Electrical

There are a couple of key issues that have led to the developments and advancements in the Uninterruptible Power Supply (UPS) arena.  The first, and the most talked about in general, is the continual greening of IT and data centers.  UPSs have taken a cue from other data center components and have jumped aboard the environmentally friendly bandwagon. In addition, compliance issues and the mainstream acceptance of flywheel technology are helping the UPS industry deliver significant energy efficient solutions while eliminating hazardous waste.

Data Centers Going Green……Down to their UPSs
The greening of IT has been steadily gaining a foothold across all businesses and public facilities for quite some time.  Data centers are natural candidates as they are extremely power hungry beasts that consume energy on a 24/7 basis. (Fig.1).   A wide variety of energy efficient solutions have gained widespread acceptance, and UPS technology has jumped on the green train as well According to David Joy, vice president of marketing for the power division at Emerson Network Power, “An increasing trend is seen to maximize efficiency and minimize environmental impact.”

(Fig.1) A Liebert FS flywheel system is the first line of energy storage defense for Total Card’s data center.

One key area of concern for data centers is the lack of space that they have available, otherwise known as footprint.  According to Bill Campbell, senior product manager of Emerson Network Power’s Liebert line of power system products, “Some facilities, such as large ’Tier-IV’ type data centers, specify redundant equipment: e.g. two UPSs in parallel in case one of them where ever to fail, and similarly for the generators, energy storage, etc. When flywheels are used in parallel with lead-acid batteries, a much higher level of reliability is attained compared to that of using two parallel strings of batteries.” 

Flywheel Technology
“When used in parallel with batteries, the flywheels cover ALL the short-term energy discharge needs, whether for bridging the time for the backup generator to start or just to cover the momentary power glitches common to all utility feeds. This saves the batteries for only the longer term power outage requirements (assuming no genset) and extends the relatively short cycle life of UPS batteries by isolating them from any momentary power outage cycling,” Campbell added.

Batteries are rather temperamental, and their life is impacted every time they are used (or "cycled," i.e. discharged and then recharged). In contrast, cycling has no impact on flywheel longevity. Used without batteries, flywheels provide the 10 to 30 seconds of DC energy required to get a standby genset on-line.

This all translates into increased power reliability, reduced space requirements, and vastly lower own-and-operate expense, much to the delight of data center operators who struggle with other high costs. 

Compliance Continues to Effect Everything

The growing list of federal mandates effecting data and its storage has had a trickle down result that has touched upon just about every component within an organization’s IT infrastructure; and that includes UPSs.

According to Campbell, “Major efforts are underway in the mission critical cooling and UPS power industries to improve end-to-end electrical efficiency, from the service entrance through the UPS and power distribution and cooling equipment right down to the chip level in servers.”

Flywheel Technology Ramps Up

Piggybacking on environmental responsibility, flywheel technology (Fig.2) has grown in both acceptance and popularity.  It has emerged as one of the new go-to options for those with both environmental and cost saving concerns.  According to Joy, “Regarding the energy storage component of a UPS system, facilities are trending away from lead acid batteries and toward flywheel energy storage systems.”

Fig. 2. Cutaway of Pentadyne’s VSSdc+ Flywheel System
 
UPS batteries contain toxic lead bathed in sulfuric acid – the antithesis of environmental responsibility. Lead-acid batteries also emit explosive hydrogen gas, enough to literally blow the roof off one data center near Sacramento. The gases released by lead-acid batteries also have an impact on global warming. Special handling is required for these toxic materials during their operating life as well as careful disposal. And since they have to be replaced every two to four years, sustainability is limited.

Regarding energy efficiency, batteries generate heat all the time – especially when they cycle – and must be kept cooled to a temperature of around 75°F. Flywheels and UPS equipment can operate in environments of 100°F or more without the dedicated air conditioning needs of batteries and their associated HVAC equipment and utility costs.

Carbon fiber flywheels such as the Liebert FS made by Pentadyne use only half the space needed by VRLA type batteries (the most compact, commonly used UPS batteries) and consume less than 300 watts, just like a battery float charge. Due to weight, battery cabinets often must be installed in basements or on reinforced floors. The relatively lightweight carbon fiber flywheel system (1,300 lbs versus about 4,000 lbs for a battery cabinet) can be rolled into place on their casters and installed virtually anywhere. 

There's no need for dedicated HVAC – thus saving HVAC energy costs – nor all the personnel safety equipment required where lead-acid batteries are used. These flywheels have very high uptime availability due to their extremely infrequent maintenance needs: just a one-hour capacitor change recommended once every six years. Front access to the flywheel further eliminates space issues and opens up installation site flexibility in support of future data center expansions and re-arrangements.

For the end user, advantages of flywheel technology over batteries include much better reliability, vastly higher uptime availability, smaller footprint and greater energy efficiency (charging time is seconds, not hours, and there’s no HVAC needs). As to the bottom line, own-and-operate cost savings versus batteries can easily amount to more than $100,000 per flywheel deployed over the course of the flywheel life.

According to Liebert’s Campbell, “Power quality studies by EPRI (Electric Power Research Institute) show that nearly 99% of all power disturbances last less than 10 seconds, a time period easily bridged by flywheel stored energy. When used without batteries, 10 seconds is enough time to start standby generators (10 second generator start time is a requirement for medical facility backup power systems).  When used with batteries, the flywheel handles all of the utility short term outages, saving the batteries for only the longer term outages (assuming no standby generator), which are far fewer in occurrence.

Looking Forward

In terms of where the UPS industry is headed next, it appears as if it will continue down the same path; one that lends itself to being both environmentally efficient and cost effective. Coupled with its ability to help organizations protect the vast amounts of data they have acquired, the UPS area is a double-digit growth industry as more and more end users realize just how important UPSs truly are.

This all means that data center managers and IT personnel need to be aware of what UPSs can and cannot do, and that technology is changing - scalability, modularity, redundancy and manageability are incorporated into a great number of solutions.  Users need to have the tools, training, and support that are needed to understand the solutions and succeed in the marketplace.  

Joy summed up the overall trend, “UPS products are following a similar improvement path - more efficient, smaller footprint, lighter weight, easier to install and later relocate, easily adaptable and scalable for future facility growth, re-arrangement and reliability requirements. The development of flywheels as an environmentally-friendly, more reliable alternative to lead-acid batteries is a key factor in support of this trend.”

All in all it appears that UPSs are evolving at the same rate as other technology and it remains important to keep in mind that they are rooted in technology. 

About the Author: Keith Field, Pentadyne Power