Data center power backup systems are not always top of mind for facility operators – but they’re essential to avert crippling outages that often cost over $100,000.

In the event of a power outage, these systems provide the necessary backup power to keep data centers running and prevent data loss or downtime. However, building and maintaining an efficient and reliable backup power system can be complex and expensive.

Effective data center operators should have a strong understanding of their backup power systems so they can identify and execute opportunities to optimize them.  

Optimization of backup power systems will inherently involve maximizing reliability and minimizing cost. However, there are additional characteristics to consider as well, such as safety and sustainability.

The environmental impact of data centers has gained increasing attention in recent years as businesses face growing pressures from investors, consumers, and regulatory agencies to incorporate sustainability into their operations.

To improve the sustainability of backup power systems without sacrificing reliability, operators will need to take into consideration the components that make up these systems, including the uninterruptible power supply (UPS), genset starters, and the generators themselves.  

The UPS

The UPS is a critical component of a data center power system. In the event of a utility power outage, it provides immediate backup power to sensitive equipment like servers, cooling systems, and switches.

The UPS, operating via its batteries, acts as an essential bridge while the data center’s generator prepares to take over. However, the reliability of the UPS can be affected by battery performance.  

UPS systems must contain backup batteries that perform reliably under any circumstances. UPS batteries must perform in parallel strings to provide adequate power and run time to the UPS in the event of an outage.

In lead-acid and lithium batteries, if any single cell in one of these batteries fails, one of the battery strings does not operate. This risks potentially making the data center’s UPS unable to supply enough power or run time when an outage occurs.

Traditional UPS systems use lead-acid batteries, which are heavy, bulky, and require regular maintenance and replacement. One strategy to improve a UPS system’s reliability is using nickel-zinc (NiZn) batteries.

Unlike cells in lead-acid or lithium-ion batteries, cells in NiZn batteries remain conductive even if weakened or depleted. This allows the battery string to continue operating and makes what would otherwise be an emergency, into a simple note for replacement at the next planned maintenance cycle – no added maintenance costs or operational impact. 

In addition to being more reliable, NiZn batteries are also more power-dense than either lithium or lead batteries. Over a short timeframe, they can discharge over twice the power of leading lithium-ion batteries.

This makes them the ideal option for a data center UPS, as less space is required to temporarily power the facility during an outage. This allows more real estate within the data center to be dedicated toward revenue-generating hardware such as servers and storage, increasing the center’s profits as well as its reliability.  

Alternative UPS batteries also offer an opportunity to improve data center sustainability. For example, because nickel and zinc are four and five times more abundant in the Earth’s crust than lead and lithium, and boast more sustainable mining and manufacturing processes, NiZn batteries have six times the GHG avoidance compared to lithium-ion, and four times relative to lead-acid. They also reduce overall water usage, eliminate volatile organic compounds during manufacturing, and are non-flammable.

The generator starter

The generator starter is another critical battery-related component of a data center backup power system, as generators can't provide needed power if the engine doesn't start. According to Cummins Power Generation, “weak or undercharged starting batteries are the most common cause of standby power system failures.”

A data center generator's ability to act as primary power or as a last resort in mission-critical backup applications is gated by the availability and reliability of the starting batteries. 

While lead-acid batteries are the industry standard for generator starting batteries, they’re unfortunately not the most reliable choice. One alternative is using nickel-cadmium (Ni-Cd) batteries, which have proved over several decades to be more reliable and longer-lasting than lead-acid batteries.

However, Ni-Cd battery systems are expensive and require much more space than lead-acid systems. Like lead-acid batteries, Ni-Cd batteries also contain toxic heavy metals.

By using NiZn batteries in genset starters, data center managers can improve the reliability of their backup power systems and reduce costs. Like Ni-Cd, NiZn offers a much longer life than lead-acid. With safe and powerful performance over the past decade, NiZn batteries have also proven to be:

• The smallest and lightest-weight starting energy source for data center class gensets
• One of the lowest maintenance, requiring no regular battery maintenance
• The longest life of currently available engine starting batteries  
• An ideal energy storage device for engine starting due to no thermal runaway, high power density delivering high cold cranking amps, high cycle-life, and recyclability

The power delivery and long-life advantages of NiZn chemistry make these batteries ideal for high-reliability, cold-cranking amps generator applications. A NiZn generator starter battery system provides the same power as an equivalent lead-acid battery system, in a 75 percent smaller footprint – freeing up valuable space in the data center.

While lead-acid batteries require frequent maintenance and replacement, the service life of NiZn engine starting battery systems exceeds ten years and needs no regular battery maintenance.

Today, integrated NiZn engine starting systems can effectively replace the entire lead-acid battery, charger, and control system.

These integrated systems simplify the entire starting battery system while improving reliability and sustainability, lowering lifetime costs, and eliminating the hassle of lead-acid battery maintenance and replacement.

The generator

While the importance of generators cannot be understated, they pose environmental challenges, primarily due to their reliance on fossil fuels.  A series of strategies have been developed to strike a balance between maintaining generator reliability and promoting sustainability. 

One of the most effective ways to reduce the carbon footprint of generators is by switching fuel sources. For example, several data center facilities are beginning to replace diesel with biofuels, which are made from organic materials and are a more sustainable choice compared to traditional fossil fuels. They burn cleaner, reducing the emission of greenhouse gases.  

High-efficiency generators offer superior performance with lower fuel consumption and emissions. While the initial investment may be higher, the long-term benefits in terms of reduced emissions and operational costs are substantial. 

Finally, running generators at optimal loads can significantly improve their efficiency and reduce fuel consumption. Implementing load monitoring systems can help manage power distribution effectively, ensuring generators operate at their most efficient level. 

While generators are an indispensable part of data center backup power systems, there is ample scope to enhance their sustainability. By adopting greener fuels, investing in high-efficiency models, and optimizing power load, operators can make significant strides toward a more sustainable system without compromising on reliability.

When developing a new data center, modular construction techniques allow more efficient use of resources, reduced waste, and easier implementations of sustainable technologies.  

In conclusion, building and maintaining a reliable data center backup power system requires careful consideration of the components involved. The UPS batteries, genset starter, and generator all play a crucial role in ensuring the continuity of data center operations and must be both reliable and sustainable.

Data center professionals must understand and optimize their backup systems to sustainably maintain business continuity and reduce the risk of costly downtime. 

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