Ask MetaFilter questions tagged with co2

Kegging and transporting kegged beer.

Packy_1962 — Fri, 04 Sep 2009 17:14:06 -0800

I am going to keg my homebrew for the first time and take it to a friend's wedding. I have the CO2 system set up and I have checked it for leaks and practiced with H20. Everything is set to go. I need some help about what do next however, because I have to transport the beer twice and I don't have a fridge to keep the beer in (my plan is a cooler and ice). Here's the scenario: Beer is ready to be kegged, the wedding at which it will be served is in 14 days. The beer is in a carboy two hours away from my home and I will need to transport it to my home this week before the wedding. Then, two days before the wedding I will need to transport it from my home 5 hours away to the wedding. What would you do? From my understanding it takes about a week for the carbonation to form in the beer with the pressure set at 12-15. Once I put C02 in the beer do I need to keep it cold continuously until the wedding? What would you do? Transport the beer the first time in the carboy, keg it a few days before the wedding and then transport it to the wedding in the keg in a cooler? Wait to keg it until I get to the Wedding? If I do transport it in the keg, should I turn off the gas and detach the hose. . will it keep its carbonation? A lot of this hinges on whether I need to keep it cold once the co2 has been added or if it can sit at about 65* in my basement.

What effect does respiration have on global C02 levels?

zeoslap — Tue, 17 Mar 2009 06:08:55 -0800

What effect does respiration have on global C02 levels? Since 1900 we've added 4 billion people to the planet, what effect does all those people breathing have on C02 levels (i.e is it significant?)

Where could I find a ranking of foods by their carbon footprint?

GIMG — Tue, 10 Mar 2009 17:28:49 -0800

Where could I find a ranking of foods by their carbon footprint? I remember hearing that cheese, fish, and tomatoes, even have a higher carbon footprint than chicken.

Does anyone know where I could get an extensive and reliable list of foods by carbon footprint?

Ask a chemist - cooling CO2

gspm — Thu, 24 Jul 2008 14:51:12 -0800

A question for chemists - I am doing a calculation about the energy requirements of taking CO2 at atmospheric pressure and temperature and compressing it to 2 MPa (2000 kPa, about 300 psi) and cooling it to -31ºC and am a bit uncertain about handling the phase change from gas to liquid. The 2 MPa, -31ºC is the IPCC's state for transport of CO2 by road or rail tanker.

I've assumed an isentropic two-stage compression to get to 2 MPa.

I've calculated that the gas would be around 140ºC after the compression is complete. So, one can assume that no energy is required to cool to atmospheric temperature. But to cool it further would require refrigeration... and then there is the phase change (heat released going from gas to liquid?).

What do I need to do to calculate the energy required for that 2 MPa at 25ºC to 2 MPa at -31ºC step?
∆h = cp∆T but what about the phase change? (I knew how to handle this, once, long ago)

What's the carbon intensity of my diet?

bumpkin — Fri, 02 May 2008 20:50:33 -0800

Trying to conduct a carbon audit of the food going through a small sized cafeteria. Most of the information I have found is very general, sometimes vague, and the various footprint calculators I've seen are bad for providing sources. We have managed to compile invoices for a year for the operation, and identified suppliers. Although the general principles are clear (processed foods and imported out of season fruit are more carbon intensive), finding rigorously done analyses is proving frustrating. I have access to academic journals, so those kinds of sources could really useful. I also feel that there must be think-tank or non-profit research groups that have worked on this problem (eg. an outfit like Lester Brown's Worldwatch Institute). This is really out of my field, and I am not making much progress.

omg global warming in my window!

nihlton — Sun, 17 Jun 2007 18:43:49 -0800

would my window sill plants benefit from enclosing them and ramping up co2 levels? assuming of course I also ramped up water, nutrients and heat. (ill worry about appropriate levels later - i just want to know if it would be worth it before i go any further)

if the species help - im growing lychee, pomegranate, artichoke, lime and mahuang.

My Own Private Venus

bjrubble — Wed, 14 Feb 2007 19:03:30 -0800

How can I reduce CO2 levels in my house? My girlfriend brought a professional air quality monitor home from work, and the CO2 level in the house is over 900ppm (1000ppm is a common regulatory threshold). This is surprising considering how drafty the house is, but it's a fairly small house with two people and a dog. It's too cold to keep doors and windows open -- is there another way to keep the CO2 level below brain-clouding concentrations?

Can I use any kind of CO2 cartridge for making soda at home?

redteam — Fri, 25 Aug 2006 20:24:24 -0800

Can I use any kind of CO2 cartridge for making soda at home? I have a seltzer bottle that uses these little CO2 cartridges you can buy at fancy schmancy foodie stores. I used to be able to get 10 for under $10 but I can't anymore. Those bastards raised the prices! Can I use any kind of CO2 cartridge that I want? I'm thinking of the kind you can use in paintball or BB guns.

Please don't respond unless you can justify your answer. I've hesitated and done plenty of wondering on my own.

Can't see the forest for the carbon absorption rates

andifsohow — Mon, 24 Jul 2006 18:49:12 -0800

I'm trying to figure out carbon absorption rates by trees. So far the best source I have is an eBay ad. I understand that this all depends on what kind of tree and any number of factors. But I haven't even been able to get very good numbers on how many trees it takes to offset 1 ton of CO2 or, conversely, how much CO2 100 trees would offset. This eBay ad suggests that three trees can offset 1 ton over the next ten years. How do I find better data than that? It's for a research project on the development of sustainable timber farms.

Why is carbon dioxide often used as a compressed gas?

edd — Wed, 29 Mar 2006 01:42:44 -0800

Why is CO₂ used as a compressed gas to inflate things like lifejackets and bike tyres? From Wikipedia:
Carbon dioxide is often used as an inexpensive, nonflammable pressurized gas. Life jackets often contain canisters of pressured carbon dioxide for quick inflation. Steel capsules are also sold as supplies of compressed gas for airguns, paintball markers, for inflating bicycle tires, and for making seltzer. Rapid vaporization of liquid CO2 is used for blasting in coal mines.

This suggests it's because of the price, but there must be more to it than that. Compressed air would be perfectly ok for filling tyres, lifejackets and for firing airguns and paintguns for instance. What is it about CO₂ that makes it best for these applications?