ELECTRICAL SUPPLY
many charges and discharges – for example if a UPS is used for energy storage to power a medical imaging device in a mobile application or regular use.
A longer design life It is not only the battery cycling capabilities of lithium-ion that make them an ideal choice for powering sensitive applications. With a longer design life, the technology also improves the reliability, efficiency, and flexibility of the facility’s overall backup power infrastructure. HTM 06-01 recommends that batteries used for tertiary power supplies, such as those for a UPS, should have a design life of 10 years. While specialist VRLA batteries do meet these guidelines, a standard lithium-ion battery has an average lifespan of 15 years, with no battery replacement necessary. Despite the benefits presented by this technology, it is still significantly more expensive than traditional VRLA batteries, which is why uptake of lithium-ion UPS systems across the healthcare industry is still low. Runtime and power
configurations are also still limited within lithium technology, and, due to the battery management, not all UPS are currently compatible. If choosing lithium-ion for hospital tertiary power over traditional VRLA batteries, UPS designers should consider the greater need for individual cell monitoring and charging control.
Are hospitals ready for lithium-ion? Currently, UPS specialists can typically choose from a range of UPS and battery products to provide a preferred solution. In theory, lithium batteries can be used for a diverse range of UPS and runtimes – although realistically this is difficult at present, because there are many technical considerations when installing lithium with UPS technology.
UPS manufacturers are fundamental in developing compatible UPS technology and providing set menu lithium solutions. At present, lithium UPS units are available for smaller plug and play single- phase systems and large data centre UPS systems. The smaller lithium UPS are used for comms and telecoms cabinets, perhaps in remote and warm environments. The large data centre UPS systems using lithium batteries are at the cutting edge of UPS technology, and are most likely the driver for technology that filters down into the mid-range commercial market.
Unfortunately, at present, there are not many lithium solutions suited to the UPS and runtime required for hospitals, and especially for operating theatres. Lithium UPS systems will most likely make their introduction into the larger centralised UPS or the IT areas first.
Within hospitals and healthcare HTM applications, there will be advancements in UPS technology. However, more
66 Health Estate Journal October 2021
Battery replacement and closed cabinet for an NHS Trust in Yorkshire.
The X2 Ingenio plus 80 kVA UPS system in parallel.
important than technological progress are the reliability and maintainability of UPS and compliance with healthcare requirements. We anticipate that in another decade, lithium-ion batteries will become more commonplace across a plethora of sectors, including healthcare.
Can UPS and battery technology support an all-electric hospital? Following commitments made by the NHS in 2019 to reduce carbon emissions by 51% against 2007 levels by 2025, with key initiatives including phasing out coal and oil fuel for primary heating uses, power and efficiency feature high on an NHS Trust’s board agenda.
The approaches to carbon reduction are multi-faceted, and include implementing low carbon systems and offsetting carbonised fuel sources. This can be done via renewable technologies or greener electrical systems.
With that in mind, there are areas where UPS and battery technologies can be used to replace carbonised fuel sources. Aside
from IT load, UPS are used in hospitals to support healthcare environments under the HTM guidelines as tertiary power supplies. As defined by the HTM, a tertiary power supply is a third power supply that supplements the PES (primary energy supply) and the SPS (secondary power supply), usually in the form of a UPS or battery system. The SPS is usually standby generators, but may also be CHP or alternative energy plants. Standby generators are proven and used worldwide for a wide variety of standby back-up requirements. However, recent health and safety and environmental pressures have pushed designers to look at alternative methods of back-up power as alternatives to storing multiple litres of diesel, and facing restrictions around emissions.
Over recent years we have seen batteries begin to replace standby generators in life safety systems and commercial standby applications. Batteries are preferred in city locations where generator emissions are harder to manage, and fuel storage is a concern, especially on public buildings. However, standby diesel generators are a reliable and cost-effective method of providing standby power, and many would argue that they don’t produce exhaust emissions while in standby – i.e. the majority of the time.
Can UPS or standby batteries replace standby generators? There is no doubting that the technology is there, as UPS with standby batteries are being installed in 1 MW and 2 MW applications. However, there is a limit to the autonomy that the batteries can provide, and the autonomy if a generator is always available if there is diesel in the system. Generators can also be connected to the high voltage (HV) sub-station, while most UPS and battery storage systems need to be connected
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