2.4.1. Regulation Constraints

Regulations relating to hospital power have been considered in our conceptual scenario of a multi-generation health precinct. Standards vary at the intra- and inter-national scale. For example, in the US, the updated code NFPA 99 allows for fuel cell systems as alternate sources of power since 2015 [64]. The code also now allows for oxygen concentrators as central supply sources for hospital medical oxygen systems, which could be integrated to support on-site production from electrolysis. Returning to the Australian context, the relevant standard for emergency power supplies in hospitals from 1998 (AS/NZS 3009:1998) states the power source may be provided by central battery systems, provided they are of a type specifically designed for continuous float charging conditions [65]. Lead-acid batteries meet this criterion but others do not, despite alternative battery technologies and contemporary digital battery management systems.

The N + 1 supply configuration is a commonly accepted practice that shapes the design of emergency power systems, including those for hospitals [66] in NSW [20], to ensure enough redundancy is built in to ensure a highly resilient system. This means building in one additional piece of key equipment than is strictly required, so that one sub-system can fail and operations can continue. Providing capacity modularity to meet an N + 1 guideline is straightforward with battery packs and fuel cells stacks; the most critical point of failure would relate to the inverter. The need for multiple inverters can be seen as a prohibitive cost or as an opportunity to install valuable assets able to provide ancillary services to electricity networks [67]. Demonstrations of the ability to replace the mechanical inertia of conventional power plants with battery-powered digital inertia are underway [68].
