Renweable energy sources work great until you really need them. and then they are not there. Usiing averages gives falso answers. In my opinion you are not wrong!
1. Iowa with 65% renewables has 1/3rd of the lost time per customer of neighbouring Illinois which is 70% FF and nuclear
2. Denmark has moved from importing 17% of its power and generating 37% from fossil fuels in 2015 to having a small surplus last year and generating 82% from renewables while becoming the most reliable grid in Europe
3. SA is the most reliable region on the mainland with 73% wind and solar over the last 12 months despite reducing net imports by 2/3rds and eliminating coal over the last decade
At the moment hydro runs 24/7 however, as wind and solar increase, low hydro periods will increase. For example in the last week hydro has varied between 700 and 5,000 MW. With roughly 4 X wind and solar there would have been about 80 hours where hydro could have been near zero during the day even with no coal and gas. At night there were times where 4 X wind would have supplied 90% of demand. From the middle of August 2024 to the middle of March 2025 there was not one week where 4X wind and solar would not have supplied more energy than the NEM used
As there is currently 10.3 GW of hydro on the NEM with about 5GW of pumped hydro approved and potential for upgrading existing hydro by at least 1 GW and possibly up to 3 GW, it is not unlikely that on low wind nights, hydro could peak at 10-12 GW without using any more water over the year.
Then there is demand profile.
About 20% of nighttime demand is from "offpeak" rates designed to keep coal plants going, often at below cost rates. Much of that demand will switch to "solar soaker" or dynamic rates designed to soak up excess wind and solar. That would mean the 20 GW nightime demand will probably fall despite increasing electrification.
Finally, electrification of everything will require much less electricity than people imagine. France is a highly electrified economy by Western standards and has a lot of wasteful electric resistance heating and yet uses 6.2 MWh/ person. Australia uses about 9.2 MWh/person down from a peak of about 11 MWh
I suspect David is a bit optimistic, however there are many ways in which he is conservative.
a) At the turn of the century we, like most thermal grids, had enough coal and gas capacity at normal capacity factors to supply 50% more energy than they actually did. David only has 15-20% excess capacity at normal capacity factors. With 50% overcapacity most of your concerns go away.
b) New wind farms are now being specified to maximise output at medium and low wind speeds rather than simply maximse annual output. So, for example, in the last week when winds have been below average, newer wind farms have produced 10-20% more energy per MW than older units. However, this trend is only in its infancy, new turbines, particularly in China are being built with 20-50m taller towers to catch better winds and with rotor area/MW up to 50% higher than current standards. This means that in a breeze where say McArthur is barely turning over, the new wind farms will be at 20-30% capacity and when McArthur is at 35% the new farms will be at 80-100%
c) Most of the early solar farms were fixed tilt north-facing , Now they are tracking units and increasingly bifacial. That means early and late eg at say 8am or 5pm their output per MW of capacity is nearly double that of the original farms. Further, panels are so cheap that panel capacity is often 50% or more than nominal output eg 150 KW of panels for connection capacity of 100 kW so that on hazey days or for an extra half hour morning and night output can be maintained at 100 kW. This is the same reason that truck horsepower has doubled over the last thirty years not so you can go faster on the flat, but so you can maintain speed up the hills.
d) Rooftop solar is so cheap that people will keep installing it and combining with flexible demand, smart EV charging and customer batteries. With 22-28% efficient solar panels, Australia has enough unshaded area over paved areas and roofs to supply about 150% of its annual electricity demand.
e) He has completely neglected flexible demand and V2G to soak up excess wind and solar and compliment peak demand.
f) He has almost certainly under-estmated the quantity of storage that will be on the grid. He shows that we need 120 GWh to be 98% renewable. Lake Cethana (Tasmania), Snowy II, Kidston, Borumba and Musswellbrook will provide 460 GWh. In addition more than 180 GW/450 GW of battery projects have been announced and by 2032 there will be be between 5 and 10 GW behind the meter as well as probably 2-5 GW of vehicle to load
I see that both you and Chris are heavily and emotionally invested in this debate (as both of your comments show)!
From an outsider's point of view this highly technical discussion is interesting but ultimately you will both probably be wrong (but for different reasons). I suspect Chris's arithmetic is correct - which is all he's trying to claim, in which case - and under his assumptions, there will be problems.
So you are rightly questioning his assumptions, not his calculations. To an outsider like myself, your comments on future supply/demand, like solar tracking panels, seem reasonable but of course subject to many additional assumptions (e.g. the tracking panels will be maintainable, the price of panels will continue to drop, the hydro and battery projects will indeed be built, etc.)
This all matters because of the long term nature of these changes and the huge investment required. If we the west/the human race get this wrong we're stuffed.
Although it's unarguable that we have to stop using fossil fuels in the long term (as they'll eventually run out) I think we're going too far too fast. This headlong rush will have zero effect on climate anyway as atmospheric concentrations of CO2 mean it's no longer effective as a 'greenhouse gas'.
Unfortunately Chris's arithmetic is a good example of GIGO, garbage in/Garbage out. Even if there were three hundred hours when gas provided 36% of demand or thirty days where it provided 25% of the day it is still lss than 2% of annual demand.
On the highest hydro day in the last year hydro ran at 27% capacity for the 24 hours and peaked at about 60 %. For the highest week it ran at 21%. By the time Cethana, Snowy II, Borumba and Kidston are on line peak hydro can be doubled and output for a week can be more than doubled. Nowhere is that accounted for in Chris's calculations
Regardless of whatever strategy we pursue we will need to build new generation, most of our coal plants and many of our gas plants are either now or will be within the next ten years beyond their design life. The fixed costs of new coal and gas plants before an ounce of fuel is delivered or a single security guard let alone operators and maintenance staff is hired are more than the total capital, operation and maintenance costs of wind solar and batteries
Why wouldn't tracking solar be maintainable? It currently costs less per MWh to maintain a solar farm than wind, coal or gas so even if the power price were to halve and coal was free, solar still has a market.
The weighted average of wnd/solar/batteries on the NEM is $76/MWh, black coal $128 for existing and $180-200 for new and gas $250/MWh so regardless of climate change why would you not buy more $76 power and less $128 and $250 power
I think Chris's point, which is backed up by the detailed results he displays, is that power outages will certainly occur in these 'renewables' based systems. If you have tried to reproduce his calculations and got different results, then please share your working.
Of course, just a few seconds of power loss in any part of a grid has huge knock-on effects - as the Spanish experience showed.
As for solar tracking, each panel has to have motorised altazimuth mounts. With millions of these in operation in all weather there will indeed be a maintenance issue.
Aside from having enough capacity to meet demand for every second of the 86400 in a day there are serious engineering issues this novel technology. You should look at some of the engineering problems involved in managing it and there's a good explanation at https://www.youtube.com/watch?v=7G4ipM2qjfw&t=736s
1. His detailed results have significantly underestimated hydro so no further discussion is required. Further, it is not as if this is his only mistake. This is one of his least erronious posts
2. Of course solar trackers need maintenance, so do coal and gas plants. Kogan Creek is the newest, lowest cost coal plant on the NEM has had 5 weeks offline for maintenance in the last year following a three month shutdown in 2022 and an even longer one in 2019. Callide C3 has just vreturned to service after 8 weeks off line, 4 weeks in june/July last year and 18 months from November 2022 etc etc.
3. What capacity limitations can there possibly be. Texas is smaller than NSW and this year will generate more power from wind and solar than the whole of Australia generates from coal and gas. China is only 25% larger than Australia and in April generated almost enough energy from wind and solar to power Australia for a year and in April connected almost twice as much solar as Australia has connected in the last 20 years.
4. The Video you referenced explains that these engineering challenges are being solved and solved quickly, that is why SA now operates safely for hours and even days at a time with just 80 MW of spinning reserve having reduced imports by two thirds and limininating coal over the last 12 years, why Britain can close coal altogether and halve nuclear output and the Southwest Power Pool in the US which supplies slightly more energy than the NEM has run at up to 92% renewables
I've made an extra post especially for you and DO.
Once you've chewed on it, and ONLY if you find an error in my methodology or arithmetic, let me know.
But if your 1st comment above "results have significantly underestimated hydro " refer to the PUMPED ENERGY STORAGE schemes you previously listed, you have totally misunderstood that PUMPED ENERGY STORAGE is energy storage (a net drain on the NEM) not new Hydro generation.
The whole point of David Osmond's proposed capacity is to have sufficient wind and solar capacity to generate 15-20% more energy than we need at normal capacity factors, just as in the good old days in 2000 we had enough coal and gas to generate 220 TWh/y at normal capacity factors when it only supplied 165 TWh.
That excess wind and solar energy is used to recharge the batteries/pumped hydro almost every day. On the very worst day renewable day last year wind and solar peaked at 11 GW out of 28 GW of demand. Adjusted to current capacity that would have been 12 GW. Using David's latest multipliers that would have been around 31-32 GW thus partially recharging the storage. On the majority of days storage would have been in a better state at the end of the day than the start.
The key difference is that in the good old days, the marginal cost of pumping our pumped hydro was $40-70/MWh and after considering transmission and round trip losses and the excess coal capacity that we had, it rarely made sense to use the pumped hydro.
Now with almost zero marginal cost wind and solar and much higher cost coal, wind/solar/pumped hydro/batteries is still cheaper than coal or gas, that is why utilisation of Wyvenhoe has quadrupled over the past three years compared to a decade ago.
As for the supposedly impossible quantity of batteries there is 28 GW/55 GWh in operation, commissioning or construction now, already 30+ times Warratah and some 130 GW of proposals announced. not to mention 350 GWh in Snowy II and around 60 GWh in Cethana, Kidston and Borumba
In 2008/9 drought capacity in the Snowy dams was below 10% including Tantangara at the top of SH2. The south QLD dams were also below 10% at that time. You therefor cannot assume hydro will save us and you need a firm power source such as nuclear or gas.
It is quite likely that we will need 2-5% from a thermal source and up to 30% for short periods and maybe even 20% for a week, but that can still be around 2% of annual demand.
That suits gas, it could also suit biomass fired steam or gas turbines or coal slurry fired diesel engines or even just ordinary old coal plants with 4 MW/20-25 MWh of storage per MW of coal. The coal plant might then run for 6-10 weeks at a time appearing to the grid as anywhere between a 3 MW load or a 5 MW generator all the while sitting at a near constant 1MW output. In a good renewable year, it might run only a few weeks just to keep it running order and to allow hydro dams to fill more. In a drought year it might run for 6-8 months but still not supply much more than 8% of demand.
One source it does not suit is nuclear because the capital cost of nuclear requires it to runa at lifetime capacity factors of close to 90%
All the rest of your spiel in this comment and in your previous comment is irrelevant to the analysis of the current numbers and his simulation being wrong.
Just returning to your comment "What if I was wrong?".
I tried to allow for doubt in my comments but clearly you are determined to be right.
None of us know what the future mix of supply and demand will be.
How do you know how much the demand profile will change?
How do you know what the mix of tracking/bifacial solar will be vs fixed North facing or east west solar on roofs vs north facing by the time David's targets are reached?
How do you know what the geographic mix of wind will be or the CF of the wind turbines built over the next ten years?
You have one interpretation of the numbers he has another. Your admitted lack of knowledge of hydro is clearly one area where you are wrong.
Given that almost everyone, including of course me, will be shown to be wrong over the next few years, but more importantly almost every post you have made on the topic of renewables is way off, I would be just a bit more cautious about telling other people that they are WRONG.
It might just be a case of the pot calling the kettle black
Renweable energy sources work great until you really need them. and then they are not there. Usiing averages gives falso answers. In my opinion you are not wrong!
That would explain why:
1. Iowa with 65% renewables has 1/3rd of the lost time per customer of neighbouring Illinois which is 70% FF and nuclear
2. Denmark has moved from importing 17% of its power and generating 37% from fossil fuels in 2015 to having a small surplus last year and generating 82% from renewables while becoming the most reliable grid in Europe
3. SA is the most reliable region on the mainland with 73% wind and solar over the last 12 months despite reducing net imports by 2/3rds and eliminating coal over the last decade
https://open.substack.com/pub/chrisbond/p/follow-up-to-but-what-if-im-wrong?r=om40y&utm_campaign=post&utm_medium=web&showWelcomeOnShare=true
Re hydro and demand profile:
At the moment hydro runs 24/7 however, as wind and solar increase, low hydro periods will increase. For example in the last week hydro has varied between 700 and 5,000 MW. With roughly 4 X wind and solar there would have been about 80 hours where hydro could have been near zero during the day even with no coal and gas. At night there were times where 4 X wind would have supplied 90% of demand. From the middle of August 2024 to the middle of March 2025 there was not one week where 4X wind and solar would not have supplied more energy than the NEM used
As there is currently 10.3 GW of hydro on the NEM with about 5GW of pumped hydro approved and potential for upgrading existing hydro by at least 1 GW and possibly up to 3 GW, it is not unlikely that on low wind nights, hydro could peak at 10-12 GW without using any more water over the year.
Then there is demand profile.
About 20% of nighttime demand is from "offpeak" rates designed to keep coal plants going, often at below cost rates. Much of that demand will switch to "solar soaker" or dynamic rates designed to soak up excess wind and solar. That would mean the 20 GW nightime demand will probably fall despite increasing electrification.
Finally, electrification of everything will require much less electricity than people imagine. France is a highly electrified economy by Western standards and has a lot of wasteful electric resistance heating and yet uses 6.2 MWh/ person. Australia uses about 9.2 MWh/person down from a peak of about 11 MWh
https://open.substack.com/pub/chrisbond/p/follow-up-to-but-what-if-im-wrong?r=om40y&utm_campaign=post&utm_medium=web&showWelcomeOnShare=true
I suspect David is a bit optimistic, however there are many ways in which he is conservative.
a) At the turn of the century we, like most thermal grids, had enough coal and gas capacity at normal capacity factors to supply 50% more energy than they actually did. David only has 15-20% excess capacity at normal capacity factors. With 50% overcapacity most of your concerns go away.
b) New wind farms are now being specified to maximise output at medium and low wind speeds rather than simply maximse annual output. So, for example, in the last week when winds have been below average, newer wind farms have produced 10-20% more energy per MW than older units. However, this trend is only in its infancy, new turbines, particularly in China are being built with 20-50m taller towers to catch better winds and with rotor area/MW up to 50% higher than current standards. This means that in a breeze where say McArthur is barely turning over, the new wind farms will be at 20-30% capacity and when McArthur is at 35% the new farms will be at 80-100%
c) Most of the early solar farms were fixed tilt north-facing , Now they are tracking units and increasingly bifacial. That means early and late eg at say 8am or 5pm their output per MW of capacity is nearly double that of the original farms. Further, panels are so cheap that panel capacity is often 50% or more than nominal output eg 150 KW of panels for connection capacity of 100 kW so that on hazey days or for an extra half hour morning and night output can be maintained at 100 kW. This is the same reason that truck horsepower has doubled over the last thirty years not so you can go faster on the flat, but so you can maintain speed up the hills.
d) Rooftop solar is so cheap that people will keep installing it and combining with flexible demand, smart EV charging and customer batteries. With 22-28% efficient solar panels, Australia has enough unshaded area over paved areas and roofs to supply about 150% of its annual electricity demand.
e) He has completely neglected flexible demand and V2G to soak up excess wind and solar and compliment peak demand.
f) He has almost certainly under-estmated the quantity of storage that will be on the grid. He shows that we need 120 GWh to be 98% renewable. Lake Cethana (Tasmania), Snowy II, Kidston, Borumba and Musswellbrook will provide 460 GWh. In addition more than 180 GW/450 GW of battery projects have been announced and by 2032 there will be be between 5 and 10 GW behind the meter as well as probably 2-5 GW of vehicle to load
I see that both you and Chris are heavily and emotionally invested in this debate (as both of your comments show)!
From an outsider's point of view this highly technical discussion is interesting but ultimately you will both probably be wrong (but for different reasons). I suspect Chris's arithmetic is correct - which is all he's trying to claim, in which case - and under his assumptions, there will be problems.
So you are rightly questioning his assumptions, not his calculations. To an outsider like myself, your comments on future supply/demand, like solar tracking panels, seem reasonable but of course subject to many additional assumptions (e.g. the tracking panels will be maintainable, the price of panels will continue to drop, the hydro and battery projects will indeed be built, etc.)
This all matters because of the long term nature of these changes and the huge investment required. If we the west/the human race get this wrong we're stuffed.
Although it's unarguable that we have to stop using fossil fuels in the long term (as they'll eventually run out) I think we're going too far too fast. This headlong rush will have zero effect on climate anyway as atmospheric concentrations of CO2 mean it's no longer effective as a 'greenhouse gas'.
Unfortunately Chris's arithmetic is a good example of GIGO, garbage in/Garbage out. Even if there were three hundred hours when gas provided 36% of demand or thirty days where it provided 25% of the day it is still lss than 2% of annual demand.
On the highest hydro day in the last year hydro ran at 27% capacity for the 24 hours and peaked at about 60 %. For the highest week it ran at 21%. By the time Cethana, Snowy II, Borumba and Kidston are on line peak hydro can be doubled and output for a week can be more than doubled. Nowhere is that accounted for in Chris's calculations
Regardless of whatever strategy we pursue we will need to build new generation, most of our coal plants and many of our gas plants are either now or will be within the next ten years beyond their design life. The fixed costs of new coal and gas plants before an ounce of fuel is delivered or a single security guard let alone operators and maintenance staff is hired are more than the total capital, operation and maintenance costs of wind solar and batteries
Why wouldn't tracking solar be maintainable? It currently costs less per MWh to maintain a solar farm than wind, coal or gas so even if the power price were to halve and coal was free, solar still has a market.
The weighted average of wnd/solar/batteries on the NEM is $76/MWh, black coal $128 for existing and $180-200 for new and gas $250/MWh so regardless of climate change why would you not buy more $76 power and less $128 and $250 power
https://open.substack.com/pub/chrisbond/p/follow-up-to-but-what-if-im-wrong?r=om40y&utm_campaign=post&utm_medium=web&showWelcomeOnShare=true
I think Chris's point, which is backed up by the detailed results he displays, is that power outages will certainly occur in these 'renewables' based systems. If you have tried to reproduce his calculations and got different results, then please share your working.
Of course, just a few seconds of power loss in any part of a grid has huge knock-on effects - as the Spanish experience showed.
As for solar tracking, each panel has to have motorised altazimuth mounts. With millions of these in operation in all weather there will indeed be a maintenance issue.
Aside from having enough capacity to meet demand for every second of the 86400 in a day there are serious engineering issues this novel technology. You should look at some of the engineering problems involved in managing it and there's a good explanation at https://www.youtube.com/watch?v=7G4ipM2qjfw&t=736s
1. His detailed results have significantly underestimated hydro so no further discussion is required. Further, it is not as if this is his only mistake. This is one of his least erronious posts
2. Of course solar trackers need maintenance, so do coal and gas plants. Kogan Creek is the newest, lowest cost coal plant on the NEM has had 5 weeks offline for maintenance in the last year following a three month shutdown in 2022 and an even longer one in 2019. Callide C3 has just vreturned to service after 8 weeks off line, 4 weeks in june/July last year and 18 months from November 2022 etc etc.
3. What capacity limitations can there possibly be. Texas is smaller than NSW and this year will generate more power from wind and solar than the whole of Australia generates from coal and gas. China is only 25% larger than Australia and in April generated almost enough energy from wind and solar to power Australia for a year and in April connected almost twice as much solar as Australia has connected in the last 20 years.
4. The Video you referenced explains that these engineering challenges are being solved and solved quickly, that is why SA now operates safely for hours and even days at a time with just 80 MW of spinning reserve having reduced imports by two thirds and limininating coal over the last 12 years, why Britain can close coal altogether and halve nuclear output and the Southwest Power Pool in the US which supplies slightly more energy than the NEM has run at up to 92% renewables
I've made an extra post especially for you and DO.
Once you've chewed on it, and ONLY if you find an error in my methodology or arithmetic, let me know.
But if your 1st comment above "results have significantly underestimated hydro " refer to the PUMPED ENERGY STORAGE schemes you previously listed, you have totally misunderstood that PUMPED ENERGY STORAGE is energy storage (a net drain on the NEM) not new Hydro generation.
And it is just as misleading as this one.
The whole point of David Osmond's proposed capacity is to have sufficient wind and solar capacity to generate 15-20% more energy than we need at normal capacity factors, just as in the good old days in 2000 we had enough coal and gas to generate 220 TWh/y at normal capacity factors when it only supplied 165 TWh.
That excess wind and solar energy is used to recharge the batteries/pumped hydro almost every day. On the very worst day renewable day last year wind and solar peaked at 11 GW out of 28 GW of demand. Adjusted to current capacity that would have been 12 GW. Using David's latest multipliers that would have been around 31-32 GW thus partially recharging the storage. On the majority of days storage would have been in a better state at the end of the day than the start.
The key difference is that in the good old days, the marginal cost of pumping our pumped hydro was $40-70/MWh and after considering transmission and round trip losses and the excess coal capacity that we had, it rarely made sense to use the pumped hydro.
Now with almost zero marginal cost wind and solar and much higher cost coal, wind/solar/pumped hydro/batteries is still cheaper than coal or gas, that is why utilisation of Wyvenhoe has quadrupled over the past three years compared to a decade ago.
As for the supposedly impossible quantity of batteries there is 28 GW/55 GWh in operation, commissioning or construction now, already 30+ times Warratah and some 130 GW of proposals announced. not to mention 350 GWh in Snowy II and around 60 GWh in Cethana, Kidston and Borumba
In 2008/9 drought capacity in the Snowy dams was below 10% including Tantangara at the top of SH2. The south QLD dams were also below 10% at that time. You therefor cannot assume hydro will save us and you need a firm power source such as nuclear or gas.
Thank you for your comments, Goronwy.
It is quite likely that we will need 2-5% from a thermal source and up to 30% for short periods and maybe even 20% for a week, but that can still be around 2% of annual demand.
That suits gas, it could also suit biomass fired steam or gas turbines or coal slurry fired diesel engines or even just ordinary old coal plants with 4 MW/20-25 MWh of storage per MW of coal. The coal plant might then run for 6-10 weeks at a time appearing to the grid as anywhere between a 3 MW load or a 5 MW generator all the while sitting at a near constant 1MW output. In a good renewable year, it might run only a few weeks just to keep it running order and to allow hydro dams to fill more. In a drought year it might run for 6-8 months but still not supply much more than 8% of demand.
One source it does not suit is nuclear because the capital cost of nuclear requires it to runa at lifetime capacity factors of close to 90%
https://open.substack.com/pub/chrisbond/p/follow-up-to-but-what-if-im-wrong?r=om40y&utm_campaign=post&utm_medium=web&showWelcomeOnShare=true
https://open.substack.com/pub/chrisbond/p/follow-up-to-but-what-if-im-wrong?r=om40y&utm_campaign=post&utm_medium=web&showWelcomeOnShare=true
You have repeated yourself five times and every time got it wrong. Start again
Hi Peter,
"I suspect David is a bit optimistic"
No, on the same numbers I showed he's WRONG.
All the rest of your spiel in this comment and in your previous comment is irrelevant to the analysis of the current numbers and his simulation being wrong.
Just returning to your comment "What if I was wrong?".
I tried to allow for doubt in my comments but clearly you are determined to be right.
None of us know what the future mix of supply and demand will be.
How do you know how much the demand profile will change?
How do you know what the mix of tracking/bifacial solar will be vs fixed North facing or east west solar on roofs vs north facing by the time David's targets are reached?
How do you know what the geographic mix of wind will be or the CF of the wind turbines built over the next ten years?
You have one interpretation of the numbers he has another. Your admitted lack of knowledge of hydro is clearly one area where you are wrong.
Given that almost everyone, including of course me, will be shown to be wrong over the next few years, but more importantly almost every post you have made on the topic of renewables is way off, I would be just a bit more cautious about telling other people that they are WRONG.
It might just be a case of the pot calling the kettle black
https://open.substack.com/pub/chrisbond/p/follow-up-to-but-what-if-im-wrong?r=om40y&utm_campaign=post&utm_medium=web&showWelcomeOnShare=true
It is still wrong
Arithmetic, Peter.
If only? you have clearly misunderstood hydro
https://open.substack.com/pub/chrisbond/p/follow-up-to-but-what-if-im-wrong?r=om40y&utm_campaign=post&utm_medium=web&showWelcomeOnShare=true
Wrong again