CHICAGO -- This year's WiMax World has 100 more exhibitors than last year, and booths seem twice as big, considering that they actually have gadgets and other gear to demo.

If you are looking for an example of someone here for the first time, you don't have to look that far.

Spokane-based ReliOn, a company building fuel cells for back-up power needs, is a newbie to the show.

Sandra Saathoff, ReliOn's spokeswoman, said the industry seems to be hitting a point at which it may need backup power solutions for cell sites.

Part of the reason is that the FCC may mandate that cellphone companies, and conceivably WiMax providers that provide voice services, must provide eight hours of backup in case of an emergency.

ReliOn has built a closet-sized system using fuel cells and hydrogen tanks that can provide 48 hours of continuous 1 kilowatt output. Cell sites could require more than that output, which would decrease the amount of time the hydrogen would last. The cabinet costs somewhere in the $14,000 range, but is much more compact than batteries, Saathof said.