Compress Air vs. CO2 Cost Estimates

[rallenhall]

We presently distribute and serve exclusively out of kegs (500 bbl/yr.), which are cleaned with a Premier two-station manual washer. We have no compressed air; all purging/pressurizing functions use CO2 from a series of four 50# tanks. Of course, the CO2 is also used for carbonation, purging our 7 & 15 bbl tanks, etc. We recently came into the possession of an acceptable air compressor (gratis), and planned to install the system with multiple ports throughout the brewery. Our CFO has since requested a projected payback period on the materials and costs of installation prior to approving funds. I've been unable to find a formula or cost analysis that compares air+CO2 vs. all CO2 in keg washing and other brewery operations, except for perhaps taking our cost per pound of CO2 and quesstimating what percentage we could save by using air. Would appreciate formulas, estimates or experiences of those who have been in similar situations.

[RipRap]

Sorry I dont have specifically what youre looking for but if youre pushing with CO2 on your keg washer I would assume you are not using caustic on your kegs. Switching to caustic could save you money there too depending on what you are currently using.

[rallenhall]

Correct RipRap, acid & detergent only. The brewer would like the ability to do a caustic was once in awhile. Can't really get that worked into any cost efficiency sheet though.

[Ted Briggs]

Exit Excell and buy an air compressor with the proper CFM and a filter.

[rallenhall]

I wish it was that easy Ted, but our accountant, who is running a tight ship due to cash flow issues, wants figures. I've dug around probrewer on this topic and found lots of "You're wasting money by using CO2,"; obvious ..... but no one has followed up with figures to say exactly how much.

[mmussen]

Figures are very hard to give as they'll be specific to your brewery.

You should be able to work out how much CO2 your using per purge cycle on the keg cleaner as its simple gas law equations. Caustic is considerably cheaper than a good acid detergent on a per use basis, but again that will depend on your chemical supplier and the exact dosage rates your using for the keg washer.
If the keg washer uses pneumatic valves the spec sheet from the manufacturer will tell you how much gas its using per cycle (or at least give you a good baseline based on their minimum gas requirements). If you're using beer pumps on your tap lines that's another savings.
The thing is all these factors are unique to your system. Air lines and fittings tend to be pretty cheap as brewery parts go. Most of the parts for my air lines came from equipment already around the brewery (spares, extra gas lines etc)

[a10t2]

I'm assuming you know what you're spending on CO2; the per-keg electric costs of the compressor should be minimal but you could certainly break them out based on its specs. Then you can just amortize the costs of whatever gas fittings you need to plumb the compressor in - although since it should be many thousands of kegs that may be negligible as well.