MOTHER EARTH NEWS built and tested a Minto wheel, with disappointing results.
MOTHER EARTH NEWS put the Minto solar-powered wheel to the test.
At the age of 11, when most young sprouts are deeply engrossed in adventure tales of one sort or another, Walter Minto bought a college chemistry book for 10¢ in a used book store. "I thought it was more fun than any story I had ever read," he says now.
Maybe that explains why, by the time he was 15 (in 1936), Wally and his dad were deeply engaged in research on atomic energy. "Nobody cared about uranium in those days," he says, "and we could get it for the hauling from refineries that were interested only in the radium they could extract from pitchblende. Pretty soon we had about 50 tons of really high-grade stuff sitting in our backyard . . . enough to give us a corner on the market when President Roosevelt set up the Manhattan Project to develop the atomic bomb during World War II. So we sold it all to the government and I went with the Manhattan Project as the head of the radioactivity lab, special problems division."
After the war, Minto moved on to develop a line of ultra-low-cost radioactivity detectors but, by 1949, his interest in atomic energy had given way to a fascination with geothermal energy. Low temperature geothermal energy . . . and, before long, he had developed a Freon engine designed to tap this source of power.
But petroleum was dirt cheap then and nobody was interested in his ideas. So Wally soon involved himself in a study of the pollution problems that he could already see developing years before most of today's environmentalists were out of short pants.
Somewhere along the way Minto was also drawn into a still-secret project for the Navy because of some controversial electromagnetic discoveries he had made and—as many of us well remember—he revived his low-temperature Freon engine in the late 60's, put it into an automobile, and proved that his updated variation of the old Stanley Steamer was highly efficient and virtually pollution free. Datsun, the Japanese manufacturer of cars and trucks, is currently toying with the idea of putting the Minto Freon steam engine in a line of its vehicles.
All of which is to say that Wally Minto has long been involved in the development of what—at the time he first took up tinkering with them—have been considered "crackpot" ideas . . . particularly energy ideas.
We (and Popular Science and Solar Energy Digest and a number of other periodicals) were understandably interested, then, when Minto's Sun Power Systems in Sarasota, Florida recently announced Wally's latest Freon engine: a solar-powered wheel that turned as Freon was boiled and forced to expand from the bottom of the vertically mounted, liquid-filled rim to its top.
Three or four months ago a couple of MOTHER people even flew down to Sarasota to see Sun Power Systems' six-foot model of the wheel run on nothing but the energy it received from the solar rays reflected on it by a mirror (see photos to the left of this text).
Well . . . the wheel turned, that was for sure. But we still weren't absolutely certain that it would do any useful work. So we called Steve Baer out in Albuquerque, who told us, "We've fooled around with the concept and the wheel will turn and it'll make other things turn but it won't really do the kind of useful work that we've come to expect from our engines."
And then we began to get letters and phone calls from all kinds of people who had seen our little article in MOTHER NO. 38. "God bless you for promoting this new energy source," said some of the correspondence. "You rip-off artists! Whatta ya mean promoting that piece of junk," said others.
So, in the interest of delving deeper into the workings of something that could arouse such widely differing opinions in our audience, we decided to build a 22-foot-tall Minto wheel of our own and test it.
Result: At least based on our experiments, Steve Baer was right. The wheel will turn and it will do useful work (if you call lifting Dennis Burkholder off the ground as shown in the Image Gallery "useful work"). It'll even break two-by-fours in two (as we found out) when you stick them through its spokes in an effort to stop the turning of the monster. And it'll run a cement mixer (which we just happened to have handy in the shop and which we hooked up with a rope "belt" to our wheel).
But the dang thing turns over so slowly. (We were shooting for a one-revolution-per-minute speed with our 22-foot wheel loaded with Freon 12 . . . but the close-to-250-pounds-per-square-inch pressure we were getting in the tanks was too scary. So we switched to Freon 11 . . . which cut our operating pressures down to 48 pounds per square inch . . . and the wheel's rpm to one every five minutes!)
And it was a sad disappointment to find, contrary to Minto's confident prediction that our wheel would work on a temperature difference of "three to twenty degrees", that we had to fire our "heater"—a water tank that enveloped the circular engine's bottom edge—up to a temperature difference of 70°F . . . even 100°F. And when you're heating water to as much as 180°F to make a wheel turn, you might as well heat it on up to 212° or so and run a real steam engine.
It also becomes quickly apparent to anyone who fools around with one of these wheels that the blamed thing will run better if heat is applied to its rim not on the bottom, but somewhere in the range of 15 to 30 degrees up its "back" side. And that immediately rules out water and throws you—if you want to use the sun as your energy input—on the mercy of parabolic reflectors which have to be rigged to track Ole Sol across the sky and other complications that, again, make you sorta suspect that "ordinary" sun-powered steam engines are a better bet than the Minto wheel.
And that's where we stand on the whole idea right now. Although we sincerely wish otherwise, we've just spent $12,000 proving that the Minto wheel isn't really a practical solar-powered engine. Waste heat from other sources might be a different story . . . but forget running the backwoods homestead on a sun-powered wheel.
We've stuck our necks out . . . so that you can now invest your money in flat-plate collectors, Steve Baer's skylids, and all the other solar hardware that past performance has shown does work. But we don't mind. That's what we're here for. That's what MOTHER's research facilities are all about. Next idea, please.
And, Wally Minto, we still love you. Because a heck of a lot of your other ideas have delivered the goods as advertised.
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