CO2 Generator





Introduction: CO2 Generator

How to make CO2 or, more to the point, carbonated water. I used some empty soda bottles and bits left over from installing an inline filter on my ice-maker. The rest I picked up at the hardware store.

  • 1/4" O.D. plastic tubing (ice-maker tubing)
  • a 1.5L soda bottle
  • one or more 500 mL soda bottles
  • an inline valve for 1/4" plastic tubing
  • two 1/4" tube to 3/8" M adapters
  • two 3/8" F couplers
  • Teflon tape
  • active dry yeast
  • sugar

I wandered around the hardware store with the various pieces, trying different combinations until I came up with something that would work. You don't have to use these exact pieces. Just about anything similar will do.

Standard Disclaimer: Not liable for damages due to use or misuse. No warranties expressed or implied. For educational purposes only. Safety goggles may be required during use. Some belching may occur.

Step 1: Making the Connecting Tube

The connecting tube consists of two soda bottle caps, tubing and an inline valve.

Assembly is pretty straightforward. Most of the connections are "quick-connect". No special tools required.

To attach the caps:
1. drill holes just large enough for the adapters
2. wrap the threads of the adapters with Teflon tape
3. use the couplers to tighten the adapter onto the cap

Note: I used brass couplers. I would've preferred plastic ones but couldn't find any.

Step 2: Brewing Some CO2

Fill the 1.5L bottle halfway with warm water. Add sugar and yeast. Proportions aren't critical. I used roughly a cup of sugar and a tablespoon of yeast. Mix thoroughly.

Close the valve on the connecting tube. Attach one end to the 1.5L bottle but don't fully tighten it yet.

Squeeze as much air as possible out of the bottle, then tighten the cap. This will ensure that most of the gas you end up with is CO2.

Wait. It'll take hours for the CO2 to build up to a decent pressure. The bottle will eventually expand and become firm.

Note: There's a chance that the connecting tube will leak or pop apart. If you leave the bottle too long, it could explode. Both of these are potentially very messy.

Step 3: Filling a Bottle

Take a 500mL bottle and fill it 3/4 full with cold water. Attach it to the free end of the connecting tube but don't tighten it fully.

Squeeze the air out and tighten the cap.

Open the valve. The bottle will expand and pressurize.

Shake the 500mL bottle to dissolve the CO2 in the water.

Close the valve and remove the cap.

You should now have a bottle of carbonated water. You can either drink it right away or cap it and store it in the fridge for later. Depending on how much pressure you've built up, you might be able to fill several bottles.

Note: Shaking the 1.5L bottle will help increase the pressure but take care not to get any of the yeast water in the tubing. It'll mess up the taste of the water.

The liquid doesn't have to be water. You can use orange juice and make orange soda. Or maybe some vanilla and sugar to make creme soda.

I'm not sure how renewable the CO2 source is. Presumably, you can just keep feeding the yeast sugar to make more CO2. I suspect, though, that the yeast will eventually die and you'll need to start a new batch.

Step 4: Pressure Gauge

If you're feeling ambitious, you can add a T connector and a pressure gauge. I found that 30 psi is about right for filling a bottle. I'm not sure how much pressure this setup can contain. I may have to push it to the point of failure just to find out.

Update: The highest pressure I've managed so far is 70 psi.

My current rig has two yeast bottles, each with its own valve, and a master valve. This allows me to switch out one of the bottles while maintaining the pressure.



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    I am thinking about a 24hr timer ,aquarium air pump, a large plastic reservoir tank and the yeast thing mounting the air pump on the outside sticking a pipe in the air intake base rubber of the pump to the tank. heh ? growers this is my first time , would that work ?

    I have been thinking about carbonating drinks... the hardware is exactly what I was thinking, however, instead of using yeast, sugar and water, use white vinegar (very cheap and a baking soda. All you need is about 40 pounds of pressure, which can be achieved easily enough with a half bottle of vinegar and around 1/2 tsp soda. Everything would be much faster, so I recommend a quick connect on the reaction bottle.

    Hey just a little heads up. The yeast will eventually die off. The fermentation process yields cO2 and alcohol. Once the alcohol content rises above 6-8% it will kill off normal bakers yeast. Upside is that you can now get drunk on your super ghetto sugar wine.

    Is there some way to transfer the carbon dioxide to another bottle or something?

    Does anybody know a way you could transfer the C02? Maybe to another bottle?

    It's illegal to make that sugar, water and yeast thing here in Finland. It's called kilju or sugar wine (as wikipedia told)

    The sugar, water and yeast is used to create the CO2, which carbonates the beverage in a separate container. That mixture is not being drunk.

    I know that, but still, you're making that sugar wine there, eventhough you're not gonna drink it. Jus for an example: you can't make moonshine for fuel purposes, as I know.

    It IS illegal to distill alcohol for fuel purposes without a permit, however, it is not illegal to ferment it. This process is completely different. Of course, I am only referring to U.S. law. Your mileage may vary.

    I know that fermenting just something like beer or wine isn't illegal, but here in Finland (at least) it's illegal to make "wine" that has "no" flavour (yeast doesn't count as a flavour here). There are some laws that control when your wine is legal and when not.