKay actually used 20% efficiency for the efficiency of PVs, price notwithstanding. He looked at all energy needs, including food, but presumably the UK will remain a net food and stuff importer for some years.
The big difference between MacKay and newer UK numbers were MacKay's estimates for floating turbines, from what I found. Current estimates are much higher.
I see a range of US numbers for wind capacity factors from official organizations, frustrating. I don't know how much of improved capacity factor for recent projects is due to improved designs or newer wind turbines are in better condition, they will age later, let alone the ubiquitous "wind is up/down in recent years".
Well before California got to 20% solar power, the wholesale price paid per kWh electricity when the sun is out (1-2¢/kWh) had fallen well below the cost of new solar (just counting rooftop and industrial solar from in-state, not that bought from out of state). This occurs with wind in windy areas, although to a lesser extent. The wholesale price of electricity in the late afternoon and evening rose, a lot.
Thank you for your work.
In contrast to many of the commenters, these numbers look good to me as a first order approximation. My strongest argument is about the demand side. I think it is likely that the demand will actually be much higher than the 'high' demand assumed. Why? Four things jump out: 1) mitigating the effects of climate change already baked in. 2) Building the infrastructure to remove existing carbon from the atmosphere. 3) Powering the AIs that are going to help us figure out how to do those things and much more. 4) Stuff we don't even know about that we haven't been able to contemplate because the energy needed was never there.
Given those and only those, we might be looking at an order of magnitude more demand.
This is very poor. Idiotic in fact.
1. The lowest priced solar CfD operational is currently worth £106/MWh.
2. The idea of an offshore wind capacity factor of 50% is absurd. The fleet average has been 40% or thereabouts for 10 years now. Big wind turbines are wearing out *very* quickly.
3. Floating offshore wind is probably the most expensive way of generating electricity deployed at scale. The levelised cost of Kincardine Windfarm, for example, is around £288/MWh.
4. Do you understand that if you have supply equal to double demand, your unit costs increase? Wind power at £288/MWh into hydrogen storage comes out at £822/MWh (35% round trip efficiency). It will be more expensive still if the windfarm is curtailed half the time. Utter madness.
5. Do you understand that if you put windfarms far out at sea, the costs increase? Presenting figures as a percentage of the UK's EEZ could be construed as being highly deceptive.
6. Do you understand that as windfarms move away from highland areas onto farmland, the load factor will go down? Claiming 48% is easy, but looks absurd when the current figure is less than 30%.
Sorry, but this is embarrassingly awful.
Very cool Hannah, Dave McKay's book has been a big inspiration for me too and I'm eternally grateful that it was available for free online. And it's good to update those figures indeed. If I remember correctly, he did put his caveat on his big "NO" that much cheaper floaters for floating wind would be a joker. Delivering such cheap platforms is indeed one of the most exciting engineering problems of the day for northern Europe - they are not there yet, and I'm afraid prospects for those currently in the water are rather challenging.
That being said, I think this whole hullaballoo about 100% vs 70% renewables is more of an academic pastime than a real issue. The problem facing us still is going to 50% renewables, down from 80% fossil today (energy, not electricity).
You may want to correct the wee typo that currently says "appaling delusion", balanced, as it is, between 'appealing' and 'appalling' :D
Everything I have read suggests getting to 85% renewables should be very doable without addressing most of the concerns brought up over the last few %. The focus this decade should really be on building out renewable sources as fast as possible. It’s worth noting that additional renewable sources can also make future contributions to the potential for renewables. Floating solar in particular might increase the area available considerably and doesn’t seem to have been considered. Then there’s also still geothermal and tidal etc.
The interesting question isn't really can you power [insert name of country here] with wind and solar, but why would you want to? Most of the costs of electricity aren't in the generation but the grid. With nuclear you just plug it in and it works, with wind and solar you need a massive redesign and rebuild effort ... particularly with rooftop solar in places like Australia. A heavy rollout of rooftop PV and batteries is already breaking our grid in South Australia. We are going to have enough trouble opening enough mines fast enough for EV batteries, so why waste precious resources backing up environmentally destructive collectors of electricity like wind and solar? Please consider ...https://www.blog.geoffrussell.com.au/post/energy-spin-and-the-running-of-the-bull-shit
Thanks Hannah, really good blog to read. I had similar reaction to David MacKay’s work, in that it / he inspired me to go into policy facing work in the civil service, realising my background in science could be useful. Great to get this update to the figures in SEWTHA!
An idea for an extension, which I found helpful when I was working directly in the policy area, if you want to look beyond the totals at dispatchability and get a sense of scale of storage or other technologies needed was to look at the demand curve. If you plot half-hour demand on the grid for the year, ordered from high to low along the x-axis, you get something that looks a bit like a trapezium going from winter peak to a summer lull. You can plot a typical wind and solar profile against that. You’d expect this would show excess supply on the RHS, and an unmet demand in the LHS. You can then ask how much can be shifted around with say 4hrs of storage (very doable with cheaper batteries), and then what residual demand will you need to meet with another tech like gas, or demand response, or nuclear, or closed loop geothermal (which can also act as a kind of storage…). The optimal split depends on a mix of economics and politics. Appreciate this might be a bit too in the weeds though!
Hannah tries to "work out if Britain could power itself from renewables," which if I understand correctly means whether Britain could get all (or almost all) of its electricity from wind and solar.
This post unfortunately shows the limitations of the author's data-driven approach — the most important factors are left out because they can't be computed as easily as less important ones.
The post considers (1) the amount of energy Britain could get from wind and solar and (2) the cost of wind turbines and solar panels. The post concludes that there are enough resources available and that turbines and solar panels have become much cheaper, therefore yes Britain can get most of its electricity from renewables.
But these aren't remotely the main costs or constraints anymore. The main costs in adding solar and wind to a grid are related to (3) grid transmission and distribution, (4) storage and overbuilding to handle renewables intermittency, and (5) project finance.
Grid transmission and distribution — According to the chairman of Iberdrola, for every dollar invested in renewables, another dollar needs to be invested in grid transmission and distribution.
https://twitter.com/BloombergNEF/status/1719010207836316015
Handling intermittency — A recent report from the Royal Society explains that we'd likely need to store energy for decades because of long term trends in wind power generation:
> Wind supply can vary over time scales of decades and tens of TWhs of very long-duration storage will be needed. The scale is over 1000 times that currently provided by pumped hydro in the UK, and far more than could conceivably be provided by conventional batteries.
It calls for storing about 100 TWh. The only technology (they claim) to be viable is hydrogen storage.
https://royalsociety.org/topics-policy/projects/low-carbon-energy-programme/large-scale-electricity-storage/
However, as far as I'm aware, large scale hydrogen production, transport and storage is still in its infancy and therefore we need demonstration projects before estimating its cost with any certainty.
Finance costs — The constant drumbeat of offshore wind project cancellations reminds us that finance costs are important. Since most of the costs are incurred upfront but revenues are recognized over 20+ years, higher interest rates make projects more expensive.
https://www.bloomberg.com/news/articles/2023-07-22/biggest-offshore-wind-power-plans-in-crisis-iberdrola-orsted-vattenfall-hit
Energy analyst Ira Joseph often issues the following challenge to promoters of small modular nuclear reactors: "Just build one." That is the only way to understand if they are practical and economically viable.
The same goes with any electrical grid that is powered (almost) entirely by renewables. Until one is built and we can evaluate its costs, discussions are likely to focus on some factors of the total cost but miss out more important ones.
I’m all for crunching numbers but expecting wind and solar to decarbonise the UK and provide security of supply is straight out of Ed Miliband dummies guide to energy.
The deployment of either technologies to the levels required to achieve and sustain that level indefinitely are well beyond credibility both from a material resources, manufacturing, construction and maintenance point of view.
David MacKay’s numbers and reasoning still has validity 15 years later.
I totally agree with Andrew Mont ford's assessment.... IDIOTIC AND IGNORING LAWS PHYSICS....