[Fis] Again about coupling resources and information

Dear FIS Colleagues,

Sorry for not replying in the last week, due to real overload for other commitments. Let me try to say something about the "value" problem raised in several recent postings. In so doing, I also would like to remove some misunderstandings about my last message.

a) Pedro quotes one sencence from my message out of the right context ("seeds, money, DNA, books, software, religions, cities, database, have no hope to last, reproduce, or even survive against the law of entropy, if resource flows are not provided every day to counter their degradation.") and says that it implies hard-core reductionism. He makes me to say something that I never said (the need for entropy analysis of DNA or of seeds!) and then states that this is wrong.I agree, of course.In fact I never said this. I said something that is much more different and that Luis clearly summarizes in his posting: whatever we do (be it making a house, teaching or thinking) we need resources: building material, energy, food, water, electricity to power our computer, energy and resources to keep the whole University system working. Due to the entropy degradation, further maintenance is needed at the expenses of additional resources. Making and disseminating copies of the achieved information is the strategy that ecosystems as well as humans follow (1) to avoid information losses, (2) to make it tested by "trial and error" processes and (3) to move on to the new information levels or dimensions pointed out by Loet. Resources and energy are a pre-requisite for any of such activities (Enzo underlines this very clearly in his message; Luis correctly talks about "energy that we have available for a sustainable development"). These resources can be misused or even lead to the creation of Leonardo's "Mona Lisa": the quality of the result (we may say: its information content) is not directly proportional to the input of resources, nor these two aspects appear to be linked in any quantifiable way (although a qualitative link cannot be denied). Yet, no resources, no result (no information). The sun generates information via the photosynthetic process (sometimes we talk of a flow of negentropy from the sun). The following steps (i.e. the ways and the extent of biodiversity generation) cannot be easily linked to the amount of solar negenergy, since they depend on the evolution process, where several other factors affect the system (e.g. scarcity of nutrients, chaotic fluctuations of any environmental parameters, choices). Yet, again, no solar radiation, no photosynthesis, no further steps.To point out that material and energy resources are a pre-requisite does not mean to claim that we are able to "force" the evolutionary process and drive it where we like. It only means that resources are important and that their good use and conservation are of primary importance for future development. Everybody knows that some resources can be replaced by others, but this is not true for every resource, nor it is true for the solar radiation. Even if the "stone age did not end for lack of stones", our sustainability may be significantly affected by lack of primary resources or by the disruption of the environmental context (another kind of resource) in which our activities develop ("Supply-Side Sustainability", Allen, Tainter and Hoekstra, 2002).

b) Pavel refers to me by saying that "basic analysis of energy flows and "stocks" tells very little about information content of the system". I agree. In fact I never said that we know the information content of something by knowing its energy content.The information content of something is so hard to explore and describe, that even thinking of its quantification is almost impossible. The problem here is that energy analysis is a First Law method, while Exergy and Emergy analyses are Second Law-based and take into account the entropy generation occurring when a resource is generated (emergy) or used (exergy). This is not without interesting consequences.

Exergy ("the amount of work obtainable when some matter is brought to a state of thermodynamic equilibrium with the common components of the natural surroundings by means of reversible processes, involving interaction only with the above mentioned components of nature", Szargut et al., 1988) measures the physical and chemical "information" of an item in relation to its conversion into useful work (mechanical, electric, etc). Since exergy refers to reversible processes (and real processes are never reversible), it states very clearly an upper limit to the work obtainable and allows a sustainability assessment mainly focussing on the way resources are used and on what can be obtained from them (i.e. an user-side sustainability). Of course, we are not talking here of the exergy of a person or a standing tree, since exergy is not sensitive to life (using Luis' words). Herefore, we do not use exergy to measure the work of an artist or the complexity of a flower or fruit (as Enzo also pointed out).

As far as emergy is concerned, I would like to clarify that emergy is not energy. It is the memory of the resources previously used up in a process (by the way, measured in exergy terms_ Odum, Environmental Accounting, 1996) during the whole pathway from primary inputs to the final product. By measuring input flows by means of their exergy content, emergy calculations acquire a "built-in" ability to account for local scale entropy production. In addition, by integrating exergy inputs over time and space for the calculation of transformities, natural trial-and-error processes are also considered, thus taking into account the production of entropy during the "metabolic" processes leading to the final product via a set of intermediate steps. Therefore, by converting all inputs into only one form unit (e.g. solar equivalent joules), by means of suitable conversion coefficients, we measure the (sometimes very approximate) environmental support that is required for a process to occur. Since the ultimate sources of resources are flow-limited (solar, deep heat, gravitational potential), the higher the support demand, the less renewable the product. In some a way, this is a measure of source-side sustainability. Edgar suggests in his posting that the "virtual" replacement of non-renewable resources has a cost which could be measured in exergy terms.

Source-side sustainability and user-side sustainability are useful categories to better understand a process dynamics in terms of upstream and downstream flows. They are NOT, however, deterministic measures of what will happen within the system thanks to the resources supplied to it. The system reacts in many different unpredictable ways to the resource flows and some of these ways will be selected by the natural selection.

Luis is right when he underlines the need for a further effort to find a measure of the organizational level of an ecosystem also in relation to life. Unfortunately, measuring what already happened and what is presently happening is relatively easy, while predictions are quite difficult and maybe impossible. Sven Jorgensen, University of Copenhagen, made interesting steps ahead towards assessing and modelling the level of organization of an ecosystem, by also including "Shannon" estimates of species diversity. His goal-function is also called exergy, but maybe it should be given a different name.

Let's now turn to Loet's Dutch tomatoes: what he says is simply impossible. Photosynthesis cannot occur without solar radiation. Replacing the sun by means of electric light is in principle possible (the growth of plants under artificial light has been already investigated), but would require a tremendous input of fossil fuels to power the electric plant and a consequent related atmospheric pollution. In general, greenhouse tomatoes in cold climates require a greenhouse (plastics or glass, concrete and structure metals), an artificial substrate (such as rock wool), fertilizers, several added chemicals as pesticides and micronutriens, and a huge heat from fossil fuels. It is completely unsustainable from a resource availability and environmental constraint point of view. There are several studies on this topic, from which it can be clearly inferred that the economic sustainability of this practice only relies on the existence of cheap fossil fuels as well as on neglecting the environmental aspects of their use (contribution to the greenhouse effect increase, among other problems). In addition, greenhouse tomatoes represent a simplified ecosystem and a significant loss of biodiversity, since they are selected to fit greenhouse conditions and survive in a very artificial atmosphere. I already pointed out this kind of contradiction when Loet claimed that we can have plenty of paper, ignoring the constraints imposed by the huge (source and sink side) environmental problems generated by paper production. This is what generally happens when we ignore the physical constraints within which all our actions are embedded. Adding new dimensions has a resource and environmental cost and resources are very often non-renewable, no matter how we measure them. Greenhouse tomatoes cannot be considered a sustainable new dimension.

If we care the development of information and the growth of sustainable systems able to generate and maintain information, we must pay a huge attention to our resource basis. Ecosystems do not grow without resources, Universities decline when funding is not appropriate, economies and Empires collapse and are replaced by competing systems when their resource basis shrinks.

The following references may be useful at this regard:

Tainter J., 1988. The collapse of complex societies. Cambridge, England: Cambridge University Press.

Odum H.T. and Odum E.C., 2001. A Prosperous Way Down: Principles and Policies. University Press of Colorado.

I am also attacching a recent paper from Hall et al., Hydrocarbons and the evolution of human culture, published in the Issue 426 of Nature, 20 November 2003, which you may find of some interest.

Greetings to all.

Sergio

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Sergio Ulgiati
Energy and Environment Research Unit
Department of Chemistry
University of Siena
Via Aldo Moro
53100 Siena (Italy)
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