Energy consumption optimization of a two-link planar robotic arm is considered with the system's efficiency being the target for optimization. A new formulation of thermodynamic principles within the framework of dynamical systems is used. This approach is applied by considering cyclic motions for the robotic arm and analyzing the cyclic averaged energies while the robotic arm is tasked with going from point A to point B in the task space while resisting an external force. The energy transfer rate between the links is classified into positive and negative and the results combined with the averaged energy quantities, are used to address the optimization problem while adhering to the constraints imposed by the second law of thermodynamics in its new formulation.