High-Availability Power Solutions Explained

March 21, 2002
Bottom Line Energy Issues - March 2002 - Part 4
Interview with Art Mannion , Ex. VP of SurePower Corporation (www.surepowersystem.com).  Q: What does the phrase “power availability” mean? 
A: Availability is used to measure the probability that a utility-run electric grid or an onsite generator system will function at a future instant in time. Availability figures are usually publicized by utilities as a percentage of 100. For example: 99.9 percent or “three nines”; 99.99 percent or “four nines”; 99.999 percent or “five nines,” and so on. This becomes a problem, however, when vendors and commentators attempt to market their products by multiplying these percentage figures by the 8,760 hours in a year, and then claiming that the resulting number (in minutes, seconds or hours) is the downtime a building faces with a particular system. Building owners need to understand that these figures do not take into account the time to repair. Statistics show that major power systems that fail take an average of 16 hours to repair.  
Q: What role does power quality play in availability? 
A: Nominal voltage fluctuations are enough to shut down sensitive electronic devices. Power quality is the reason high-tech facilities use power-conditioning devices. Businesses that rely on electronic controls must examine power quality along  with availability.  
Q: How can building owners increase availability and power quality? 
A: There are several options. To enhance availability, buildings often employ energy storage devices like batteries or flywheels to provide back-up power for long duration (from 15 minutes to a few hours). Uninterruptible power supply, or UPS, devices provide insurance against very short outages of a few seconds by storing a limited amount of energy in order to deliver a continuous AC signal. For serious power outages of 24 or 48 hours, many building owners install back-up emergency generator systems designed to provide electricity to the facility, including its UPS and cooling systems.   With increasing frequency, businesses are turning to distributed generation, or “DG.”  DG means locating power systems directly at a large business user’s premise or near office parks and other clustered areas. DG power plants can be primary (replacing the grid), parallel (operate along with the grid), back-up, or peaking (run only under optimal financial and/or load conditions). DG power plants by themselves do not deliver high availability, computer-grade power. However, DG can be incorporated into primary power systems that can supply computer-grade power at high availability levels.   To provide the highest levels of availability, one commercial system uses a highly engineered array of low-emission gas reciprocating engines, fuel cells, gas or steam turbines linked with rotary UPS and flywheels. This DG system allows businesses to operate independently of the utility grid with a capital cost no more than grid-based power plus the conditioning and backup equipment. It is also modular and scalable to allow growth that matches power needs without disrupting operations. 
Q: What do you see as the future of high-availability, high quality power? 
Adding more generating capacity on the grid is a dubious solution since most availability and quality issues arise from the aging transmission lines and distribution systems. Because of this problem, we see many facilities moving from grid-plus-back-up systems to complete distributed generation systems. Private DG power systems could enable a significant portion of the nation’s energy-reliant businesses to create their own highly reliable power onsite and under their own control. In addition, many DG systems have minimal environmental impact compared with that of large central power plants or traditional grid-plus-back-up solutions.  Editor: The U.S. Department of Energy is increasing its emphasis on Distributed Generation. To learn more visit the site at (
http://www.eren.doe.gov/distributedpower).Continue >> Part 5 - Commentaries on Enron

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