Optimal Oversizing and Operation of the Switchable Chlor-Alkali Electrolyzer for Demand Side Management

Flexible operation of the switchable chlor-alkali process is a novel strategy for minimizing electricity costs in markets with volatile prices (Bree et al. (2018)). This strategy allows for adjusting the process to electricity price profiles, by varying the production rate and by switching the operation between two different modes: the H-2 mode and O-2 mode. The size of the electrolyzer is a crucial factor because oversizing on the one hand leads to higher operational flexibility but on the other hand to increased capital costs. Here, we combine the optimization of the operation and electrolyzer size in the switchable chlor-alkali process for given electricity price profiles. To arrive at the optimum in reasonable computation time, we use a piecewise linear approximation and decomposition method employing the golden-section search. We verify that electrolyzer oversizing in the switchable chlor-alkali process is a suitable strategy for reducing the total production cost when the specific capital costs of the oversizing are low enough and the electricity price strongly fluctuates.