Stirling Update #1
Date: Sun, 15 Sep 1996 00:04:58 -0700 / From: Gregory Glenn
Hi Jerry, I'm a photovoltaic cell engineer for Hughes Aircraft (satellite solar power systems). I just want to give you my thoughts on the Cummings Sterling Engine. By the way, I have my own solar stirling engine and have studied them in some detail, as they have been proposed for powering the Space Station "Freedom" (currently the space station will have solely solar cells for power, as stirling or rankine cycle engines have gas retention problems in the vacuum of space).
The 9kW power in 8 sq. ft. of collector must be a typo, unless some "free energy" mechanism is in effect. The reason is as follows:
Terrestrial solar power is rated (or standardized) at 1000 W/m^2. The 8 ft^2 collector described in the abstract is only 0.743 m^2. At 100% efficiency the engine would produce 743 watts. However, stirling engines coupled to generators produce up to only about 35% efficiency, and that's at very high temperatures. At 35% efficiency the Cummings engine would produce about 260 watts, which is about 3% the energy claimed. Based on the above calculation, one would need a 277 sq. ft. (25.74 m^2) solar collector to produce 9 kw of electrical power.
I am totally a Free Energy enthusiast, but when one talks about SOLAR ENERGY, one has to realize that there's a fixed maximum amount of solar radiation striking the earth. By the way, there's about a 1/3 more available in space (1,353 w/m^2). If the Cummings Engine is somehow tapping into Zero Point Energy, well that's another matter...!
Hope this has been "enlightening". - Best regards, Greg Glenn