Monday, May 19, 2008

The Cyclic Nature of Beer CO2

I was asked the other day why more breweries don't recover their CO2 from fermentation. After all, quite a bit of CO2 is produced in the process, and a lot of that gets vented to the atmosphere. So I thought I'd address this briefly.

First of all, CO2 recovery is not easy. You don't just attach a hose to the top of a fermenter and send it to a tank. You need compressors, scrubbers, distillation columns, and more compressors. It takes quite a bit of energy to recover and purify CO2 from brewing sources. So when you balance the CO2 'saved' from being emitted to the atmosphere you need to subtract the CO2 generated from power plant to make the energy to recover the CO2. That being said, it seems that this process usually works out positively for larger breweries who can afford the huge capital cost of a recovery system.

The main point I'd like to make though is this: beer production has a natural CO2 recovery system. Beer is made from malted barley. The sugars that the yeast break down into CO2 come from the barley grains. The barley grains produce their sugar with -- yep, CO2 from the atmosphere. There is a cycle there.

In theory, the barley needs to take in more CO2 than we are releasing to the atmosphere during fermentation, as not all the sugars are fermented completely. But perhaps thats an oversimplification. For 'carbon neutrality', we'd also need to consider the CO2 from transport, malting, energy needed for brewing, more transport, etc etc etc. So I'm in no way arguing that beer is carbon neurtal, but that there has been a natural recovery system already in place for many hundreds of years.


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