As a Duke in the Kingdom of Weselton, I've been commanded to exploit the riches of our trade partners and cement our dominant economic status. It was my good fortune to attend the coronation of our most mysterious trade partner Arendelle's new queen. During the after party, newly crowned Queen Elsa revealed she was a sorcerer with the power to create ice, snow, and even frozen lifeforms. Unfortunately, she won't willingly use her powers to fuel my industrial revolution with frozen slave labor. Why she decided to have me and my delegation deported in an abusive manner instead of considering my proposition I'll never understand....

My best scientists and engineers back in Weselton have so far been unable to figure out how we can use her frozen sorcery to our economic advantage. They've talked endlessly of us becoming a chief exporter of ice, but that isn't where the real money is. I want to use her powers to fuel our factories. If she had tropical magic that produced white sand beaches and heat our engineers could harness it in a multitude of ways. Alas that is not the case...

Can you help me unlock the secret to harnessing cold as an energy source that my engineers can use to power the factories of Weselton?

For people unfamiliar with the source material I'm building off of the Duke of Weselton is a character in the movie Frozen.

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    $\begingroup$ Ice might indeed be where the money is at. The real world ice trade was huge business. At one point, the largest business in the world was an ice export company. $\endgroup$
    – Luke
    Oct 9, 2017 at 19:27
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    $\begingroup$ "fuel my industrial revolution with frozen slave labor." I can't stress enough how exact the opposite slave labor is from industrial revolutions work. $\endgroup$
    – RonJohn
    Oct 9, 2017 at 22:25
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    $\begingroup$ @RonJohn No one ever claimed the Duke is the brightest bulb. The Duke could be trying to apply old methods to a new paradigm. That being said golems that produced meaningful work without requiring any sustenance could power a mill via a treadmill as effectively as a stream with a waterwheel and transport the goods to market cheaper than a horse drawn canal barge. Cheap labor can be exploited in any economy. Industrial revolutions are about mechanization not about how much you compensate the workers. $\endgroup$
    – Erik
    Oct 9, 2017 at 22:47
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    $\begingroup$ "Industrial revolutions are about mechanization not about how much you compensate the workers" - that is exactly why slave labor is the opposite of an industrial revolution. The use of lots of labor to accomplish goals is the opposite of using as little labor as possible to accomplish goals. $\endgroup$
    – GrinningX
    Oct 9, 2017 at 23:17
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    $\begingroup$ This is a crazy idea about sorcery. You should just let it go. Let it go... $\endgroup$
    – Machavity
    Oct 10, 2017 at 12:58

19 Answers 19


One option is to use stirling engines. They work just as well on cold as on heat. Or rather, they work on a temperature gradient. One of these toys will work if you place it on a cup of hot water or on an ice cube.

You might also look at thermal electric generators, or TEG. These create a small amount of electric power from a heat gradient, and so also work with either a heat source or a 'cold source'.

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    $\begingroup$ All thermal engines work on a temperature gradient; that's actually their definition. $\endgroup$
    – AlexP
    Oct 9, 2017 at 19:25
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    $\begingroup$ @anon Do/are they now. :D youtube.com/watch?v=cVCtgB66T28 Actually Stirling engines are usually much less prone to vibration compared to internal combustion engines since the compression and combustion means that the engine is subject to rapidly shifting pressures, and the crank shafts are subject to much jerk. And since vibration is a prime source of wear and tear, I dare say that your claim is not entirely accurate, at least not compared to an ICE. $\endgroup$
    – MichaelK
    Oct 10, 2017 at 10:37
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    $\begingroup$ Just to expand on this, steam factories were built around a single giant steam engine which almost never stopped (unlike current factories with many smaller electic motors that stop all the time). You could have Elsa at the center of a spoked wheel with each spoke extending through many factories. $\endgroup$
    – majjam
    Oct 10, 2017 at 11:09
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    $\begingroup$ @majjam city-sized cogwheel? Let me know when I can see it! $\endgroup$ Oct 10, 2017 at 12:01
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    $\begingroup$ This is the answer. Actual engines that can "run on cold". $\endgroup$ Oct 10, 2017 at 15:55

Don't Look for Energy - Go for Infrastructure

The problem with freezing powers is that they actively suck energy out of wherever they are used. The movement of the energy itself could be useful, except that it's simply magic'd away to nothingness, which is not very helpful. However, the queen's magic is also capable of very quickly building robust structures (eg. castles in seconds) and fine items (eg. finely tailored dresses) - which are very useful attributes.

Rapid Prototyping

The ability to quickly test ideas to identify what works and what doesn't is a HUGE accelerator for all manners of innovation. 3D printing revolutionized industry for us just a few decades ago; imagine what the world would have been like if it existed hundreds of years ago!

Instead of taking dozens of years to refine industrial designs, the Queen could help refine them in DAYS.

Ice-Dams and Hydro-Power

One such use in an industrial revolution is to quickly create very large dams capable of holding vast amounts of water. Such dams could be fitted to power anything from mills to hydroelectric generators, very quickly allowing you to leap ahead technically. Sure, they will need a re-charge every so often, but if you kept a sawmill in operation with the output you could probably cut all the wood you need to replicate it in wood before long.

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    $\begingroup$ Your dam is actually the most logical explanation from all the other answers! $\endgroup$
    – Vylix
    Oct 10, 2017 at 2:45
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    $\begingroup$ I probably should have made this explicit but since Elsa kicked me out of her country I can't count on her cooperation. Things like rapid prototyping and building castles would require complete cooperation. I'm not going to edit the question now to specifically say that Elsa isn't going to cooperate since it would invalidate your otherwise good answer. $\endgroup$
    – Erik
    Oct 10, 2017 at 3:16
  • $\begingroup$ She also can build bridges (of course hard to maintain in the summer) and help a lot enginnering large infrastructure with temporary ice walls and columns. She actually can provide a large shapes just ready to be filled with concrete. Alas freezing concrete is a nice thecnique used to improve large concrete constructions like Itaipu Dam with a one quilometer concrete wall $\endgroup$
    – jean
    Oct 10, 2017 at 13:33
  • $\begingroup$ FORMS. You use ice to make the forms for the actual construction material. $\endgroup$ Oct 12, 2017 at 4:59
  • $\begingroup$ The 3D printing and rapid prototyping idea is one of the best uses of her power and can be made to work even with Elsa hostile to your regime. Use spycraft to co-opt her rapid prototyping shop. Turn, coerce, or replace her chief designer thereby ensuring that the reports she receives are "It didn't quite work out but I think we're getting close" while the actual successful results are transmitted to Weselton. Don't try to face her directly militarily. Improve your industrial base and commercial output, develop trading partners, and eventually render her kingdom an irrelevant icy backwater. $\endgroup$
    – Kengineer
    Oct 13, 2017 at 2:25

You just need to have Elsa turn lots of gas into liquid. The liquid form could be used to power lots of equipment when reverting to gaseous form by expanding through a turbine.

What you really would like is a gas that can be freely vented to the atmosphere once it returns to gaseous form. If Elsa could "crank it up" and turn nitrogen into liquid nitrogen, you would have a great power source. Liquid nitrogen requires -196 C -- so this may well be beyond Elsa's power. Perhaps Refrigerant R-12 is a common atmospheric component on your world -- If so, that would work great assuming Elsa can manage -30 C. Perhaps CO2 would work, Elsa would need to be able to generate -79 C, and you need a little extra pressure (5 atm) to keep it as a liquid.

If you are a twin of planet Earth, and Elsa does not have much "reserve power", you will probably have not be able to use this option, at least not in this simple form. You could in theory do this trick with lots of other gases, but they would have to be captured and returned to Elsa.

Perhaps there is a nice choice that could be easy combined into a compound that could be used. Chlorine seems like a possible choice (although a bit complicated because it is poisonous and corrosive). Chlorine will readily combine with many things and form dense compounds for return shipping to Elsa, where the compound can be split and the chlorine converted back to a liquid.

But, instead of a single gas, maybe you could use a combination of Chlorine and Sulfur Dioxide (also toxic). These could be combined to yield Sulfuryl Chloride SO2Cl2 giving you a nice closed loop solution when the liquid SO2Cl2 is returned to Elsa -- allowing pipeline transportation in both directions.

  • 1
    $\begingroup$ CO2 sounds like the best bet. I'm thinking she could distill it straight out of the air into dry ice even, and forget about the 5atm necessary to keep it liquid. Feed it with pellets. $\endgroup$ Oct 11, 2017 at 4:25
  • $\begingroup$ @guenthmonstr -- liquids are preferable for large-scale material movement, nothing beats a pipeline for transportation efficiency. If you are running your economy on it, put it in a pipeline. $\endgroup$ Oct 12, 2017 at 19:13
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    $\begingroup$ I see the merit of what you are saying, but she is living in a pre-industrial civilization. For the time being, Weselton needs to find a way to integrate her unique abilities with existing tools and techniques, which is why I think that the wherewithal to handle liquid CO2 may be lacking, at least for now. Then again, maybe I'm underestimating the state of technology at the time period of 'Frozen'. $\endgroup$ Oct 12, 2017 at 19:45
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    $\begingroup$ This is a good answer and very practical. - energystorage.org/energy-storage/technologies/… $\endgroup$
    – KalleMP
    Oct 13, 2017 at 5:28
  • $\begingroup$ Liquid helium is rather expensive too. It's \$5/litre where liquid nitrogen is more like \$0.1 per litre. $\endgroup$
    – Sobrique
    Oct 13, 2017 at 12:48

I'd suggest building nuclear and using elsa to cool the rods and protect your kingdom during meltdowns. You can bypass all sorts of regulations if you have an ice sorceress.

  • 56
    $\begingroup$ While I appreciate the diabolical nature of placing Elsa inside of a nuclear reactor and forcing her to cool the reactor or die, I feel this approach is slightly above my kingdom's technical ability. $\endgroup$
    – Erik
    Oct 9, 2017 at 19:34
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    $\begingroup$ @Erik "While I appreciate the diabolical nature ..." Now I know what sort of person you are... $\endgroup$
    – Vylix
    Oct 10, 2017 at 2:46
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    $\begingroup$ @Vylix lol I disavow all comments or questions made in the Duke's voice $\endgroup$
    – Erik
    Oct 10, 2017 at 2:54
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    $\begingroup$ I don't think any nuclear regulatory agency would accept "Possibly Hostile Ice Princess" as the primary method of cooling, let alone as fail-safe backup method. So having Elsa at hand would not let you bypass any regulations. $\endgroup$
    – Johnny
    Oct 10, 2017 at 18:33
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    $\begingroup$ Alternatively, just build coal power stations. Address any concerns about global warming by dropping ever larger ice cubes in the ocean, thus solving the problem once and for all. $\endgroup$
    – gmatht
    Oct 11, 2017 at 1:37

Elsa is able to move and project her ice, not just create it. This is evidenced in her throwing ice-spikes and the control required to build a castle.

Given this there is a very simple option, have her create a giant slab of ice and then rotate it. She can move a turbine by moving her ice, and depending on the upper bounds of her power (which seems pretty high considering the stuff she has shown), she could generate a good amount of electricity just by moving a single turbine.

Unfortunately you, good Duke, appear not to have discovered electricity yet, from what I have seen of the recent Documentary Movie about Elsa's coronation. Given this fact, I fear many of the suggestions above are of limited use. Then again, you have somehow discovered computer and internet technology in order to post this question; quite impressive, so you could always try stopping by Wikipedia for the secrets of electricity while you're here ;)

Assuming you are not able to steal our secrets of electricity, I fear it's much harder to exploit her gifts, as you lack the automation techniques required to make massive use of anything she does.

I will, however, notice that Elsa managed to build things by thinking about them, without a perfect understanding of what she wanted. She likely lacked the architectural knowledge required to build a stable castle, nor the time to fully visualize the castle in her mind during the seconds spent building it. I'm certain she lacked knowledge as to how to create life, this appears to have been accidental. This seems to imply that her powers are in some form imagination based, so long as she can imagine what she wants to create, her powers will figure out how to do it, up to creating life itself.

This opens up a far greater use then any infrastructure or power generation option in the realm of research and prototype development. Have her create things that you currently lack the means to generate, and see what happens. Perhaps she can construct devices out of ice which you can then dissect and learn the secret of building on your own, assuming that they function based off of solid physical principles that can be recreated.

If they are purely magical constructions, there is still quite a lot of room for her to create objects that can simply not be duplicated by man. For instance, I know Elsa refused to create sentient snowmen for slave labor (what is it with princesses and their insistence on pesky 'morality' anyways!? It's such an inconvenience). However, I believe her complaints were based off of the 'sentience' part. It seems quite likely she could create non-sentient snowmen, without 'thoughts' or 'feelings' or any of that Disney nonsense, just constant moving objects to propel wheels on their own. If my men in charge of understanding 'ethics' are correct this should be morally acceptable to her.

Of course why limit ourselves there? Imagine self-propelling ice-ships! Load your cargo on a ship, point it in the correct direction, and tell it to sail to the other continent on it's own. Imagine imagine an auto-sled made out of ice that could be operated by drivers to rapidly travel from place to place! This is just the beginning, with some experimentation an imagination fueled power could no doubt be expanded to generate any number of useful contraptions!

I should remind you she also was able to create an infinite flurry of snow to support the entity named Olaf, so she can do the same to ensure that any contraption she generates will last forever without need for maintenance. She can thus mass produce and sell all these magical wonders.

Though I must warn you, my Good Duke, that you must convince her to do this of her free will. While no doubt men such as us understand that force is generally a better means of getting lesser creatures to do our will my researchers warn of something the call the "princess effect". Apparently attempts to compel a princess to actions will result in magical resistance, animals will become sapient and serve the princess's will, magical faeries will show up to grant wishes, and of course everyone knows of the pesky meddling of the Princes of the Kingdom Hansom in the affairs of good tyrants (how can one kingdom have so many princes anyways, that king really gets around!). Why just the other week King Horrid of the kingdom Tyrania lost his throne to a princess and her pet baby dragon after trying to force the marriage of the princess of the the lands of Plucky!

It may sound horrible, even unnatural, but the one method I know of reported to prevent the Princess Effect is something they call 'caring'. I don't fully understand it myself, but a group of magical multi-colored bears keep telling me about it before threatening to shoot mind control beams at me from the tattoos on their bellies. Anything able to power such mind control powers must be worth harnessing for our own gains!

Still, with some wisdom and creativity, I think you should be able to create and sell all manner of magical ice contraptions to the common man.

  • 5
    $\begingroup$ I really enjoy the voice of this answer. $\endgroup$
    – Erik
    Oct 10, 2017 at 16:44



there's quite a few ways Elsa "I control more joules than most nuclear weapons" of Arendelle could use her powers productively.

As you mention she can produce ice golems which can drive machinery but that doesn't require they be slaves, they can merely be big strong creatures who like walking in big hamster wheels. but that's basic level.

She can produce pykrete ships almost for free allowing for easy cheap trade:

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She can sell services to hotter kingdoms effectively ending droughts by creating glaciers to provide a steady supply of water to farms.

enter image description here

For that matter she can create massive damns, basically glaciers deeply rooted to hold inland lakes to drive water wheels.

enter image description here

Her ice is shown to be able to expand and contract pushing soil,earth and rock so she can probably shape large areas of landscape quickly to make way for construction and can definitely create large temporary structures.

Add to that she can probably use the ice to create canals and grind stone between ice sheets to create roads.

  • $\begingroup$ Additionally it appears that she can melt ice, when she returned the kingdom to summer $\endgroup$ Oct 11, 2017 at 17:03

Since you may already have a lot of steam engines lying around you might be able to convert some of them to use liquid Nitrogen. Get Queen Elsa to fill some flasks with liquid Nitrogen and then feed it into the steam engine boiler. Allow ambient air temperature to turn the liquid into gas and away you go (zero carbon emissions as well). You might need to have an external heat absorber system (instead of a radiator cooling system) to prevent over cooling.


You can always a regular steam engine using a fluid which boils at ambient temperature; just build the engine inside a room where Elsa maintains a temperature below the boiling point of the fluid and use the external environment as the heat source. For example, butane boils at 1 °C; boil it in a boiler outside the cold room (using the heat of the ambient atmosphere) and have the vapor power a regular steam engine inside the cold room.

In real history, butane was discovered in 1910, but since it's a simple hydrocarbon one can easily imagine it being discovered a little bit earlier, especially given the incentive of making steam engines with the boiler at ambient temperature.


So you have a person that can create frozen water out of thin air without using up energy effectively giving you an unlimited amount of potential energy.

Sounds pretty straight forward to me - forget about using the cold, build some kind of icemill or let it melt and use the big waterfall.


Unfortunately, thermodynamics dictate that the maximum efficiency of a heat engine is :

1 - Tcold / Thot

Where Tcold and Thot are the temperatures of the cold and hot sources, respectively. Since both are expressed in Kelvins, if we use ice at 0°C (273°K) and ambient air at 25°C (298°K) then the maximum theoretical efficiency is 8.4% which means poor Elsa will have to work a lot for very little energy output.

It would be more profitable for her to start an air conditioning business in a hot country, methinks.

  • $\begingroup$ You screwed up the Carnot efficiency, it should be about 8.4% $\endgroup$ Oct 9, 2017 at 19:54
  • $\begingroup$ I don't get it. Tcold can be as close to zero as we want. It mean that 1 - 0/298 efficiency. In other words 100%. $\endgroup$
    – talex
    Oct 10, 2017 at 1:57
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    $\begingroup$ I don't know how cold she can go but she's been shown to make iron manacles so cold they become brittle and break. $\endgroup$
    – Erik
    Oct 10, 2017 at 3:21
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    $\begingroup$ @guenthmonstr People who want to make ice cream very quickly. $\endgroup$
    – reirab
    Oct 12, 2017 at 3:12
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    $\begingroup$ @reirab she could turn fruit into sherbet! Mmmm, tasty... $\endgroup$
    – bobflux
    Oct 12, 2017 at 20:47

Gradient and Lack of Friction

Engineers can design something around the idea of Hyperloop and really perfect it.

  • Use this almost fuel-less transportation system for moving goods and people around.
  • You can have this transportation system installation and maintenance contracts with other kingdoms and build huge business around it.

Ice Castle!!

Same as Ice Hyperloops, engineers can build huge ice castles that will melt strategically. These can be big hit in deserts. These castles can provide shelter, source of water. Refrigeration would be bonus (a hole in floor for beer bottle).

This is again, never ending contract, benefiting both parties, and no real competition.

It's Not Cold, It's Heat

Since cold is not really a thing but just lack of heat, we can assume that Elsa's power is not really to create cold but to manipulate heat. And, once you have control over heat, there are all sorts of ways to fuel Industrial Revolution.

  1. You could dominate most food trade. You now have capability to refigerate things. Which means a lot of trade goods that were hitherto impossible to transport and store is now possible. This is a huge ecoonomic advantage.

    She can even make permanent localized effects it seems (snowmans private snowstorm) so they can now sell refigeration units that cost nothing to run.

  2. Forget industrial revolution, terraform land. Elsa can capture huge amounts of atmospheric humidity as snow. The sheer amount of snow generated in such short period of time means that Elsa is getting either humidity for free or harvesting it from a huge area possibly from very high up.

    This means Elsa can turn arid, and desert areas into very habitable places. Even without the snow generation this is potent enough to generate dramatic low pressure areas allowing humidity to flow in aeas where there are none.

  3. Winds, elsa can produce gale storm level winds, just slightly more controlled effect and you can power a entire farm of windmills in a way that could do all kind of mechanical work. No steam engine needed even pre industrial tech levels could do this.

  4. Elsa can produce heat, why else would the snow and ice melt sonfast once she cancels the spell. Though it is magic so who knows how it works.


This is a relatively low-tech approach, but I think it is fitting in the universe you have drawn inspiration from:

Do recall that Elsa can create animate objects from snow. Just have her create endless rows of ice treadmills and endless snow golems to power each, and voila! Free energy!

  • 7
    $\begingroup$ That was the Duke's first thought but Elsa didn't want to sell her snow golems into slavery $\endgroup$
    – Erik
    Oct 10, 2017 at 2:16
  • $\begingroup$ Oh I'm sorry, missed out that part of your question. The shame! $\endgroup$
    – Xenocacia
    Oct 10, 2017 at 2:25
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    $\begingroup$ OK, but what does Elsa think about creating frozen indentured servants? Or frozen third world citizens who will work for 50 cents of fiat currency a day? $\endgroup$
    – gmatht
    Oct 11, 2017 at 1:29
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    $\begingroup$ @gmatht I have a feeling she'd view that as functionally equivalent to slavery especially considering the only stores they'd be able to spend their 50 cents a day would have inflated prices and be owned by the factory management... $\endgroup$
    – Erik
    Oct 12, 2017 at 22:31

She is perfectly able to create sentient lifeforms. How about sentient factories crawling the forests chopping wood and replanting followed by fast ice carriages taking the wood down to shore. She is capable of doing an industrial revolution on her own since her powers seem to be almost unlimited and perfectly capable of customizing sentient beings.

This might also be of interest: https://www.fanfiction.net/s/10327510/1/A-Bluer-Shade-of-White



Elsa could provide her sorcery in order to cool down Liquids, like Helium, Methan, Oxygen, ... thus preventing spoilage of such liquids.

Chemical Engineering

By providing unlimited freezing power, Elsa could help to engineer new molecules on extrem low temperatures.

Building storage units

Elsa could form warehouses which could be used by her lifeforms

Heat Exchanges

You could use the same mechanics as fridges, but just vice versa in order to create power. However, this might need some adjustments in physics.


Water Wheels

Elsa's power, as shown in the movie, allows her to trigger massive snowfalls, and then subsequently a rapid thaw.

When you have a thaw event in the hills and mountains, it causes streams to flow.

When you switch back to winter storm mode, that water gets taken back up into the clouds to make more snow that gets dumped back at the top of the mountain.

It then flows down the mountain again next time it thaws.

It's just like the natural water cycle, only under control, much faster, and without requiring the power of the sun to drive it.

It is effectively a perpetual motion machine. A never-ending flow of water running downhill.

Once you have her under your control, all you have to do is build lots of water wheels to harness the energy, and you'll be unstoppable.


See if she can create non sentient moving objects.

If she can create a rod that spins within a stationary collar, you can power just about any industrial bit of machinery. Mount the collar on something that doesn't move and then mount something (like a mill or anything else) to the rotating rod.

By using clutches and gearing you can start, stop and modify torc and speed. You could even make rudimentary automobiles by having the wheels clutch onto at rotating axle.


Cooling is just pushing heat somewhere else. Since Elsa can cool anything at near instant speeds it stands to reason that she can freely control energy.

Look up some scientific break downs of how iceman's powers would work IRL. Essentially, you have access to nearly infinite energy all the time anytime because you can push the heat, out of pretty much everything. All you have to do is engineer things to organize the random movement that makes up heat to do work and you're set.


Elsa Lies: Conservation of Energy Means She Has Heat Too

The first law of thermodynamics says that energy must be conserved. If Elsa is creating ice castles, she must be holding on to the heat somewhere.

Because Elsa must be lying, she is hiding something from you, and you cannot trust her. I would not assume you could harness her cold energy at all. But she did invite your delegation to a meeting, meaning she is interested in something about you.

Perhaps she seeks to destroy you, and she knows granting you her powers will destroy you, much like colonists did with opium. Or perhaps, she is simply bartering her cheap powers for something more valuable, much like the smae colonists traded guns and horses for land.

She Wants Something Else

So given that she is lying, and that she harnesses such immense power, the only reason she is speaking with you is because she must want something else. Unlikely that it'll be anything materialistic, with her power she could easily obtain anything that can be made.

More likely, Elsa wants something more ephemeral, perhaps respect, friendship, or even love.

Figure out what she wants, and you will have your power over her. Attempt to engineer her powers to your will, and you can only bring yourself ruin.

  • 1
    $\begingroup$ This seems to be answering a different question. Elsa's decisions would be off-topic here. We're only analyzing whether making use of her power is physically and scientifically possible. This is an off-topic answer. $\endgroup$
    – Brythan
    Oct 13, 2017 at 2:50

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