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  _aavaa_
  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.
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  sideshowb
  The updated version of this book is available in game format with the blessing of UK government https://my2050.energysecurity.gov.uk/?levers=111111111111111Risking the HN hug of death here, but my own prototype of a car miles model inspired by the David's approach can be found at https://trafred.cardiff.ac.uk/
• zbs1970
  Not commenting on the physics of this; I want to point out that I thought the narrative structure of this book was amazing. I have not read a hard-core piece of analysis in any field before or since that I thought was a page-turner the way this was. When I read it in 2008 I remember completing each chapter and feeling like "we're screwed" and then the next chapter feeling like "ok, we're going to make it." Presenting such analysis in the form of a race between supply and demand was narrative genius and I think should serve as an example of how ideas can be presented in a way that is both exciting and not-dumbed-down.
• sam1r
  The original author was blogging just a couple days prior to his death. Rest in peacehttps://itila.blogspot.com/2015/09/what-do-you-tell-children...
• seltzered_
  This needs a 2008 tag.There was some rough discussion in 2025 about where Mackay's models ended up being off: https://bsky.app/profile/ketanjoshi.co/post/3lmdeoxe2pk2iAnd of course some credit that he was right on some technologies not making much sense like electric planes: https://bsky.app/profile/thierryaaron.bsky.social/post/3mwjx... referencing ch 5 pg 35 of 'sustainability without the hot air'
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  nirinor
  Actually, the better link might have been <https://withouthotair.org/changes>.Note the .com->.org: its a version of the book whose numbers are maintained here <https://github.com/life-itself/without-hot-air/commits/main/>.
• mbgerring
  Site last modified in 2015Lots of us working in clean energy read this book, and everything that’s happened since it was published makes the projections here useless
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  js8
  Love the book, but as others have noted, it is very much dated. Although I believe someone started a project some years ago to update it.
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  abetusk
  I find it interesting that the average energy consumption of a person (or household?) is roughly 30kWh/day and the energy usage of a car is roughly 40kWh/day. I wonder if it's some kind of truism that our transportation needs roughly equal our energy needs.I'd be interested to know if that's just a coincidence or whether there's an underlying reason.
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  hungryhobbit
  Dear god, this page is like an argument against every person who has ever said "graphic design doesn't matter".The colors are gross, it took me ten minutes just to figure out what I was looking at (a book), and heaven help me if I actually wanted to read that book in that format!
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  peri-cl
  The author is coincidentally the author of a (free-to-read) information theory book which is also popular on HN,https://news.ycombinator.com/item?id=34618613 ("Information Theory, Inference, and Learning Algorithms (2003) (inference.org.uk)")
• ml_basics
  The untimely death of David MacKay was a tragic loss for the scientific community. It's astonishing that he wrote the textbook on information theory for the ML community as well as his contributions to rational discussion about energy policy.He had a direct personal impact on my life since my introduction to ML came from video recordings of his lectures on ML and information theory. I am grateful to have learned from such an excellent teacher. Like a Feynman of our times.
• PaulDavisThe1st
  The publisher of this book (and the series) was my second programming mentor, and the person who introduced me to the GNU Project and libre software in general, back in 1986/87. I call him Dr. X and he calls me "The Professor".
• bencord0
  RIP Professor MacKayI remember him giving this talk to my physics class when I was in University. It was so inspirational to me that the UK just might be able to go 100% renewable.From what I remember, the calculation worked out how we could do it all with Solar. I don't think he quite saw how close we are to achieving the goal, not with Solar, but with Wind within the next decade.
• rekabis
  Holy 1997 web design, Batman.
• danrecht
  David McKay was a great public speaker as well: https://youtu.be/GFosQtEqzSE?si=Gyrcep1VDae6xDo1&t=110
• citizenfishy
  Lings Cars!
• anon
  undefined
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  perennialreport
  Worth reading even with the dated numbers. MacKay's lasting contribution isn't any specific forecast - it's the discipline of expressing everything in the same units (kWh per day per person), which makes energy arguments commensurable instead of vibes-based. Once you've internalized that, most energy coverage in the media starts reading like category errors. The specific figures have moved - solar costs, EV adoption, heat pump uptake - but the arithmetic habit hasn't aged at all.
• throwawayffffas
  I see a lot of hot air in this.Two quick points:1. Gasoline powered energy metrics do not translate to electric vehicles, due to the much higher efficiency of electric motors.2. There are about twice as many people as cars in the UK so the comparison between 40 kwh/d per car and 20 kwh/d per person for the wind energy is at minimum misleading.