Power loss is a serious concern for data centers. It used to be standard for USPs to be used to ensure continuous power, but there are more modern ways to ensure continuity, more efficient ways. The flywheel system described is much more energy-efficient, and allows for less downtime. This makes the system not only more reliable, but also greener.
Read the full article here to learn more:
http://www.datacenterjournal.com/facilities/greening-data-center-flywheels-true-efficiency/