Techno-Economic Comparison of Flexibility Options in Chlorine Production

In order to allow demand side management in the chlorine industry, we suggest seven modifications to the conventional chlor-alkali process. The modifications include the oversizing of electrolyzer cells, replacement of electrodes, and integration with flexible auxiliary units. We optimize the operation of the processes for four scenarios with different electricity price profiles and hydrogen prices. We then rank the processes in a merit order of three economic metrics including investment costs, operating costs, and payout time. While reasonable payout times are achieved with many of the flexible processes, the best option with the shortest payout time highly depends on the prices of hydrogen and electricity. The results indicate that flexible chlor-alkali processes without auxiliary units outperform steady-state chlor-alkali processes with flexible auxiliary units. In particular, the combination of two electrodes or the implementation of a bifunctional electrode for operational mode switching seems to be the best compromise.