I thought beer made its own bubbles. Why do brewers need CO2?
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Most commercial beer is not naturally carbonated. Natural carbonation is tricky and can’t be controlled as well as forced carbonation. I had heard that a micro brewery I know of was considering capturing and using the CO2 they generated, but I don’t think it was very cost effective.
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I have a friend who works for AirCapture, a startup that is manufacturing direct-air capture technology that could easily service the a micro-brewery’s needs. See the 9:40 mark of this video. Not sure of the product & installation costs tho.
Beer does make its own bubbles, but CO2 is used throughout the process to purge lines, tanks, and kegs of oxygen to avoid oxidation. It was also mentioned above that almost all beer is force carbed these days especially since almost are filtered and there isn’t any yeast remaining for natural carbonation.
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Followup question:
Is (un)filtering that the way to tell if a beer is self-carbonated or force-carbonated? Or are there other ways?
I think the only definitive way would be it says so on the label. Back when I was doing a lot of home brewing, some folks claimed that natural carbonation resulted in finer bubbles. I was kegging my beers and did it both ways. When I got it right, you could not tell any difference.
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Filtering is done moreso to clarify the beer and make it prettier since yeast can cloud things up. Very few breweries advertise filtering since it isn’t super hip these days, but the big companies all do it. There’s just too much variability when you add priming sugar and rely on the yeast in suspension.
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Tony is correct. CO2 can be used to force carbonate, purge tanks and lines, and to move beer. Oxidation is a huge concern in brewing, so every non-fermenting tank gets purged before beer goes into it. Our beers are naturally carbonated, but we are one of the few that does that. Probably less that 5% of craft breweries naturally carbonate their beer.
Very large breweries will generally collect CO2 from carbonation, but I haven’t seen a system yet that works in breweries our size. Even if it makes sense now, whether it makes sense over the long run is another question.
A number of breweries are switching to using Nitrogen to purge tanks. Nitrogen doesn’t work as well for pushing beer (though it could work in a number of situations) or carbonating (obviously).
Filtering is a time saver if you’re mainly concerned about having pretty beer. It’s generally not good for shelf life or flavor.
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