With regards to CO2 tanks, multiple people have already pointed out that this is CO2 that was already in the atmosphere, captured, and bottled.
But if you're really curious about how much CO2 I go through for kegs, I have a 5 pound tank of CO2. That lasts me about 5 homebrewer kegs (at 5 gallons apiece). That gets me both the initial carbonation and all of the pouring. In comparison, burning one gallon of gasoline gets you about 19 pounds of CO2 released into the atmosphere.
I've never put the fermenter on the scale before and after fermentation - I imagine that would be the best way to track CO2 emissions, as the only thing that should leave the fermenter in this time is CO2. However, let's assume the volume of the beer doesn't change that much during fermentation. I start with 5 gallons at a specific gravity (density of the beer / density of water) of 1.06. That's 42.4 pounds. I end up with about 5 gallons at a specific gravity of 1.01. That's 40.4 pounds. So assuming the volume of the beer doesn't increase, that's 2 pounds lost. In reality, since alcohol is less dense than water, there should be a larger volume in the end, and so the final weight is probably above 40.4 pounds.
So in the worst case scenario, there's 3 pounds of CO2 involved in the fermentation and serving of 5 gallons of beer. I bet that having my stove on full blast for 2 hours to boil the water emits much more CO2 than that. Heck, me driving to the homebrew store 6 miles away definitely emits more than that.
So in conclusion - I think it makes much more sense to focus on the costs involved with distributing the beer and heating the water that makes the beer, and much less on the fermentation and kegging systems.
I find that I enjoy the broad, technical perspective that comes from working in the field, and I'm thinking about moving out of development and into technical sales. Moreover, I've interviewed several techies in my company who are now in sales and all tell them they love it. Several have reported that a techie can make more money in sales. But I have several reservations: I am an introvert and a full day of face-time can really sap my energy, many sales people I've worked with are "sharks" (which I simply cannot be), and I don't like the idea of putting part of my salary at-risk.
Are you a former developer who went into sales? If so, what were your experiences like from a professional and personal perspective? What advise would you give to a developer considering a new career in sales?
'Is free-market innovation the best way to develop viable, sustainable energy alternatives?
The free market will ignore solutions that can't turn a profit. Any firm that fails to follow this simple maxim won't be in business for long. The corollary to this maxim is that the free market will ignore any solution that cannot be controlled, either through property interests (enforceable intellectual property, monopoly licenses, etc.) or because economies of scale demand centralized operation. This means that free market innovation is structurally incompatible with a huge portion of the universe of possible energy solutions.'"