Technology: Cool Fuel

Environmentalists and engineers know that hydrogen would make a better jet fuel than the standard aviation kerosene. In its liquid form, hydrogen packs more energy per pound than any other non-nuclear fuel and, burning, produces a plume of H2O. But there are major drawbacks, including cost. Extracting hydrogen from water or natural gas and cooling it to -423 degrees F make the fuel many times more expensive than kerosene, which goes for about $1 per gal.

Now interest in the novel fuel has been rekindled by news that the Soviets have conducted a successful test flight of a Tupolev Tu-154 passenger jet modified to burn a mixture of liquid hydrogen and natural gas. The three- engine jet, which lifted off near Moscow and flew for 21 minutes, was the first aircraft to use the fuel in takeoff. Says Senator Spark Matsunaga, a Hawaii Democrat and a leading advocate of a U.S. hydrogen-fuel research program: “It appears that the Soviets have stolen a technological march on us.”

The benefits of hydrogen have not been lost on one group of U.S. researchers. Engineers working on the proposed National Aerospace Plane say that hydrogen is the only combustible that ignites fast enough to boost the craft to orbital velocity, roughly 25 times the speed of sound. The frigid fuel could also be used in a cooling system to keep the plane from burning up during its fiery re-entry into the atmosphere. Test flights are scheduled for 1994.