What is the primary principle conveyed by the First Law of Thermodynamics?

The First Law of Thermodynamics, often referred to as the law of energy conservation, fundamentally states that energy cannot be created or destroyed; it can only change forms. This principle emphasizes that within a closed system, the total amount of energy remains constant. For example, when energy is converted from one form to another—such as from chemical energy in fuel to thermal energy in steam—the total energy before and after the conversion remains the same, although it may be distributed differently or transformed into heat and work.

This understanding is critical in power engineering, as it informs engineers about the efficiency and limitations of various energy conversion processes. They utilize this principle to design systems that optimize energy use, reduce losses, and improve overall efficiency.