The COVID-19 pandemic has completely upended the definition of business as usual, highlighting the need for a newer, different way of thinking. This especially rings true for today’s enterprise, cloud, and colocation facilities handling the data explosion caused by remote workers, virtual classrooms and events, telemedicine, video streaming, social media, and a myriad of other processes. And, as 5G rolls out, AI, ML, and IoT data will further challenge the IT infrastructure.

Worldwide spending on data center hardware and software reached $41.4 billion in the second quarter of 2020, fueled by a 25% spending spike by public cloud providers like AWS, Google, and Microsoft up 7% year over year, according to Synergy Research Group.

“For the remainder of 2020, organizations that expand remote work functionality will prioritize collaboration software, mobile device management, distance learning educational solutions, and security, as well as the infrastructure to scale to support increased capacity,” said Sid Nag, research vice president at Gartner.

With this accelerated IT infrastructure focus, electrical power feeding the data center must be always on, as any disruptions will wreak havoc on digital ecosphere.

The Costs of Power Outages

The costs of unplanned power outages are rapidly increasing. According to the Ponemon Institute, which has been tracking the price tag of data center power outages since 2010, the average cost of an outage has steadily increased from $505,502 in 2010 to $740,357 in 2016 (or a 38% net change). Given today’s state of digital reliance, one can only conclude that the costs in 2020 and beyond will be even higher.

As part of the study, Ponemon captured direct and indirect costs, including damage to mission critical data; impact of downtime on organizational productivity; damage to equipment and other assets; cost to detect and remediate systems and core business processes; legal and regulatory impact, including litigation defense cost; lost confidence and trust among key stakeholders; and diminished reputation.

And it’s not just data centers that are vulnerable to outages; all mission critical applications — from medical facilities to industrial plants, transportation systems, defense, and microgrids — require reliable power for continuous operation.

The Power Grid

The resilience of the electric grid in many parts of the U.S. is still very questionable. In California, heat, fires and utility-mandated blackouts that mitigate fire spread or control demand peaks can be a big problem. Even though strides have been made in modernizing the grid, thanks to the American Recovery and Reinvestment Act (ARRA) of 2009 along with grants and private investments, reliability continues to be a challenge.

In a recent blog from the Union of Concerned Scientists, it was reported that “…the U.S. needs to invest in our bulk electricity transmission system to relieve congestion, update aging infrastructure, and carry new renewable energy to load. We need investments in our electric distribution systems and workforce to accommodate widespread rooftop solar and new energy efficiency and flexible demand technologies.”

Powering the Infrastructure

According to Verified Market Research, the global data center power market was valued at $17.45 billion in 2019 and is projected to reach $28.44 billion by 2027, growing at a compound annual growth rate (CAGR) of 6.32% from 2020 to 2027. Today’s data center operators spend a considerable sum on power systems to ensure 24/7 operational continuity. However, with more energy-efficient systems available, such as energy storage, the total cost of ownership (TCO) decreases while efficiencies increase.

The ongoing move by enterprise, mid- to large-sized data centers, and colocation and hyperscale facilities to incorporate energy-efficient and lower-cost power systems is driving considerations for innovative ideas. Not surprisingly, data center operators and facility managers typically take what they view as a no-risk approach to protecting their IT infrastructure. The need for more efficient power protection has driven major UPS vendors to make significant advancements in their three-phase systems, including efficiencies up to 99%, modular power electronics, scalable designs, and much smaller footprints. A critical component to the UPS is the DC energy storage system, which requires special consideration.

Chemical-Based Energy Storage

Valve-regulated lead-acid (VRLA) batteries have long been the go-to for UPS energy storage. They are proven and have a lower upfront purchase cost than other battery technologies. However, they have many downsides, including:

  • Failures — according to the Ponemon study, 55% of unplanned data center outages and one-third of UPS failures were caused by VRLA batteries.
  • Short life spans, which equate to frequent replacements.
  • Cooling requirements.
  • Frequent testing and maintenance needs.
  • Space and weight constraints.
  • Recycling and disposal compliance.
  • Acid leak containment.

Some of the major UPS companies offer lithium-ion batteries as an energy storage option. And, while they have a higher energy density and longer life than VRLA batteries, they have disadvantages as well. Per the NFPA 855 standard, lithium-ion batteries must include an approved battery management system (BMS) with thermal runaway management to mitigate fires, 3 feet of clearance around battery cabinets is required to mitigate fire spread, and they have a high total cost of ownership despite their longer life span.

Due to their chemical nature, there is no perfect battery system — not yet, at least. A safe and environmentally friendly approach to energy storage is to move away from chemical-based batteries to a mechanical-based storage solution.


In the quest for lower environmental impact, mission critical operators are turning to flywheel systems to provide the power protection they need, reduce their carbon footprint and utility costs, and eliminate or greatly reduce the use of batteries.

Operating like a dynamic battery, a flywheel system stores energy kinetically by spinning a mass around an axis. Leading flywheel systems include a high-speed motor generator, active magnetic bearings used to levitate and sustain the rotor during operation, and a control system that provides information on system performance. Electrical input quickly spins the flywheel rotor up to speed, and a standby charge keeps it spinning 24/7 until called upon to release the stored energy. The amount of energy available and its duration is proportional to its mass and the square of its revolution speed. These technologies enable the flywheel to charge and discharge at high rates for countless cycles.

The flywheel system connects to the DC bus of the three-phase UPS. At the onset of a power event, the flywheel is the first source of backup power. When a power disturbance or complete power failure from the grid occurs, the flywheel will immediately support the load until the standby generators are started and online, typically less than 30 seconds. Some might say that 30 seconds is not enough backup time (see Figure 1). 

“Knowing the available energy level at any point in time is a key differentiator for flywheels versus batteries, said Mike McDaniel, vice president of facility engineering for Cavern Technologies. “Given the ability of our generator plant to be online in under 10 seconds, the Vycon flywheels were a perfect fit for our design.”

For those who still want to use batteries, some flywheels can operate in parallel with batteries to provide what is known as battery hardening, which minimizes the cycle demands that limit battery life. In this configuration, the flywheel is the first defense against short, transient power anomalies, saving the batteries for prolonged power outages. By being first to provide the necessary energy to ride through power faults, the flywheel system significantly increases battery life by absorbing over 98% of the discharges that would have normally caused the batteries to cycle. Every time a battery is cycled, its life is diminished.

Using flywheel systems as an energy storage option offers reliability, a 20-year life span, cost savings from reduced cooling requirements, a small footprint, energy efficiency, simple installation that’s hazmat-free, N+1 redundancy options, and a wide temperature tolerance.

Due to their proven reliability and beneficial environmental characteristics, managers of data centers, hospitals, industrial operations, electric rail, and microgrids are overcoming the limitations of batteries and reaping the many benefits of clean energy storage that flywheels offer.