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And on that subject

Let's Burn Coal To Refine Ethanol!

Late last year in Goldfield, Iowa, a refinery began pumping out a stream of ethanol, which supporters call the clean, renewable fuel of the future.

    There's just one twist: The plant is burning 300 tons of coal a day to turn corn into ethanol - the first US plant of its kind to use coal instead of cleaner natural gas.

    An hour south of Goldfield, another coal-fired ethanol plant is under construction in Nevada, Iowa. At least three other such refineries are being built in Montana, North Dakota, and Minnesota.

    The trend, which is expected to continue, has left even some ethanol boosters scratching their heads. Should coal become a standard for 30 to 40 ethanol plants under construction - and 150 others on the drawing boards - it would undermine the environmental reasoning for switching to ethanol in the first place, environmentalists say.


The reason for the shift is purely economic. Natural gas has long been the ethanol industry's fuel of choice. But with natural gas prices soaring, talk of coal power for new ethanol plants and retrofitting existing refineries for coal is growing, observers say.

    "It just made great economic sense to use coal," says Brad Davis, general manager of the Gold-Eagle Cooperative that manages the Corn LP plant, which is farmer and investor owned. "Clean coal" technology, he adds, helps the Goldfield refinery easily meet pollution limits - and coal power saves millions in fuel costs.

    Yet even the nearly clear vapor from the refinery contains as much as double the carbon emissions of a refinery using natural gas, climate experts say.

Notice that the article authors don't even stray near the question of whether the energy in 300 tonne of coal  exceeds the stored energy in the ethanol produced by the plant per diem.  But we know the game has to be net-negative as a whole, because of the Three Laws (no, not robotics, thermodynamics).  Now this is an unplanned improvised riff, so bear with me (and feel free to yomp in with calculations, etc)...

Let's understand something very basic here:  Entropy is Not Mocked.  It takes a certain number of calories H (heat) to make a certain number of calories' worth E of ethanol, out of a certain number of calories R (raw) cane or corn or any other sugar-rich source material.  We know that E will always be less than H+R.  In severe cases, E may even be less than H!  [I don't know that this is the case for the operations in question since the article slithers past this point, but it is the case for petro-intensive farming in general.] Supposing for a moment that we do get less energy out in the ethanol form than we burned in the coal form, then it would have been more efficient just to burn the coal in the cars.  (This might have more negative implications for particulate emissions control, but I am talking only about energy math here).

We will also get less calories out in ethanol per unit feedstock than we put in (in raw feedstock form), because some of the feedstock will be waste;  but the output product will be denser.  [If you really want your head to hurt, consider that the average calorie of high-sugar factory farmed corn has already cost iirc 7 to 10 fossil calories to grow by the time it is cut down and hauled off -- using fossil fuel -- to the fossil-fuel-powered processing plant.  So even if 300 tonne of coal in a day produces the energy equivalent, stored as ethanol, of more than 300 tonne of coal, the corn that was processed into the feedstock was net-negative EROEI to start with.  I think we went through some of this math on a thread long, long ago.]

Here's a way I've been thinking about the problem.  This isn't a finished POV but a kind of cartoon that I keep [NPI] trying to refine...

This game is all about energy density, and the only way to achieve high energy density is time plus pressure (and usually heat).  What coal and petroleum really are, is biotic feedstock plus aeons of time plus aeons of pressure, producing a high energy density which we then make even higher by refining processes which require more heat/pressure cleverly applied.  

So what we are trying to to is to compress time (i.e. energy) in the same way we do with a spring trap or crossbow;  we spend N minutes winding the thing up and then all that invested energy is released in N/X minutes where X is a very big number.  [A a lever or winch works the other way around, extending the time needed to move the weight and thus reducing the calories expended per second -- time expansion, lower energy density aka lower burn rate.]

The private auto, the jet aircraft, and the planing heavy vessel are the ultimate worst case for fuelling, because they require high energy density (high burn rate), which is the costliest thing to achieve in a fuel.  They work only by releasing very large amounts of energy very quickly and keeping up this high burn rate for extended periods.  Thus they require the most grotesque conversion factors from raw (feedstock) calories in to calories out.    [and the reason they do this is not only because of the physical inefficiencies of internal combustion and excessive carcass weight, but because we insist on using them for extreme time compression, i.e. extremely high speeds.]

We have traditionally got this staggering conversion factor by looting geological/evolutionary time, i.e. spending, in a scant century or two, the fossil wealth "wound up" out of biotic processes plus sunlight (heat) plus pressure plus geothermal heat plus aeons of time.

If we now try to produce this same energy density or burn rate using immediate biotic sources, we run into a little problem -- a time travel problem as it were:  a normal growing season doesn't deposit that much energy in a vegetable crop.  Our desired burn rate is grotesquely disproportionate to the growth rate of biotic sources, whether vegetable or animal -- you couldn't drive around carrying the amount of raw feedstock needed to produce the calories to keep the vehicle moving.  So we have to invest a lot of heat/pressure (i.e. energy) to provide even a feeble approximation of the time compression we want.  In other words, burn a lot of coal (or something else fairly dense) to make ethanol;  and burn a lot of fossil fuel in artificial soil enrichments and fossil-powered factory farm equipment to force a higher-than-natural yield rate, to wrench as many calories per acre as we can from depleted soil.  (Again trying to optimise density, not overall EROEI).

Heinberg once wrote in a whimsical "letter from the future" (in which he affected to look back from a life after the oil peak, and write to his real contemporaries today, me and you):

At first, most people thought the shortages could be solved with "technology." However, in retrospect that's quite ludicrous. After all, their modern gadgetry had been invented to use a temporary abundance of energy. It didn't produce energy.  [...]  With the exhaustion of fossil fuels, no technology could have maintained the way of life that people had gotten used to. But it took quite a while for many to realize that. Their pathetic faith in technology turned out to be almost religious in character, as though their gadgets were votive objects connecting them with an invisible but omnipotent god capable of overturning the laws of thermodynamics.  [boldface mine]

And here's the rub.  We don't produce energy. (Nor can we "produce" time.)   There are only three processes that produce energy:  sunlight striking the surface of the planet, the thermal activity of the molten core, and the instability of certain isotopes found in the crust [and many an astrophysicist would scoff at this and say that these things no more produce energy than a Duracell battery -- they merely release, over time, the tremendous initial energy of the Big Bang, the original Wound Up Spring].  What we do is harvest or concentrate energy -- what all life processes do, in fact.

We (humans) have a persistent and aggravated history of overharvesting stored energy, that is, consuming biotic energy resources at a rate that exceeds their regeneration or replacement rate -- whether this be for immediate alimentary needs or for more sophisticated applications like cooking, heating, clothing, etc.  We have a history of looting the stored biotic wealth of topsoil, for example (formed by millennia of forestation) in an extractive mode so as to reap exaggerated harvests from it for a limited time -- depleting it so severely that after the boom period is over, our return on labour invested diminishes rapidly and we have to fall back through a (usually pretty quick) series of devolving crops and practises.   This fallback and devolution is touched on by Jerome in the article;  a frantic spiral downwards from one to another apparently cheaper (slower, less dense) substitute until either equilibrium is restored, or desertification and die-off or migration result.

One end product of this kind of liquidation in an agrarian culture is an arid scrubby biome, xericultivated, with frugal animals like sheep and goats and chickens/rabbits being farmed, and mules or donkeys used for transport, rather than extravagant animals like beef cattle and heavy horses.  With concomitant changes in diet and social organisation a stable human population can live rewarding lives even in such a degraded biome.

The fossil fuel boom is (my view concurring with a school of historical/political thought here) just another one of these stories of looting, in a compressed time period, the accumulated energy discovered "free for the taking".  Whether it be topsoil or petroleum, the initial high burn rate cannot be sustained, and attempts to sustain it hit the walls of thermodynamics very quickly.  This is the final refutation of the infamous doctrine of substitutability:  we can't eat rocks and sand.

Nor, imho, can we sustain an insanely profligate burn rate as required by our present models of transport, housing, commerce, and agriculture by any sustainable substitutions for fossil fuels.  The burn rate itself is inherently unsustainable. This is at present a minority viewpoint, but it is mine until I see some compelling evidence to the contrary.  We should have been called, not homo habilis (clever though we are), nor homo sapiens, nor even homo economicus ("oikonomikos" is in its original usage the management of the finances of a household, and liquidation is piss-poor blind-drunk management);  perhaps we should have been called homo spendthriftus, the species with the high burn rate.

The difference between theory and practise in practise ...

by DeAnander (de_at_daclarke_dot_org) on Thu Mar 30th, 2006 at 06:57:33 PM EST

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