michael_nielsen

This table of energy density is really useful: https://en.wikipedia.org/wiki/Energy_density#Table_of_energy_content … How do you think oil or some other more energy dense fuel could be used to power electronic gadgets?

Great graph! Fun to think about where fission, fusion, and antimatter sit! The second was (mostly) a joke. Oil actually can (& does) power electricity, but I don't know what the energy efficiency is. Maybe quite a bit lower than we get from fat, but I really don't know.

Oops, the graph is: https://en.wikipedia.org/wiki/Energy_density#/media/File:Energy_density.svg …

TBC: fats really do have higher energy density than lithium ion batteries. But that energy does have to be converted into a form the laptop can use, and so there will be some loss, maybe very substantial.

Yeah! Natural gas based power plants are about 50% energy efficient (source: https://en.wikipedia.org/wiki/Combined_cycle_power_plant#Difference_between_HHV_and_LHV …). But for a laptop, if we used oil to power it, we'd need an internal combustion engine which would make the laptop much heavier...

Why does it need to be very heavy? Why not try to invent a very small, very light approach? (Not entirely wild about this idea, for climate reasons. But it's fun to think about a bit.)

Heat engine efficiency is governed by 2nd law of thermo (Carnot theorem). To achieve high efficiency, radiators in an ICE & cooling towers in a power plant need to have large surface areas as they dissipate heat through convection. Other option is to burn fuel at very high temp.