The aim of this paper was to create a computational model that will enable the evaluation of the operation of a conventional inertia accumulator. This is an issue that is relevant as storage of energy is becoming increasingly important, in particular when it comes to generating electricity from renewable sources. In the course of the conducted works, an analytical model was developed based on the available literature, and then, it was introduced into the environment for numerical calculations. Four variants resulting from different geometrical parameters of the flywheel were adopted successively. On this basis, a series of simulations were performed, which allowed for obtaining the characteristics of the analysed solutions. As a consequence, a number of characteristics related to the mechanical power and energy of the simulated kinetic energy accumulators were obtained. The test results therefore provide a basis for comparing kinetic energy accumulators with different geometries and drive solutions.