T hermodynamic principles have long been applied to ecological systems, yet a minimal formal structure capable of describing energy degradation and useful work within ecosystems remains limited. In this case report, It is presented a simplified thermodynamic formulation based on the decomposition of energy into useful energy and anergy. A basic ecological system is described using measurable variables such as biomass and metabolic potential, treated as conjugated thermodynamic variables. From these quantities, key thermodynamic state functions-including internal energy, enthalpy, entropy, useful energy, and anergy-can be defined. The formulation illustrates how irreversible processes generate anergy through entropy production and how biological work emerges from interactions between biomass and metabolic potential. T his minimal framework demonstrates how ecological systems can be described using classical thermodynamic structure while accounting for the irreversible degradation of energy quality.