Answer: By transforming energy from one type to another.
Step-by-step explanation:
Energy is not destroyed, it is conserved. During a thermodynamic process, it is transformed from one type to another. The first law expresses a system energy balance. Energy flows in a system (work and heat) are related to changes in system Energy. Thus the first law of thermodynamics says: "The sum of the heat exchanged by a system and the work done by or in a system is equal to the variation of the internal energy of that system."