Batteries Not Included…
By Thomas E. Reed, PE
New Technology Emerging in Uninterrupted Power Supply Systems
For corporate real estate directors, facility managers, IT managers and other executives involved in office facility planning and operations, there is a new uninterrupted power supply system which may eliminate DC battery back-up in the event of an emergency power loss. This new technology may be cleaner, less costly, more environmentally sound and require less maintenance in operation.
Once used primarily in emergency facilities, uninterrupted power supply (UPS) systems are becoming more commonplace as many types of companies seek to maintain the performance of mission critical functions in the event of an emergency power loss. UPS systems are no longer reserved for emergency centers or hospitals, but are being sought out for financial services organizations, pharmaceuticals, information technology companies and many others.
Traditionally, the vast majority of UPS systems deployed in the United States utilize various technologies based on converting Utility AC power to DC power and then back to AC power. This technology requires DC batteries to provide back-up power during utility outages.
Some of the new opportunities in UPS technologies available provide owners significant advantages, while virtually eliminating batteries and the associated environmental impacts and costs for maintenance and replacement.
To follow is a snapshot of the new opportunities being developed for UPS systems. The first alternative would be to utilize UPS system with a flywheel energy storage device backed up by a separate diesel generation system. The flywheel type UPS system is similar to a static battery type system except that the DC battery plant is replaced with a flywheel kinetic energy device. The inertia and energy of a rotating flywheel is used to provide the uninterrupted power ride-thru capability in the event of a normal power loss for the 10-15 seconds it takes to start the on-site backup standby generator system.
This system is provided with a 25-second ride-thru capability to allow time a generator (plant) to start and parallel sufficient units as appropriate. The 25-second ride-thru capability can be achieved using multiple flywheel units.
Another alternative would be to utilize the flywheel energy concept UPS with the back-up engine generator directly coupled to the system. This UPS system is a development of the flywheel energy concepts mentioned previously with the backup engine-generator directly coupled to the system and closely integrated in its operation and control. The unit provides 3-5 seconds of ride-thru kinetic energy and is directly coupled to the engine-generator unit mounted in-line with the output generator.
While often a standard approach to replacing, upgrading, or installing new UPS technology seems most appropriate and comfortable, there are new solutions and technologies that can provide significant benefit to owners, operators, and “benefactors” of UPS systems; especially when the life-time of the equipment is considered and not just first cost. The preceding provides a snapshot of the alternatives being developed today. Additional alternatives such as Fuel Cells and Micro-turbines have also made a significant impact in the market and warrant consideration. Overall, the replacement cost and environmental issues associated with battery replacement will continue to play a significant role in Total cost of Ownership of UPS technology and leveraging options can be of real benefit.