Energy storage has the potential to help with hospitals’ PV self-consumption, peak shaving and resiliency, a sustainability executive from South Africa-based private hospital group Mediclinic said.
The company is installing rooftop PV across its hospitals in South Africa, which should lead to a total renewable energy consumption of around 43%, said Petrus Swanepoel, Infrastructure Sustainability Manager for the Southern Africa division of Mediclinic.
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However, the current strategy only involves using that energy for self-consumption, with no exporting to the grid or storing in batteries. Mediclinic has also concluded PPAs with external companies.
“My proposal for our new strategy, and this is something that still needs to be approved by the board, is to use energy storage to maximise maximum PV generation, by storing some of the excess energy in the batteries and then using that during peak tariff times,” Swanepoel said.
The battery systems could also compensate for load shedding by grid operator Eskom, an issue endemic to the country’s electricity system, he added.
The company runs private hospitals in South Africa, Namibia, Switzerland the UAE, with nearly 9,000 beds under its operation in South Africa.
Swanepoel also said he “does not believe lithium-ion is the right option” due to environmental issues, the amount of water that is used, the question of its end-of-life as well as the obvious question of fire risk.
“Vanadium redox flow batteries (VRFBs) are something I would like to pursue further,” he added. “I will do more investigating once the proposal has been accepted, but my personal view is it will be a mix of chemistries and lithium will not be the only source.”
He went on to discuss a general hospital’s typical energy usage, curve and consumption patterns. Energy use starts to pick up at 5 am and peaks around or just before midday, dropping slowly over the rest of the day to about 9 pm.
Peak energy consumption is about 45% higher than the baseload on weekdays and about 25-30% higher on weekends (when hospital are generally less busy).
The biggest users of energy in a hospital are its HVAC systems (Heating, Ventilation, and Air Conditioning), meaning that thermal energy storage is also a potential option, although not one Swanepoel had yet considered due to its lack of maturity as a technology.
Mediclinic two years said it was aiming to become completely independent of Eskom by 2029.