It's typically captured either from processes that make ammonia or hydrogen from methane (with CO2 being the only major byproduct), or by capturing the output f

It's typically captured either from processes that make ammonia or hydrogen from methane (with CO2 being the only major byproduct), or by capturing the output from large-scale fermentation. Source: http://www.uigi.com/carbondioxide.html http://www.uigi.com/carbondioxide.html