Carbon Dioxide

Carbon Dioxide is a naturally occurring gas in Oxygen Not Included and one of the most common waste products of colony activity. It is heavier than most breathable gases, so it sinks and pools in low areas, making it easy to collect in pits, low chambers, and funnel-shaped spaces. This behavior also makes it a useful material for early gas management, because colonies can intentionally trap it instead of fighting it everywhere at once.

It has several important gameplay uses. Carbon Dioxide is considered sterile, so food stored in it spoils more slowly, and if the food is also kept frozen it will not rot at all. Because it settles at the bottom of rooms, it is often used to create simple food storage zones or to help maintain air pressure in enclosed spaces. It is also the atmosphere required by Dusk Caps and Oxyferns, and it serves as a food source for Slicksters and Molten Slicksters, which convert it into Crude Oil and Petroleum respectively.

Several buildings and systems either consume or produce Carbon Dioxide. Duplicants exhale it continuously, and many power generators and industrial machines output it as a by-product. Coal, Natural Gas, Wood Burner, Petroleum, Gas Range, Ethanol Distiller, and Polymer Press all add Carbon Dioxide to the environment. On the utility side, Algae Terrariums and Carbon Skimmers can convert it into Polluted Water, while the Soda Fountain consumes it along with water to provide morale and science bonuses. Beeta also consumes Carbon Dioxide; when fed, it falls asleep and stops stinging Duplicants, while a sleeping Beeta produces radiation.

Carbon Dioxide can be found from multiple world features and space sources. Carbon Dioxide Vents emit hot gas, while Liquid Carbon Dioxide Geysers produce colder output that is easier to use immediately, especially for cooling industrial areas. Rocket engines can also exhaust superheated Carbon Dioxide, and meteor showers may bring some with them. In space, it can be harvested from several renewable points of interest, including Forested Ore Fields, Radioactive Gas Clouds, and Glimmering Asteroid Fields.

Practical uses and handling notes:

• If cooled below its condensation temperature, Carbon Dioxide can be stored safely as a liquid or solid.
• Its tendency to pool at the bottom makes it easy to collect in low chambers, pits, or compressed storage areas.
• Early colonies often build dedicated “carbon pits” to contain buildup until it can be skimmed, compressed, vented to space, or otherwise processed.
• Although it creates a sterile environment, it does not stop Compost from working and is safe for plants.
• In the game’s simulation, Carbon Dioxide can exist as a liquid, even though real-world carbon dioxide only becomes liquid under much higher pressure than ordinary atmospheric conditions.