Thermodynamics Law of Degradation Of Energy

The energy of a system decreases as its temperature or pressure decreases and approaches that of the dead state where its value is zero. When heat is transferred from a system, its temperature decreases and the quality of its energy deteriorates and its energy decreases. The degradation of energy of the system is more when heat loss occurs at a high temperature than that occurring at low temperature.

Quantity wise the energy loss may be same, but quality wise the losses are different.

While the first law states that energy is always conserved quantity wise, the second law emphasizes that energy is always degraded quality wise. When a gas is throttled adiabatically from a high to low pressure, the enthalpy or energy of gas per unit mass remains the same, but there is a degradation of its energy or capacity of doing work. The same holds good for pressure drop due to friction of a fluid flowing through an insulated pipe. If the first law is the law of conservation of energy, the second law is called the law of degradation of energy.

Energy is always conserved, but its quality is always degraded.

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