Emergy and Transformity

As stated above energy decreases along transformation chains, therefore along a chain or a web, transformities increase and emergy, following 'memorization' laws, may remain constant or grow down-chain. Figure 2 is useful for evaluating emergy and transformity at different steps in an energy flow sequence. If the producers are forage plants and the consumers (C) are cows, the sun transfers energy to the plants from the boundary of the system, the plants use it by photosynthesis and transpiration, taking up soil nutrients and fertilizers. The transformity of the plants is clearly greater than 1 (i.e., the solar transformity of the sun) because the energy in the forage is obviously much less than that of the incoming solar energy, but the plant increases the organization of the sun-forage-cow system. Similarly, the forage transfers its solar-derived energy to the cow. The cow's transformity is much greater than 1 because of the cow's low energy with respect to the solar energy that has been used for it. Since the forage contains energy derived from the sun, so does the cow, and energy embodiment increases as energy dissipates along food chains.

As a general rule, the transformities of similar products are compared to obtain information about production efficiency. If, for instance, the transformity of forage from one field is 4 x 104 sej J_ 1 and that from another field is 1 x 105sejJ_1, the forage from the first field can be said to be more efficient (less emergy per unit of product).

Transformities of different classes of product (e.g., forage and cow) can also be compared. In this case, transformities indicate the relative 'position' in the global hierarchy of processes. All energy transformations can be represented in sequence and the position of each energy flow in the sequence is indicated by the transformity.

Feedback control loops

Feedback control loops

£ (b) Aggregated

103 102

103 102


n r






Degraded energy

102 103 Transformity


*•* • *

• • • • • •

• • •

Increasing unit size and size of territory








->- Increasing period and pulse amplitude

Figure 3 Energy hierarchy in space and time. Reproduced by permission of Elsevier.

Energy system diagrams show energy hierarchy with small fast turnover units on the left and aggregations in space and time on the right (Figure 3).

Emergy is the same from left to right (Figures 3b-3c), whereas available energy decreases after each transformation and the transformity increases. The higher the transformity, the greater the demand for energy to make that flow or product. So in order to overcome natural selection, systems reinforce their networks with feedbacks. Units receiving feedback from units further down the chain are reinforced by a small energy flow of high quality, that is, more concentrated and therefore more capable of doing work.

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