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An artist rendering of the potential orbiting solar plant. It would beam power to a massive lake-sized collector for optimal efficiency.   (Source: Kris Holland/Mafic Studios)

John C. Mankins, since leaving NASA, has spoken about his dream of space power both at various high profile news conferences. Now he has his biggest audience yet, with a historic proof-of-concept test airing on the Discovery channel.  (Source: Space Power Association)
New advances in power transmission would make Tesla proud

After decades of dormancy, interest in transmitting power wirelessly is finally heating up in the tech community.  Intel recently demoed its new wireless charging tech which it says could power its next generation chipsets.  Now, a former NASA researcher is revealing even grander plans to transform the business of power generation as we know it.

Funded by the Discovery Channel, John C. Mankins finished a four month experiment which began by collecting solar power, nothing out of the ordinary.  What happened next was relatively extraordinary, though -- he transmitted the power 92 miles (148 km) between two Hawaiian Islands. 

Terrestrial power transmission is only of interest to Mr. Mankins as a proof of concept.  Mr. Mankins' true plans are out of this world.  He envisions a network of 1,102 lb. (500 kg) satellites beaming solar power collected from panels back to Earth, satisfying all the world's power needs.

After working loyally for NASA for 25 years, he resigned after the solar program at the agency was terminated.  Now he's completed one of the more ambitious transmission experiments in history -- enough to make Nikola Tesla, the man who first envisioned wireless power transmission, proud.

The work still has a long way to go, though.  The transmission only successfully received one one-thousandth of the total power sent, a very low efficiency.  This was primarily because the receivers were so tiny.  Larger receivers, would still be rather inefficient, but could in theory, achieve much higher efficiencies.  Furthermore, the costs were relatively high at $1M USD, but Mr. Mankins believes the costs would decrease as the technology was scaled up.

In total each of the nine solar panels in the transmission assembly sent 2 watts of power.  They were originally equipped to send 20 watts, but the U.S. Federal Aviation Administration would only approve the lower power transmissions.

The encouraging results have reaffirmed Mr. Mankins' commitment to one day bring space-based solar power to the world.  His vision is that one day a fleet of satellites will beam power down to lake-sized receivers.  He enthuses, "The test was in no way fully successful, (but) I think it showed it is possible to transmit solar power quickly and affordably."

Mr. Mankins is president of ARTEMIS Innovation Management Solutions LLC, a startup which provides "strategic planning, technology assessment, and R&D management objectives" to government agencies.  He is also president of the Space Power Association.

The U.S. military is investigating similar plans to use satellite based solar power to beam power to troops on the battlefield.



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RE: efficiency
By Schrag4 on 9/15/2008 10:38:42 AM , Rating: 2
quote:
They tested it side by side to a normal cell, and they produced 8 times the energy with just this addition.


Ok, this doesn't make sense. Let's pretend that a 'normal cell' has an efficiency of 15% (this is pretty low by today's standards by the way). 8 x 15% = 120%

quote:
The technology was neat, and for a quick experiment, I was pretty impressed.


Yeah, I would be pretty impressed too if it were true.

...8 times. :-)) You just made my day. I'm still chuckling..


RE: efficiency
By Gzus666 on 9/15/2008 10:55:50 AM , Rating: 2
OK, take it up with the guys on the show, I am merely regurgitating what they pointed out. The man stated 8 times the power output. Watch the Project Earth episode about it, true or not, I have no stake in it, I am merely impressed by the simple addition providing a increase in power output.


RE: efficiency
By Gzus666 on 9/15/2008 10:58:51 AM , Rating: 2
And on the same note, it wasn't the efficiency of the cell that was increased, but the intensity of the light. Focusing the light more effectively yielded more energy, which technically has nothing to do with the efficiency of the cell itself, which is exactly the same as the other. The lens was a flat, flexible piece that had multiple mini prisms shaped into it, which amplified and directed light towards the cell.


RE: efficiency
By masher2 (blog) on 9/15/2008 11:32:37 AM , Rating: 2
I can only assume this lens was a fresnel-like concentrator that had 8 times the collecting area as the cell itself. That's the only way you can increase the intensity of incident light-- you can't otherwise just"amplify" light.


RE: efficiency
By Gzus666 on 9/15/2008 11:38:23 AM , Rating: 2
You would be correct sir. Nice call, I forgot the name of the thing.


RE: efficiency
By Innocent Hawk on 9/15/2008 11:33:24 AM , Rating: 4
It never ceases to amaze me how many people utterly FAIL at math when dealing with multiplication and/or percentages.

When he said it increases the power output by 8 times, that just means that the efficiency of the solar cell is applied to the new power output. The efficiency did not change, but the usable power attained at the end still does.

Solar cells have an efficiency between 5% and 18% depending on who made it and how it was made. Lets use your value of 15% however.

If a current solar cell generates, say, 100 watts but has an efficiency of 15%, then that means 15 watts were generated for use. If the prisms previously mentioned do indeed multiply the power 8 times, then that means we now are getting 800 watts. The panels are still stuck with a 15% efficiency rating however. This means that we get 15% of 800 watts , which means the end result is 120 watts.

Review/Math Checking:
15% of 800 = 120
15% of 100 = 15
15 x 8 = 120
Conclusion: 8 times more power was gained from the solar cell.


RE: efficiency
By chmilz on 9/15/2008 1:40:35 PM , Rating: 2
Wasn't it Chris Rock that made fun of how dumb people are at math?

"What's four plus four?"
"Ummm... jello?"
http://www.youtube.com/watch?v=WJ7dO2YPyZ4


RE: efficiency
By rcc on 9/15/2008 5:32:54 PM , Rating: 2
Like the definition of lottery?

"A tax on people that can't do math".


RE: efficiency
By mindless1 on 9/16/2008 10:29:56 AM , Rating: 2
Completely wrong. If a solar cell generates 100W with an efficiency of 15%, that means that 100/.15 = 667W worth of light was cast upon them. A 100W solar cell is a 100W solar cell, you utterly FAIL.


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