The energyRt model comproses around 90 predefined equations to describe an energy system and its operation. Additional equations can be added using newConstraint methods or added to the model code directly. The original model has been formulated in GAMS, and translated in Python/Pyomo, GLPK/Mathprog, and Julia/JuMP. Mathematical formulation of energyRt with dropped mapping parameters in equations for readability can be found here.