NEW APPLICATIONS OF MAGNETRONS

Running microwave ovens is not a new application, but a joyous one: 70% of US households now have a microwave oven, a stinging defeat of the Greens who tried as hard as with food irradiation to have them banned. (Very powerful microwaves do damage retina and testicles, but they have no chance to get through the lock and the viewing grid of an oven.) The frequency is the resonant fre-quency of a water molecule, and in any case, since food is conduc-tive and dishes are generally not, only the food is heated by free electrons bumping into the ion grid, the equivalent of friction. The dishes get hot only by conduction from the food (unless some carbon is purposely added to the dish for roasting etc).

The new method uses "char," microwaved coal, as a catalyst to absorb both pollutants. When the char is saturated with the pol-lutants, it is again heated by microwaves, breaking down the pol-lutants into their constituent parts, sulfur, nitrogen and oxygen. There is no sludge, the volume is small, the process efficient, and the sulfur can even be sold to the chemical industry. The first large-scale trial is scheduled for next year.

Attempts to use microwave heating for extracting oil from oil shale ended with the collapse of oil prices.

The Electric Power Research Institute (EPRI) in Palo Alto, the research institute of the utilities, is now also trying to use microwaves for clothes dryers. Whether this will be successful remains to be seen, and I am somewhat skeptical about it. Apart from problems like metal zippers and other conductors in the laundry, there is the question of efficiency. Whenever you convert one form of energy to another, you lose some as heat. When you are after heat only, the efficiency can be very high, because the only losses are heat that goes where it is not needed or wanted (e.g., up the stack, chimney or duct). A magnetron, being tuned to water molecules, might do the job faster, but not more cheaply, and not even faster than a regular dryer with higher power. Nor can I see any reason why the efficiency should be improved.