2.4.2. Specification Constraints

The ongoing trend towards modularity facilitated by batteries and other clean technology in the energy sector brings flexibility to concept design which can be readily adjusted for specific requirements and translated to different sites. To provide an accessible example, we present a design concept for a hypothetical 550-bed hospital for a small city such as Newcastle, NSW, Australia.

We consider average energy demand, assumed to be 41 MWh per day based on an annual average of 27 MWh per bed [69]. Total energy use consists of electrical and thermal demands which will vary

based on climate and facilities. Using an average value from previous studies, it is assumed here that 49 percent of the total energy use is electrical demand and the remainder is thermal [24,29,69,70]. There are analytical data available for medical oxygen in hospitals [49] and the demand for this scale is assumed to be 708 kg per day. here that 49 percent of the total energy use is electrical demand and the remainder is thermal [24,29,69,70]. There are analytical data available for medical oxygen in hospitals [49] and the demand for this scale is assumed to be 708 kg per day. 2.4.3. Design Goals

### 2.4.3. Design Goals The key constraints discussed above are:

The key constraints discussed above are: • 41 MWh per day total average energy demand.


Meeting hospital demands sustainably within these constraints is the goal of our design work presented below. Re-imagining a healthcare precinct as a renewable energy hub in this way uses public infrastructure to build resilience, improve public health and accelerate the energy transition. presented below. Re-imagining a healthcare precinct as a renewable energy hub in this way uses public infrastructure to build resilience, improve public health and accelerate the energy transition. **3. Results and Discussion: Design Specification for Hospital Renewable Energy Ecosystem** 

### **3. Results and Discussion: Design Specification for Hospital Renewable Energy Ecosystem** We re-imagined a multi-generation energy system for a sustainable hospital precinct that

We re-imagined a multi-generation energy system for a sustainable hospital precinct that integrates renewable hydrogen and battery energy technologies to reduce harmful emissions while supporting reliable operations. To present the integrated systems, we break down the concept design into two sections. The first replaces fossil fuel combustion with fuel cells and batteries for reliable power with redundancy. The second broadens the scope, presenting a networked multi-generation system to sustainably provide other resources in addition to heat and power for deep decarbonization. integrates renewable hydrogen and battery energy technologies to reduce harmful emissions while supporting reliable operations. To present the integrated systems, we break down the concept design into two sections. The first replaces fossil fuel combustion with fuel cells and batteries for reliable power with redundancy. The second broadens the scope, presenting a networked multi-generation system to sustainably provide other resources in addition to heat and power for deep decarbonization.

### *3.1. Replacing Engines and Turbines 3.1. Replacing Engines and Turbines*

flexible capacity can be added with VRBs.

In this case, we consider only the requirement for electrical power. The conventional generator setup could be replaced by a hydrogen fuel cell with storage to meet the set number of hours for the given location. This would take the form of a hybrid energy storage system with a battery, as shown in Figure 5. In this case, we consider only the requirement for electrical power. The conventional generator setup could be replaced by a hydrogen fuel cell with storage to meet the set number of hours for the given location. This would take the form of a hybrid energy storage system with a battery, as shown in Figure 5.

**Figure 5.** Electrical backup system with hydrogen fuel cells during emergency operation. **Figure 5.** Electrical backup system with hydrogen fuel cells during emergency operation.

This energy storage system for emergency power could consist of 1.5 h in lead to comply with AS/NZS 3009 and 24 h in hydrogen. If the system is configured with a suitable amount of spare capacity, this secondary power supply need not be reserved solely for emergencies. The hybrid supercapacitor technology broadens the usefulness of the lead-acid battery cells, and additional This energy storage system for emergency power could consist of 1.5 h in lead to comply with AS/NZS 3009 and 24 h in hydrogen. If the system is configured with a suitable amount of spare capacity, this secondary power supply need not be reserved solely for emergencies. The hybrid supercapacitor technology broadens the usefulness of the lead-acid battery cells, and additional flexible capacity can be added with VRBs.

Starting with the fuel cell backup, six containerized 200-kW units [71] would provide 1.2 MW of power to meet the N + 1 redundancy guideline for an additional unit. 24 h storage would require 850

Starting with the fuel cell backup, six containerized 200-kW units [71] would provide 1.2 MW of power to meet the N + 1 redundancy guideline for an additional unit. 24 h storage would require 850 kg of hydrogen, which could be replenished by a high capacity 300-bar truck trailer. This could be stored on site at 165 bar in approximately 40 tubes with mature technology, or two of the type of containerized solid state 17-MWh units planned for demonstration in Australia [30].

Three commercially available containerized hybrid lead-acid battery units would provide 2.5 MW of peak power with 1.5 MWh of storage [72] to meet a 1.5-h specification for tertiary power supply. An emergency capacity of 2.4 MWh exceeds this by almost 90 percent, meeting the AS/NZS required margin of 1.33 times minimum capacity at install. This also meets the N + 1 redundancy guideline, as two of three units could meet the demand if required.

A vanadium battery secondary supply could consist of four containerized 250-kW units, with a range of capacity options [73]. In a three-hour configuration, this would translate to 3 MWh of capacity and 1 MW of nominal power. This could provide a limited secondary power supply alone, whilst together it could contribute to electricity system security and reliability. For BEVs, this could support up to 100 vehicles with 10-kW vehicle-to-grid connections.

An alternative to this setup is a CHP installation which is typically matched to the heat demand. Two containerized SOFC units would deliver 880 kW of power and 900 kW of heat [74]. Heat pumps, boilers and chillers would support the tri-generation system to reliably meet the variable thermal demands of the facility. In this scenario, a gas-fueled CHP system can be the normal supply, and the electricity grid the backup.

Batteries and stored hydrogen are still desirable for a system like this, connected to both gas and electricity networks, providing greater redundancy whilst making a larger contribution to network security and reliability. Twenty four hours of storage is suitable for VRE penetration of 90 percent [75] and building this in to provide reserves will help deliver fast-responding power assets in the grid that are missing incentives [76]. To achieve the full potential of this approach, though, hydrogen should be enabled to act as a two-way resource as with the battery system.
