Despite current economic difficulties, the companies that construct and operate the data centers that run the Internet and store vast amounts of corporate and government data are expecting growth this year of about 19%. (Source: Datacentre Dynamics survey 2011).
This is not surprising when you look at current trends in the information technology sector. This year, mobile Internet handsets are estimated to send more than eight trillion text messages, process over $240 billion in mobile commerce payments, and transmit over six million terabytes of data. (Source: DEA-543 © 2012 General Electric Company) In the next decade, global digital content is forecast to increase some 30 times to 35 zettabytes (that’s 35 trillion gigabytes) and cloud computing will grow to a $240 billion market. (Source: DEA-543 © 2012 General Electric Company)
The cost and availability of energy for our power-hungry computers is a top concern, and national governments and industry agree that we must find ways to control energy demand and at the same time reduce our carbon footprint. Data centers are estimated to consume 2% of the U.S. electrical grid capacity, resulting in $2 billion per month in utility bills. A McKinsey & Company study estimates carbon dioxide (CO2) emissions from data centers will quadruple to exceed emissions from the airline industry by 2020, owing to the rapid growth in global demand for computing power. (Source: DEA-543 © 2012 General Electric Company )
The US Department of Energy is focused on “green” initiatives to improve energy efficiency and have set a target to create energy savings of 10% overall in U.S. data centers, which is 10.7 billion KWh or the equivalent of electricity consumed by one million typical U.S. households. Although most of the industry effort has been on improving the efficiency of information technology (IT) and cooling equipment, the uninterruptible power source (UPS) is now in the spotlight for energy optimization with manufacturers such as General Electric. (Source: DOE 2011)
The U.S. Department of Energy (DOE), the U.S. Environmental Protection Agency (EPA), The Green Grid and other organizations are developing metrics to measure data center efficiency and track improvements. The EPA has new programs for Energy Star ratings for data centers, IT servers and UPSs in various stages of development. The Green Grid consortium has established the power usage effectiveness (PUE) measurement to define and track data center efficiency.
PUE, a ratio of the total power consumption divided by IT power consumption, measures the energy efficiency of the electrical and cooling infrastructure supporting the IT loads. A typical PUE is around 2.0, with the IT load, cooling system and UPS system being the largest energy consumers. Recent energy optimization of the cooling system has resulted in a PUE of 1.5 or less for new data centers. To improve PUE below 1.5, optimization of UPS efficiency is required.
The UPS is a critical part of the data center power infrastructure that improves the reliability of power supplied by an energy utility company from a typical 99.9% to the 99.999% required by a data center facility. Double conversion UPS systems have become the preferred technology for data center applications.
There are significant improvements in UPS energy efficiency available today, based on new technology, better understanding of IT server power-quality requirements and reliability of the utility grid. Recent technology improvements in the high-efficiency operating mode (previously called “eco mode”) for double conversion UPSs significantly reduces UPS energy consumption by almost 75%. The data center industry will be able to adopt this high-efficiency mode for double-conversion UPSs without compromising operational reliability.
The power quality of the utility grid determines the availability of the UPS high-efficiency operating mode. The more reliable the utility power, the higher the availability of the UPS high-efficiency mode. EPRI developed the System Average RMS Variation Frequency Index to measure the actual utility voltage variation at more than 200 substation sites around the U.S. for a two-year period.
EPRI shows that the average outside the ITI (CBEMA) curve is only about 25 utility events per year. Although most of these events are of very short duration (less than 10 seconds), a conservative assumption of one-hour duration per voltage event results in the UPS only needing to operate in double-conversion mode about 25 hours per year; the high-efficiency operating mode availability would exceed 99%.
The eco mode UPS is included as an energy-efficiency recommendation in the recent Green Grid Data Center Maturity Model, and The Green Grid will be offering a presentation entitled “Evaluation of Eco Mode” at the upcoming Green Grid tech forum in March. Also, the U.S. EPA has included eco mode in the upcoming EPA Energy Star specification for UPSs, and it even stated that using eco mode is an innovative strategy for saving energy in UPS systems.
The cost savings of the high-efficiency UPS operating mode are significant when evaluated over a 10-year life cycle. For a data center with 5 MW of IT load, operating the UPS in traditional double-conversion mode will entail power costs exceeding $4.5 million over 10 years, assuming $0.10/kWh. The same data center operating in UPS high-efficiency mode will only have power costs of about $1.2 million, providing a savings of $3.2 million over 10 years.
If the data center industry adopted UPS high-efficiency mode as normal operation, the impact would be significant. According to Frost & Sullivan UPS World Reports, the last 10 years of UPS-installed base is between 60,000 to 70,000 MW, and the efficiency of this legacy UPS double-conversion technology is probably 90% or less. If this installed base were replaced with UPSs operating in high-efficiency mode, the data center industry would be able to realize at least 4,000 MW of energy savings, producing annual energy cost savings of more than $3 billion per year. (Source: Frost & Sullivan 2011)
UPS Manufacturers like GE have responded with a new range of energy-efficient models, and although the conversion of the legacy UPS-installed base to high-efficiency UPS mode will not happen overnight, the technology is proven, the business case is clear and the opportunity for new data centers to install and operate UPSs in high-efficiency mode is attainable today.
About the Author
Brad Thrash is a product manager at GE Energy working in the power-quality business and is responsible for the global three-phase UPS product line. He has over 25 years of experience in GE power generation and power-quality businesses, with leadership roles in application engineering, service engineering, sales and product management.
Brad has a degree in mechanical engineering and is a licensed professional engineer. He is also a member of IEEE and ASME and is on the Power Sub Work Group of The Green Grid. He will be presenting a paper on the Evaluation of Eco Mode for UPS at the Green Grid Forum 2012 on March 6 in San Jose, California.
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