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Comment by Ekaros | Hacker News Reader

Considering just how cheap renewable energy can be, even poor efficiency might not matter. If you have process that can be scaled by supply of cheap electric power, it could work even if there is inefficiencies in process and in use.

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It's not a matter of electricity cost, it's a question of watt hours per Kg. A battery powered plane cannot fly far, no matter how cheap electricity is, because the energy density just isn't there: https://en.m.wikipedia.org/wiki/Energy_density#/media/File%3...

I'm really talking about synthetic fuels made using electric energy.

Traditional fuels would also benefit from the cost savings of cheap renewable energy.

Don't forget watt per volume. H2 has great w/kg but poor w/liter.

It's not generating the energy -- it's storing it. Fossil fuels are massively more energy dense than our current electric batteries.

Fossil fuels are literally dead animals pressurized by Earth... all that energy went into the fuel. Planets work on massively larger scales of energy than human society right now and we're using stored energy created by planets to fly.

> Fossil fuels are literally dead animals

By mass, fossil fuels are mostly from plants, algae, and bacteria rather than animals.

The energy is not exactly stored in the fossil fuels directly. Indeed you have to put in extra energy to break those bonds - pulling atoms apart is work. The “stored” energy comes from the fact that long time ago various processes split various compounds into two components, A and B. And putting them back together makes them snap like magnets with enough force to release some extra heat. We call A “fuel” since that’s the part that’s somewhat difficult to come by. We often forget about B altogether as it’s literally all around us. Fossil fuels are fundamentally efficient for flight since the oxygen is something you don’t have to carry around with you (unless of course you’re going to space).

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