With the increasing requirements for compute and storage, there is a discernible growth in the data centre industry, which is driving a correspon­ding growth in the energy needs of data centres. There is also mounting pressure owing to costly outages, significant op­ex and environmental concerns. Lea­ding data centre operators are deploying new-age technologies to stay ahead in the game while also minimising costs and complying with sustainability standards. Energy storage and battery systems are critical components of data centre infrastructure that are undergoing a marked transformation to address the emerging challenges in the segment.

A look at the current trends in the energy storage segment, and the existing and upcoming battery solutions for powering next-gen data centres…

Energy storage trends

A high level of uninterrupted uptime is a cornerstone of the services offered by data centres. According to the International En­er­gy Agency (IEA), data centres are estimated to use 1 per cent of global electricity. At full capacity, servers in a modern hyperscale data centre can use as much power as 80,000 households. Besides the hu­ge volume of energy consumption, these facilities also require uninterrupted power supply and a reliable energy storage solution. Despite great advancements in power grids, data centres are still vulnerable to out­ages and fluctuations. Traditio­nally, mo­st data centres have relied on diesel-powered generators as the primary backup source of power to the public grid. The technology has been proven in terms of reliability, scalability and affordability. One of the main shortcomings of diesel power is its negative impact on the environment, in­cluding emissions of carbon monoxide, ni­trogen oxide and hydrocarbons.

Today, due to the ongoing climate em­ergency and a global rise in energy prices, the transition to cleaner energy has picked up pace. Governments, businesses and da­ta centre operators are beginning to focus on research and investment in cleaner, non-fossil-fuel-based backup energy systems. The shift towards such solutions is imperative not only for sustainability but also from a corporate responsibility standpoint. This makes energy efficiency, as measured by power usage effectiveness, an important target.

Renewable energy sources such as solar and wind have garnered interest as alternatives. However, there is still a lack of adequate national or global infrastructure for these resources to replace conventional power systems effectively. In this context, three energy storage and production technologies have emerged as viable options to achieve carbon neutrality in da­ta centre operations. These are batteries, biofuels and hydrogen fuel cells.

Battery-backed architectures

Batteries are a core component of the mo­­dern data centre infrastructure. They are key to keeping servers up and running, as well as powering the cooling systems and all their components, the monitoring eq­uipment needed to oversee operations, and other aspects such as lighting and se­cu­rity systems. Uninterruptible power su­pply (UPS) systems help operators ensure that servers and other critical hardware are not subject to public grid outages or power quality issues.

Key innovations in battery solutions for data centres include:

Lead acid batteries

Valve-regulated lead acid (VRLA) batteries with static UPS systems have traditionally been the go-to solution for the data centre industry. However, the performance of these batteries depends on the temperature, which leads to a higher load on air-conditioning systems. They are also generally high maintenance and heavy. Further, these modular cell battery systems need to be replaced in 3-10 years, which is quite frequent. VRLA batteries also lose their power storage over time.

Li-ion batteries

A promising alternative is lithium-ion (Li-ion) battery technology. The key benefits offered by Li-ion batteries over VRLA batteries are their nearly three times lower weight for the same amount of energy, few or no battery replacements, up to 10 tim­es more discharge cycles subject to chemistry, technology, temperature and depth of discharge, around five times faster charging and four times lower self-discharge. More­over, lithium iron phosphate has no cobalt, a metal that comes with ge­o­political concerns and a hefty price tag. It is amongst the least volatile, with the highest safety ratings and is also popular for renewable energy storage on account of its longer lifespan –  particularly for stationary applications.

Due to these benefits, the adoption of Li-ion batteries is rising rapidly in the data centre segment. According to a Frost & Sullivan report, Li-ion batteries will ac­count for 38.5 per cent of data centre en­ergy storage needs by 2025. Bloomberg predicts that Li-ion batteries’ share in the overall demand for battery backup in data centres in North America and Europe al­one will rise from 1 per cent in 2016 to 35 per cent in 2025. However, Li-ion batteries have certain challenges in terms of sustainability. There are constraints in the use of lithium throughout its life cycle, from its extraction, which requires large volumes of water, to strict transportation regulations and complexity in the recycling process. In contrast, VRLA batteries have a long-established recycling supply cha­in, which can recover over 98 per cent of co­mponents. The industry is exploring more efficient and innovative solutions to repla­ce the existing battery systems.

Na-ion batteries

Sodium-ion (Na-ion) battery systems are fast emerging as an improvement over Li-ion. These batteries substitute li­thi­um with sodium, which is far more abundant and less expensive. Although the technology is not particularly new, lower prices are now driving its adoption among data centre players. However, the major problem with Na-ion batteries is their life cycle as they are not expected to last as long as their Li-ion counterpart. The issue needs to be addressed before these batteries can meet the demands posed by the growing data centre industry.

Hydrogen cell technology

A fairly new innovation in the data centre industry is the use of hydrogen cell technology, which offers an energy-dense and clean power source. The technology may present a more lightweight solution as co­mpared to battery cells; however, the sol­ution is still too expensive and lacks suffi­ci­ent support infrastructure. There are also several challenges and inefficiencies in the hydrogen production process.

Other viable battery technologies em­erging in the industry include sodium-sulphur, sodium-nickel-chloride, nickel-cadmium, vanadium redox flow battery, and zinc-bromine flow battery. According to ex­perts, liquid-metal batteries can be a potential game changer in various UPS types, owing to a better life cycle, footprint, res­ponse time, upfront system cost, operating cost, and geographical dependency.

Deployments by hyperscalers

Globally, batteries are taking on a more prominent role in data centre energy storage. Hyperscalers including Google and Amazon are testing the expansion of their existing UPSs. For instance, Google initiated a pilot in 2021 to deploy large-scale batteries at its data centre in Saint-Ghi­slain, Belgium, to advance its goal of running its data centres and global operations on 24×7 carbon-free energy by 2030. As the data centre’s batteries are not operated continuously, the company also leveraged the opportunity to employ them to offer services to the Belgian grid and contribute to grid stability. Meanwhile, Microsoft an­nounced plans last year to introduce a Li-ion battery energy storage system (BESS) and a grid-interactive UPS to its Dublin data centre. The company replaced the lead acid batteries in its UPS with Li-ion ba­tteries, which will reduce the need to fire up diesel generators. The new BESS also allows controlled involvement in a frequ­en­cy regulation system run by the local utility, EirGrid, which routes power to the grid when there is a short-term need.

The road ahead

While Li-ion batteries remain the dominant technology in the data centre segment, the associated challenges and the metal’s inherently toxic nature are driving the industry to explore other alternatives. With hydrogen having production inefficiencies, Na-ion battery systems seem to be the way forward. Data centres can also deploy a combination of new and existing solutions to replace inefficient diesel generators.

Furthermore, new-age technologies are being explored to help support the energy storage needs of data centres. For instance, artificial intelligence is being tested for use in energy storage solutions for cooling and automatically charging and discharging the battery for higher efficiency and an improved life cycle. As leading data centres globally explore innovative solutions and enhanced technologies, planning ahead will be the key to achieving the cost optimisation and sustainability objectives.