TABLE OF CONTENTS Backup power is defined as any device that provides instantaneous, uninterruptible power. The term UPS (uninterruptible power supply) is an often used term, but can sometimes refer to systems that supply A/C power, or systems that supply power for no more than 30 to 60 minutes. A more general definition includes all types of power outputs and all backup times. Typical applications for backup power include telecommunications systems, information technology and computer systems, manufacturing processes, security systems, utility substations, and railway applications. Backup power systems are employed in cases where the loss of power results in a significant reduction in productivity or financial loss.
Fuel cell system requirements for backup power applications significantly differ from requirements for such systems in automotive and stationary (primary) power generation markets. As Table 10-4 shows, there are only a few common characteristics between the backup power on one side and automotive and stationary (primary) power on the other.
| Automotive | Stationary (Primary Power) | Stationary (Backup Power) | |
|---|---|---|---|
| Power output | 50 100kW | 1 10kW & 200kW | 1 10kW |
| Fuel | Reformate/H2 | Reformate | Hydrogen |
| Life (operational) | 5000 hours | >40,000hrs | <2000hrs |
| High efficiency | Critical | Critical | Not critical |
| Instant start | Very important | Not important | Very important |
| Output mode | Highly variable | Variable | Constant |
| Operation | Intermittent | Constant | Intermittent |
| Preferred voltage | >300V | >110V | 24V or 48V |
| Heat recovery | Not needed | Very important | Not needed |
| Water balance | Very important | Very important | Not critical |
| Size and weight | Critical | Not critical | Not critical |
