Dry water? The very idea seems ridiculous, as accustomed as we all are to the idea of water as "wet." But using a novel approach, it is actually possible to create a stable and dry form of water. It’s hardly a new invention, having been developed in 1968, but interest in dry water is suddenly surging. Researchers are only now discovering some of the potential applications for it, such as using it to store carbon dioxide or methane, or in fuel cells.
A more accurate name for dry water is powdered water. It is a white powder, similar in appearance to sugar, that is easily pourable. The makeup of powdered water is about 95 percent water. The remainder is silica, an abundant material found mostly on beaches. Each grain of the dry water consists of a drop of water surrounded by particles of silica. These silica particles prevent the suspended water droplets from coalescing back into a liquid because they are hydrophobic (non-polar).
Below: silica gel. This constitutes about 5% of powdered water.
Dry water’s most important characteristic is its ability to absorb gases. In fact, a recent experiment demonstrated that the dry water powder is capable of absorbing three times as much carbon dioxide as the same amount of liquid water and silica. Scientists find this ability to absorb gases very exciting, as it could be used as a greenhouse gas sequestration agent. Potentially, engineers could develop a way to trap carbon dioxide and other gases quickly and cheaply at the source. The gas combines with particles of dry water to form a hydrate, which keeps the gas from ever entering the atmosphere.
Another possible use of dry water powder is as a storage and transportation mechanism for volatile gases like methane and propane. Since the gases absorbed by dry water are not permanently bound to the water particles, it would be a relatively simple matter to remove the gases when they are needed. This could potentially prove very useful in automobiles running on natural gas or fuel cells. One major problem facing these vehicles is the difficulty of safely storing volatile gases like hydrogen and methane; if the gases can instead be stored in a powder, the need for expensive and bulky gas-storage tanks would be eliminated.
Some scientists also suggest that powdered water might be used to absorb seabed deposits of natural gas that are too difficult to retrieve by standard methods. Interestingly, something like dry water already exists at these extreme depths. At the sea floor gas hydrates sometimes form; this is a type of frozen methane often called "ice that burns."
Use in Emulsions
Professor Andrew Cooper has reported that his research team has developed a method for creating dry water emulsions. An emulsion is a mixture of liquids that do not dissolve in one another, like milk. The team demonstrated a technique to turn an emulsion into a dry powder, much like dry water. This could help industry transport and store dangerous liquids with an added degree of safety, as the powdered form would be less reactive.
Dry Water as a Catalyst
Cooper’s team also demonstrated a method for using dry water in reactions between hydrogen and maleic acid. This reaction creates succinic acid, which is a material used to manufacture drugs, various foods, and other products. The reaction normally requires extensive stirring to occur, but scientists have shown that creating a dry water hydrate with maleic acid speeds up the reaction. This method also eliminates the need for stirring, which would result in a substantial energy savings.
Image credit: Wikimedia – Silica Gel