Talk:Carbon dioxide

There are many data with ambiguous units of measurement like "ppm" and "%" across this article (and many other articles across Wikipedia), without a clear explanation what those units stand for. Without a clear explanation, those units can stand for mass per volume, volume per volume, mole per mole or who knows what else. Can someone clarify what those units stand for, despite that is not clarified in the sources? The data about the concentrations of carbon dioxide (and other suffocating and toxic gases and substances) in the air, water, food, drinks, products, etcetera, is a very important information for readers, especially non-expert ones, so, editors should be notified about the very existence of the ambiguous "ppm", "%" and similar ambiguous units across Wikipedia. Let's discuss. I am opening a debate. What do you think? Do you agree or disagree with me, and explain why. Thanks in advance for your opinion. Bernardirfan (talk) 18:08, 30 August 2023 (UTC) [reply ]

WP:JUSTFIXIT with a WP:SCIRS source. Zefr (talk) 19:06, 30 August 2023 (UTC) [reply ]

I think another editor has now fixed the problem. Thanks for pointing it out. Not everything needs a debate, as Zefr rightly points out. Qflib, aka KeeYou Flib (talk) 14:09, 6 September 2023 (UTC) [reply ]

Thank you Qlib and Zefr for resolving my {{clarify }} tags. Bernardirfan (talk) 09:41, 16 October 2023 (UTC) [reply ]

I removed the following content that is unsourced. All biomedical claims need WP:MEDRS sourcing because we don't want people to harm themselves. Clayoquot (talk | contribs) 00:46, 30 October 2024 (UTC) [reply ]

In medicine, up to 5% carbon dioxide (130 times atmospheric concentration) is added to oxygen for stimulation of breathing after apnea and to stabilize the O₂/CO₂ balance in blood.

Carbon dioxide can be mixed with up to 50% oxygen, forming an inhalable gas; this is known as Carbogen and has a variety of medical and research uses.

Another medical use are the mofette, dry spas that use carbon dioxide from post-volcanic discharge for therapeutic purposes.

The article currently gives a lot of weight to the use of CO2 in the food and beverage industries and various industrial niches. These are relatively small uses of CO2, which is primarily used in urea production and in the oil and gas industry or not used at all. I plan to update it to give a more balanced overview of commercial use. To replace the last paragraph of the lead, I have drafted the following text (adapted largely from the IEA, CC-BY):

Globally, 230 million tonnes (Mt) of carbon dioxide (CO2) are used every year. The largest consumer is the fertilizer industry, where 130 Mt CO2 is used in urea manufacturing.^{[1] : 3} The oil and gas industry consumes 70 to 80 Mt CO2 annually for enhanced oil recovery.^{[1] : 3} Other commercial applications include food and beverage production, metal fabrication, cooling, fire suppression and stimulating plant growth in greenhouses. ^{[1] : 3} Some usage of CO2 results in long-term sequestration underground or in products. However, as the the potential for commercial use of CO2 is relatively small, the vast majority of CO2 is a waste product.^[2]

Clayoquot (talk | contribs) 21:38, 30 October 2024 (UTC) [reply ]

I've removed the content below from the "Commercial uses" section as they describe technologies that are still at pre-commercial stages of development (or possibly at extremely early commercial deployment if I've missed a recent update). The older predictions of glory have not gone anywhere. Recent sourcing on these issues: Allam cycle [1] [2], enhanced coal bed methane recovery[3], algal biofuels.[4] Clayoquot (talk | contribs) 18:54, 1 November 2024 (UTC) [reply ]

Supercritical CO₂ is used as the working fluid in the Allam power cycle engine.

In enhanced coal bed methane recovery, carbon dioxide would be pumped into the coal seam to displace methane, as opposed to current methods which primarily rely on the removal of water (to reduce pressure) to make the coal seam release its trapped methane.^[3]

It has been proposed that CO₂ from power generation be bubbled into ponds to stimulate growth of algae that could then be converted into biodiesel fuel.^[4] A strain of the cyanobacterium Synechococcus elongatus has been genetically engineered to produce the fuels isobutyraldehyde and isobutanol from CO₂ using photosynthesis.^[5]

Researchers have developed an electrocatalytic technique using enzymes isolated from bacteria to power the chemical reactions which convert CO₂ into fuels.^{[6] [7] [8]}

The table in the "Below 1%" section lists a concentration of "700 ppm" with the note "ASHRAE recommendation", but the linked source says (my emphasis)—

Thus, maintaining a steady-state CO2 concentration in a space no greater than about 700 ppm above outdoor air levels will indicate that a substantial majority of visitors entering a space will be satisfied with respect to human bioeffluents (body odor).

So, the ASHRAE recommendation isn't "700 ppm", but rather "700 ppm above outdoor air levels". The table as-written is incorrect. 73.171.45.17 (talk) 20:07, 7 December 2024 (UTC) [reply ]