school energy&environment

Energy transformation

All energy forms can be transformed into other forms of energy: by burning coal we transform its chemical potential energy into thermal energy (heat). Thanks to the steam engine, the heat can in its turn be transformed into kinetic energy, i.e. the motion of the locomotive.
Thermodynamics is the science studying the transformation of energy into work and vice versa. It is based on two principles valid only within closed systems such as the Earth. The Earth is a closed system because it can exchange energy with outside but cannot exchange matter. If it were not able to exchange energy either, it would be defined an isolated system. If it exchanged matter too it would become an open system.
First principle of thermodynamics
There is a natural law limiting these transformations, i.e. the law on the conservation of matter, according to which energy cannot be created nor destroyed (“nothing is created and nothing is destroyed”). The energy can be transformed from a form into another but the sum of the different forms must remain unchanged. Therefore “nothing is created nor destroyed, everything is transformed”.
Second principle of thermodynamics
Whereas the first law of thermodynamics deals with the global balance of energy, the second law deals with its transformations and its natural tendency to move towards more degraded forms, which cannot be used any longer. Actually, the second law of thermodynamics includes two wordings. The first states that the heat always moves from a warmer to a colder body, never the other way round. The second unveils the natural tendency to the dispersion of heat, i.e. that the heat from a source cannot be fully transformed into work. This does not mean that the total quantity of energy present in the universe is decreasing, rather that its ability to work is.
The thermodynamic function assessing the degree of energy dispersion is called “entropy” . Entropy in the universe tends to increase to reach a state of balance in which the total degradation of energy is achieved corresponding to the complete inability to work. Fortunately, biological systems are open systems, which thanks to the incoming of energy from outside, restore the positive global energetic balance.