Electrical Area Classification Safety-in-Design Considerations for a Large Alkaline Electrolyzer Hydrogen Plant

This abstract focus is safety in design considerations relative alkaline electrolysis equipment (pressurized) electrical area classification as applies to large hydrogen production facilities. Alkaline electrolyzers are unique due to size/capacity, and open style design. While alkaline electrolyzer technology is quite mature, we explore common design challenges around electrical area classification.

The basis of this abstract was formed in large part from Lessons Learned on the ACES project, the world’s largest industrial green hydrogen facility and storage project in Delta, Utah, for Advanced Clean Energy Storage I, LLC (“ACES”).

Hydrogen Safety Design Basis Considerations

Pressurized Alkaline electrolyzers with open style design, with no individual enclosure around the stack, and located indoors will be discussed. Electrolyzer building ventilation considerations, and the overall space of the room containing the electrolyzer and other hydrogen generation equipment, as well as hazardous areas classifications per NEC, section 500 and 501, Class 1 Division 2, Group B will be examined. Considerations and challenges related to rating the space around the electrolyzer stack, including the DC electrical connections, areas immediately surrounding the electrolyzer, and areas to protect personnel or other objects that could cause an arc are part of safety design discussion, as well as leak sources, ventilation equipment interlocks, hydrogen leak detection instruments, LEL/LFF limit calculations, manufacturers recommendations for ventilation / air changes, location and number of hydrogen leak detectors, and design of both passive and active ventilation.

Finally, this abstract will also consider prescriptive design analysis using modeling, vs. a prescriptive code driven approach. Many international standards allow use of non-classified equipment, such as IEC 60079-13 and ISO 2274, while US codes and standards appear to be more prescriptive.

Codes and Standards

IEC 60079-13, ISO 22734, NFPA 2, NFPA 70, Section 500c, 501, NFPA 497