Cousin Of The 'Ice That Burns' Emerges As Greener New Way To Fight Fires

Toshihisa Ueda and colleagues note in the new study that firefighters have used water and carbon dioxide as fire extinguishing agents for decades. That knowledge led the scientists on a quest to see if carbon dioxide hydrates, frozen crystals made of water and carbon dioxide bonded together, may serve as promising fire-suppressing materials. Such icy chunks occur naturally in some parts of the world, including hydrates containing methane. Methane hydrates are a potential new source of natural gas, and are renowned as the "ice that burns." They burst into flame when ignited.

To test their idea, the scientists used a special reactor to produce tiny pellets of carbon dioxide hydrates in the laboratory. They compared the fire-suppressing performance of these hydrates to similar-sized pellets made of normal ice (frozen water) and dry ice (frozen carbon dioxide) after sprinkling them onto several small, carefully controlled fires. The hydrates extinguished flames faster than the other two substances, they say.

The hydrates also used less water than ordinary ice and released less carbon dioxide than dry ice, they note. Grinding the pellets into smaller pieces boosted their flame-fighting efficiency, the researchers say.