I was very lucky to spend a lot of time in my first job calculating S-curves (alongside learning curves).
It's *all*'about the assumption you make about the eventual saturation level.
You can get some idea of final saturation from the historic data (v rapid takeoff probably means a bigger final market), but fundamentally you have to take a punt on his big you think market will be once all the transients die out (hype, market development support, lack of supply chain, startup balance sheets, etc).
That's why the hydrogen ladder is about where the soil level will end up per end use might settle, after the unsustainable mountain of subsidy carrots has decomposed.
It's also a big reason why all the big official energy agencies' solar forecasts are worthless. As soon as you bury the wrong saturation level deep in your model (solar can never supply more than 10% of electricity because the sun doesn't shine at night) not only do you get the future energy mix wrong, you immediately get next year's solar market wrong too.
I looked at this in my piece on the "solar singularity" back in 2018.
I suggest one looks at s-curves from 3 perspectives.
1. Technology
2. Economics
3. Politics and belief systems.
So with solar the underlying technology is made in a factory and assembled on site. (Prof Bent Flyvberg) So limitation to s-cuve is economics. The 30/30/30 policy of Australia (30c/W installed, 30% efficiency and by 2030) means wholesale cost of $au20/MWh.
So the framework to be s-curve is in place. Politics will either increase or decrease rate. No barriers to end. Enough roofs, so even land not an issue.
Contrast that to CCS or H2. Both have no visible technology pathway (yet) to be at that price point). So only politics or belief systems. And ignoring competitive technology.
Of course, if s-curves are post hoc just-so stories, then policies that rely on them have a high likelihood of failure and our decarbonisation plans in particular are over-indexed on specific technologies. Are heat pumps in the UK on an s-curve, do you think?
If you mean "will heat pump uptake follow a smooth S-curve, it's a silly question.
But if you need a long-term estimate of market size to make decisions about things like where to site factories, or how many heating engineers to train, S-curves are pretty much the only game in town.
I would assume a saturation level for heat pumps at about 75% of UK space heating by 2075. To model the next five years you can do granular work on grant programmes, new plants, infra build-out etc. Then you blend your five-year outlook with your long-term S-curves.
You should review the saturation level and date every five years in the light of emerging data - and only tweak them if it's clear that actuals are racing ahead or falling behind.
But if one's plan to decarbonise the economy explicitly rests upon the presumption that a particular technology is on an s-curve - something which I agree is unknowable in advance - that rather presents a problem for one's decarbonisation strategy, does it not?
No. Lots of policies are predicated on the unknowable. I have house insurance but not medical insurance, it doesn’t mean I know I will get robbed and know I won’t get ill. We all just need to get used to the fact the future is unknowable. That’s where real decision making happens!
I'm confused. Is it appropriate to use a s-curve to make claims about the future or not? Is it justifiable for technology lobbyists to make the claim that their tech is on an s-curve? This is a quite wide-ranging epistemological claim that has significant impact on how the Government makes policy choices, after all.
I think S curves are far more useful as a framework to caution against projecting accelerating growth indefinitely into the future. See the complaints about solar install rate projections being to low. This will be true until it isn't... (and then who is complaining about the projections will change)
Wouldn’t the success or failure of the S-curve for different technologies also depend on external factors — such as the availability of capital, skilled labour, and, perhaps most importantly, access to the necessary input materials?
For example, the rapid fall in solar costs (and the corresponding surge in global installations) would have been unlikely without China’s massive investment in manufacturing capacity over the past two decades.
Similarly, one of the main challenges with scaling heat pumps in the UK today is that electricity remains relatively expensive compared to gas, and there’s still a shortage of qualified installers to deploy them at scale.
I was very lucky to spend a lot of time in my first job calculating S-curves (alongside learning curves).
It's *all*'about the assumption you make about the eventual saturation level.
You can get some idea of final saturation from the historic data (v rapid takeoff probably means a bigger final market), but fundamentally you have to take a punt on his big you think market will be once all the transients die out (hype, market development support, lack of supply chain, startup balance sheets, etc).
That's why the hydrogen ladder is about where the soil level will end up per end use might settle, after the unsustainable mountain of subsidy carrots has decomposed.
It's also a big reason why all the big official energy agencies' solar forecasts are worthless. As soon as you bury the wrong saturation level deep in your model (solar can never supply more than 10% of electricity because the sun doesn't shine at night) not only do you get the future energy mix wrong, you immediately get next year's solar market wrong too.
I looked at this in my piece on the "solar singularity" back in 2018.
https://open.substack.com/pub/mliebreich/p/linkedin-scenarios-for-a-solar-singularity
I suggest one looks at s-curves from 3 perspectives.
1. Technology
2. Economics
3. Politics and belief systems.
So with solar the underlying technology is made in a factory and assembled on site. (Prof Bent Flyvberg) So limitation to s-cuve is economics. The 30/30/30 policy of Australia (30c/W installed, 30% efficiency and by 2030) means wholesale cost of $au20/MWh.
So the framework to be s-curve is in place. Politics will either increase or decrease rate. No barriers to end. Enough roofs, so even land not an issue.
Contrast that to CCS or H2. Both have no visible technology pathway (yet) to be at that price point). So only politics or belief systems. And ignoring competitive technology.
And similarly with batteries. Production at scale. Minimum installation. Household batteries in Australia example.
Of course, if s-curves are post hoc just-so stories, then policies that rely on them have a high likelihood of failure and our decarbonisation plans in particular are over-indexed on specific technologies. Are heat pumps in the UK on an s-curve, do you think?
The point of the post is that we can’t know if something is on an s curve! So I don’t think that is a relevant question.
If you mean "will heat pump uptake follow a smooth S-curve, it's a silly question.
But if you need a long-term estimate of market size to make decisions about things like where to site factories, or how many heating engineers to train, S-curves are pretty much the only game in town.
I would assume a saturation level for heat pumps at about 75% of UK space heating by 2075. To model the next five years you can do granular work on grant programmes, new plants, infra build-out etc. Then you blend your five-year outlook with your long-term S-curves.
You should review the saturation level and date every five years in the light of emerging data - and only tweak them if it's clear that actuals are racing ahead or falling behind.
Et Oila! as you put it :-)
But if one's plan to decarbonise the economy explicitly rests upon the presumption that a particular technology is on an s-curve - something which I agree is unknowable in advance - that rather presents a problem for one's decarbonisation strategy, does it not?
No. Lots of policies are predicated on the unknowable. I have house insurance but not medical insurance, it doesn’t mean I know I will get robbed and know I won’t get ill. We all just need to get used to the fact the future is unknowable. That’s where real decision making happens!
I'm confused. Is it appropriate to use a s-curve to make claims about the future or not? Is it justifiable for technology lobbyists to make the claim that their tech is on an s-curve? This is a quite wide-ranging epistemological claim that has significant impact on how the Government makes policy choices, after all.
I think S curves are far more useful as a framework to caution against projecting accelerating growth indefinitely into the future. See the complaints about solar install rate projections being to low. This will be true until it isn't... (and then who is complaining about the projections will change)
Really informative post, Arthur!
Wouldn’t the success or failure of the S-curve for different technologies also depend on external factors — such as the availability of capital, skilled labour, and, perhaps most importantly, access to the necessary input materials?
For example, the rapid fall in solar costs (and the corresponding surge in global installations) would have been unlikely without China’s massive investment in manufacturing capacity over the past two decades.
Similarly, one of the main challenges with scaling heat pumps in the UK today is that electricity remains relatively expensive compared to gas, and there’s still a shortage of qualified installers to deploy them at scale.