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Comment by fdewrewrewf | Hacker News Reader

>Making all this plastic stuff can't be energy cheap...

Plastic is relatively cheap, energy-wise. Your embodied energy usage is dominated by semiconductors.

Edit: Google tells me that a laptop takes 4500MJ to manufacture. If you were living in a 2kW society, you'd have to save up 1250kWh, or about a month, to get your laptop.

Obviously personal car ownership is right of the question.

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> Plastic is relatively cheap, energy-wise. Your embodied energy usage is dominated by semiconductors.

Given how energy costly cement is, and how much quantity we use, I'd be really surprised if it didn't dwarf semiconductors by several orders of magnitude.

Concrete takes 1.1MJ/kg to manufacture[1]. So, you get ~4000kg of concrete for one laptop's worth of embodied energy. Amortised over the expected lifetimes of the items in question, manufacture of high-density electronics still represents our greatest usage of energy.

[1]https://en.wikipedia.org/wiki/Embodied_energy

Thanks for this. Something to keep in mind - concrete weighs an awful lot and comes in at 2.2-2.5 tons per cubic meter. That 4000kgs is less than 2 cubic meters of concrete.

If it’s reinforced steel the energy usage leaps up.

Building is incredibly energy intensive and very wasteful.

Thanks for your link, it’s really interesting.

Yeah, concrete is dense and we use a enormous amount of it! We're making 4 billion tons of concrete each year, nnd without even counting the energy needed for transporting it (which is also high, because of the enormous mass involved), concrete production represent 8% of the total CO2 emissions!

https://www.archpaper.com/2019/01/concrete-production-eight-...

I'm wondering whether the 1.1MJ/kg takes into account that the heat used for cement production is often used for heating nearby households.

If a laptop lasts 5 years then a month doesn't seem too bad. That's only 1/60th of your allowance. It shows the importance of continued software support for old hardware though. It's a hell of a lot better if a laptop can be used for 10 years rather than 5.

In the future, you'll take out a 5-10 year energy mortgage that eats up 1-2% of your daily energy allotment just to get a single laptop.

There's a vision we can all get excited about.

But lots of people have multiple devices. Laptop, phone, maybe an ereader or tablet.

Well maybe they'll have to have less, or keep them longer. Or we'll have to get better at prioritising energy consumption in manufacturing, and creating products that can be used for longer. Seems to me that there's no reason an ereader shouldn't last for 20 years or longer for example.

I definitely agree. Just wanted to point out how the personal computer energy challenge might have a larger scope than just laptops.

I just picked laptop as a convenient example, and because it might remind people that they probably have a house full of similar gadgets (and with a similar level of embodied energy).

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