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Time-Fill CNG Fueling Stations


Time-fill CNG stations are used primarily by fleets.  This type of setup works great for vehicles with large tanks that refuel at a central location every night.  Time-fill CNG stations can also work for small applications, such as a small station at a driver’s home.  At a time-fill CNG station, a fuel line from a utility delivers fuel at a low pressure to a compressor on site.  Unlike fast-fill CNG stations, time-fill CNG stations may have smaller compressors and the vehicles are generally filled directly from the compressor, not from fuel stored in tanks.  Although there is a small buffer storage tank, its purpose is not to fill vehicles, but to keep the compressor from turning off and on unnecessarily and wasting electricity.

The time it takes to fuel a vehicle depends on the number of vehicles, compressor size, and the amount of buffer storage.  Vehicles may take several minutes to many hours to fill.  The advantage of time-fill is that the heat of recompression is less so you usually get a fuller fill than with fast-fill.  And you can control when you fill the vehicles, and thus, get better electricity rates needed to run the compressor, such as off-peak hours at night.

Time-fill CNG stations are carefully architected based on the application.  A transit bus company may need a larger compressor that can deliver 8 to 9 gallons per minute, while a refuse truck company may be fine filling trucks at 3 gallons per minute using a smaller compressor.  A consumer application may need far less—such as, less than half of a gallon an hour.  These differences account for the large variance in the cost of installation.

Benefits of a Time-Fill CNG Fueling Station