Holistic Idle Periodic Evaluation method for mass balance monitoring at hydrogen refuelling stations

Hydrogen refuelling station (HRS) is an intricate system consisting typically of compression, storage, and dispensing subsystems. Thus, monitoring of HRSs has become a challenge in a real-time operation. Mass balance analysis of such a system consists of evaluating for a given timespan the amount of hydrogen received (produced or delivered on-site) and the amount of hydrogen dispensed to the vehicles. Previous work focused on off-line evaluation of hydrogen losses of HRSs with on-site hydrogen production. This article proposed a solution to holistically evaluate hydrogen mass balance and periodically evaluate hydrogen losses at HRSs in a continuous operation environment. We applied the Holistic Idle Periodic Evaluation method on real-time operational data of two HRSs with off-site hydrogen production and deployed the system for online monitoring of the hydrogen losses. The two stations were found to have hydrogen mass balance of 94.2% and 83.6% with an uncertainty of $\pm 5.0\text{\%}$. Our method can track normal and anomalous system operations in real time. It is applicable for HRSs with both off-site and on-site hydrogen production and only requires one mass flow meter used for metering hydrogen being dispensed to vehicles.