Fig. 6 shows the turbine inlet temperature which at steady state equals the dew point temperature to which the spent cathode air must be cooled in the condenser for process water recovery. Also shown is the calculated motor power needed to drive the CEM for the 100kWe FCS. In calculating the shaft power we have allowed 3 psi (20.4 kPa) pressure drop between the compressor and expander at rated flow and have assumed that the pressure drop scales up linearly with flow.Fig. 6 indicates that at 42 ◦C ambient temperature 6.2kW is needed at the shaft at rated flow. The system actually needs a motor larger than 6.2kW to satisfy the requirement of 1 s Fig. 7. Modeled performance map of a high-speed induction motor for 100kWe FCS.response time. In our modeling analysis, we determined the motor size such that the air management system can adjust to provide the cathode flow necessary for the FCS power toincrease from 10% to 90% of rated power in 1 s. Assuming that the motor can be overloaded by 50% for 1 s, we calculate that the 100kWe FCS requires a motor of 9.3kW rated power.With the oversized motor, the air management system can continuously supply 120% of the rated flow at 42 ◦C ambient temperature if the stack is warm (80 ◦C stack/turbine inlet temperatures) and 110% of the rated flow if the stack is cold (20 ◦C ambient and stack/turbine inlet temperatures).At 20 ◦C ambient temperature, the maximum capacity of the air management system is greater than 120% if the stack is warm (80 ◦C stack/turbine inlet temperatures).