Passage V

Researching “Frozen Smoke”

[1]

Nicknamed “frozen smoke” because their semitransparent when formed into bricks—silica aerogel is the lightest solid material known. Approximately 99 percent air by volume, considering silica aerogel has a density only three times that of air. The dry, spongelike substance is created by scientists who apply heat and pressure to silica gel until all the liquid has been removed. Only a solid, 3-D framework of dried-out gel, consisting mostly of empty space that will be filled with air, remains.

[2]

The structure of silica aerogel—air trapped in a highly porous web of dried gel一makes it an ideal insulator and soundproofing material. It’s thirty-seven times more effective as an insulator than the widely used insulating material called fiberglass. Researchers claim that a one-inch-thick window of silica aerogel has the insulating properties of a ten-inch-thick system of glass windows. [A] The use of silica aerogel to insulate buildings would discharge huge energy savings through reduced heating and cooling costs.

[3]

So far, silica aerogel has rarely been used in building construction or other industries isolating small applications, such as to insulate skylights. Large-scale use has been limited by the high cost of processing tetraethyl orthosilicate, the type of silica most commonly used to create aerogel. For years, though Dr. Halimaton Hamdan of Malaysia, has been researching a way to lower aerogel manufacturing costs. [B]

[4]

Hamdan’s findings that discarded rice husks offer a nearly limitless supply of silica. [C] Rice husks, which are 20 percent silica, by weight are readily available from Malaysian farmers, who must find a way to dispose of great quantities of the husks after harvest. Although the husks are cheap to obtain, Hamdan claims that using them as raw material could reduce silica aerogel production costs by 80 percent. [D] Hamdan hopes her process, when perfected, will make silica aerogel affordable to a variety of industries for the first time, with energy-saving benefits to follow.