With Cloud, managed services, edge, 5G, AI, machine learning, robotic process automation, IoT and many other new technologies and ideas seemingly being embraced by businesses of all shapes and sizes in their quest for digitalisation, why is it that a recent data centre UPS development - the lithium-ion battery – is struggling to gain widespread acceptance? This question seems particular relevant when one considers that lithium-ion (Li-ion) batteries hit the sweet spots of two likely future data centre developments – the rise of high rise data centres and a marked increase in the number of modular data centres. A Li-ion battery’s light weight, when compared to that of sealed lead-acid (SLA) or valve regulated lead-acid (VRLA) batteries, is a major advantage when it comes to building high rise data centres; and the smaller footprint (typically, Li-ion batteries provide the same power density as SLA/VRLA batteries in under half the space) is a major advantage for the modular data centre market. And the Li-ion advantages over the tried and tested SLA/VRLA technology don’t stop there. Yes, SLA/VRLA batteries are reliable and, relatively speaking, inexpensive to purchase, but their operating temperature is limited to approximately 20-25 degrees centigrade – hence they often need air-conditioning to cool them down – they need regular maintenance and, as their impedance increases over time, they need to be replaced an estimated every three to five years. In contrast, Li-ion batteries are not only smaller and lighter than SLA/VRLA cells, they are virtually maintenance-free, have something like a 15 year lifespan and can operate in temperatures up to 40 degrees centigrade (there’s the suggestion that this attribute could do away with the need for a separate battery room as required for SLA/VRLA batteries). Ah, but the purchase price of Li-ion batteries is significantly higher than for SLA/VRLA units; Li-ion batteries need constant monitoring and there are some safety concerns surrounding their use – existing fire suppression systems might need to be modified. CAPEX v OPEX is a familiar debate across many industry sectors. In the case of the data centre industry and the choice between Li-ion and SLA/VLRA batteries, it seems that the higher purchase price of the Li-ion technology is a significant obstacle at the present time. That said, data centres currently using the SLA/VRLA batteries in their UPS systems may well consider Li-ion alternatives the next time their lead-acid batteries need replacing. There really do seem to be very few, if any, significant downsides to Li-ion technology and it would be strange if data centres owners and operators continued to ignore the benefits they offer. Especially when one considers that the price of Li-ion batteries is only going to come down further – economies of scale will surely come into play as and when the electric car industry starts to boom. There is one more potential benefit of using Li-ion batteries, when compared to SLA/VLRA cells, and that is the much talked about opportunity possibility of ‘demand-side response’. As of today, there could be as much as 4 gigawatts of electricity stored in Li-ion batteries in the UK. As the smart world develops (smart cities, the smart grid etc.), there’s the very real opportunity of using this ‘nascent’ power source to feed into the nation’s power grid and to earn money for doing so. Clearly, data centre UPS systems are bought to guarantee facility uptime, and anything that could adversely impact on this activity might be viewed with suspicion. However, there are plenty of Li-ion advocates who make a convincing argument for the technology being able to both offer data centres the uptime levels they required, and also to feed power into the grid at certain times. (As an aside, it’s worth noting that traditional lead-acid batteries are responsible for a significant amount of the unplanned downtime experienced by data centres at the moment). When one considers that waste heat recovery/re-use has long been possible in the data centre – yet few facilities put this into practice, maybe we should not hold our breath as to the likelihood of Li-ion-based UPS systems being used to meet the need for demand side response. However, as liquid cooling gains significant traction within the data centre, bringing with it the possibility of much more efficient, financially worthwhile waste heat recovery/re-use, maybe the complimentary idea of demand side response will gain corresponding traction. The data centre industry is split between the glass half full or half empty when it comes to energy resources. However, with the recent news that the current, parlous state of the UK’s water resources threaten supplies into 2020, and the failure of at least two significant, planned nuclear power station builds, it’s not impossible to envisage a scenario where energy efficiency will become critically important into the future. Clearly, anyone running a data centre will specify the optimal UPS system for the facility, regardless of any spin-off benefits. With Li-ion batteries offering so many benefits when compared to lead-acid cells, it’s highly likely that more and more data centre specifiers and managers will choose this technology. And if there’s the added benefit of making some money back over their lifecycle, what’s not to like?!