Fig. 2: Schematic sketch of the linearization of the characteristic curve of the electrolyser stack.
a, The specific energy consumption of the electrolyser stack \({{\varepsilon }_{{{{\rm{Stack}}}},t}}\) as a function of the stack power consumption PStack,t. b, The convex search space between the stack power consumption PStack,t and the hydrogen mass flow of the electrolyser \(\dot{m}_{{\rm{Ely}},t}\). The red dots in a indicate the evenly distributed operation points {1, 2, 3, …, J} chosen to derive the linear inequality constraints in b that in turn form the characteristics curve of the electrolyser stack. The linear constraints act as an upper bound of the depicted search space for optimal operation points, and the black straight line, with the reciprocal of the specific energy consumption at nominal power \(\frac{1}{{\varepsilon }_{{{{\rm{nom}}}},{{{\rm{Stack}}}}}}\) as its gradient, acts as a lower bound. Detailed information in Methods, particulary around equations 9-12.
