Over the past few years chemists have discovered an assortment of oddly shaped carbon molecules, such as the microscopic tubes in these images. Last March, researchers at the National Renewable Energy Laboratory in Golden, Colorado, announced that they’d managed to use molecular tubes like these as miniature storage tanks for hydrogen gas. This seemingly esoteric stunt may have a very practical payoff: it could provide the means to safely store clean-burning hydrogen gas in a new generation of nonpolluting vehicles. Says materials scientist Michael Heben, who worked on the project: This points to the possibility of high-density hydrogen storage at room temperatures. One of the drawbacks to using hydrogen gas, which liquefies at –423 degrees, to power cars and trucks is the difficulty of storing enough of it to provide the energy equivalent of a tank of gas. Cooling and liquefying the gas, for example, requires expensive and bulky equipment. But the Colorado researchers found that when hydrogen gas flows over carbon nanotubes, the tubes soak up the gas like sponges. The researchers estimate that a gas-tank-size block of carbon tubes filled with hydrogen could power a typical car for 200 miles.