(147aj) Effective Control of High Temperature Steam Electrolyzer Modules That Use Variable, Renewable Electricity

Research Interests: advanced process control, dynamic optimization, dynamic modeling, process optimization, clean hydrogen, machine learning for process control

High temperature steam electrolysis (HTSE) is an electrochemical process that uses solid oxide electrolysis cells (SOECs) to produce hydrogen and oxygen from steam, typically around 800 ℃. A benefit of HTSE is that it can use less electric input to produce the same amount of hydrogen compared to other electrolysis technologies, due to electricity to the reaction being supplemented with thermal heating. Currently, HTSE electrolyzer modules are being developed commercially and it is hoped that they will be able to be used with renewable electricity to produce clean hydrogen at a large scale.

In this study, a detailed dynamic model of an HTSE electrolyzer module including a 1-D spatial model of SOECs is used to investigate effective control of the module, particularly concerning varying electricity inputs. One HTSE electrolyzer module is nominally 1 MW_e-DC and brings steam and air from 500 ℃ and 550 ℃, respectively, to 800 ℃ before going through stacks of SOECS where the electrolysis reaction occurs. The electrolyzer modules are operated in parallel to create multi-megawatt plants where latent heating of the water and heating of the air from ambient temperature is performed by larger units that can support multiple electrolyzer modules.

This study looks at how electrolyzer modules that are running in parallel can be brought online from a ‘hot standby’ state to production in the most efficient and effective way to match renewable electricity generation from wind or solar. Several control methods are explored looking at individual electrolyzer module operation and multiple electrolyzer modules operating together. Special consideration is taken to limit temporal and spatial gradients in the SOECs that can cause damage to them. Results indicate that methods of control presented can be used for large-scale clean hydrogen production to effectively produce hydrogen, even with a varying electric input.