The books is good(ish) for it's time, but some of its analysis and forecasts are fundamentally flawed since it falls for the primary energy fallacy by comparing the chemical potential energy (in J) directly to electrical energy (also in J). The two are fundamentally different things and called be compared 1:1. E.g. To heat up your home with natural gas you need ~1J of chemical energy to get 1J of heat into the home, but with a electric heat pump you only need 1/6 J to get 1J of heat.
It is also a product of its time in terms of wind/solar vs nuclear. His forecasts of the impact of solar and wind is based on prices and performance from 2008. Prices have come down an order of magnitude since then, and performance and lifespan have increased drastically.
Heat pumps, and their efficiency (getting more than X Joules of heating for X Joules of electricity) are discussed in chapter 21 Smarter Heating, see for example the diagram and discussion on page 150: <a href="https://www.withouthotair.com/c21/page_150.shtml" rel="nofollow">https://www.withouthotair.com/c21/page_150.shtml
I imagine the economics (and perhaps technical improvements) of some things may have changed more than the book could forecast. But heat pumps were definitely understood by the author.
I’m not saying he was unaware of heat pumps, I’m saying he’s comparing apples to oranges simply because they use the same units.
Look at “3 - Cars” on page 29. He says the typical car uses 40 kWh/day. 40 kWh of what? Chemical energy in the gasoline.
The go to page 33 where he looks at how much energy onshore wind could produce per days in the UK. His number is 20 kWh/d. 20 kWh of what? electricity
He then compares those two numbers directly and uses that comparison as the basis of his arguments: “Britain’s onshore wind energy resource may be “huge,” but it’s evi-
dently not as huge as our huge consumption.”
This is simply incorrect. A combustion engine converts less than half of the chemical energy in the gasoline into mechanical work that can move the car. The electric model converts >90% of it. So we don’t have to replace 40 kWh/day, we have to replace less than half of that since the electric process is more efficient.
This same issues, the primary energy fallacy, underpins large parts of the book.
He does correct for the efficiency of both electric cars, and heat pumps in later chapters. His line of argument is "here is the current energy supply and demand - now here are ways we can increase one and reduce the other".
The wind analysis was reasonable for the time, iirc the main error there was that he failed to foresee offshore wind dropping in price so much.
I disagree. The framing of focusing on primary energy and then sprinkling efficiency afterwards has two issues: 1) it pulls focus away from the thing we want (the end result) and 2) it makes it much easier to misunderstand (or to misrepresent) because the efficiency differences can be omitted.
And graphs like the one comparing wind turbine output to petrol car consumption are inherently deceiving. Two values are put side by side with the same units and then talk about directly as if they are comparable. But they simply are not. A kWh of chemical energy and a kWh of electricity have as much in common as a US dollar and a Jamaican dollar.
I agree with you. I read it cover to cover at the time and felt like a smart ass ("AksHuALLy renewables can't work alone!"), then wondered a few years ago how his calculations turned out in the real world.
1. Sad that he died from cancer
2. Noticed he compared primary energy and felt stupid for missing that
I never got a blanket claim of "actually renewables can't work alone" from the book. It seemed more like "actually you need to understand things quantitatively or you are doomed to talk nonsense".
MacKay's "renewables can't work alone" claim always seemed carefully scoped to the economics of 02008 (when solar modules cost 33× as much as they do now) and also his own densely populated, rather polar country. Renewables were already working nearly alone, at scale, in equatorial countries and more sparsely populated countries; I live in Argentina, whose grid was mostly hydroelectric at the time, and next door to Brazil, where a large fraction of the automotive fleet ran on sugar-cane-derived ethanol, which is a viable renewable energy source (unlike, apparently, corn ethanol).
There is nowhere that renewables are remotely close to working "nearly alone" if you are talking about total energy needs (which MacKay is/was).
There's some incredible progress for electricity generation, but there's still huge amounts of energy being used in ways that are not currently electrified and not close to electrifiable in the short term.
We should celebrate the forward progress, but also not be blind to what is not yet feasible (while also hoping that it may soon be so).
Right, as long as you specify “without energy storage”, renewables “can’t work alone,” even though energy storage is included in most common sense definitions of “renewables”
Thankfully, energy storage is being deployed worldwide, so this is a moot point, and renewables can and will replace fossil fuel electricity generation.
We're going to need more than grid-scale batteries to electrify trucks, ships, and long-distance airplanes. PaulDavisThe1st is right about that! Solar-powered fuel production from CO₂ is one possibility.
Planes are unlike other sorts of transportation in that their energy consumption is pretty closely proportional to their weight, because they are constantly spending energy throwing air downward to support their weight, so the low energy densities of rechargeable batteries are very unappealing for long-distance flight. Plausible alternatives include airships, ultra-low-stall-speed planes like gliders and Burt Rutan's Voyager, aluminum-air batteries, and synfuel. Of course, short-distance planes are already going electric with Joby.
Ships, we'll see. Most shipping ships are container ships (as opposed to, say, tankers, cruse ships, or ship shipping ships shipping shipping ships), and those are already slow enough that a substantial part of world trade is by airplane now, because inventory on a container ship is inventory you can't sell yet, or at least can't deliver yet. You could imagine a future where container ships are partly powered by onboard sails and partly powered by giant lightweight solar farms towed behind them on hydrofoils, but I don't think we're going to see container ships powered by lithium-ion batteries. Aluminum-air, maybe.
You're right, and I appreciate the correction — even Norway mostly runs its transport on fossil fuels, not electricity, and trucking and ships aren't going to be electrifiable in the short term. Here in Argentina, when we ran our grid mostly on hydroelectric, the cars were still running mostly on gasoline and compressed natural gas.
> He does correct for the efficiency of both electric cars, and heat pumps in later chapters.
There's something really important to understand when evaluating non-fiction books: nobody reads the later chapters, and the authors generally know this. They can present tremendously one-sided information in the first few chapters, giving the spin that they want, and then in later chapters give a more balanced approach to shield themselves from criticism. Almost everyone who reads the book will read only the spin, but any criticism levied against the author will be met with "but I specifically say, in the later chapters ...". It's a slimy technique that you start to see everywhere once you're aware of it.
> There's something really important to understand when evaluating non-fiction books: nobody reads the later chapters
Asserted without evidence, and I very much doubt that it's true. I suspect it varies dramatically by subject matter, intended audience, book length, data density, and more. I have no evidence for any of that. Do you?
There was some statistics on capital in the 21st century by Picketty (maybe from Kindle readers?) that most owners of the books only read the first 10 pages or so. Am on mobile but should be easy to find.
Not necessarily saying this generalises to all non fiction books though
No, the wind analysis was not reasonable for the time - he used data from a previous generation of turbines (and in turn, the next generation of turbines were certain to be 40% bigger & etc.), from a wind farm that had quite flukey winds.
I saw him present 18 years ago, and asked him why: he said that he didn't want to rely on any predictions or models, but only discuss real data. Which is sort of defendable as a position, but ignored the fact that renewable energy was progressing so incredibly fast, and that these engineering predictions were not speculative but very much concrete.
Similarly the silicon solar panel industry in 2008 had a roadmap to get to £1/Wp over the next few years (which they did, and which led to the ~2012 explosion in solar installations), by mass producing the 'expensive' ~20% efficient (mono-crystalline silicon) technology.
Mackay uses a 10% figure throughout.
So overall this was a bit like making predictions in the year 2000 assuming everyone will be stuck on 56k dial-up forever, because most people are on 56k dial-up.
These biases are present in all of the discussion of renewable technology, yet nuclear gets a free-ride / magical thinking in terms of uranium extraction, waste disposal and cleanup.
And then there is the persistent obsession with land use in the book.
This led me to the conclusion (which I still hold) that this was an example of the tail wagging the dog: David MacKay wanted the 'obvious' physicists answer of nuclear power to be the natural conclusion, and by construction made it so in his book. Just because you are a Bayesian does not mean that you are unbiased!
David MacKay was an amazing scientist, but I do not think this book is accurate (even for its time), or that useful in public understanding of what we now call 'Net Zero'. It certainly popularised the idea of actually thinking through individual energy budgets, which can only be a good thing, but it was a massive missed opportunity to treat heat (chemical) energy (maximum entropy) and electrical (which can directly do work) as equivalent, just because they have the same unit.
Later on, as the 'Climate Tsar' he made a web app where you could play with the future balance of generation with a simulated model of the UK, and set your own costs for the different technologies, which I thought was much more useful. You could choose your own energy mix, and understand some of the tradeoffs.
And yes, very sad that he died so young. In the context of this book it would have been interesting to see how he dealt with the increasing mismatch of reality and his predictions as time passed.
Just before he died in 2016 he gave an interview "revealing" his true thoughts on the matter but I think like you say it came through obviously enough in his work:
> There is this appalling delusion that people have that we can take this thing that is currently producing 1% of our electricity and we can just scale it up and if there is a slight issue of it not adding up, then we can just do energy efficiency,” he said. “Humanity really does needs to pay attention to arithmetic and the laws of physics – we need a plan that adds up.”
> Prof MacKay had previously avoided being drawn into the political debate about energy, but told Lynas: “I have always tried to avoid advocating particular solutions but maybe because time is getting thinner I should call a spade a spade.”
> The key for the UK, he said, was a zero-carbon solution that works in the winter, when energy demand is highest but sunshine is lowest and winds can drop for days at a time. “The sensible thing to do for a country like the UK, I think, is to focus on CCS, which the world needs anyway, and nuclear,” said Prof MacKay.
> The decision on a new nuclear power plant at Hinkley Point, which the government hopes will be the first of a new generation of plants, has been delayed until September.
> “Then if you ask what is the optimal amount of wind and solar to add in then the answer is going to be almost zero,” he said. “I love wind turbines – they are the cathedrals of the modern age – but they are a waste of money if you have a low carbon solution that gets you through the winter … because when the wind blows you are going to have to either turn them down or something else down that you have already paid for like nuclear or CCS.”
Maybe he would have changed his mind as prices and delivery timelines diverged but many of the people who were most enthusiastic about his work because it reflected their nuclear preference didn't, so who knows.
Though maybe his kind of person that liked nuclear and heat pumps and EVs all just changed their mind based on new evidence and we are left with the people who mysteriously like nuclear but don't want to use the output for heat and transport.
_aavaa_ · · focus · HN ↗
It is also a product of its time in terms of wind/solar vs nuclear. His forecasts of the impact of solar and wind is based on prices and performance from 2008. Prices have come down an order of magnitude since then, and performance and lifespan have increased drastically.
azornathogron · · focus · HN ↗
I imagine the economics (and perhaps technical improvements) of some things may have changed more than the book could forecast. But heat pumps were definitely understood by the author.
_aavaa_ · · focus · HN ↗
Look at “3 - Cars” on page 29. He says the typical car uses 40 kWh/day. 40 kWh of what? Chemical energy in the gasoline.
The go to page 33 where he looks at how much energy onshore wind could produce per days in the UK. His number is 20 kWh/d. 20 kWh of what? electricity
He then compares those two numbers directly and uses that comparison as the basis of his arguments: “Britain’s onshore wind energy resource may be “huge,” but it’s evi- dently not as huge as our huge consumption.”
This is simply incorrect. A combustion engine converts less than half of the chemical energy in the gasoline into mechanical work that can move the car. The electric model converts >90% of it. So we don’t have to replace 40 kWh/day, we have to replace less than half of that since the electric process is more efficient.
This same issues, the primary energy fallacy, underpins large parts of the book.
sideshowb · · focus · HN ↗
The wind analysis was reasonable for the time, iirc the main error there was that he failed to foresee offshore wind dropping in price so much.
_aavaa_ · · focus · HN ↗
And graphs like the one comparing wind turbine output to petrol car consumption are inherently deceiving. Two values are put side by side with the same units and then talk about directly as if they are comparable. But they simply are not. A kWh of chemical energy and a kWh of electricity have as much in common as a US dollar and a Jamaican dollar.
ralfd · · focus · HN ↗
1. Sad that he died from cancer
2. Noticed he compared primary energy and felt stupid for missing that
kragen · · focus · HN ↗
MacKay's "renewables can't work alone" claim always seemed carefully scoped to the economics of 02008 (when solar modules cost 33× as much as they do now) and also his own densely populated, rather polar country. Renewables were already working nearly alone, at scale, in equatorial countries and more sparsely populated countries; I live in Argentina, whose grid was mostly hydroelectric at the time, and next door to Brazil, where a large fraction of the automotive fleet ran on sugar-cane-derived ethanol, which is a viable renewable energy source (unlike, apparently, corn ethanol).
PaulDavisThe1st · · focus · HN ↗
There's some incredible progress for electricity generation, but there's still huge amounts of energy being used in ways that are not currently electrified and not close to electrifiable in the short term.
We should celebrate the forward progress, but also not be blind to what is not yet feasible (while also hoping that it may soon be so).
mbgerring · · focus · HN ↗
Thankfully, energy storage is being deployed worldwide, so this is a moot point, and renewables can and will replace fossil fuel electricity generation.
kragen · · focus · HN ↗
DangitBobby · · focus · HN ↗
kragen · · focus · HN ↗
Ships, we'll see. Most shipping ships are container ships (as opposed to, say, tankers, cruse ships, or ship shipping ships shipping shipping ships), and those are already slow enough that a substantial part of world trade is by airplane now, because inventory on a container ship is inventory you can't sell yet, or at least can't deliver yet. You could imagine a future where container ships are partly powered by onboard sails and partly powered by giant lightweight solar farms towed behind them on hydrofoils, but I don't think we're going to see container ships powered by lithium-ion batteries. Aluminum-air, maybe.
kragen · · focus · HN ↗
(Yes, I know that makes me sound like an LLM.)
feoren · · focus · HN ↗
There's something really important to understand when evaluating non-fiction books: nobody reads the later chapters, and the authors generally know this. They can present tremendously one-sided information in the first few chapters, giving the spin that they want, and then in later chapters give a more balanced approach to shield themselves from criticism. Almost everyone who reads the book will read only the spin, but any criticism levied against the author will be met with "but I specifically say, in the later chapters ...". It's a slimy technique that you start to see everywhere once you're aware of it.
sideshowb · · focus · HN ↗
PaulDavisThe1st · · focus · HN ↗
Asserted without evidence, and I very much doubt that it's true. I suspect it varies dramatically by subject matter, intended audience, book length, data density, and more. I have no evidence for any of that. Do you?
cycomanic · · focus · HN ↗
Not necessarily saying this generalises to all non fiction books though
jarvist · · focus · HN ↗
I saw him present 18 years ago, and asked him why: he said that he didn't want to rely on any predictions or models, but only discuss real data. Which is sort of defendable as a position, but ignored the fact that renewable energy was progressing so incredibly fast, and that these engineering predictions were not speculative but very much concrete.
Similarly the silicon solar panel industry in 2008 had a roadmap to get to £1/Wp over the next few years (which they did, and which led to the ~2012 explosion in solar installations), by mass producing the 'expensive' ~20% efficient (mono-crystalline silicon) technology. Mackay uses a 10% figure throughout.
So overall this was a bit like making predictions in the year 2000 assuming everyone will be stuck on 56k dial-up forever, because most people are on 56k dial-up.
These biases are present in all of the discussion of renewable technology, yet nuclear gets a free-ride / magical thinking in terms of uranium extraction, waste disposal and cleanup. And then there is the persistent obsession with land use in the book.
This led me to the conclusion (which I still hold) that this was an example of the tail wagging the dog: David MacKay wanted the 'obvious' physicists answer of nuclear power to be the natural conclusion, and by construction made it so in his book. Just because you are a Bayesian does not mean that you are unbiased!
David MacKay was an amazing scientist, but I do not think this book is accurate (even for its time), or that useful in public understanding of what we now call 'Net Zero'. It certainly popularised the idea of actually thinking through individual energy budgets, which can only be a good thing, but it was a massive missed opportunity to treat heat (chemical) energy (maximum entropy) and electrical (which can directly do work) as equivalent, just because they have the same unit.
Later on, as the 'Climate Tsar' he made a web app where you could play with the future balance of generation with a simulated model of the UK, and set your own costs for the different technologies, which I thought was much more useful. You could choose your own energy mix, and understand some of the tradeoffs.
And yes, very sad that he died so young. In the context of this book it would have been interesting to see how he dealt with the increasing mismatch of reality and his predictions as time passed.
ZeroGravitas · · focus · HN ↗
> There is this appalling delusion that people have that we can take this thing that is currently producing 1% of our electricity and we can just scale it up and if there is a slight issue of it not adding up, then we can just do energy efficiency,” he said. “Humanity really does needs to pay attention to arithmetic and the laws of physics – we need a plan that adds up.”
> Prof MacKay had previously avoided being drawn into the political debate about energy, but told Lynas: “I have always tried to avoid advocating particular solutions but maybe because time is getting thinner I should call a spade a spade.”
> The key for the UK, he said, was a zero-carbon solution that works in the winter, when energy demand is highest but sunshine is lowest and winds can drop for days at a time. “The sensible thing to do for a country like the UK, I think, is to focus on CCS, which the world needs anyway, and nuclear,” said Prof MacKay.
> The decision on a new nuclear power plant at Hinkley Point, which the government hopes will be the first of a new generation of plants, has been delayed until September.
> “Then if you ask what is the optimal amount of wind and solar to add in then the answer is going to be almost zero,” he said. “I love wind turbines – they are the cathedrals of the modern age – but they are a waste of money if you have a low carbon solution that gets you through the winter … because when the wind blows you are going to have to either turn them down or something else down that you have already paid for like nuclear or CCS.”
Maybe he would have changed his mind as prices and delivery timelines diverged but many of the people who were most enthusiastic about his work because it reflected their nuclear preference didn't, so who knows.
Though maybe his kind of person that liked nuclear and heat pumps and EVs all just changed their mind based on new evidence and we are left with the people who mysteriously like nuclear but don't want to use the output for heat and transport.