Okay, gnu, here it is.

Doug Johnson, one time guitar student, and table partner over many cups of coffee in a University District restaurant, rather enjoyed science fiction, and as an engineer, he tried to come up with technologies that would actually work.

How to supply cheap, continuous electrical power for a manned base on the moon.

He noted that Native Americans in the Southwest had a unique method for refrigeration. This works best, he said, in a desert area with fairly extreme temperature changes between day and night. And on the moon, of course, those temperature changes would be very extreme.

Put a heavy blanket or other insulating covering over a patch of ground several days in a row, shielding it from the sun, then take it off at night and let any heat it absorbed radiate away. Repeat this drill for a while and you wind up with a patch of ground that, Doug tells me, is cold enough so that the Native Americans could make something very similar to ice cream!

Doug started sketching rapidly on restaurant paper napkins as the explained what he had in mind.

"Now," sez Doug, "suppose you develop the idea. Take a really large area, install rails on either end of it, and bury a mesh of pipes containing a fluid just under the ground, running back and forth from one side to the other. Along the halfway line, install turbines that the fluid must pass through. Then cover half the area with an insulating sheet of some kind. Fiberglass, whatever. You mount this sheet on the rails. During the day it covers half of the area. Come nightfall, it moves to the other half of the area. What happens is that you wind up with two areas side by side, one of which is extremely hot, having absorbed the sun's heat during the day, adjacent to an area that is frosty cold, having radiated what heat it contains into the cold night sky. The hot fluid rushes through the turbines producing electricity, then cools down, runs back through the pipes to be reheated again.

"Electrical power. With no charge except initial installation of the system and whatever maintenance it may need.

"This would work like Gangbusters on the moon where the temperature changes are very extreme, but it would also work quite well in any, say, desert or prairie area, where the temperature changes between day and night are quite wide.

"Pretty neat, huh!?"

We were just slinging ideas around for inclusion in science fiction stories, but as an engineer, Doug assured me that it would work very nicely, even here on earth.

I'm pretty sure he didn't patent the idea.

Don Firth

P. S. I put the idea out there, but I'm also open to any critiques of the system.