It's not too often carbon dioxide (CO2) is called environmentally-friendly, but research into fire-fighting methods has found that a frozen mixture of water and CO2 can put out fires more quickly, and without using as much water or releasing as much CO2 as other methods.

Researchers in Japan compared the effectiveness of ice, dry ice (frozen carbon dioxide) and pellets of carbon dioxide hydrates (water and carbon dioxide bonded together) in putting out small, controlled fires. Carbon dioxide has already been widely used in fire fighting.

The hydrates put the fires out quicker than the other two methods, they used less water than ice, and they released less carbon dioxide than dry ice. The researchers had produced their own pellets of the hydrates, and found that the pellets were more effective the smaller they were made.

Carbon dioxide hydrates occur naturally, and some include methane, which can burn, earning it the name moniker of "ice that burns." The researchers, though, only used hydrates that did not contain any flammable material. Their findings are published in the American Chemical Society's Industrial & Engineering Chemistry Research journal.

^{Fire - CC license by CarbonNYC and Craig Lebowitz}