(83a) Enabling a Load-Flexible Operation of an Electrified Downstream Process for Bio-Based Carboxylic Acids

In recent years, electrification of chemical processes have become more and more important. However, the operating costs of these processes are strongly influenced by electricity prices. In 2020, the average electricity price on the German day-ahead market was still 30.47 Euro/MWh [1]. Then, in 2021, the electricity price increased to 96.85 Euro/MWh and reached a maximum of 620.00 Euro/MWh on December 21, 2021 [1]. Load-flexible operation of electrochemical processes is essential reduce the electricity costs of these processes. In addition, load-flexible operation can help stabilize the power grid and adapt it to the increasing but fluctuating supply from wind and solar energy. In 2021, 20.1 % of the total net electricity generation in the U. S. was generated by renewable energies [2]. In the same year, renewable energies accounted for 42.6 % of the total electricity generation in Germany [1]. This share will increase in both countries in the coming years. However, due to their fluctuating availability, especially of solar and wind power, it will become increasingly difficult for power grid operators to keep the power grid frequency almost constant. Load-flexible processes can thus help keep the grid frequency within narrow tolerance limits by adjusting their power supply. This provides opportunities for additional revenue and thus establishes the chemical industry as a system-relevant player in the electricity market.

We developed an electrochemical pH-swing extraction process for the purification of carboxylic acids produced by fermentation [3-6]. This process was developed to avoid the emission of waste salts generated in the conventional downstream process by the addition of acids and bases for pH adjustment. This problem is solved by changing the pH value with protons and hydroxide ions generated by electrolysis. This pH-shift electrolysis also allows the process to operate in a load-flexible manner. To ensure that the upstream fermentation and the following downstream process can run continuously, the pH shift electrolysis is decoupled from the other unit operations. An intelligent load adjustment system (ILAS) was developed that autonomously plans the dynamic operation of the process and adapts the power consumption based on electricity market data. In load-flexible operation the ILAS adjusts the power consumption of the pH-shift electrolysis in such a way that an economic benefit is generated while the production target and quality specifications are maintained.

References:

[1] Bundesnetzagentur für Elektrizität, Gas, Telekommunikation, Post und Eisenbahnen. Die Entwicklungen im Überblick, January 7, 2022.

[2] U. S. Energy Information Administration. Electric Power Monthly. March 24, 2022.

[3] M. Gausmann, A. Jupke, Chem. Ing. Tech. 2020, 92 (12), 1953-1961.

[4] M. Gausmann, C. Kocks, M. Doeker, A. Eggert, T. Maßmann, A. Jupke, Sep. Purif. Technol. 2020, 240, 116489.

[5] M. Gausmann, C. Kocks, J. Pastoors, J. Büchs, N. Wierckx, A. Jupke, ACS Sustainable Chem. Eng. 2021, 9 (28), 9336-9347.

[6] C. Kocks, J. Görtz, A. Holtz, M. Gausmann, A. Jupke, Chem. Ing. Tech. 2020, 92 (3), 221-228.