The 3KVA Evolution UPS from MGE UPS Systems Inc., Costa Mesa, Calif. (www.mgeups.com), provided power to a rack of computer-networking equipment and a large plasma-screen display while a portable fuel-cell generator kept a small refrigerator, lighting, and other small electronics operating during the hour-long presentation.

The fuel-cell modules, called the Nexa RM Series, come from Ballard Power Systems, Burnaby, B.C. (www. ballard.com). Fuel cells will operate as long as they have fuel, so the duration of the backup depends on the size and quantity of fuel-storage tanks. Typical range is 4 to 24 hr. Hydrogen is fed to the fuel cells via an adapter kit from standard 31-in.-high Q or 51-in.-high K-style pressurized gas cylinders from Praxair Inc., Danbury, Conn.(www.praxair.com). The fuel-cell modules produce a dc voltage that is then bused to the UPS.

Each 1 kW fuel-cell module has a ±24-Vdc output and produces 40 A of current. Three of the 85-lb modules go in the Evolution UPS configuration. The UPS uses 3.5 in. of rack space and weighs 80.4 lb. It includes connectors to accept dc input from the fuel-cell modules and six standard 15-A NEMA receptacles as well as USB, serial, and SNMP/Web-connection options. Commercial production is slated for next year.