A schematic of a hybrid compressed air system is shown in the figure below. The benefit of a hybrid system is its flexibility to allow base-loading the unit whose fuel cost is the least expensive at the time of use. Normally, this means base-loading natural gas units during peak cost periods for electric rates and base-loading electric units during other electric rate periods.
Hybrid Compressed Air System Schematic
(Click on each of the four sections to enlarge)
A sample operating schedule for a hybrid system is shown in the figure below. In this case, two compressors were installed at 66% of peak capacity. The compressors operate two shifts per day. The gas engine-driven machine (dark gray) is shown to be operating at 100% of its capacity during the on-peak hours of operation, while the electric machine (light gray) picks up the remainder of the load. During mid- and off-peak periods, this situation is reversed. By operating in this manner. Maximum energy expense reduction can be realized by always using the least expensive fuel to compress air.
Hybrid System Operating Schedule
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