Ok so here’s the skinny….
We all love solar energy, woohoo its cool. right. yeah. BUT, there’s so much more solar energy in space. SO…
What if we put a bunch of solar panels up in space, we could get like 10X the solar radiation per area that we would on earth. Plus, we could get like 24 hrs/day of sunlight potentially.
Then we could transform DC electricity from our PV into microwaves or lasers, and beam it down to earth to rectennas, which are rectifiers and antennas, which could convert microwaves/radio waves back to DC for transmission.
The other option would be to laser beam (yes, a frickin’ laser) energy down to the planet from the laser, which would solve the whole frequency/wavelength/large receiving rectenna issue. BUT the US is under treaty with Russia not to beam lasers from space towards the earth. Go figure…
Below are some very schematic images of what SPS might look like…
Here’s a concept by a Japanese team:
A note on solar power: when the SPS idea was initially ideated in the 70’s, solar panel efficiency was around 7-10%. This made the whole project a tough sell. But today efficiencies are getting up around 50% (PV developed by NASA). Anyways, the JPL says now they’re reconsidering this idea and the DOD has put some money towards it… link below to a recent article.
Here’s some more technica-ish information i gathered from Wikipedia…
The Skinny on Tranmitting Power:
Power Transmission (DC to photons)
Wireless power transmission was early proposed to transfer energy from collection to the Earth’s surface. The power could be transmitted as either microwave or laser radiation at a variety of frequencies depending on system design. Whatever choice is made, the transmitting radiation would have to be non-ionizing to avoid potential disturbances either ecologically or biologically if it is to reach the Earth’s surface. This established an upper bound for the frequency used, as energy per photon, and so the ability to cause ionization, increases with frequency. Ionization of biological materials doesn’t begin until ultraviolet or higher frequencies so most radio frequencies will be acceptable for this.
As well, to minimize the sizes of the antennas used, the wavelength should be small (and frequency correspondingly high) since antenna efficiency increases as antenna size increases. But, higher radio frequencies are typically more absorbed in the atmosphere than lower radio frequencies.
For these reasons, 2.45 GHz has been proposed as being the most reasonable compromise. However, that frequency results in large antenna sizes at the GEO distance. A loitering stratospheric airship has been proposed to receive higher frequencies (or even laser beams), converting them to something like 2.45GHz for retransmission to the ground. The proposal has not been as carefully evaluated for engineering plausibility as other aspects of SPS design.
THE HISTORY
The SPS concept was first described in November 1968. At first it was regarded as impractical due to the lack of a workable method of sending power collected down to the Earth’s surface. This changed in 1973 when Peter Glaser was granted U.S. patent number 3,781,647 for his method of transmitting power to aver long distances (eg, from an SPS to the Earth’s surface) using microwaves from a, perhaps square kilometer, antenna on the satellite to a much larger one on the ground, which came to be known as a rectenna. Glaser then worked at Arthur D. Little, Inc., as a vice-president. NASA became interested and signed a contract with ADL to lead four other companies in a broader study in 1974. They found that, while the concept had several major problems — chiefly the expense of putting the required materials in orbit and the lack of experience on projects of this scale in space, it showed enough promise to merit further investigation and research.
During the period from 1978 - 1981 the US Congress authorized DOE and NASA to jointly investigate. They organized the Satellite Power System Concept Development and Evaluation Program. The study remains the most extensive performed to date. Several reports were published addressing various issues, together investigating most of the possible problems with such an engineering project.
(Nasa Rendering)
http://www.spacefuture.com/archive/conceptual_study_of_a_solar_power_satellite_sps_2000.shtml
http://en.wikipedia.org/wiki/Solar_power_satellite
http://www.foxnews.com/story/0,2933,265380,00.html
http://science.nasa.gov/headlines/y2001/ast23mar_1.htm
Here’s another cool solar product, which i helped develop:
Its a solar-powered backpack, made by voltaic systems out of new york.
These bags and packs will charge and power your mobile devices as you roam about.
They use lithium ion batteries as a transformer for the three 24% efficiency solar panels, which can generate something like 14 watts… pretty soon they’ll have a model out that can charge/run your laptop. now its mainly for satellite phones, cell phones, ipods, lights, gps, etc… small electronics…
More at voltaicsystems.com - if you want a bag i can probably get them for ya half-off ($150-ish)…
