Assessing the Realizable Flexibility Potential of Electrochemical Processes

Abstract

Demand response is a viable concept to deal with and benefit from fluctuating electricity prices and is of growing interest to the electrochemical industry. To assess the flexibility potential of such processes, a generic, interdisciplinary methodology is required. We propose such a methodology, in which the electrochemical fundamentals and the theoretical potential are determined first by analyzing strengths, weaknesses, opportunities, and threats. Afterward, experiments are conducted to determine selectivity and yield under varying loads and to assess the additional long-term costs associated with flexible operation. An industrial-scale electrochemical process is assessed regarding its technical, economic, and practical potential. The required steps include a flow sheet analysis, the formulation and solution of a simplified model for operation scheduling under various business options, and a dynamic optimization based on rigorous, dynamic process models. We apply the methodology to three electrochemical processes of different technology readiness levelsthe syntheses of hydrogen peroxide, adiponitrile, and 1,2-dichloroethane via chloralkali electrolysisto illustrate the individual steps of the proposed methodology.

Reducing the cost of industrial decarbonization: Demand response by combined product and energy storage for chlor-alkali electrolysis and vinyl chloride monomer production

“…The minimum load of operation of the direct chlorination process has been found to be 70 %, limiting the process significantly in flexible operation [9]. In this work, the range of operation of the direct chlorination process has therefore been limited to 75 to 105% [10].…”

“…In this work, the full ramp rate of one hour of operation therefore exceeds 100 % of the load. The main operational limit of the CAE is therefore the minimum operational limit at 66 % of nominal load [10].…”

“…Hoffmann et al [10] and Hofmann et al [7] used a similar approach, but with restricted overcapacities caused by technical limitations. Both found the reduction in electricity costs of flexible operation of CAE to be in the range of 3 % to 5 % for a 5 % overcapacity in the electrolyzer.…”

Electrochemical Chlor-Iron Process for Iron Production from Iron Oxide and Seawater

“…The high-temperature and corrosive environment in these processes leads to stringent material requirements and thus increased capital costs of the plant relative to low-temperature cells (20). Processes with molten electrolytes are also less tolerant to shutdowns, which may limit their use their capacity to participate in demand response or their ability to directly integrate, "behind-themeter", with electricity derived from wind and sunlight (21,22).…”

Dynamic Ramping Constraints for Demand Response of Flat MIMO Processes

“…Traditionally, such challenging scheduling MIDO problems are simplified by introducing static ramping constraints that define the rate of change of the production rate ρ as degree of freedom ν and limit ν with constant ramping limits ν min , ν max , see e.g., Carrion and Arroyo (2006); Mitra et al (2012); Adamson et al (2017); Zhou et al (2017); Hoffmann et al (2021):…”