Comments on: Tech Pieces: Darkest Material May Boost Solar Conversion Efficiency

By: Rob Mahan

Rob Mahan — Wed, 17 Dec 2008 01:50:49 +0000

Lonnie Johnson, an Atlanta-based scientist and inventor, has worked for SAC and JPL, holds about 100 patents ... and he invented The Super Soaker squirt gun! The revenue from squirt gun sales has allowed him to continue to be creative and he was recently honored for a new technology deemed the "Johnson Thermo-Electrochemical Converter System" (JTEC). It is a solid state, closed system thermodynamic engine that uses a temperature differential to generate electrical energy by pushing hydrogen ions through two membranes. The closed JTEC system does not burn oxygen and heat is the only fuel required. It is claimed to be highly scalable and suitable for space-based applications. When I read about JTEC, I thought it might be a possible alternative to PV cells for collecting and converting space-based solar power. The naturally occurring temperature differential in the vacuum of space would fuel the system and it seems like it might be much easier to harden it against damage from micrometeorites and space debris. Here is the website where I read about JTEC: Johnson Electro Mechanical Systems : JTEC. I hope some of the contributors here will take a look at JTEC and see if it merits further evaluation for a space-based solar power application. Rob Mahan Citizens for Space Based Solar Power

By: Neil Cox

Neil Cox — Sun, 22 Jun 2008 16:58:15 +0000

It is unlikely the black can help photo voltaic, but it is helpful for thermal solar. Using concentrating mirrors the upper temperature is the temperature of the Sun’s photosphere = about 8000 degrees f, but all material is a gas, more corectly plasma at 8000 degrees f, so the practical upper limit, for solar thermal is about 4000 degrees f, a bit hotter than is practical on Earth’s surface.
My guess is the light polution by SSP is minor for astronomers. Venus is brightest when it is about 80 million miles from Earth, and has a diameter of almost 8000 miles. An 8 mile diameter SSP 80,000 miles from Earth should appear the same size as Venus. A two mile diameter SSP, 20,000 miles from Earth should appear the same size as Venus. In most cases dimmer than Venus. Neil

By: Robert

Robert — Wed, 18 Jun 2008 17:30:33 +0000

OK. I vote for dark sats as a tribute to Kubrick and Clarke, if for no other reason. However, I’ll never get over the swinging food tray as it drifted off of Dr. Floyd’s lap.

By: Akhenaten

Akhenaten — Sat, 31 May 2008 22:26:10 +0000

Many amateur astronomers might well fear that solar power satellites will cause more light pollution in the night sky; I imagine the ultra-low albedo material spoken of here would obviate this concern?

By: Robert

Robert — Mon, 31 Mar 2008 16:52:29 +0000

I’ll get off my movie kick. I’m sure the shape and appearance of an SPS will follow its function well enough. Always enjoy the progress on these pages.

By: Dan Lantz

Dan Lantz — Wed, 26 Mar 2008 18:37:29 +0000

All:

I suspect that this darkest material is already in the realm of vanishing returns, in that true radiators(collecting and dissipating) will work well at the high temps needed for industrial purposes, as long as they are fairly dark. Going from 99 to 99.9% is great if you are doing sensitive dectection of faint cold signals, as it is a 10-fold improvement. Doing the same when 80-90% works somewhat well is only a small improvement, relatively. I doubt it is a major breakthru, from our point of view, esp if expensive to produce.

By: Edawg

Edawg — Mon, 24 Mar 2008 01:37:39 +0000

Robert #6~solar-fired space-based processing plants

could this uber dark material be used in solar fired smelting ovens?You could have a all in one SSP plant/ISRU facility!

By: Robert

Robert — Fri, 21 Mar 2008 04:14:26 +0000

Arthur Clarke has just died. Thank you for your reply, Neil. And thank you Mr. Clarke and Mr. Kubrick, on behalf of more of us than we know here today. I’m alright with the idea that those 40 ft. deep lunar pits in the film “2001: A Space Odyssey” might in fact yield large flat black rectangular objects which, when placed purposefully in Clarke orbit (and cutting very much larger profiles thanks to the magic of stortelling and solar-fired space-based processing plants), would indeed represent “the first evidence of intelligent life off the earth”, namely our own children, living in O’Neill habitats, who will make a fine living delivering clean energy to the earth and to ships and homes beyond the moon, via those magnificent black rectangular objects planted mysteriously in our situation by uncompromising Uncles Arthur and Stanley.

By: Neil Cox

Neil Cox — Sun, 16 Mar 2008 08:10:38 +0000

Yes Robert, a large black rectangle, except we need narrow access strips to carry the energy in and out of the rectangle and to make repairs.
My idea is several satellites connected by power cords and/or flexable steam pipes. Each several kilometers long. This allows each unit to aimed (and positioned) separately, provide redundency and helps keep the size within reason. One or more parabolic mirrors to concentrate the sun’s energy. One or more heat disposal platforms which can be in the shade of the other platforms. One or more receivers which make electricity and/or steam. One or more platform to send the energy from space to Earth.
Hybred dynamic, sun pumped laser and photo voltaic might be best, with the photovoltaic using the outer edge of the illuminated spots. The center of the illuminated spots would be too hot for photovoltaic.
The concentrating mirrors can possibly illuminate part of the night side of Earth when not needed to make power. A concentrator mirror would look like Venus over several million square kilometers of Earth, when aimed at Earth. Aimed elsewhere the concentrator would look like a dim asteroid. Several concentrators would light up the night usefully. Neil

By: Robert

Robert — Mon, 10 Mar 2008 18:27:07 +0000

Well, I’ll go ahead and ask. Except for the discussion of the parabolic reflector, could the satellite logically be a large flat black rectangle floating in space? (Give me some slack, I’m a musician type.)