A facility uses an 23 hp fan to blow-dry products on an conveyor belt in a plant that operates 24 hours a day, 365 days a year. For 34% of the time, the fan needs to run at full load, but for the remainder of the time the fan could run at 43% speed and meet the plant's needs. However, the plant currently runs the fan at 100% speed at all times. You recommend that the plant install a Variable Frequency Drive to allow the fan to run at the reduced speed when possible. Assume that the motor efficiency is 91.4 and the motor power factor is 0.85. Assuming that the plant pays $0.09 per kWh, and that a VFD costs $250 per hp, what is the simple payback period for this recommended change (in years)?