One chemical phenomenon to account for is the calculation of chemical equilibrium, be it for transient or steady-state simulations. Conventionally, chemical equilibria are calculated by stoichiometric or non-stoichiometric methods . By this definition, the stoichiometric method refers to calculation of the equilibrium extent of reaction, 𝜉 eq , of one or more linearly independent simultaneous equilibrium reactions from their respective thermodynamic equilibrium constants . The resulting set of one or more polynomial equations can be solved by root finding in a way that all single equilibria are fulfilled . One major drawback of this approach is that all possible reactions of a system as well as their thermodynamic equilibrium constants must be known . While this may seem straightforward for simple systems like the ammonia synthesis equilibrium, it quickly becomes problematic for more complex systems with more species, e.g. the methanation or the biomass gasification system . Thus, simultaneous equilibria are often calculated using the non-stoichiometric method of Gibbs Energy minimization . This method is based on the total Gibbs energy of a system being minimal at equilibrium . Calculation of the total Gibbs energy of a system does not require any knowledge about possible reactions and their stoichiometries, but only the species and components that can occur in the system . This method is also applicable when dealing with condensed or non-reacting species .