The exhaust is water vapor and CO2. Steam produced in the CSA is returned to the reformer where it is used for fuel processing. The electronic controls for the entire power plant are also contained in this section. Nitrogen, used to shut down the chemical reactions within the fuel cells, is stored in a large tank nearby and can be flowed into the cells through a separate piping system. The 700,000 BTUs of recoverable heat from each fuel cell are channeled to the USPS facility's boiler heating system where it is converted into hot water.
Excess steam is vented through the air stacks.
If one or more of the fuel cells shut down, and load exceeds output, the switch system will automatically start drawing from the grid to maintain uninterruptible power. In essence, the grid functions as the facility's back-up power supply. Typically, to prevent the problem, the end-user will have to install a UPS or battery system to bridge over the gap between the grid failure and the generator picking up. With the quarter-cycle transition, Healy adds, the UPS or battery system is not needed, since the switchover is so fast. As far as the computers and machinery on the load side are concerned, the power supply never halted.