Power outages come in many shapes and forms, and can be local, regional or widespread. One of the best ways to minimize damage from any of these forms is to immediately switch to your own power source—at least for the short term.
At the local level, you can pay (often quite a lot) for your local utility to run a second line to your business. Located as far away as possible from the main line, the second line will lower the odds that both lines are damaged by the same physical event. Also, be sure your on-site electrical distribution equipment is properly maintained. Problems with this equipment can cause more than their share of outages.
To protect against common short-term dips and spikes, consider uninterruptible power supplies (UPS). A standard feature in many data centers, a UPS uses stored energy to bridge the short gap between when an outage hits and when you’re able to switch to another power source or, at least, to properly shut down equipment. For longer outages, on-site emergency generators can supply power for as long as their fuel lasts--but they can’t come on line nearly as fast as a UPS.
Finally, distributed power equipment/cogeneration systems provide substantial, proactive protection. Similar to an emergency or backup power generator, these systems are intended to be run regularly and not just during outages. Companies often use them regularly during hours of peak demand or peak electrical cost to preempt possible brownouts while lowering costs.