On different system behaviours
in relation to storage or flow


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It is important to understand that a self-organizing system behaves differently when it uses a storage (e.g. an non-renewable resource) than when it utilizes a flow (e.g. a continually renewable resource). 
The existence of a storage implies a behaviour that increases the utilization to the ultimate limits, i.e., to the elimination of the store (depletion).
Classical examples of store dependent, short-lived populations are bacteria on a carcass, and mould on a slice of bread. They will ultimately use up their store and their populations willreturn to a level where they use a flow. Another interesting example is the present socio-economic system regarding fossil fuels.

The kinetics are different depending on whether a source or a flow is used. 

In the utilization of a storage, there is a trend towards intensity, i.e. more of the store is used per unit time. This behaviour is only limited by the decreasing accessibility (depletion) of the store, or by a decreasing energy return on investment, EROI .
In the utilization of a flow, there is an increasing difficulty of utilization when it is approaching the amount of the flow. To increase consumption, the system has to react with an increasing efficiency of utilization. An excellent example of this is the maturation of ecosystems. The difference between the use of a store and a flow is illustrated in Diagram 1.


Diagram 1. Difference between the utilization types generated from a storage and from a flow. Click on the diagram to see an enlargement

The human population has changed very little during 99% of its existence of a million years or so. During this time, the population increased to about 10 millions. Only during the last one percent of its history, the human population has changed dramatically.
During the time from the first settlements to medieval time, the population changed from about 10 millions to around 500 millions. This change occurred in only 10,000 years, or about 1% of the time of our species has existed.

These differences are reflected in Diagram 2.


Diagram 2: The change in antropoid population during the last million years.

From medieval time to about 1850 there was a stepwise increase of the population.A large change occurred from medieval time to about 1850. In 0.1% of our species existence, the population doubled to about 1 billion.
After 1850, industrialization occurred and fossil fuel usage began. The slope of the curve changed dramatically (even in logarithmic terms). At this break, the human population got the opportunity of using more energy in an activity than it gives back (EROI below 1, The rabbit limit.).
This opportunity is used in nearly all industrial processes, including food production. In about 100 years, 0.01% of the existence of the species, the population grew to 6 billions.
Although we often regard the world of today as 'the normal world', this 0.01% is from an evolutionary viewpoint highly un-normal. Genetically, we are adapted to be hunter-gatherers in a spacious environment, not to the present situation.

This change is described in Diagram 3.


Diagram 3. The change in total and urban population and fossil energy use in the last thousand years. The correlation coefficient between total population and fossil fuel use is 0.82

It is interesting to compare Diagram 1 and Diagram 3. Regard the changes in the population curve until 1850 and after 1850 in Diagram 3. Compare it with the two curves in Diagram 1.

After 1850, the human population changed from using a flow (sun and its derivatives) to using a storage (fossil fuels). This is reflected in the population growth curve.
When speaking of a change from a store to a flow, (renewable energy sources), you also have to invent a new (logistic) economy, since our current economy is adapted to the energy extraction from a storage.



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Updated:
2013-01-06