A new source for ethanol: Coal

[Dilb]

Ya.. well-
If you are going to charge the planting, growing, harvesting and processing of biologicals (corn, wheat, barley(yum!)) against their ethanol yield, it seems only fair to charge the digging, blasting, hauling, elevating, crushing, processing, and environmental/human resource costs against coal.
I'm kinda picky that way.

That's not what I'm getting at, though. The article doesn't make any sense when they say

Right now, ethanol is primarily made out of corn or sugarcane. It's expensive and time-consuming to make, a problem. A gallon of ethanol derived from plant matter also only has around two-thirds of the energy content of a gallon of gas. A gallon of ethanol derived from coal-created synthetic gases could provide more energy.

"You could avoid an energy penalty" with coal ethanol, Spivey said.

Either it's complete nonsense, as the ethanol has the same energy in either case; or it's a poorly worded way of saying "We'll produce energy with ethanol from coal, unlike with ethanol from corn". First, that would be incorrect, as growing ethanol from corn does produce energy. Second, they're counting the energy of what goes into producing corn ethanol, but they aren't counting the energy that goes into coal ethanol: namely, coal.

For every MJ of oil that is converted into corn, you get something like 1.3 MJ of ethanol. For every MJ of coal converted, you get something like 0.5 MJ of ethanol (something less than one, anyway). Claiming coal "could provide more energy" or "You could avoid an energy penalty" is only true if you ignore the MJ of coal that goes into it. As burning coal is unpopular, they can claim "since we couldn't just burn the coal, there's no opportunity cost to using it, so we don't have to account for that energy".

If I believed CO2 sequestration will work, it would actually be a reasonable argument.

 

[Dilb]

But if its not about CO2 emissions, why not just find a way to convert coal to gasoline? It basically needs more H2, but you can get there.

See mhaze's post.

 

[joobz]

errr...

Fuel lifecycle analyses are complicated. An intellectually honest analysis/comparison will try to compare like with like. So, you have to define what you mean by "well-to-wheels," in either process. Part of this is determining your basis of comparison. The most strictly honest is KJ of process energy per KJ of energy delivered at the pump. A useful measure is KJ of process energy per Km driven, because you may get some benefit like enhanced combustion.

When looking at energy efficiency, it can be found that conventional oil and gas gives about 0.3 KJ process/KJ pump, whereas ethanol from grains (avg. wheat and corn) might be about 0.75 KJ process/KJ pump. Both processes are energy efficient (despite the outright lies you might have heard about ethanol), but clearly, conventional sources are 'cheaper.'

If a cheap, clean coal conversion can be found, then you'd be laughing! This is not necessarily woo. EtOH is made from C, H and O (empirical C₂H₆O), all of which are found in CO and H₂.

ETA: phildonnia, CO2 emissions are a separate (if not totally unrelated) issue from energy economics. It just depends what your policy makers (or voting public) are prioritizing...

Very nice summary, Jimbo07. I fully agree, and would like to add that you need to also account for other product formation during processes. If, for instance, one method has "waste streams" that can actually be sold for other uses, this process has a much higher usable yield that wouldn't be accounted for in the kJ comparison. This isn't just better in terms of economics for the company, but is the industrial analog to using the whole buffalo and not just the meat.

 

[rwguinn]

That's not what I'm getting at, though. The article doesn't make any sense when they say


Either it's complete nonsense, as the ethanol has the same energy in either case; or it's a poorly worded way of saying "We'll produce energy with ethanol from coal, unlike with ethanol from corn". First, that would be incorrect, as growing ethanol from corn does produce energy. Second, they're counting the energy of what goes into producing corn ethanol, but they aren't counting the energy that goes into coal ethanol: namely, coal.

Yeah-- I ignored that stuff since it is obviously complete hogwash. Like a pound of lead is heavier than a pound of feathers.

For every MJ of oil that is converted into corn, you get something like 1.3 MJ of ethanol. For every MJ of coal converted, you get something like 0.5 MJ of ethanol (something less than one, anyway). Claiming coal "could provide more energy" or "You could avoid an energy penalty" is only true if you ignore the MJ of coal that goes into it. As burning coal is unpopular, they can claim "since we couldn't just burn the coal, there's no opportunity cost to using it, so we don't have to account for that energy".

If I believed CO2 sequestration will work, it would actually be a reasonable argument.

There is something terribly wrong and inconsistent in that argument, but I'm not sure how to pinpoint it. It doesn't pass the "smell test"---Like they would contine to mine it when they cannot use it...

 

[neutrino_cannon]

So, basically this is a different variant of coal gasification, which was used on a large scale by Nazi Germany in WWII, correct?

It's hardly news, although the desired end product had been diesel in the past.

And, if I reach into the dark recesses of memory, the process is rarely cost-efficient in a free market with wide scale access to petroleum.

 

[MRC_Hans]

It may not be about CO2 emissions, but unfortunately (for them) the idea of using ethanol in the first place IS about CO2 emissions. There are very few sensible reasons for using ethanol for fuel, except to reduce CO2 emissions. The only other one really being lack of adequate access to fossil fuels (like in the case of Brazil), but if you have coal ....

Of course, coal is not very practical for use in the transportation sector (although Benz's first internal combustion engine burned coal dust), but it can be converted to gasoline (Germany did that during WW2).

In a scenario where we are running out of oil, converting coal to liquid fuels could buy us some time, of course.

Hans

 

[Dilb]

It may not be about CO2 emissions, but unfortunately (for them) the idea of using ethanol in the first place IS about CO2 emissions. There are very few sensible reasons for using ethanol for fuel, except to reduce CO2 emissions. The only other one really being lack of adequate access to fossil fuels (like in the case of Brazil), but if you have coal ....

Ethanol as fuel has some pretty good properties. Compared to gasoline it has a higher octane rating, it's cleaner burning, it's less toxic (although maybe I shouldn't count this, as it would almost certainly be methylated), and it's not carcinogenic (and maybe not this either, if they dehydrate ethanol with benzene). It even works in existing engines with a few modifications. None of these justify the expense of producing ethanol, but they're still nice properties.

 

[joobz]

Ethanol as fuel has some pretty good properties. Compared to gasoline it has a higher octane rating, it's cleaner burning, it's less toxic (although maybe I shouldn't count this, as it would almost certainly be methylated), and it's not carcinogenic (and maybe not this either, if they dehydrate ethanol with benzene). It even works in existing engines with a few modifications. None of these justify the expense of producing ethanol, but they're still nice properties.

yeah, but it's highly solvent like on seals. It's fully miscible with water (and can absorb water from the atmosphere) which could cause problems in systems that aren't well sealed. and cleaner burning isn't really an issue since cars have a catcon. Also, it being such a short chain and already partially oxidized, it just doesn't have the same amount of energy as gasoline.


My money is for Deisel (in particular biodesiel). It is much safer to use, has a much higher energy denisty, modern engines are extremely clean, and doesn't require as much processessing. The only concern is the sulfur content, but this has already been decreased.

 

[Hindmost]

yeah, but it's highly solvent like on seals. It's fully miscible with water (and can absorb water from the atmosphere) which could cause problems in systems that aren't well sealed. and cleaner burning isn't really an issue since cars have a catcon. Also, it being such a short chain and already partially oxidized, it just doesn't have the same amount of energy as gasoline.

The water absorbtion problem will mean that ethanol can't be pumped through existing pipe systems and will have to be trucked around...certainly a problem when diesel trucks will be required for transport.

My money is for Deisel (in particular biodesiel). It is much safer to use, has a much higher energy denisty, modern engines are extremely clean, and doesn't require as much processessing. The only concern is the sulfur content, but this has already been decreased.

Biodiesel is fine, however, the amount of oil produced that can be used for biodiesel is limited. It does give the same type of problems with corn and ethanol as it is difficult to produce in significant quantities. The US uses about 50-60 billion gallons of diesel for transportation each year. Biodiesel can probably contribute about 5 to 10%. I would venture to say other countries will have similar issues.

glenn