THE LAWS OF THERMODYNAMICS

fundamentals that can not be negotiated

Entropy

Exergy

  1. Energy can neither be created nor destroyed
  2. In all energy transformations, energy quality will be consumed

These are Natural Laws, i.e. they are fundamental and can not be negotiated. On the other hand, if somebody find out something that might falsify them, they will cease to be fundamental.

The First Law tells us that energy can be neither created nor destoyed.
(The production or consumption of energy is impossible. Anyone who speaks about 'energy production', or 'energy consumption' is probably ignorant about the First Law). This means that the amount of energy in the universe is constant.

So, the First Law tells us something about the state of the universe and all processes in it.

The Second Law tells us that the quality of a particular amount of energy i.e. the amount of work, or action, that it can do, diminishes for each time this energy is used. This is true for all instances of energy use, physical, metbolic, interactive, and so on.
This means that the quality of energy in the universe as a whole, is constantly diminishing. All real processes are irreversible, since the quality of the energy driving them is lowered for all times.

Thus, the Second Law tells us about the direction of the universe and all processes, namely towards a decreasing exergy content of the universe. Processes that follows this general principle will be preferred.

Some people seem to think that this law should be revoked... But perhaps they are misled by their notion of entropy.

The usable energy in a system is called exergy, and can be measured as the total of the free energies in the system.

Unlike energy, exergy can be consumed.

To more easily understand the concept of exergy, you can consider this picture as an analogy: You buy is the (toothpaste) tube. But you have to squeeze it to get at what you really need, the toothpaste. When the tube is empty of paste (exergy) the tube is still there, the same amount as when you bought it.
In theese circumstances, the word entropy often comes up. In the picture this is represented as the depression in the tube. The depression increases as the amount of paste diminishes, but the depression is not a negative paste. (You can not take the depression and unbrush your teeth!)
Entropy is not negative exergy, but another description of the system. Furthermore, it is not defined in far-from-equilibrium systems, as living systems and other organised systems.

Life-processes consume the exergy in the energy. After the energy is used, it contains a lower amount of exergy. The extracted energy is low-exergy energy, not entropy.

Exergy consumption by living systems

Life-processes are more efficient in consuming exergy than non-living processes. Therefore, when living systems appears, they offer a faster route of exergy consumption, and hence a better way of 'obeying' the Second Law.

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Updated:
2013-01-06