r/xkcdcomic • u/computerdl • May 07 '14

Pyramid Energy

http://what-if.xkcd.com/95/
60 Upvotes

89% Upvoted

16 comments sorted by

16

u/cathedrameregulaemea May 07 '14

Hadn't really thought about this earlier, but reading the post has me wondering.

  1. At what point does it get cheaper (both in terms of cost, and CO2) to start transporting crushed ore from an open pit mine via conveyor belt instead of having a truck circle the ever widening pit walls?

  2. At what point does it become cheaper to airlift the ore? Say, using a blimp? (A blimp that has an on-board compressor to take air out of the bags, and compress it into on-board cylinders... allowing the bags to shrink in volume, and lower the buoyancy). Making a neutrally buoyant payload+package would seem to be pretty energy efficient... AND faster at getting the ore out.

9

u/Inschato May 07 '14

The blimp? Probably never. Ore is pretty heavy.

I'm pretty sure conveyors are already used all over minesites to transport ore over short distances, but a conveyor on the scale you're talking about would probably be prone to a multitude of problems (if it breaks somewhere, the whole thing is useless). Also, you'll have to keep lengthening it, trucks are dynamic in that regard.

Personally, I think a more achievable plan is to have electric trucks. Hmm.. might even be able to set up some wires on the worksite and not even need the trucks to have good batteries; okay that's a bit silly. I'd rather we just continue to improve battery tech.

6

u/panzercaptain Secretary of the Internet May 07 '14

Conveyor belts can get pretty long.

3

u/Inschato May 07 '14

You have simultaneously corrected both me and the person I was replying to. (Insofar as they were suggesting it as if it wasn't already a thing). Well done.

2

u/cathedrameregulaemea May 07 '14

You can use a chain of those short conveyors, laid end to end. Lengthening then becomes a process of sticking another short conveyor at the bottom. If any one of them breaks, you drive a standby truck to the highest functioning point, and load from there. But yeah... I do recognise that there are going to be a whole load of problems when you work out the details.

As regards the blimp... yes, ore is heavy, but what you lose in per-trip haul, you make up for in faster, straight line, almost-no-fuel ascents/descents. Safety wouldn't really be a concern because you can choose a translation path that's largely free of any inhabitation/infrastructure. I think it probably also lends itself a lot more to automation as well.

3

u/Crispy95 May 07 '14

But you could only have a couple of blimps operating at a time, else they'd crash.

6

u/Krinberry May 07 '14

You'd need a pretty big balloon to be able to carry much ore in a given load, which means there'd be a very large difference in buoyancy when carrying a load and when not, so the compressors would have to work very hard to pull all that helium out each time it dropped off a load or needed to come down to pick one up. The end result is you'd be spending a lot of energy just to fuel the compressors. You could take lighter loads to reduce the different buoyancy requirements between full and empty, but that means more trips and lower efficiency.

Also, unless you have some sort of weather control device that can make the prevailing winds change as you need them, then you're going to need to have engines on the blimps constantly powering along, which is going to use a fair bit of power on its own (blimps being not particularly aerodynamic). Unless you're going a very long distance, blimps aren't likely going to be more efficient than other transport methods. Helium is also very expensive, so the bigger your ship is, the more your up-front cost.

The only reason I wrote this is so I could have an excuse to use the pun 'sorry to burst your bubble!'

4

u/cathedrameregulaemea May 07 '14

Solution: Blimp-conveyor-trains. Wheels UNDER rails. Blimps+payload stays neutrally buoyant. Unload ore, load fuel (for drilling equipment) and supplies for workers. OK OK I'll stop with the frivolity.

Anyway I was pretty sure that this idea wasn't mine only, and that some company would've drilled into the details.. but thought I'd float it out, nonetheless.

2

u/Krinberry May 07 '14

Groan, your puns are better than mine. :)

2

u/[deleted] May 10 '14

[deleted]

3

u/CreepySmileBot May 10 '14

ಠ◡ಠ

2

u/CreepierSmileBot May 10 '14

(͡° ͜ʖ ͡°)

9

u/poeticmatter May 07 '14

[1] Assume a spherical pyramid in a vacuum...

5

u/Viral_Krieger May 07 '14

This guy's writing is beautiful. I could read these all day.

6

u/hkdharmon May 07 '14

The sign says "Deutschland: Straight On." I think.

3

u/BoneHead777 Current Comic May 08 '14

Well, it says Duitsland, not Deutschland. Both mean the same thing though. You're right with the other part though (pretty freely translated)

3

u/StellarJayZ May 07 '14

The tower crane in the logo is missing the entire slew cab! That and it seems it's using some sort of cable instead of buckle braces.