(260e) Integrated Design and Operation for Micro-Electrochemical Plants Powered By HRES with Multi-Level Process Flexibility

The imperative target of carbon neutrality to tackle the global warming issue entails a rapid energy transition of the chemical industry towards renewable sources [1]. However, high penetration levels of renewable energy pose a staple challenge for chemical processes as the intermittent nature of renewable energy sources, predominantly solar and wind energy, conflicts with the long-term stable operation conditions of conventional chemical processes. It is gradually recognized that the flexibility of chemical operation units and processes plays significant roles in both the design and scheduling of chemical factories [2]. However, the methods for the integrated design and scheduling of flexible chemical processes with hybrid renewable energy systems (HRES), considering the flexible features including capacity adjustment, ramp rate, start-up and shut-down period, storage, and operation mode shift, are still developing [3]. Further investigations into the influence of system flexibility under fluctuating energy supply are also crucial to fully exploit these abilities. To address these problems, we formulated a multiscale optimization model for integrating the design and operation (scheduling, planning) of a flexible HRES-powered electrochemical synthesis system with multiple target products. The main electrochemical processes embody the electrochemical reduction of CO₂ (ECO­₂RR) to CO followed by a Fisher-Tropsch synthesis, ECO₂RR to formic acid (FA) and electrosynthesis (ES) of H₂O₂. The electrochemical processes of the systems are outfitted with microreactors featuring different levels of flexibility. The optimization model thereby simultaneously reveals the optimal configuration of the system (the scales of the production units, energy output units, and corresponding auxiliary units) and preliminary operational policies based on the historical hourly weather data of representative weeks. Comparisons between the conventional production modes and flexible ones successfully indicate that, promoted by significant technological advances in electrosynthesis and microreactor design, chemical processes displaying sufficient flexibility are competitive and more compatible with HRES, with no large-scale energy storage systems and better tolerance of losses of power supply. Investigations on energy distribution demonstrate that energy efficiency and costs depend strongly on the complementary effects of different levels of flexibility. In general, more flexible processes consume more excess energy. However, the trade-off between flexibility and investment and O&M costs should be approximately made owing to the frequent operation adjustment. These results suggest the importance of process flexibility when electrifying the chemical industry in the near future.

References

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2. Smith C, Torrente-Murciano L. The importance of dynamic operation and renewable energy source on the economic feasibility of green ammonia. Joule. 2024;8(1):157-174. doi:10.1016/j.joule.2023.12.002

3. Lazouski N, Limaye A, Bose A, Gala ML, Manthiram K, Mallapragada DS. Cost and Performance Targets for Fully Electrochemical Ammonia Production under Flexible Operation. ACS Energy Lett. 2022;7(8):2627-2633. doi:10.1021/acsenergylett.2c01197