Sources of CO2

Sometimes it's much more expensive to find that cheaper method. The only reasonable alternative to compressed gas cylinders is using dry ice, but you may have difficulty controlling the flow rate of the gas.

Just go buy a cylinder. CO2 is VERY useful - not just for welding. You can make sand molds with sodium silicate and all types of other crap. It's also great for putting out fires, cryogenics, gas powered pumpkin canon, bla bla bla.

One big Bla Bla is keeping beer fresh in a keg.

I wouldn't try that. There are a lot of other gases and material in exhaust than CO2, most of them toxic; unburned hydrocarbons, nitrogen oxides, and carbon monoxide. Lane

I get mine from my local Pepsi distributor. They simply charge 20 for a full

20 lb tank and when you bring it back empty they charge you another 20 buck for a full one.