Their process also uses carbon dioxide generally obtained as a waste product from power stations.

But since 1980 we have used liquid carbon dioxide.

Any serious practitioner does not drown animals, but uses carbon dioxide.

In nature, plants produce oxygen by using sunlight, carbon dioxide (another gas) and water.

Female mosquitoes use carbon dioxide as a cue for finding hosts.

A previous system using carbon dioxide was removed for safety reasons.

Kidde came up with the solution to use carbon dioxide instead of steam.

Next, the operators tried to extinguish the fire using carbon dioxide.

"Safety" - Build a fire extinguisher (using carbon dioxide) and a water treatment plant.

They make food for themselves using sunlight, water, certain minerals, and carbon dioxide.