Hi Tyson,
We have evaluated your CO2 numbers from 11/30/2020 to see what the cost would be to generate your own nitrogen in place of purchasing CO2. The ROI time will depend on the efficiency of the nitrogen generator, how many hours you operate the nitrogen generator per year, if the consumption is steady or fluctuating, if you already have compressed air and what nitrogen purity you settle for. For beer dispensing, small membrane systems producing 99.5 - 99.9% purity are commonly used. For purging of kegs, bottles and cans, 99.99% purity (max 100 ppm O2) is most commonly used, requiring a Pressure Swing Adsorption type (PSA) nitrogen generator, and that is what my ROI calculation is based on. Most breweries use 40 - 50 vol% N2 mixed with CO2 when used for purging and some can seamers use 100% N2 without any issues.
We see that your annual consumption is 1,887,115 scf CO2/year. If we assume that you use 25% of the CO2 for carbonation, 1,415,336 scf/year is used for purging. If we assume that you can replace 50 vol% with N2, you will have to generate 707,688 scf N2/year. If we assume that you use the nitrogen generator on an average 5 hours, 4 days per week or 1044 hrs/year, you will need a nitrogen generator that can deliver 11.3 scfm of N2. If you have clean, dry compressed air available equivalent to what a 15 HP compressor can deliver, the ROI time for a high efficiency PSA nitrogen generator and a 120 gallon N2 receiver will be 1.48 years based on $0.10/kwh to operate the compressor. The cost per ccf (100 scf) of N2 will then be $0.17 compared to $3.52 for the CO2. If you settle for less pure N2, the ROI time for a 99.9% N2 generator would be 1.34 years so not very different. The cost per ccf for this purity would drop to $0.12 since you would only need a 10 HP compressor. If you use gas 6 hours per day, 5 days per week, the ROI time drops below one year with 99.99% purity. I will be happy to run calculations on other scenarios as well if you like. Full disclosure, my company manufactures these systems in the US but I wanted to run the numbers for the benefit of the community so you can see what the cost is to generate nitrogen compared to purchasing CO2. It is a lot less costly as you can see and a lot more environmentally friendly.
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Thorstein Holt
President
Holtec Gas Systems
Saint Charles MO
(314) 324-0284
tholt@holtecllc.com------------------------------
Original Message:
Sent: 12-01-2020 11:40
From: Mike Wayne
Subject: Nitrogen Generator ROI
Yikes. That may be overcomplicating the math...
Let me see if any of my brewery math helps you.
My math said I needed about 232kg of N2 per month as we start. This should translate to the biggest draw being ~3524 liters of N2 (290 mol; 10.4kg; ~4.2 SCFM) at 30psi within 30 minutes. This led to sizing a NGP8+ paired behind our GX4 compressor.
It takes 8 hours to regenerate the reservoir after fasssing a 30bbl tank and increasing that capacity means three reservoirs would fill in 24 hours and I could fass 90bbls on a GX4 and NGP8+.
To give you an idea of my growth expectation (pre pandemic):
CO2 Usage by Phase | bbl/month | kg/month |
Phase I, August (nowish) | 224 | 813.6 |
Phase II, May 2020ish | 403 | 1463.7 |
Phase III, Dec 2020ish | 592 | 2150.1 |
Phase IV, Dec 2021ish | 975 | 3541.2 |
Phase V, Dec 2022ish | 1540 | 5593.3 |
Max, Dec 2023ish | 1708 |
6203.5 |
This has reduced the load of CO2 demand low enough where I am able to run from 100lb cylinders (CGA320 size 44). Each cylinder costs me $100 and I attribute $12.50 of CO2 cost to a 15bbl batch producing 8 1/2bbl kegs, and 100 cases of 16oz cans. The CO2 is used for purging the bright by Audrey Skinner's method of 5psi/10bbl*hr, then carbonating the 15bbl batch to 2.75vols, then CO2 purging the cans on a Cask V5.
Beer should produce ~10lbs/bbl and consume ~8lbs/bbl. I'm watching numbers and it looks like I'm down to .83lbs/bbl of CO2 and using N2 for everything else.
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Mike Wayne
Brewmaster
Boomstick Brewing Co
Corner Brook
Original Message:
Sent: 11-30-2020 18:50
From: Tyson Read
Subject: Nitrogen Generator ROI
This is all good information, thank you all. Here are some of the numbers that I'm working with. There seems to be no doubt that N2 generated is cheaper than buying CO2. What I'm not sure about is how much CO2 we could cut by using N2 to push and purge tanks and maybe kegs during washing. Also what size generator would be needed to do that reasonably.
Currently we are paying $0.3076/lb for CO2 all in. There are 8.73 SCF/lb of CO2. This equates to $0.03519/SCF. For the sake of large numbers, I'll use CCF, so $3.52/CCF. Last year we used 215,917 lbs of CO2 or 18,871.15 CCF. 18,871.15 x $3.52= $66,426.45.
For comparison, one generator company penciled out $0.107/CCF using our current $/kwh. This is for an 822 SCFH unit @ 99.9% purity. Not sure if this would be adequate for reasonably pushing beer around at up to 60bbl/hr or purging tanks in a reasonable amount of time. Or how much of the above CO2, we could reasonably displace with a system like this.
Original Message:
Sent: 11/30/2020 8:49:00 AM
From: Mike Wayne
Subject: RE: Nitrogen Generator ROI
Hi Jaime,
You may want to check the market again. Anton Paar's CBox corroborated Atlas Copco's oxygen sensor when it said 99.9998%. This should have been 2,000ppb air (~400ppb O2) and was coming in at 5ppb on the CBox.
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Mike Wayne
Brewmaster
Boomstick Brewing Co
Corner Brook
Original Message:
Sent: 11-29-2020 22:33
From: Jaime Jurado
Subject: Nitrogen Generator ROI
For what it's worth, I have looked at this twic ein larger, regional breweries. My problem was the purity is at most 99.7% purity, and the balance is air (certainly not argon!). So you introduce alot of oxygen into the tank. the difference between 100% Nitrogen and 99.7% nitrogen is 300 ppm... so 21% of that is Oxygen: 63 ppm of O2.The slower the output rate of a pressure-swing adsorption or hollow fiber design, teh greater the purity but I doubt if you will get anything above 99.7% pure nitrogen if you want to purge a tank in a reasonable time instead of in weeks. See: https://lsn2.com/hosted/images/uploads/digital_asset/file/239059/GN2_Awareness_Guide_-_general-_3.0_LSN2.pdf and we tested the Liberty unit for several weeks on a 15-bbl tank and lateron a 200-bbl tank. You also need a DO meter that can work in gas-pahase,a nd then you simply need to get a 0.00 ppb reading and you know you have pushed out the oxygen adequately...we used a Hamilton Beverley handhand unit, but because we purged with 99.7% nitrogen, our assymptote was mostly 25-45 ppb. Had we used 100% pure N2, we would have probably found plots like SABMiller shared in https://craft-sensors.s3.amazonaws.com/695171_00_SAB_Miller_LR_EN.pdf?mtime=20180723052124&focal=none (Figure 1 was for 300-bbl tanks...I think they were 300's).One can also use this Fyrite unit: https://www.apexinst.com/product/fyrite-analyzer-duplex-kit Note that for a keg being dispensed, it's perfectly fine if your small N2 generator is blending in nitrogen that has 0.3% O2, and which the CO2 that it is blended with will reduce the overal total O2 in the dispense gas...and that keg will dispense-through fairly quickly, compared to a large tank of beer. If any manufacturer clams their nitrogen generator can do better than 99.7%, you have to ask the to verify that on a much more sensitive/costly analyzer than any optical analyzers I cite for gas-phase testing. The nice thing is the Hamilton Beverley works robustly on beer, water, etc as readily as it dos on gas purity checks. Note that slide 12 of the first link I point to discusses savings of the genetrated nitrogen versus purchased N2...it does not compare with CO2 that you plan to repalce. We found that if yoru bulk CO2 costs $75 a ton (we generally loaded in 30,000 lbs at a time in the second brewery where I did the work), the nitrogen genator was a little less than half the cost when used in purging (using a simple internal rate of return calculation based on a projection of how many tanks we would purge in a year)...but we did not meter the electricity consumption. We used the generator to also make nitrogenated beers which we kegged directly from the 15-bbl tank and it was not too hard. But at the end of the day, we did not feel ok about putting beer in tanks that measured up to 45 ppb DO in gas-phase environs when comapred to tanks purged with CO2 which measured 0.00 ppb DO. I can't recall my simple calcluations to address what would happen if all the DO in the gas-space of the tank went into the beer... maybe it would have been trivial.( I guess if the solution provider gave us 99.9% pure nitrogen, we may have sprung for this as a sustainability-related investment, like the PV arrays we put on the roof and the biogas=burner we had on the boiler that burned biogas from our aaerobic waste water plant).
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Jaime Jurado
Ennoble Beverages
Forty Fort PA
(210) 240-4731
Original Message:
Sent: 11-24-2020 13:28
From: Tyson Read
Subject: Nitrogen Generator ROI
We are exploring replacing some of our CO2 usage with a nitrogen generator. People that have done this:
- What processes did you use CO2 for that got replaced with nitrogen?
- What percentage reduction in CO2 usage (lbs/bbl) did you see?
- Were there any unforeseen operating costs or challenges with implementing the N2 generator?
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Tyson Read
Head Brewer
Iron Horse Brewery
Ellensburg WA
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