Writing a story and have questions about coal & carbon

[8BitGore]

Starting a story about a world without electricity or vehicles. Think post apocalyptic world without an apocalypse. Going back to nature. I already know how to get rid of natural gas and oil, my dilemma is coal.

We use it to power nearly 40% of America and my understanding is that carbon is the property in coal that is used to produce heat / electricity? I realize carbon is a basis of life so is it possible to have coal that couldn't be turned into energy?

 

[Fuzzwood]

As long as you can burn something, there is your energy right there. Coal is flammable. Incidentally, so is wood and peat.

[Ophiolite]

As long as you can burn something, there is your energy right there. Coal is flammable. Incidentally, so is wood and peat.

And diamond.

[Elite Engineer]

Technically if the coal was wet, it couldn't be really used efficiently, by way of 19th century standards..thats the only way I think you "couldn't" turn it into energy. But yea like Fuzzwood said, there are altneratives

 

to coal such as wood, etc. But who said you have to have high-tech to produce efficient energy? Just build a stirling engine, using wood as the heat source...first built in the mid-19th century.

 

 

~ee

[Enthalpy]

[...] carbon is the property in coal that is used to produce heat [...]

 

Carbon and hydrogen. Coal, even anthracite, is a hydrocarbon. That's why one can light it, while insisting with the lighter under a chunk of graphite won't light it.

 

Anthracite contains 92-98% carbon

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

which is as much as Pentacene C₂₂H₁₄, obviously called a hydrocarbon with its 95% C

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

[8BitGore]

Great, thank you!. So the hydrogen in Coal is what makes it burn?

Thanks for the reply!

I understand that, but it appears that the U.S. didn't build it's infrastructure to run off of these alternatives. Do we have machines that convert heat from wood into electricity? If coal were to disappear off the face of the earth tomorrow would we change to wood to power our factories, power our homes?

[John Cuthber]

You say

"I already know how to get rid of natural gas and oil, my dilemma is coal."

How?

We could do without coal- as long as we had plenty of oil.

Similarly, if we had coal we can do without oil.

The real problem is that we need energy

 

Incidentally, Enthalpy seems unaware that you can burn coke, made by heating coal until practically all the hydrogen (among other things) has been driven out leaving essentially carbon (and some ash). The other, more volatile, materials make coal easier to light but it burns without them.

 

Enthalpy, did you work at Windscale in 1957?

Edited September 26, 2014 by John Cuthber

[Enthalpy]

So the hydrogen in coal is what makes it burn?

 

Both hydrogen and carbon burn in coal, but carbon alone doesn't sustain a flame.

Incidentally, Enthalpy seems unaware that you can burn coke, made by heating coal until practically all the hydrogen (among other things) has been driven out leaving essentially carbon (and some ash). The other, more volatile, materials make coal easier to light but it burns without them.

 

Enthalpy, did you work at Windscale in 1957?

 

Coke is pyrolyzed coal (or petrol) but it's not graphite. It's one possible input material to produce graphite parts or graphite matrices after a much longer and harder heat processing.

 

Graphite doesn't sustain a flame. All my attempts with massive graphite parts consistently showed a lack of ignition, even with an acetylene burner and due patience. That's why it's used as a refractory coating in furnaces, including in air environment.

 

I once brought graphite fibres orange to yellow hot when I accelerated the polymerization of an epoxy matrix on graphite fibres. The points of electric contact where I injected about 1kW in the locally nake fibres were bad as usual, these points sort of caught fire locally but extinguished themselves spontaneously as soon as the current had to seek a different path. This was despite fibres ease fires much.

 

Graphite didn't burn at Windscale, according to Wiki

http://en.wikipedia.org/wiki/Windscale_fire#Wigner_energy

the damage to graphite was limited and localized around the fuel rods. But if you saw the graphite after the fire, tell us!

[John Cuthber]

Well, given that coke is mainly made of carbon, I guess that, since you don't believe it's graphite, you must think it's diamond or buckyballs.

Can I sell you some?

 

Anyway, if you think graphite does not burn, perhaps you should warn these people that they are wrong.

http://www.sciencedirect.com/science/article/pii/S0010218097002149

 

And this lot

http://link.springer.com/article/10.1007%2FBF00853982

and rather a lot of others, as you can confirm with a quick search of the web.

[swansont]

How married are you to the idea of this being humans on present-day earth, sans coal? Consider an alternate timeline where humans arose much earlier in the evolutionary timeline (the Chicxulub bolide impact or its equivalent was earlier, perhaps?), so there wasn't much in the way of fossil fuels because a few hundred million years' worth of animal and plant matter never got put into the ground. Any macroscopic amounts of retrievable oil and coal that was produced would be used up.

[Enthalpy]

Well, given that coke is mainly made of carbon, I guess that, since you don't believe it's graphite, you must think it's diamond or buckyballs.

Can I sell you some?

 

Anyway, if you think graphite does not burn, perhaps you should warn these people that they are wrong. [...]

 

It's not only a belief, it's observation. Graphite doesn't burn. One more example are brakes for race cars, which were made of carbon before SiC. Use put them orange or yellow hot in air but they didn't catch fire, with or without speed afterwards. In addition to ovens that use graphite as refractory bricks.

 

"Burn" can mean several things. If you have already a source of heat, and preferably in oxygen instead of air, then graphite will combine slowly with the oxygen and disappear - a bit faster than in hydrogen for instance. This is not the same thing as burning without aid, in air at normal temperature, which normal people call "burn".

 

For instance soot from an acetylene burner is essentially graphite, and despite being really hot, in tiny chips, and having oxygen available as soon as it mixes with air, it doesn't burn and stays as soot.

 

From the clear and ubiquitous evidence, I won't change my mind.

 

-----

 

Graphite is produced from carbon-rich substances like tar or coke after many hours or days at a very high temperature. Manufacturers make this effort because coke is not graphite. Coke still needs to release volatiles and to rearrange.

[swansont]

 

It's not only a belief, it's observation. Graphite doesn't burn. One more example are brakes for race cars, which were made of carbon before SiC. Use put them orange or yellow hot in air but they didn't catch fire, with or without speed afterwards. In addition to ovens that use graphite as refractory bricks.

 

"Burn" can mean several things. If you have already a source of heat, and preferably in oxygen instead of air, then graphite will combine slowly with the oxygen and disappear - a bit faster than in hydrogen for instance. This is not the same thing as burning without aid, in air at normal temperature, which normal people call "burn".

 

For instance soot from an acetylene burner is essentially graphite, and despite being really hot, in tiny chips, and having oxygen available as soon as it mixes with air, it doesn't burn and stays as soot.

 

From the clear and ubiquitous evidence, I won't change my mind.

 

-----

 

Graphite is produced from carbon-rich substances like tar or coke after many hours or days at a very high temperature. Manufacturers make this effort because coke is not graphite. Coke still needs to release volatiles and to rearrange.

 

Difficult to burn is not the same as "doesn't burn". As it's an obvious concern for graphite-moderated reactors, it's been studied. Nuclear-grade graphite burns but only in a narrow range of conditions

http://www.osti.gov/scitech/biblio/6102304

 

Add impurities and apparently it's easier.

[John Cuthber]

OK, so I have a choice.

I can believe that the carbon atoms in a lump of coal are not essentially joined in hexagonal rings and stacked in layers- even though things like the XRD patterns show that they are- and that those peer reviewed papers about burning graphite are wrong.

Or not.

 

Not the most difficult decision I have ever made.

I guess other reading this will come to their own conclusion.

[Enthalpy]

At Windscale the conditions to ignite graphite would have been perfect: air, strong heat from an other source - but it didn't burn.

Soot in an acetylene flame would have even better conditions but it doesn't burn.

Oven designers use graphite as walls because it doesn't burn.

I tried hard to light graphite rods with an acetylene burner and graphite doesn't burn.

Not even graphite lubricating powder or fibres burn. Easy conclusion.

 

The previously linked paper about "burning" graphite puts it in oxygen heated by a distinct source. With a separate heat source, graphite burns in hydrogen as well. Or in vacuum if you wish; I wouldn't call it burn, but sublimation is nearly as quick.

 

Small crystals is disorder give the same X-rays diffraction pattern as a single crystal. Though, this doesn't make the same material, especially for the combustion properties. That's why graphite manufacturers spend hours and days at big heat to transform coke or tar into graphite; they regularly impregnate the parts with more tar during the process.

 

One indication: coke's density is 1800-1950kg/m³, graphite has 2090-2230kg/m³, revealing different materials. The hydrocarbon anthracite, which has the least hydrogen among coals, has 1450-1750kg/m³.