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The concept of Entropy in Permaculture

 
Samuel Martin
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Location: Montreal, Québec, Canada
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Question for Geoff :

Entropy often comes up in your teachings.
I think I understand the basics of entropy in thermodynamics (which some say is a sure sign that I DON'T understand it!), but I'm having trouble making links with permaculture specifically. Could you expand on what is the interesting part of entropy for you?
 
Miles Flansburg
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Samuel,

Since Geoff is a student of Bill Mollison I assume he may agree with what Bills “A Designers Manual” says.
On page 10 , the first page of chapter 2, there are several quotes that make the point that, “organized systems drift inevitably towards entropy, or chaos.
In seeming violation of that, biological systems tend to become increasingly complex and efficient”

On page 13, in the same chapter.
“ Entropy is bound or dissipated energy; it becomes unavailable for work, or not useful to the system.”
Like the water in a stream when it reaches the ocean, or the food animals eat to keep them warm and alive. So useful energy slowly degrades to less useful forms , until no longer useful. Designers of permacultural systems then must think about using the energy in their system before it passes along to the next property. Such as building key line dams to collect water high up on a property.

“ Life systems constantly organize and create complex storages from diffuse energy and materials, accumulating, decomposing, building, and transforming them for further use.”
So we should think about using the materials we are given in the most effective way. An example given is manure. We can leave it on the field, which is beneficial. Or we can ferment and distill it to alcohol and route the waste to a digester to make methane. To use as fuel, for cooking or autos. Liquid effluent can be put on fields, and sludge fed to worms to make rich soil. Then the worms fed to fish or poultry.

If you get the chance you should get a hold of a copy of the manual and read lots more about this.
 
nathan luedtke
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Always remember that most statements about entropy (including the Laws of Thermodynamics) assume a closed system. "In a closed system, all energy tends towards disorder and entropy".

The Universe is a closed system (is it?). So overall, in the universe, we're headed towards entropy/heat death/red shift. But maybe we're not, cosmologists are working on it.

My point is that within The Big System, there are infinite small subsystems, of which our solar system is one. The Earth receives a constant flow of energy from the sun, which more than displaces the energy lost to entropy.

However, we have built our civilization on fossil sunlight instead of fresh sunlight, so our use of that fossil sunlight pushes entropy to higher levels. If we could learn to operate within the budget of fresh solar energy, entropy wouldn't be a concern.
 
Paul Cereghino
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The important extension of this discussion is the concept of embedded energy, or Emergy as described by some authors.

For example the reserves of organic matter in soil represent a historical investment of energy to change the structure of the soil system. Agricultural practices that degrade soil are not only founded on fossil energy And result in the loss of energy stored in organic change in the soil but also reflect a loss of soil structure and composition that was only built through the expenditure of tremendous amounts of energy over a long period of time. So the total loss of energy from useful state or entropy is very high when a system with high embedded energy is lost.

From this perspective the loss of a whole species is a tremendous example of entropy.
 
nathan luedtke
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Paul I like the direction you went here.

So a complex system necessarily has lots of energy bound up in it: the large amount of energy over time allows system-wide complexity to increase. You can extract this energy by (for example) cutting down the forest and planting a field, and you get tremendous results in the short term. But now the system is at a lower state of energy so you have to start applying additional inputs.

But if you just leave the system alone, it continues to bind up energy and get more and more complex.

The Thermodynamic Theory of Succession.
 
Manfred Eidelloth
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@Samuel:
I think Bill and Geoff sure have understood the rough concept of entropy but are both not precise in expressing it.

Entropy is a physical quantity that describes the working capacity of the energy in a system.
The bigger the entropy, the lower is the working capacity of the imbedded energy.

Therefore bill is wrong when he writes “entropy is bound or dissipated energy” although he means the right thing. He is wrong because entropy is not energy. Entropy is only describing a characteristic of the energy involved.
A better expression would be: A high level of entropy means, that the imbedded energy has lost most of its working capacity. The system has achieved a condition of deadlock.

A young system with low entropy is like a bucket full of rubber balls dashed into a space-capsule.
They are all flying around at different speeds, tossing each other and causing lots of action.
Gradually they slow down and finally they are only floating in the room, at most gently jostling each other from time to time. They have reached a condition of high entropy. A condition of high egality, if you will.

Geoff is imprecise when he says life can reduce entropy. Life increases entropy, too. But it somehow works like a motor. It is transforming energy. Plants take solar energy and use it to build complex molecules. The building of these molecules indeed reduces the entropy of the material involved. But the price for this is a higher increase of entropy for the solar power put into the system.
If would not know about solar energy, we could say: Look, life is reducing the entropy in our system!
But we know about the solar energy involved. Therefore we have to say: Life transfers the high working potential of the in solar radiation energy into chemical energy (high working potential, low entropy) and thermal energy (low working potential, high entropy).
After that we get rid of the high entropy thermal energy (by radiation or heat flux, etc.) and keep the chemical energy.
The life in our little system causes an increase of entropy in the whole solar system, but for us it transforms solar energy into diversity.

In our model catching solar energy by plants is like somebody coming by and giving one of our rubber balls a hard kick. The fun starts again. And if we can animate lots of these solar guys to come around and kick our rubber balls (hopefully not some other balls) regularly we can accelerate the action in our space-capsule to new levels.

Below the line:
It is hard to collect energy. And it is very easy to lose the working potential of the little energy we are able to collect. Therefore we should make the best use of it. Finally all energy will all become high entropy heat energy. Our goal is to but as much useful energy transformations in between this degradation from high working potential solar energy to low working potential heat energy as anyhow possible.
 
Zach Muller
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That was a great description manfred! I am taking a chemistry class and when the teacher tried explaining entropy and natural systems it was a joke compared to your post.

I think with the more common casual knowledge of thermodynamic laws, combined with people's innate interest in chaos and energy there has been ample confusion around the entropy concept.
Nice work.
 
Samuel Martin
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Location: Montreal, Québec, Canada
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Paul and Manfred, I commend your vulgarization skills. Sunlight as a force that gives a kick to one of many balls in a space capsule. Works for me!

Given that "the bigger the entropy, the lower is the working capacity of the embedded energy," and that energy is never lost or gained, does it follow that entropy has no end, no maximum, no final measure? It would explain what geoff lawton means when he says "Entropy is increasing all the time" in one of his DVDs.

Example: When energy is eventually released as heat in the atmosphere, and seems useless to us living on human timescale, it is possible that a few hundred thousand years of continuous slow release of heat may foster the right conditions for some living organisms who continue turning sunlight into new assemblages. And on and on somewhere else in the universe even after our sun explodes.

This is becoming a bit far removed from the more important matter of making a good life for ourselves on this planet, but I think the concept of entropy is quite a bit clearer now.
 
Manfred Eidelloth
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@Samuel:
It is like Nathan wrote: In a closed system entropy can only increase. It cannot shrink.
That is what Geoff means: If you have not input from outside (closed system), the working ability of the energy in your system declines (or at most keeps the same) with every energy transformation happening.
But it is practically impossible to really have a closed system.
Even the space-capsule from my example above will radiate and absorb electromagnetic waves.
If it would be perfectly isolated, all the energy from the rubber balls would turn to heat (via friction) over the time. The temperature of the capsule would slightly increase until the balls have stopped moving. As all of the capsule would have the same temperature, the heat energy stored in it would not have any working ability within the system anymore. You could call this a boundary value of entropy.
In reality you still have stored a giant amount of usable energy in your system, in the matter of the system itself. Since Einstein we know: Energy is equivalent to mass (E=mc2). The explosion of the Hiroshima-bomb only converted about 1 g of matter into energy.
You could say the universe has a certain mass. Therefore it contains a limited amount of energy. Therefore entropy of the whole thing should come to some boundary value in a very far future, when all mass is transformed and/or the system cooled down to absolute zero (=head death theory http://en.wikipedia.org/wiki/Heat_death_of_the_universe )
But I do not think we (I) know enough about our universe to give a certain answer to such questions.


If we open our little space-capsule and add the heat contained in it to some colder system, we of course gain working ability again. But this cascade is limited by absolute zero (Temperature of 0 K = -273,15°C).
 
Alder Burns
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The best author on this subject is Howard Odum. He pioneered the concepts of emergy, energy quality, and transformity. His "Environment, Power, and Society for the 21st Century" is marvelous!
I think I found this author, and several more, by looking through the references at the end of each chapter in the Designers' Manual, as well as Holmgren's bibliography. That's how I found P.A. Yeomans, too.....
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