Question about steam power

[Traab]

This is something that has popped up in a story i am reading. The world has found a source of heat that will never fade and needs no fuel to stay at a constant temp. Already they are using it for power plants and the like instead of say, nuclear power. Now, there was talk about creating steam engines for cars and other such devices to reduce the dependance on oil, (and yes, they are covering the massive global upheaval this will cause)

Anyways, my question is, Will running everything on steam have an adverse effect on our water supplies? If we did have a viable and totally clean source of heat available at any size or shape we require, would steam power be enough force in a small enough package to power things like cars? Or would they require engines far too large to be practical to contain enough pressure for what is needed?

[Shadow of the Sun]

Well, considering that almost all powerstations in the world run on steam power at the moment, I don't think it'll affect water supplies.

As for cars powered by steam? I don't think you'd get an efficient enough conversion ratio.

[Brother Oni]

It depends on how small the heat source can be to power a steam engine that can fit in a car sized package.

It also depends on the quality of the water used in the engine. During WW1 the Vickers water cooled machine gun was primarily filled with urine, since any potable water was far valuable being supplied to the soldiers.
If the engine could only take potable quality water and there was a mass switchover to steam power, then I would think there would be a potential issue.

That said, if the world otherwise has our level of technology, why not switch to electic cars instead? After all, the price of electricty should drop significantly after the initial outlay of setting up the power stations.

[factotum]

Normally I'd agree with Shadow of the Sun, but if you have a literally infinite heat source that doesn't require fuel to keep it going, who cares about efficiency?

As far as water supplies go, doing this wouldn't really affect them at all. Any water used in a steam engine gets pumped into the atmosphere, where it will eventually fall as rain and thus get recycled into the environment. Water vapour is a greenhouse gas, admittedly, but I don't think it's as potent as carbon dioxide in that regard.

The main issue with a steam car would be the amount of water it would have to carry, though--the energy density you get from just heating water for pressure is considerably lower than fossil fuels, which is why you don't see steam trains around much these days!

[EDIT] Read Brother Oni's response, and I think the main problem with electric cars would be the same in the quoted scenario as it is in our world--having to carry around half a ton of batteries (which are full of toxic chemicals) just to get half the range a petrol car enjoys.

[Shadow of the Sun]

Normally I'd agree with Shadow of the Sun, but if you have a literally infinite heat source that doesn't require fuel to keep it going, who cares about efficiency?

As far as water supplies go, doing this wouldn't really affect them at all. Any water used in a steam engine gets pumped into the atmosphere, where it will eventually fall as rain and thus get recycled into the environment. Water vapour is a greenhouse gas, admittedly, but I don't think it's as potent as carbon dioxide in that regard.

The main issue with a steam car would be the amount of water it would have to carry, though--the energy density you get from just heating water for pressure is considerably lower than fossil fuels, which is why you don't see steam trains around much these days!

[EDIT] Read Brother Oni's response, and I think the main problem with electric cars would be the same in the quoted scenario as it is in our world--having to carry around half a ton of batteries (which are full of toxic chemicals) just to get half the range a petrol car enjoys.

The efficiency issue is more about the fact that steam engines are...well, very inefficient. Steam locomotives worked because the rails give them very low friction, and because the boiler can have excess water due to the fact that it's a locomotive.

I don't think you'd be able to get a steam engine good enough that the amount of water would not be prohibitive to power a car.

Now, a Stirling Engine (http://en.wikipedia.org/wiki/Stirling_engine) on the other hand...

EDIT: steam cars do exist, but they're heavier than ICE cars, and require a lot of attention from the driver to keep going.

[Traab]

It depends on how small the heat source can be to power a steam engine that can fit in a car sized package.

It also depends on the quality of the water used in the engine. During WW1 the Vickers water cooled machine gun was primarily filled with urine, since any potable water was far valuable being supplied to the soldiers.
If the engine could only take potable quality water and there was a mass switchover to steam power, then I would think there would be a potential issue.

That said, if the world otherwise has our level of technology, why not switch to electic cars instead? After all, the price of electricty should drop significantly after the initial outlay of setting up the power stations.

Well, in this story, the items involved are rocks. Literally, rocks. They can be anything from a pebble small enough to attach to your keychain to large slabs. They do run tests on different types of rock, but the results are never mentioned. That being said, it is never clearly stated as to what level of heat they can be set at, or if the size of the stone effects the max potential heat. But I do know they at one point suggest the keychain idea for hand warmer level of heat and were in research for using this heat source as replacements for arctic gear in the military.

For the moment, lets assume the rocks can be virtually any temp short of hot enough to melt or otherwise break the stone on any size. So theoretically, you could plop a pebble into a 16 gallon fuel tank thats as hot as you would like it to be within reason. Or any size above that as I dont think a pebble could heat a tank of fresh water to the boiling point very efficiently.


The efficiency issue is more about the fact that steam engines are...well, very inefficient. Steam locomotives worked because the rails give them very low friction, and because the boiler can have excess water due to the fact that it's a locomotive.

I don't think you'd be able to get a steam engine good enough that the amount of water would not be prohibitive to power a car.

Now, a Stirling Engine (http://en.wikipedia.org/wiki/Stirling_engine) on the other hand...

EDIT: steam cars do exist, but they're heavier than ICE cars, and require a lot of attention from the driver to keep going.

They actually mention sterling engines in the story. They havent gotten to the point of actually testing this sort of thing yet. they had only just recently gotten the first power plant up and running and are still testing the thousands upon thousands of potential applications while keeping things mostly secret. A few allied governments know and are working together, and shortly the whole secret was going to be out, but the story ended on a bit of a cliff hangar and the next one hasnt started yet.

[Shadow of the Sun]

A steam car managed to hit roughly 140 mph in 2009.

So it could work, depending on how you finagle it.

[Brother Oni]

As far as water supplies go, doing this wouldn't really affect them at all. Any water used in a steam engine gets pumped into the atmosphere, where it will eventually fall as rain and thus get recycled into the environment. Water vapour is a greenhouse gas, admittedly, but I don't think it's as potent as carbon dioxide in that regard.

On a global scale, I'd agree - all that water doesn't go anywhere in the end.
Micro scale, particulaly with regards to drinking water supplies, it will become an issue (imagine a hosepipe ban being the main reason why you can't drive to work!).



[EDIT] Read Brother Oni's response, and I think the main problem with electric cars would be the same in the quoted scenario as it is in our world--having to carry around half a ton of batteries (which are full of toxic chemicals) just to get half the range a petrol car enjoys.

Electric cars are improving - take a look at the Tesla Roadster (http://en.wikipedia.org/wiki/Tesla_Roadster) with its range of 244miles on a single charge.
With the incentive of cheap electricity, electric cars may become more popular.



For the moment, lets assume the rocks can be virtually any temp short of hot enough to melt or otherwise break the stone on any size.

Well magma typically ranges from 700-1300 C, so it can still get fairly hot.

The keychain idea implies that size is directly linked to power output, as a typical hand warmer ranges from about 57-68 C and a rock that can't get hot enough to boil water is of no use to a power plant.

With regard to the pebble in a 16 gallon fuel tank, it would heat all the water up eventually, although it would take a while due to the inefficient shape of the rock.

What is this story that you're reading anyway?

[Elemental]

Anyways, my question is, Will running everything on steam have an adverse effect on our water supplies?

Only if the power plants require freshwater. If not, then we have vast reserves of water available that just collects in pools that cover most of the planet.

Of course, the difficulty with using sea water is that it tends to like to corrode everything, so the power plants would have to be designed to take that into account. That, and the generators would probable have to be near the sea... Which wouldn't be all that much of an issue since most people live near the sea and we can already transmit power over great distances.

[Erloas]

I don't work in a power plant but I work in an industrial plant that happens to make our own power (coal and natural gas). The water they use has to be fairly clean, it isn't necessarily "potable water" but in some ways it is more clean and in other ways it is less. Bacteria isn't a problem with water used in steam but minerals are. If you don't purify your water you can get a lot of build in fairly short order. Obviously once it becomes steam the minerals are left behind, but whatever vessel you are heating that water in will get a lot of build-up in it if your water quality is poor.

Also salt water is highly corrosive and would destroy your plumbing in fairly short order. You could make everything out of stainless steal but that is prohibitively expensive.

The primary issue with using it to power something like a car is the heat density. How hot it can get and how easily it transfers that heat to other things would be the key as to how practical it would be to use as a power source in smaller things like cars. Even if a pebble could heat 16G of water, the question is how hot could it get the water and how long would it take. If it takes 2 hours to get that 16G of water to 150 F that would work for heating a house or a water heater it isn't going to be usable as a power source.

[AMX]

The keychain idea implies that size is directly linked to power output, as a typical hand warmer ranges from about 57-68 C and a rock that can't get hot enough to boil water is of no use to a power plant.

Not if you want to use steam.
But you could run a Stirling engine or a thermocouple.

Incidentally, can these magic rocks be used to consume heat?

[Jaycemonde]

This all reminds me of the way artifacts are put to use by the outside world in S.T.A.L.K.E.R.

[factotum]

Electric cars are improving - take a look at the Tesla Roadster (http://en.wikipedia.org/wiki/Tesla_Roadster) with its range of 244miles on a single charge.
With the incentive of cheap electricity, electric cars may become more popular.


Electricity is already far cheaper than petrol or diesel for powering a car, but there are problems with the cars themselves that the quoted scenario won't fix:

a) Cost--a lot of the cost of an electric car comes from the aforementioned toxic chemicals in the batteries, which are rare and awkward to get hold of.

b) Recharge time--if your petrol-engined car runs short, you can stop, refuel at a garage, and be on your way again inside ten minutes. Even the most efficient electric cars take hours to go from low charge to full.

I think Shadow of the Sun's suggestion of a Stirling engine is the best solution by far, to be honest. In the OP's scenario such a car would never require refuelling, and Stirling engines are pretty simple and easy to maintain compared to internal combustion engines. Yes, they're heavier for a similar power output than the equivalent petrol engine, but I bet they're still not as heavy as all those batteries in the electric car!

[Traab]

On a global scale, I'd agree - all that water doesn't go anywhere in the end.
Micro scale, particulaly with regards to drinking water supplies, it will become an issue (imagine a hosepipe ban being the main reason why you can't drive to work!).



Electric cars are improving - take a look at the Tesla Roadster (http://en.wikipedia.org/wiki/Tesla_Roadster) with its range of 244miles on a single charge.
With the incentive of cheap electricity, electric cars may become more popular.



Well magma typically ranges from 700-1300 C, so it can still get fairly hot.

The keychain idea implies that size is directly linked to power output, as a typical hand warmer ranges from about 57-68 C and a rock that can't get hot enough to boil water is of no use to a power plant.

With regard to the pebble in a 16 gallon fuel tank, it would heat all the water up eventually, although it would take a while due to the inefficient shape of the rock.

What is this story that you're reading anyway?

Its called The Queen Who Fell To Earth. Its a Harry Potter/Dragonriders of Pern crossover. The dragons are able to use some special effect of their fire to permanently heat rocks to whatever temp they like. The keychain thing was a suggestion made as more of a gift shop type of idea. "Hey, lets give these guys a hand warmer key chain when they visit." It wasnt implied that that was the limit to how hot they could get, probably something like, "Ok, he can breathe on a pile of gravel then everyone gets one as a sample of what they can do."

As for magma and such, I dont think liquid rock would be best, and even if you left it just under that point, that would likely be too hot for safeties sake. I mean, I would imagine a softball sized rock burning at 650 C would likely flash boil a 16 gallon tank of water in a really short length of time. The steam would likely be a virtual explosion, especially confined in a boiler.

As for AMX, no, they cant consume heat. They are just constantly generating the amount of heat they are set at.

[Knaight]

Regarding steam: I don't know why we are assuming that water is necessarily the fluid being evaporated here. Sure, for industrial power plants and similar it's about the only thing that makes sense, but given that the heating element can be arbitrarily hot at no cost, using some sort of denser fluid with a higher boiling point could make things simpler, particularly if cooling is handled well. After all, the fluid just needs to be boiled to generate power, cool, flow back in the tank used for the liquid, and get boiled again. If anything, this process is more achievable at higher temperatures, as the gas will cool down much faster.

Granted, something that isn't too toxic would probably be preferred, which makes something like mercury a questionable idea, but that still leaves a lot of options. Though, if containment is good enough, mercury could be fine.

[Drumbum42]

These "hot rocks" kind of remind me of Uranium and Nuclear power. If we're worried about just using water there are several different types of coolants that can be used. Water, other liquids, gas or liquid metal.

Pros:
Water - cheap, lighter weight, non-toxic, easy to work with.
Various Liquids - Light to heavy, low power transfer to high power transfer
Gas - light
Liquid metal - doesn't explode

Cons:
Water - can explode if over pressurized
Various Liquids - can still explode, also possible environmental impact
Gas - requires higher pressure
Liquid metal - requires lots of heat, very heavy, solidifies when cooled.

It'd be possible that different vehicles would need different internals. (Like how trucks use diesel) So that could be fun.

[Traab]

These "hot rocks" kind of remind me of Uranium and Nuclear power. If we're worried about just using water there are several different types of coolants that can be used. Water, other liquids, gas or liquid metal.

Pros:
Water - cheap, lighter weight, non-toxic, easy to work with.
Various Liquids - Light to heavy, low power transfer to high power transfer
Gas - light
Liquid metal - doesn't explode

Cons:
Water - can explode if over pressurized
Various Liquids - can still explode, also possible environmental impact
Gas - requires higher pressure
Liquid metal - requires lots of heat, very heavy, solidifies when cooled.

It'd be possible that different vehicles would need different internals. (Like how trucks use diesel) So that could be fun.

I wonder if it would be workable to switch out liquid sources depending on need. Like say, picking a source that doesnt evaporate easy for long distance trips even if it might have less potential power behind it.

[factotum]

Regarding steam: I don't know why we are assuming that water is necessarily the fluid being evaporated here. Sure, for industrial power plants and similar it's about the only thing that makes sense, but given that the heating element can be arbitrarily hot at no cost

See: nuclear reactor. They still use water to cool and generate power in those. I'm also not sure that a "denser fluid with a higher boiling point" would make any difference here--in a pressurized system you can get steam to very high temperatures indeed (way above 100C). In fact, you pretty much *have* to get the steam to those high temperatures in order to use it, because if water were condensing out of the steam while it was in the turbines the water droplets would damage the turbine blades!

[Talanic]

I'm not sure that distributing these magic rocks (for lack of a better term) would be the most efficient use of them. Creating efficient battery packs and keeping those rocks as power sources for more conventional power plants would probably be better, I suspect.

Depends on the cost of making batteries, which may balance out in the long run - I suspect that it would take more effort to clean and maintain a small-scale steam engine, plus every car belching steam would possibly contribute to accidents on the road due to decreased visibility.

Regardless, this is an already-finished tale, correct? Title and author?

[Traab]

I'm not sure that distributing these magic rocks (for lack of a better term) would be the most efficient use of them. Creating efficient battery packs and keeping those rocks as power sources for more conventional power plants would probably be better, I suspect.

Depends on the cost of making batteries, which may balance out in the long run - I suspect that it would take more effort to clean and maintain a small-scale steam engine, plus every car belching steam would possibly contribute to accidents on the road due to decreased visibility.

Regardless, this is an already-finished tale, correct? Title and author?

Well, its a trilogy, and the second part just got finished. The official reveal to the world at large of the existence of dragons was the grand finale of book 2. So while the power plant thing has happened and been proven to work, everything else is still in the idea stage as scientists from a handful of countries have been brainstorming the hell out of the hot rocks and their potential applications. The Queen Who Fell To Earth, by Bobmin356 on fanfiction.net is how you can find the first book.

As for steam causing visibility issues, I see that as easily handled by having the steam escape via a coiled pipe so it cools down and returns to water droplets before fully exiting the vehicle. Hell, it might even be possible to at least partially recycle the water that way and further extend the length of time a 16 gallon drum of boiling water can last. Steam gets belched out however it is released, it goes up a tube where it hits a cooled bit of metal, turns into water, and drips back into the tank. Aside from a bit of drippage on the road it could be pretty self contained.

[Erloas]

Actually I think most steam systems are mostly closed systems. Our boilers and turbines at work do not put off any steam. Of course we have huge tanks where the water condenses again and whether or not it can be reused in the boiler mostly depends on what other processes in the plant the steam is used in.
About the only time we blow off steam is when there is a problem with some piece of equipment and we don't have anywhere else for the excess steam to go.

I also believe the steam out of our boilers runs somewhere in the 600C range (maybe 600F... I don't work in the powerhouse so I only kind of look at the numbers...)

Water vapor is actually more of a contributor to the greenhouse effect the CO2 is, but water vapor is naturally in the atmosphere anyway and cycles through relatively quickly. It could potentially have a huge impact, especially on local climates, if we were to drastically increase what is in the air. It is a positive reinforcement system.

[Emmerask]

I dont see a reason why the water could not be completely recycled inside the car (depending on technology level of course). In the end such a car could run a lifetime without ever having to refuel.

[Mando Knight]

Depending on the heat transfer rate of the hot rocks, you could forgo the steam part entirely and just use air-breathing turboshaft engines in the cars.

One impracticality of steam engines is that no matter what you do with the heat source, you're still carrying a highly pressurized boiler around. And a lot of water.

[Traab]

Depending on the heat transfer rate of the hot rocks, you could forgo the steam part entirely and just use air-breathing turboshaft engines in the cars.

One impracticality of steam engines is that no matter what you do with the heat source, you're still carrying a highly pressurized boiler around. And a lot of water.

Yeah, car wrecks would end really badly. Ive watched mythbusters, I have seen what happens when water heaters fail. :smallbiggrin: Watching that one heater shoot through the floor then the roof of a "house" makes me terrified to see what would happen if it exploded like a bomb instead of like a rocket. The rocket was bad enough. Super heated steam + shrapnel = ow ow ow ow ow!

[factotum]

Actually I think most steam systems are mostly closed systems. Our boilers and turbines at work do not put off any steam.

For static systems like you have in factories, that's perfectly reasonable. Adding a bulky, heavy condenser to a mobile steam engine is more of a problem--steam locomotives never used one to my knowledge, and they were *much* larger and heavier than any steam-powered car could afford to be.

[Traab]

For static systems like you have in factories, that's perfectly reasonable. Adding a bulky, heavy condenser to a mobile steam engine is more of a problem--steam locomotives never used one to my knowledge, and they were *much* larger and heavier than any steam-powered car could afford to be.

Did they even HAVE condensers back then? At least ones useful enough to work with a steam engine? Anyways, even if they cant make a condenser small enough for a car engine, they could still use a version of the exhaust pipe to reduce all or most of the steam to water so it can safely drip out the back instead of billowing out into the air.

[The Extinguisher]

I'm pretty sure electric is the way to go. You have literally infinite energy here. It doesn't matter how "efficient" the energy transfer is, you still have an infinite amount of energy that isnt going anywhere. Heck we already have wireless power now, you can just beam that energy everywhere so your car is always plugged in.

Fussing about with steam seems really pointless.

[Traab]

I'm pretty sure electric is the way to go. You have literally infinite energy here. It doesn't matter how "efficient" the energy transfer is, you still have an infinite amount of energy that isnt going anywhere. Heck we already have wireless power now, you can just beam that energy everywhere so your car is always plugged in.

Fussing about with steam seems really pointless.

The power still has to be produced somehow with electric cars though. Thats the real point about this hypothetical steam power. Its a limitless source of energy.

[factotum]

Did they even HAVE condensers back then?

Of course--condensers have been around pretty much as long as steam power has; one of the first steam engines ever built (Newcomen's, I think) relied on condensing the steam in the cylinder to provide the power stroke, because the steam couldn't be generated at high enough pressure to do much meaningful work.

However, it turns out I was wrong about steam locomotives not having condensers--apparently it happened:

http://en.wikipedia.org/wiki/Condensing_steam_locomotive

[The Extinguisher]

The power still has to be produced somehow with electric cars though. Thats the real point about this hypothetical steam power. Its a limitless source of energy.

Still seems to messy and pointless. You already have a limitless source of energy. Just hea t the air without having to mess around with water and steam. Even if your excess energy is tiny, its still limitless. Trying to be more efficient seems wasteful. One percent of infinity is still infinite.

[Erloas]

But energy is only one factor. There are a lot of other resources to take into account.

An inefficient engine will likely take up a lot more space and weight compared to an efficient one. That means more steel and plastic, and both of those take quite a few other resources to mine and refine. Everything you make takes a lot more then just energy to make and some of those resources are already fairly limited.

[Traab]

But energy is only one factor. There are a lot of other resources to take into account.

An inefficient engine will likely take up a lot more space and weight compared to an efficient one. That means more steel and plastic, and both of those take quite a few other resources to mine and refine. Everything you make takes a lot more then just energy to make and some of those resources are already fairly limited.

Of course an inefficient engine would be worse than an efficient one. But seriously, give it a year or two, you are comparing steam engines that havent been seriously worked in in god knows how long, if ever in the case of modern day vehicles, to electrical motors that are the current focus of a lot of research and experimentation. One of the advantages of a steam engine over an electric engine is refuel time. An electric car would either need to replace its battery/s or charge for hours. A steam engine would turn on a hose and top off the tank then continue on. We also have no real way to tell how efficient a closed system engine could be. How far could it go before needing to refill, how much power could be behind it given the space constraints, things of that nature.

The cost is another factor. Its fueled by water, doesnt require a large number of potentially hazardous chemicals to make up its battery like an electric car does, and should produce far less pollutants and in far smaller quantities than most other vehicles. After all, its powered by clean heat and water.

[The Extinguisher]

But energy is only one factor. There are a lot of other resources to take into account.

An inefficient engine will likely take up a lot more space and weight compared to an efficient one. That means more steel and plastic, and both of those take quite a few other resources to mine and refine. Everything you make takes a lot more then just energy to make and some of those resources are already fairly limited.

You misunderstand me. You get all the rocks together, and use whatever process you want to extract energy from the system and generate electricity (size doesn't matter here, cause it's a huge energy facility). You could use steam, but I'm sure there's an easier option.

Then you just beam the energy wirelessly to everything. We already have wireless power now, but it's small range cause it's massively inefficient. But you're generating infinite electrical energy, so it doesn't matter how efficient it is. You effectively just have everything plugged in. Free energy for everything. You run everything off of it and you don't need batteries or steam engines or anything.

I mean sure, eventually it'll probably destroy the whole universe cause infinite unstoppable heat is kinda bad, but at least we'll live like kings until that happens.

[Gray Mage]

You misunderstand me. You get all the rocks together, and use whatever process you want to extract energy from the system and generate electricity (size doesn't matter here, cause it's a huge energy facility). You could use steam, but I'm sure there's an easier option.

Then you just beam the energy wirelessly to everything. We already have wireless power now, but it's small range cause it's massively inefficient. But you're generating infinite electrical energy, so it doesn't matter how efficient it is. You effectively just have everything plugged in. Free energy for everything. You run everything off of it and you don't need batteries or steam engines or anything.

I mean sure, eventually it'll probably destroy the whole universe cause infinite unstoppable heat is kinda bad, but at least we'll live like kings until that happens.

I think you might be mixing energy and power. The rocks'd genrate infinite energy, but that doesn't translate into infinite power. While it'd be a great source of energy, efficiency would still be relevant.

[Ravens_cry]

Steam is still probably the best way. Water is actually a pretty awesome working fluid. See, it takes a lot of energy to transition from liquid water to steam. This means that steam, despite its fairly low temperature, has a lot of energy. That, and waters availability, mean it is still working fluid for basically any nuclear reactor's generator. Other fluids might be used for cooling, but water drives the turbines that run the generator that makes the electricity.

[thubby]

Steam is still probably the best way. Water is actually a pretty awesome working fluid. See, it takes a lot of energy to transition from liquid water to steam. This means that steam, despite its fairly low temperature, has a lot of energy. That, and waters availability, mean it is still working fluid for basically any nuclear reactor's generator. Other fluids might be used for cooling, but water drives the turbines that run the generator that makes the electricity.

yes but the problem is the weight. water is fairly heavy, corrosive, and only effective in high volumes.
there have been steam powered vehicles before. they were gigantic and exceedingly dangerous due to the threat of explosive steam release.

what you're really after is a heat engine, of which there are many. if you had an unlimited heat source, you could easily make a basic sterling engine for a car. the only reason they aren't used for anything is because they're inefficient at larger scales. but inefficiency isn't such an issue here. sure you'd need enough power to meet road needs but it's fairly trivial (people have already done it)

the sterling engine has the advantage of being very simple, 100% mechanical, and requires no springs or soft pieces. in the event of a crash it would simply break at worst, no explosive decompression or the like.
____
depending on how much heat these threw off, you could also use them to simply power something to store energy. a hydrogen combustion engine would work just fine so long as the car's hydrogen supply was being fed by a heat-stone electrolysis unit. (the current limit on H2 technology is the ability to carry large fuel loads, which this solves)

[Traab]

You misunderstand me. You get all the rocks together, and use whatever process you want to extract energy from the system and generate electricity (size doesn't matter here, cause it's a huge energy facility). You could use steam, but I'm sure there's an easier option.

Then you just beam the energy wirelessly to everything. We already have wireless power now, but it's small range cause it's massively inefficient. But you're generating infinite electrical energy, so it doesn't matter how efficient it is. You effectively just have everything plugged in. Free energy for everything. You run everything off of it and you don't need batteries or steam engines or anything.

I mean sure, eventually it'll probably destroy the whole universe cause infinite unstoppable heat is kinda bad, but at least we'll live like kings until that happens.

Its not infinite, its endless. You can only produce a limited amount of power at one time, the source will just never run out is all. As for better options than steam, what better options for power generation are there that can use an eternal heat source to generate it?

And really, the hot rock power source has three main advantages over current power sources. It never runs out, it can be any shape size and temp you want short of magma, and it produces no waste by itself. That rock will sit there glowing merrily away for decades without producing any emissions but heat or waste whatsoever, unlike nuclear power plants for example, or coal burning power plants for another. No radiation, no toxic chemicals, no refuse to cart away. Just clean renewable energy.

[thubby]

Its not infinite, its endless. You can only produce a limited amount of power at one time, the source will just never run out is all. As for better options than steam, what better options for power generation are there that can use an eternal heat source to generate it?

And really, the hot rock power source has three main advantages over current power sources. It never runs out, it can be any shape size and temp you want short of magma, and it produces no waste by itself. That rock will sit there glowing merrily away for decades without producing any emissions but heat or waste whatsoever, unlike nuclear power plants for example, or coal burning power plants for another. No radiation, no toxic chemicals, no refuse to cart away. Just clean renewable energy.

of course, they'd inevitably be the heat-death of not only the planet but also the universe.

[The Extinguisher]

I think you might be mixing energy and power. The rocks'd genrate infinite energy, but that doesn't translate into infinite power. While it'd be a great source of energy, efficiency would still be relevant.

Power is just energy per time. Infinite energy does mean infinite power. In order to do things, you need to do work, which means you need energy. Of which you have an infinite amount of. Efficiency is still irrelevant.


of course, they'd inevitably be the heat-death of not only the planet but also the universe.

Opposite of heat death actually :smalltongue: Heat death is where you run out of energy. This is where you have too much.
Work death maybe?

[Eulalios]

Aagh. Too tired to look this up, but hey, people ... Thermopiles (Peltier effect)... Rock of infinite hotness would make that Way better than your silly steam or batteries.

EDIT.. MEH. Heat death is when we run out of enthalpy. Can't believe Swype got that word right.

[Erloas]

You can create energy/heat from matter but you can't create matter from heat/energy. Heat is just one form of energy after all. Heat-death is the point at which all matter has turned into energy/heat and all of the matter is gone. Now if you can create infinite heat without using up matter then you would actually slow down heat-death slightly.

[Ravens_cry]

yes but the problem is the weight. water is fairly heavy, corrosive, and only effective in high volumes.
there have been steam powered vehicles before. they were gigantic and exceedingly dangerous due to the threat of explosive steam release.

what you're really after is a heat engine, of which there are many. if you had an unlimited heat source, you could easily make a basic sterling engine for a car. the only reason they aren't used for anything is because they're inefficient at larger scales. but inefficiency isn't such an issue here. sure you'd need enough power to meet road needs but it's fairly trivial (people have already done it)

Actually, the idea that steam cars were super dangerous was mostly advertising propaganda by their competitors.
They also weren't that big. It wasn't like every car was a traction engine (http://en.wikipedia.org/wiki/Traction_engine). Here's (http://www.youtube.com/watch?v=ACO-HXvrRz8) a wonderful overview of one of the most advanced steam cars ever built. You should be able to see it's not far of from other cars of its time. Still, another option is to convert steam power into electricity in big generators at power stations, and outfit the cars with either batteries or (potentially more efficient) supercapacitors.

[thubby]

You can create energy/heat from matter but you can't create matter from heat/energy.

actually, humanity has already created matter from energy. it's only subatomic particles ATM but we've done it.


Actually, the idea that steam cars were super dangerous was mostly advertising propaganda by their competitors.
They also weren't that big. It wasn't like every car was a traction engine (http://en.wikipedia.org/wiki/Traction_engine). Here's (http://www.youtube.com/watch?v=ACO-HXvrRz8) a wonderful overview of one of the most advanced steam cars ever built. You should be able to see it's not far of from other cars of its time.

did not know that.

as already stated, batteries capable of storing sufficient power require expensive, toxic, and exotic materials.

[tomandtish]

I don't work in a power plant but I work in an industrial plant that happens to make our own power (coal and natural gas). The water they use has to be fairly clean, it isn't necessarily "potable water" but in some ways it is more clean and in other ways it is less. Bacteria isn't a problem with water used in steam but minerals are. If you don't purify your water you can get a lot of build in fairly short order. Obviously once it becomes steam the minerals are left behind, but whatever vessel you are heating that water in will get a lot of build-up in it if your water quality is poor.

Quoted for emphasis (and others have referred to it also. Even ignoring salt water, any device that is regularly converting water to steam (esp. if enclosed) is going to have to be highly resistant to corrosion and use water that's as deionized and as pure as possible.

We made the mistake once of not reading the instructions on our first vaporizer, and just used tap water. It died in 6 months. When we were talking to the guy at the store, he pointed out that using normal tap water corrodes the heck out of it and specifically voided the warranty for precisely that reason.

[Ravens_cry]

did not know that.

as already stated, batteries capable of storing sufficient power require expensive, toxic, and exotic materials.
You act like we aren't working on, and basically have, battery powered vehicles right now. Supercapacitors have the potential to take the toxic part out and charge very quickly compared to batteries. Another possibility is fuel cells, using hydrogen electrolysed from water. You know, though it's inefficient, sufficient heat will also break water into oxygen and hydrogen. But since these magic stones create unlimited heat, it could end up being simpler at least.
Or all highways could have something like this (spectrum.ieee.org/tech-talk/green-tech/advanced-cars/korean-bus-charges-itself-while-driving).
Still, these are relatively recent developments, though they could be shoved back a little earlier at least thanks to the demand.
What might actually happen is that long distance transportation would be mainly trains still, since battery, supercapacitor and fuel cell cars would have a fairly short range.

[thubby]

You act like we aren't working on, and basically have, battery powered vehicles right now. Supercapacitors have the potential to take the toxic part out and charge very quickly compared to batteries. Another possibility is fuel cells, using hydrogen electrolysed from water. You know, though it's inefficient, sufficient heat will also break water into oxygen and hydrogen. But since these magic stones create unlimited heat, it could end up being simpler at least.
Or all highways could have something like this (spectrum.ieee.org/tech-talk/green-tech/advanced-cars/korean-bus-charges-itself-while-driving).
Still, these are relatively recent developments, though they could be shoved back a little earlier at least thanks to the demand.
What might actually happen is that long distance transportation would be mainly trains still, since battery, supercapacitor and fuel cell cars would have a fairly short range.

current battery powered cars are actually net ecological drains compared to combustion engines and cost substantially more.
it's not a design problem, it's a materials problem. that's the kind of thing people wait lifetimes for. battery powered cars have been "right around the corner" for 2+ generations now.

high temperature electrolysis does look very feasible. by building the entire machine around the heating element, even a relatively unimpressive heating unit could be used to essentially build an engine that makes its own fuel. the trick would be making it still run a dynamo while not in operation so it could replenish its fuel supply when not in use.

[Ravens_cry]

current battery powered cars are actually net ecological drains compared to combustion engines and cost substantially more.
it's not a design problem, it's a materials problem. that's the kind of thing people wait lifetimes for. battery powered cars have been "right around the corner" for 2+ generations now.

The point is that they work. Sure, they are expensive, now, and don't quite have the range, but they work.

high temperature electrolysis does look very feasible. by building the entire machine around the heating element, even a relatively unimpressive heating unit could be used to essentially build an engine that makes its own fuel. the trick would be making it still run a dynamo while not in operation so it could replenish its fuel supply when not in use.
I think you are better off, even with the high volume of hydrogen tanks, having the hydrogen made at a more central facility than on-board the vehicle itself. Them is some high temperatures you are dealing with and it will be more consistent heat compared to the little explosions of a internal combustion engine.

[factotum]

The point is that they work. Sure, they are expensive, now, and don't quite have the range, but they work.

You're ignoring the main issue with them, which is that you have to put a massive amount of highly toxic, difficult to extract chemicals into the batteries for them to work. I don't think there's any feasible way to ramp up production of current battery technologies to the point at which we could power all the world's cars using them, so that means we need to find a new battery technology that's more efficient and made from more readily available materials. If we're having to discover new technologies in order to make the thing viable, we might as well do more development on steam or Stirling engines, since we know the end result will work better than an electric car even if the battery problems are solved.

[Drumbum42]

I think that hydrogen is the best solution, because doing 0-60 in a steam powered car will take several minutes (and batteries are toxic). This is also assuming that making a stream powered car that can go 60mph would be cost effective. The only steam powered vehicles that really got to high speed were trains, and 20 ton cars is not a good thing. Going long distance in a steam powered car at 25mph would take a really long time.

There may be an issue with hydrogen though, would these magic rocks produce enough hydrogen needed by the car? I don't know a lot about hydrogen power, but it seems like if you're driving at high speeds, you may exceed the rock's capacity to produce hydrogen. You could probably run at a deficit for a while, but if you burn up power by accelerating really fast, or driving really fast your car might stall. The flip side of that is having a really hot rock that is capable of producing the power, but wouldn't that make the car REALLY hot on the inside?

That is unless we have hydrogen stations where you "gas up." But that may defeat the point.

[The Extinguisher]

Thinking about it, I'm pretty sure that with infinite energy we don't need cars anyway. We could probably just tube transport people everywhere. Or develop some sort of teleportation system. Or something more efficient and crazy that would never work with finite energy.

Cars seem like a weird idea when you can do whatever you want.

[Erloas]

The problem with most massive social projects, isn't the energy, it is all of the other resources required. The tubes would be made of either glass, plastic, or metal, and while all of those materials might be power intensive to make there is a good chance that power isn't even the largest part of their production cost.

We create our own power at the plant I work at, I think the energy overhead in the cost of our product is in the 10-20% range, so even with free power our cost would only drop 10-20%. Most of our cost comes in paying employees, the rest coming in maintenance and wear and tear on equipment. What we make is used in the making of glass and we are working with a finite resource, to the point where I don't think it would be possible to mine enough to create enough glass to put tubes across the entire US, let alone the whole world. (And yes, that is taking into account the amount our competitors can produce as well). At least on top of all of the glass being produced for other things such as buildings.

There is a lot of iron left in the world, but most of it isn't easy to harvest or refine. And while steal production is a very energy intensive process, even cutting out that part of the cost there is other limiting factors. You'll run out of easily accessed ore fairly quickly if the demand skyrockets.

[factotum]

I think that hydrogen is the best solution, because doing 0-60 in a steam powered car will take several minutes

Er, no, that's not the case at all--Fred Marriott drove a steam-powered car at more than 120mph in 1906; see also some of the cars that Stanley (who built Marriott's car) built for normal road use. The main reason steam cars stopped being viable was simply because they got overtaken by the internal combustion engine, not because they were not viable in the first place!

[Traab]

Also, so what if steam engines dont end up being as compact or light as internal combustion? So long as we arent stuck driving humvee+ size vehicles everywhere to get around, its nothing more than a design change.

[Mando Knight]

I think that hydrogen is the best solution, because doing 0-60 in a steam powered car will take several minutes


Er, no, that's not the case at all--Fred Marriott drove a steam-powered car at more than 120mph in 1906; see also some of the cars that Stanley (who built Marriott's car) built for normal road use. The main reason steam cars stopped being viable was simply because they got overtaken by the internal combustion engine, not because they were not viable in the first place!
More specifically, steam cars were eclipsed by ICE cars when the latter's starter became safe and convenient. Steam cars may need to spend several minutes getting enough steam to do the work, but can apply all their torque as soon as they have the steam, even without a complex transmission system like an ICE vehicle needs.

The magic-hot-rocks could probably cut down on the time required to start the engine as opposed to a conventionally-fired steam engine (since you could get the rock as hot as the container could withstand and then drop it into the boiler when you start), but it would still (probably) be slower to start than an internal combustion engine.

[SiuiS]

Wanna read this story.


Well, considering that almost all powerstations in the world run on steam power at the moment, I don't think it'll affect water supplies.

As for cars powered by steam? I don't think you'd get an efficient enough conversion ratio.

A closed circuit could, though. Not sure about specifics of efficiency of the machine that would run on steam and be a closed circuit, but a contained amount of water or fluid could do it. You'd just have to accommodate for weight, and without a massive fuel tank, and without half the stuff that goes into a car, you could get it to work much easier.


It depends on how small the heat source can be to power a steam engine that can fit in a car sized package.

It also depends on the quality of the water used in the engine. During WW1 the Vickers water cooled machine gun was primarily filled with urine, since any potable water was far valuable being supplied to the soldiers.
If the engine could only take potable quality water and there was a mass switchover to steam power, then I would think there would be a potential issue.

Well, it's literally not the water/steam at question, but the heat source. You have infinite free heat, you could throw just about anything in there and it would run until it corroded the works.



That said, if the world otherwise has our level of technology, why not switch to electic cars instead? After all, the price of electricty should drop significantly after the initial outlay of setting up the power stations.

Huh. Good point.

I would think bus size (computer wise). Infinite energy doesn't mean unlimited energy; every vehicle in the country on the power grid would have the same issue as with potable water, wouldn't it? Until they built enough power factories to keep everything going forever.


Normally I'd agree with Shadow of the Sun, but if you have a literally infinite heat source that doesn't require fuel to keep it going, who cares about efficiency?

As far as water supplies go, doing this wouldn't really affect them at all. Any water used in a steam engine gets pumped into the atmosphere, where it will eventually fall as rain and thus get recycled into the environment. Water vapour is a greenhouse gas, admittedly, but I don't think it's as potent as carbon dioxide in that regard.

The main issue with a steam car would be the amount of water it would have to carry, though--the energy density you get from just heating water for pressure is considerably lower than fossil fuels, which is why you don't see steam trains around much these days!

[EDIT] Read Brother Oni's response, and I think the main problem with electric cars would be the same in the quoted scenario as it is in our world--having to carry around half a ton of batteries (which are full of toxic chemicals) just to get half the range a petrol car enjoys.

Basically.

As for electric, if all vehicles are electric, you'd be fine. Put a small infinite-heat water motor on an alternator for emergencies, and every highway would have cabling installed and charge stations.


The efficiency issue is more about the fact that steam engines are...well, very inefficient. Steam locomotives worked because the rails give them very low friction, and because the boiler can have excess water due to the fact that it's a locomotive.

I don't think you'd be able to get a steam engine good enough that the amount of water would not be prohibitive to power a car.

Now, a Stirling Engine (http://en.wikipedia.org/wiki/Stirling_engine) on the other hand...

EDIT: steam cars do exist, but they're heavier than ICE cars, and require a lot of attention from the driver to keep going.

Your stirling engine is where I went inmediately, yes. It would also be relatively trivial (compared to infinite heat) to develop a more efficient energy transfer medium. And with the unit being self contained it's much smaller because you never run out of fuel – it's like worrying about how much copper wire you need for a battery system. The steam is just the transfer medium.



Well magma typically ranges from 700-1300 C, so it can still get fairly hot.

The keychain idea implies that size is directly linked to power output, as a typical hand warmer ranges from about 57-68 C and a rock that can't get hot enough to boil water is of no use to a power plant.

With regard to the pebble in a 16 gallon fuel tank, it would heat all the water up eventually, although it would take a while due to the inefficient shape of the rock.

What is this story that you're reading anyway?

But once the water was warm, it would stay that way, or close enough that it could be reheated again quickly. With a closed circuit, you'd probably need a bar or coil, something to get more surface area though. Otherwise the cooled, condensed stuff coming back in would take too long to reheat, and would fire cylinders too slowly.

I'm seriously wondering though, why instead of cars or devices or even entire houses where everyone has their own small, non-critical unit that generates electricity, they would maintain the design that has one big building making and then distributing a lot of electricity. It doesn't even seem valid for economic reasons, just like people got a new technology and didn't think about better applications, just upgraded old methods.

A car that ran on electricity and had a stirling engine on board could work much better. You have "down time", where the car runs so much on a full tank and then needs charging before going again, but you also can get discrete units. Each motor is like, two square meters and puts out so much energy/time unit, holding a maximum of [X], and work from there. Need a mobile home? Well, two units could power a vehicle of that bulk, but three units would allow for cycling so you wouldn't need as much if any down time, and make it four units to also run amenities as well as making up for the weight of the units.

[Traab]

Would we even need power companies? I mean, how hard would it be to get a generator for your house that runs off a never ending heat source? You can already go to the nearest costco or walmart and buy a backup generator that runs off gas and will provide a decent amount of power until the fuel runs out, but with these hot rocks, it should be possible for every house and business to have its own personal power source, removing the need for power lines.

[factotum]

with these hot rocks, it should be possible for every house and business to have its own personal power source, removing the need for power lines.

Given the lower efficiency of small generating units, you'd need a lot more materials to have a generator in every home than you would to generate the same amount of power centrally, and I doubt the additional materials for the power grid would compensate for that! Also, power companies don't just supply the power, they maintain the power systems and keep them in good repair--who would do that job for all these individual generating sets in people's houses?

[Traab]

Given the lower efficiency of small generating units, you'd need a lot more materials to have a generator in every home than you would to generate the same amount of power centrally, and I doubt the additional materials for the power grid would compensate for that! Also, power companies don't just supply the power, they maintain the power systems and keep them in good repair--who would do that job for all these individual generating sets in people's houses?

An entirely new trade would be developed! Hot rock generator repairmen! In all seriousness though, I know there are a number of people out there who would just love to get off the power grid and not have to pay electric bills. It may not become the norm for everyone, but I bet a lot of people would gladly pay for one, depending on cost and size and such. I mean, not many people would willingly sacrifice half their backyard for a generator for their house, but if it would take up a reasonable amount of space, im sure they would sell like hotcakes.

[Ravens_cry]

Problem I see is market saturation. After all, if the rocks provide indefinite amounts of energy (which is only the same thing as infinite over an infinite period of time), then, aside from repairs, after awhile there will be far less people to sell them to because everyone who wants one will have one. It would be smarter, from a continued business perspective, for more centralized locations to make the electricity and then sell that to the average consumer. Far more profitable.

[Traab]

Problem I see is market saturation. After all, if the rocks provide indefinite amounts of energy (which is only the same thing as infinite over an infinite period of time), then, aside from repairs, after awhile there will be far less people to sell them to because everyone who wants one will have one. It would be smarter, from a continued business perspective, for more centralized locations to make the electricity and then sell that to the average consumer. Far more profitable.

New houses get built, new businesses open up, people want to upgrade their service because their house now has an extra 3 air conditioners it needs to handle running, generators break down over time like any appliance does, etc etc etc. There would be far fewer hot rocks sold if they only went to the power companies. A couple bigass slabs of really hot rocks and thats it for the entire city or whatever. By selling them to individual households and businesses, that produces a larger volume of need for the rocks, and far more frequent likelihood of needing replacements or new ones sold due to expansion.

[Ravens_cry]

Ah, but you aren't selling the rocks, you are selling the power. Even with new construction, compare that to selling electricity every day to all those buildings and homes, and hydrogen to all those cars with your only costs being repairs, maintenance and employees. There is also the convenience factor. Anyone in the real world could go off the grid if they wanted to, potentially cheaper long term too, but people still pay the gas man and the power company. A few boilers blowing on home units would be more than enough to convince people to leave hot rock power generation to the engineers.

[Traab]

Well obviously the electric companies wouldnt want people producing their own, but in this case, at least in the world where these rocks exist, the makers wouldnt have any problem I can think of directly selling to manufacturers willing to make household sized power generators. The way I sort of envision it, it would be like getting central air installed, only easier because no duct work needed. Just replace the connection from the power line with the connection to the prefab generator and turn it on.

[Ravens_cry]

Well obviously the electric companies wouldnt want people producing their own, but in this case, at least in the world where these rocks exist, the makers wouldnt have any problem I can think of directly selling to manufacturers willing to make household sized power generators. The way I sort of envision it, it would be like getting central air installed, only easier because no duct work needed. Just replace the connection from the power line with the connection to the prefab generator and turn it on.
The hot rock makers would be the power companies.
One area I would really like to see hot rocks would be in space exploration. Imagine, Hot Rock NERVA (http://en.wikipedia.org/wiki/NERVA)! Hmm, HRERVA? Bad acronym aside, it would have all all the advantages of nuclear propulsion, high ISP, and be even better because you wouldn't need all that heavy shielding, nor would you have to worry about it coming down on your head in a bunch of lovely radioactive material.
Yes, this has happened. (http://en.wikipedia.org/wiki/Kosmos_954)

[Mando Knight]

What would be ideal for a closed-circuit heat engine, though, would be if there were coldrocks that were counterparts to the hotrocks: a rock that could absorb an infinite amount of energy without changing temperature (essentially, an ideal heat sink to mirror the hotrock's ideal high-temp source).

Due to material requirements, you couldn't use an absolute-zero coldrock any more than you could use an eleventy-billion K hotrock, and even more "reasonable" temperature differences would need to be carefully weighed against the possibility of thermally-accelerated fatigue...

[factotum]

What would be ideal for a closed-circuit heat engine, though, would be if there were coldrocks that were counterparts to the hotrocks: a rock that could absorb an infinite amount of energy without changing temperature (essentially, an ideal heat sink to mirror the hotrock's ideal high-temp source).

I'm pretty sure the OP said that the hot rock temperature could be set at any level. Even if we assume that means "any level above 500C", a 500C hot rock is still darned cool compared to a 3000C one--maybe that would be enough?

[Shadow of the Sun]

I'm pretty sure the OP said that the hot rock temperature could be set at any level. Even if we assume that means "any level above 500C", a 500C hot rock is still darned cool compared to a 3000C one--maybe that would be enough?

At that point, it's best just having a decent cooling vent to expel the heat that's transferred.

[Traab]

I'm pretty sure the OP said that the hot rock temperature could be set at any level. Even if we assume that means "any level above 500C", a 500C hot rock is still darned cool compared to a 3000C one--maybe that would be enough?

Its actually pretty much any level above room temp. Like I said, at one point they were making hand warmers, and earlier they planned to make arctic gear for the military. Jackets and pants and such with hot rocks in them to provide warmth without being stupidly bulky. So im fairly sure that means they can be set at under 100F. And the rocks just radiate that specific temp, so I fail to see how a rock set at 100f could do anymore as a heat sink than a chamber without a rock at all.

[factotum]

I was assuming that the rocks would attempt to transfer heat to or from their surroundings so the environment would match their own temperature--it would seem odd if the rocks could heat the environment, but not cool it, surely? It's just a heat transfer in a different direction!

[Traab]

I was assuming that the rocks would attempt to transfer heat to or from their surroundings so the environment would match their own temperature--it would seem odd if the rocks could heat the environment, but not cool it, surely? It's just a heat transfer in a different direction!

All they do is constantly radiate heat. The only difference between a hot rock and say, a bit of red hot metal at the same temp, is that if you drop both into a tank of water, the metal will cool down while the stone keeps radiating the same temp. If you stick a hot rock into say, a kiln at a higher temp than the rock is set at, it wont magically cool down the kiln to match. Will the rock heat up further? That isnt covered, but it wont reduce the temp of the kiln.

[factotum]

Will the rock heat up further? That isnt covered, but it wont reduce the temp of the kiln.

Way I see it, there are only two ways this can work (albeit these things break laws of physics like they're going out of fashion, so your mileage may vary):

a) The "set" temperature of the rock is a minimum temperature it will return to no matter what happens, but it *can* be heated above that temperature by external means.

b) The rock stays at its set temperature no matter what. In this case, simple thermodynamics indicates that, if the atmosphere around the rock is hotter than the set temperature, the rock *must* stay cooler than it and will thus act to cool the area around it.

(b) makes a lot more logical sense to me than (a) does!

[Knaight]

The hot rock makers would be the power companies.

Which are competing. Any one of them (particularly if they are already beginning to go under) could switch to rock production and sale, and hit up that market. It would work very well for them, even if the power companies as a whole would lose money and power long term.

[Ravens_cry]

Which are competing. Any one of them (particularly if they are already beginning to go under) could switch to rock production and sale, and hit up that market. It would work very well for them, even if the power companies as a whole would lose money and power long term.
On a small scale, like generators for places of the grid.
Running a steam generator is a complicated business though. Most people would prefer power from the power company I shouldn't wonder.

[Traab]

On a small scale, like generators for places of the grid.
Running a steam generator is a complicated business though. Most people would prefer power from the power company I shouldn't wonder.

Maybe, but I bet they would get simplified greatly for common usage if they became viable on this level. I mean, we dont even have to have the slightest idea on how an internal combustion engine functions in order to drive a car. We just have to know which pedals do what. And if they break down we take them to a mechanic who knows everything about them and can fix them.

Also, I just need to reiterate, the power companies have no control over hot rock production or distribution. They just got the first large scale use because it was the easiest thing to adapt. One heat source gets yanked out, and shaped hot rocks get plopped in. (Yes im sure there was more to it than that, but you get my drift) I really doubt the dragons would give a damn about pissing off the power companies, considering they are already pissing off OPEC by massively cutting oil usage world wide. So at the same time selling hotrocks to manufacturers for small scale generators for homes and businesses would just be another revenue stream for them.

Oh, and factotum, I think a is the most likely result. If I pop a heating element into a oven and turn them both on but the heating element is say, 100 degrees lower. The stove will still hit its set temp, and the element likely will too. But then when i turn off the stove, the heating element will eventually return to its set temp. It wont magically make the oven colder somehow.

[factotum]

Oh, and factotum, I think a is the most likely result. If I pop a heating element into a oven and turn them both on but the heating element is say, 100 degrees lower. The stove will still hit its set temp, and the element likely will too. But then when i turn off the stove, the heating element will eventually return to its set temp. It wont magically make the oven colder somehow.

Yeah, but we're talking about things that don't (and can't) exist in the real world here. I guess the only answer we'll get about how they work is if the question arises in the book series the things come from!

[Traab]

Yeah, but we're talking about things that don't (and can't) exist in the real world here. I guess the only answer we'll get about how they work is if the question arises in the book series the things come from!

Probably right, I honestly have no idea how many laws and theories of physics those rocks break. The only testing that they really brought up on how they work was more to test how long they last without losing temp. So far its looking like indefinitely. Makes sense though, the story was more about harry trying to convince the world that dragons arent dumb beasts and deserve the same rights as anyone else and the political issues that arose. The hot rocks were mostly used as a method of getting their foot in the door. "Hey Britain. How would you like to reduce your oil usage by 60% over the next couple decades for cheap? All you have to do is admit that these clearly intelligent dragons are people with the same rights and privileges as you have."

[Ravens_cry]

Might be interesting trying to convince the dragons that those crunchy things that taste good with ketchup are not to be eaten.
But man, we could make a starship with these things!

[factotum]

But man, we could make a starship with these things!

Really? How? I can see being able to make a clean version of a nuclear engine using a really, really hot rock, but that does not a starship make...

[Mando Knight]

Really? How? I can see being able to make a clean version of a nuclear engine using a really, really hot rock, but that does not a starship make...

Not just out of them, but the engine and fuel are generally the only things holding us back from making more and larger spacecraft. A clean NERVA (http://en.wikipedia.org/wiki/NERVA) using hotrocks would be fairly simple.

[Ravens_cry]

Really? How? I can see being able to make a clean version of a nuclear engine using a really, really hot rock, but that does not a starship make...
As I mentioned earlier and Mando Knight just mentioned, a non nuclear NERVA would be one way, though that's more interplanetary. However, hot rocks can go literally as hot as needed. As long as you have enough cooling to keep the rest of the ship from melting, you could make a torchship (http://www.projectrho.com/public_html/rocket/torchships.php)! Pure photon thrust! Now that's ISP! Just don't point that thing at anything you care about, OK? It isn't called a torchship for nothing.

[factotum]

Right. How would one actually *stop* the thrust so you could do something useful in such a vessel? And the whole "cooling" thing is quite important too...unless the hot rocks *do* work like I suggested earlier, so you could use cooler ones to shield the really, really hot one?

[Ravens_cry]

Right. How would one actually *stop* the thrust so you could do something useful in such a vessel? And the whole "cooling" thing is quite important too...unless the hot rocks *do* work like I suggested earlier, so you could use cooler ones to shield the really, really hot one?
If the 'colder hot rocks sheild hotter rocks' work, you just enclose the engine in a shell of cool hot rocks.
For in-system, a better system might be something like NERVA. It can give a even higher ISP than NERVA as hot rocks can go to higher temps without melting, unlike fuel elements, while still giving thrusts that are much more comparable to chemical rockets.

[Willis888]

You would not need, and probably not want cars that have internal steam engines.

Steam powered engines have a low thrust to weight ratio and are therefore inefficient as a means of propelling a car.

However, a hypothetical society that had an unlimited supply of heat energy could convert it into other forms of energy.

The heat can be transformed into electricity or liquid fuel, and either of those are better options for cars.

[Ravens_cry]

You would not need, and probably not want cars that have internal steam engines.

Steam powered engines have a low thrust to weight ratio and are therefore inefficient as a means of propelling a car.

Thrust alone is a terrible way to run a car anyway.:smallconfused:

[factotum]

The heat can be transformed into electricity or liquid fuel, and either of those are better options for cars.

Electricity certainly isn't, for the reasons already mentioned several times--namely, that the problems of batteries being made of horribly toxic materials and long charge times aren't going to go away just because you're generating your electricity more cleanly! More interested in the liquid fuel thing--how exactly would you go about doing that?

[thubby]

Electricity certainly isn't, for the reasons already mentioned several times--namely, that the problems of batteries being made of horribly toxic materials and long charge times aren't going to go away just because you're generating your electricity more cleanly! More interested in the liquid fuel thing--how exactly would you go about doing that?

you just need a store of energy. hydrogen like I mentioned, or something a bit more exotic.
fundamentally anything that can be created with thermal energy and also produce mechanical energy.

thought just occurred to me, couldn't you make these cars work like reverse air conditioning? refrigerants have better transfer rates than water so you could probably use less of it.

[Shadow of the Sun]

you just need a store of energy. hydrogen like I mentioned, or something a bit more exotic.
fundamentally anything that can be created with thermal energy and also produce mechanical energy.

thought just occurred to me, couldn't you make these cars work like reverse air conditioning? refrigerants have better transfer rates than water so you could probably use less of it.

Ala, a stirling engine. Which I think I mentioned in the second post.

[factotum]

you just need a store of energy. hydrogen like I mentioned

Hydrogen has its own issues--even when liquified it has a much lower energy density than fossil fuels, and you really wouldn't want to be using liquified hydrogen in a car; it's too difficult to handle and store. Pressurised hydrogen would have an even lower energy density and its own attendant health and safety issues (imagine what happens if the filling nozzle becomes detached while you're pumping hydrogen at several hundred atmosphere pressure into your car!). What you really need is a fuel that's liquid at room temperature, and I don't know of any way you could easily produce such a thing--Willis888 suggested there *was* such a way, which is why I was asking him what it was.

[tyckspoon]

More interested in the liquid fuel thing--how exactly would you go about doing that?

Heat is a major component of processes used to generate things like ethanol, biodiesel, and other organically-derived oils and gases that have potential fuel uses. One of the major obstacles to larger use of them today is that the required energy input is kind of expensive, especially compared to petroleum-derived fuel; hot rocks would reduce or remove that barrier, either in the form of cheaper power from rock-fired powerplants or directly using the rocks as the heat source in the procedure.

You'd still have to do some altering of the infrastructure and possibly the vehicles using it - ethanol is probably the closest fuel-alternative to mass-production feasibility, and it's nowhere near as energy-dense as gasoline. That means you either pack extra fuel on your vehicle (much, much larger and heavier fuel tanks or carrying around some 'gas' cans of spare fuel), rearrange fueling stations so they're closer together, or give up on using the substitute fuel for long-distance traveling.

(Also, regarding the concerns about water usage in this thread - the described hot rocks would also make desalination and water purification via distillation processes much more economical, potentially opening up the oceans themselves as at least an industrial water source if not a human-potable source.)

[TuggyNE]

Oh, and factotum, I think a is the most likely result. If I pop a heating element into a oven and turn them both on but the heating element is say, 100 degrees lower. The stove will still hit its set temp, and the element likely will too. But then when i turn off the stove, the heating element will eventually return to its set temp. It wont magically make the oven colder somehow.

A heating element is not comparable, since it does not magically maintain a minimum temperature any more than it does a maximum. Rather, it has a certain rate of heat production, and a regulator system to produce heat when below the minimum temperature; the result is that heat is produced and then distributed, and as heat escapes the system more is produced to replace it. However, if you continually poured fresh liquid nitrogen on the heating element, it would produce heat as fast as possible but would still be far below freezing. Similarly, if you broke the regulator in a way that left the element on, it would continue heating up to a very high temperature, or until it melted or otherwise failed.

The hot rocks are quite different, though, since they have no regulator at all, and no maximum capacity for heat transfer: they simply are a certain temperature, and everything around them shifts heat around accordingly at the maximum rate possible for those materials at that temperature. It's physically impossible for a hot rock to heat materials beyond its set point. Logically, then, heat can flow into it (and vanish within its boundless capacity) just the same as it can flow out.

[Ravens_cry]

t would certainly make things more interesting. For the starship, enclosing the million kelvin hot rock in a shell of much cooler hot rock would make it a lot easier to handle.

[Traab]

t would certainly make things more interesting. For the starship, enclosing the million kelvin hot rock in a shell of much cooler hot rock would make it a lot easier to handle.

Of course, you would have to find a material you could heat up that far without it vaporizing into particles so tiny you couldnt spot them with an electron microscope first.

On a related note, how hot would it have to be to reduce a soviet ww2 era tank to a 4 foot high pile of slag in under 10 seconds of exposure? Ballpark estimate.

[Ravens_cry]

Of course, you would have to find a material you could heat up that far without it vaporizing into particles so tiny you couldnt spot them with an electron microscope first.

In other words, a flame.