BEYOND ELECTRICITY

An HTGR runs at a higher temperature than an LWR; Ft. St. Vrain runs at 750 degrees C, and a little 15 MW plant in Julich, Germany, has been running at 1,000 degrees C since 1967. (It was Germany's first nuclear plant; last summer it produced its billionth kWh and is still running merrily.)

Higher temperature means higher efficiency; HTGR's have an efficiency of 39%. And high-temperature energy is high-grade energy, the type that can easily be converted to forms of energy more "valuable" than heat. (One can always convert all of any energy to heat, but not all of it back to non-thermal forms.) Electricity is such a form; it is mainly suited for energy transport and distribution.

But as an energy carrier, electricity has two disadvantages compared with gaseous fuels. First, almost twice as much energy is lost as heat in the conductors of an electrical transmission line as in a gas line (for powering the pumps and by leaks). Second, and more important, electricity cannot easily be stored: At 3 a.m. millions of dollars invested in generating equipment lie idle; at 3 p.m., it may barely cover the demand. But a chemical fuel holds its energy until it is needed for release.

Nuclear energy is tapped as heat, which is then used to generate electricity. The HTGR can do that, too, but its heat can also be used for other purposes, in particular, for the production of chemical fuels. Coal gasification and liquefaction, and the processing of oil shale is one large class of applications. Another is water splitting to extract hydrogen from it. (Chemical processes at high temperatures are more efficient than electrolysis, for which any source of electric power can be used.)