The uses and benefits of a nitrogen generator in a craft brewery (with the backdrop of the CO2 shortage)

November 7, 2022Keith Gribbins

The commodity crunch continues to challenge craft breweries — cans, barely/malt, hops. CO2 is another shortage item. Breweries use a lot of CO2 onsite from moving beer and prepurging tanks to carbonating product and pouring draught beer in the tasting room. For almost three years now there has been a CO2 squeeze (for a number of reasons), making supplies limited and usage more expensive depending on the season and the region.

Because of this, nitrogen has been gaining more acceptance and awareness as a CO2 alternative at breweries. I’m currently working up a big story on the CO2 shortage and various alternatives. I interviewed Chuck Skypeck, technical brewing projects director at the Brewers Association about a week ago, and he was cautiously optimistic about the increased usage of nitrogen in various brewing applications.

"I think there are places where nitrogen can really be used effectively [in the brewhouse]," said Skypeck, but he also cautioned that nitrogen "behaves very differently. So, you’re not going to just substitute it one for one and expect it to perform the same."

There are a number of beer making, packaging and serving functions that Boston's Dorchester Brewing Co. has been able to transfer to nitrogen. The company has been using nitrogen as an alternative as local CO2 supplies has been constrained and expensive.

"Some of the most impactful areas we use nitrogen is for purging tanks and for blanketing gas during the canning and seamer processes," said Max McKenna, senior marketing manager at Dorchester Brewing. "These have been the biggest deltas for us, since those processes require such a high volume of CO2. We also for a long time have had dedicated nitro beer lines in the taproom, so while that's separate from the other transitioning, it's also recently moved from our series of fruited blonde ales on nitro [for the summer] to some super tasty dark beers on nitro for winter [starting with a collab with a local ice cream shop to do a Mocha Almond Stout called Does Not Contain Nuts]. We use a dedicated nitrogen generator to generate all of our nitrogen for the taproom — for both the dedicated nitro lines and also for our beer gas mix."

Nitrogen generators are an interesting alternative for creating nitrogen onsite. An on-site nitrogen extraction unit using a generator provides breweries the ability to produce the required quantities of inert gas itself, removing the need to bring in expensive CO2. Of course, the energy equation is never that simple and each brewery will need to calculate whether the cost of a nitrogen generator is justified (as CO2 is not in short supply in some parts of the country).

To learn about the potential for nitrogen generators in craft breweries, we sent some questions over to Brett Maiorano, and Peter Asquini, industrial gases business development managers at Atlas Copco. Here are some of their insights.

Maiorano: When purging tanks between uses, utilizing nitrogen makes the tank oxygen-free. It keeps wort, beer and residual mash from oxidizing and contaminating the next batch of beer. For similar reasons, nitrogen can be used to push beer from one tank to the next. Lastly, in the brewing process's final stages, nitrogen is the ideal gas for cleaning, inerting and pressurizing kegs, bottles and cans before filling.

Asquini: Using nitrogen is not about fully replacing CO2, but we do think brewers can reduce their consumption by around 70 percent. The main driver is sustainability. Any brewer can create their own nitrogen very simply. You will no longer be using a greenhouse gas, which is better for the environment. It will give you a payback from month one which will go straight to the bottom line, and if this cannot be shown before you purchase then don't purchase. That's our simple rule. Also, the demand for CO2 to make products such as dry ice, which uses a significant amount of CO2 and is necessary to transport vaccines, is proliferating. Breweries across the United States share concerns over supply levels and question if they can cope with breweries’ demand while keeping pricing levels consistent. Here we summarized the P.R.I.C.E. benefits…

Asquini: We joke that most breweries already have an air compressor and thus are already 50 percent of the way there. All they need to do is add a small generator. Essentially, a nitrogen generator separates nitrogen molecules from the oxygen molecules within compressed air, resulting in a purified supply of nitrogen. The other great thing about creating your own is that you can control the purity levels needed for your application. Many applications require the highest purity of 99.999, but for many applications, you could use a slightly less pure nitrogen and create even more savings for your bottom line. Less pure does not mean less quality. Learn the difference …

Maiorano: There are four core questions to estimate size:

We offer six standard packages which cover 80 percent of all breweries — from a few thousand barrels a year to several hundred thousand barrels a year. A brewery can oversize its nitrogen generator to accommodate for growth while maintaining efficiency. Plus, the modular design can add a second generator if the brewery's business expands substantially.

Asquini: The simple answer is wherever you have space. Some of the smaller nitrogen generators are even wall mounted, so they don't take up any floor space at all. These packages can cope well with changing ambient temperatures and have a great temperature change tolerance. We do have outdoor installations, and these work well, but in areas where they have extreme highs and lows, we do recommend installing them inside or building a small outhouse facility, but not outside in conditions with big ambient temperatures. They are very low noise and can be installed right at the heart of the workplace.

Maiorano: The generators really are as close to ‘fit and forget’ as possible. Some consumables, such as filters, require semi-regular changes but real service is often only around every 4,000 hours. The same team who takes care of your air compressor would also take care of your generator. The generators come with a simple controller — similar to your iPhone — and come with full remote monitoring capability via an app. A subscription service is also available where Atlas Copco also monitors all alarms and any issues 24/7. Think how your home alarm provider works, and SMARTLINK works in exactly the same way — for less than a couple of dollars a day. Training is another great advantage. The large display and intuitive design means you are an expert in under an hour.

Asquini: A small nitrogen generator costs around ~$800 per month, based on a five-year lease-to-own program. From month one, a brewery could easily save close to a third of what they pay for CO2 today. The total investment would depend on whether you also need an air compressor or whether your existing one has the function and capacity to cope with also producing nitrogen.

Maiorano: There are lots of forum articles online on the topic of using nitrogen, its benefits and the effect it has on removing oxygen. For example, as CO2 is heavier than nitrogen, you may need to purge from the bottom and not the top. Dissolved oxygen [DO] is the amount of oxygen that is incorporated into the liquid during the brewing process. All beer has dissolved oxygen, but when and how you handle the beer during and after the fermentation process affects the quantity of DO in the beer. Think of nitrogen or CO2 as an ingredient in the process.

Talk to somebody who has the same challenges as you, especially when it comes to the types of beer that the brew master is making. Lastly, if nitrogen is right for you, then you have many choices of supplier and technology to make. Find the one that's right for you and make sure you fully explore the TCO [Total Cost Ownership] and compare electricity costs between units and service costs. You will often find the one with the lowest purchase price is not the right one for you over its lifetime.