Japanese Firm Proposes Microwave-Linked Solar Plant On the Moon 330
littlesparkvt writes "Harnessing the sun's power is nothing new on Earth, but if a Japanese company has its way, it will build a solar strip across the 11,000 mile Lunar equator that could supply our world with clean and unlimited solar energy for generations." Some of the company's other projects look just as ambitious.
11000 miles? (Score:5, Informative)
Gravity wells and other distance issues (Score:5, Informative)
A major issue is that the moon is fairly far up Earth's gravity well. It is easy to get things to low-Earth orbit and already tough to get things to even geo-stationary. The main saving of putting anything on the moon will come if you can do a large part of your construction on-site since otherwise moving that much material up is going to be tough. If you are doing automated construction on site you also are going to need to be able to make mainly a lot of solar cells. Solar cells are primarily silicon and there's already been prior research on refining the moon's regolith for silicon to manufacture electronic components and that looks possibly doable but one does need to get over some technical chemistry issues. See e.g. http://www.asi.org/adb/02/13/02/silicon-production.html [asi.org].
The other issue is distance for power transmission: most designs for microwave power involve power transmission from at most a little over geo-stat at about 35,000 km. The distance to the moon is about 10 times that, so if you don't have a really tight beam, there are going to be issues. Also, since the moon change's position you are going to need a large number of sites on Earth that can receive the beam, and if you can't switch off smoothly between them always (which would itself require massive planet-wide infrastructure), you would still need power sources on Earth (possibly just massive storage facilities?) to deal with those times.
Overall, a really cool idea with a lot of technical hurdles. I hope they can make it work but I'm not optimistic.
Re:FTFY (Score:4, Informative)
Some of the company's other projects look just as ludicrous.
Helps when you put the D in there.
Re:ambitious? (Score:4, Informative)
After the oil runs out, there won't be any money. Details here [ourfiniteworld.com]. Warning -- it's a harrowing read.
Dr. David R Criswell and Shimizu (Score:5, Informative)
Shimizu Corporation intersects with Dr. Criswell in another way that I just discovered today after searching for his more recent patents.
We've got to attract technological civilization's population away from natural ecosystems into idealized artificial environments such as Shimizu Corporation's design for what it calls the "Green Float" [shimz.co.jp]. You can house the entire population of civilization in beach-front property on the boundary of a tropical rain forest where people can swim, fish, hunt and gather recreationally, as well as access the height of urban lifestyle. From there space habitats are likely to emerge so that the natural propensity of these "cells" to replicate endlessly needn't destroy Earth's biosphere. Interestingly, I came up with a geometry that looks very similar to that years ago, with the Solar Updraft Tower Algae Biosphere proforma [oocities.org] and, over the subsequent years, I found a floating photobioreactor technology that requires little more than 2 layers of polyfilm that has demonstrated production per cost figures far in excess of what I projected in that proforma. Before I ran across Shimizu Corp's Green Float I had further refined the idea based on the Atmospheric Vortex Engine [blogspot.com], which, like Shimizu's "Green Float", is ideally sited in the equatorial doldrums and could make use of the central tower of the Green Float. I posted some preliminary thoughts over at the Seastead Institute's blog [seasteading.org].
A key problem I attempted to address in my preliminary thoughts was the early market for energy from the Atmospheric Vortex Engines that would form the nuclei for Shimizu's Green Floats. A big problem was the fact that the electric power markets are thousands of miles away from the floating AVEs even if you could build on the order of a terawatt of oceanic power transmission lines thousands of miles long. Early markets are critical for attracting capital -- the lack of which renders such grandiose ideas "non-starters".
I had thought it would be very nice to have a microwave transmission technology that could dynamically switch the power distribution to achieve the holy grail of "dispatchable [wikipedia.org]" power generation for peak loads, but wasn't aware, until just now, that Dr. Criswell's recent revision of his patent [google.com] serves precisely that purpose.
Re:11000 miles? (Score:5, Informative)
Yes, I don't however see any data on their website about how wide they are planning to build the ring out. If their graphical renderings are accurate, they display a 195 pixel moon with a 22 pixel ring. Given that google tells me the moon's radius is 1737 km, that means the ring should be about 200 km wide.
So considering that we have a 11,000 km ring that is 200 km width, the power generation for the light-facing half should be what you'd expect from 5500km x 200km or 1,100,000 square kilometers. I've seen estimates of 1.2 mw per square km for solar [youthkiawaaz.com]. Using that as a basis we'd expect 1,320,000 mw of constant power generation. Wikipedia says to take off 10% due to conversion inefficiencies of microwave transmission of electricity [wikipedia.org] and we probably should take off another 5% or so for weather and atmospheric disruptions or inefficiencies. That leaves us with 1,122,000 mw of constant power.
As a point of comparison, all the wind power in the entire world added up to 238,351 megawatts in 2011 [wikipedia.org], so it is roughly five times the capacity of that. However, in 2008 the world had an average power consumption rate of 15 terawatts [californiaphoton.com]. 1,122,000 mw is 1.12 terawatts, so this project could supply roughly 7% of the worlds electricity if it was operational today.
The moon has an area of 37,932,000 square km though, so if we coated the entire moon and got energy from the sunny side and do the same math we get 19.34 terrawats. So, at our current state of energy usage it could power the world if we coated the moon in solar panels.
I'm not sure about the aesthetics of it though, a racing stripe on the moon.
Re:11000 miles? (Score:5, Informative)
I've seen estimates of 1.2 mw per square km for solar
I wouldn't trust that estimate. That's all of 1.2W/m^2. Solar radiation at our average orbit is more than 1000x that. Silicon and GaAs panels would be 200-300W/m^2. Even thin film panels should be in the several tens of watts. Remember, there's no atmospheric dissipation, nor any issues with weather. All you have to worry about are eclipses, micrometeorite damage, and radiation damage. Better have enough storage capacity to hold you over during those eclipses.
Unit error (Score:5, Informative)
You got your units wrong here, I'm afraid. The source you are referring to is not speaking about 1.2 MW per square km. It is speaking about 1.2 MW per km of road. Roads are pretty thin, so installing solar panels along them does not result in many square kilometers per km.
This mistake leads to your result being off by a huge amount. The solar constant is 1.361 GW per square km. Normally this is reduced by 30% by the atmosphere, but that does not apply in space. Neither are there clouds to worry about, so we can pretty much use this number directly, after dividing by pi to account for the lunar day/night cycle, giving us about 0.45 GW per square km. High-end satellite solar cells get up to 29% efficiency. Using that, we get 0.13 GW per square km. With an area of 11,000 km by 200 km = 2.2 million square km (we have already taken the night into account in our numbers), that results in a total production of 286 TW, which is 19 times the world's current total energy use. Of course, one has to get this energy down to earth somehow too. This seems to have an efficiency of about 85% (possibly squared - unclear) [wikipedia.org]. That partially negates the advantage of being outside the atmosphere, but we still end up receiving 206-243 TW.
So no, the main objection to this plan isn't that there wouldn't be enough energy available. It is how much resources would be spent making it. I think one will need some sort of self-replicating solar-cell-producing robot on the moon to avoid this requiring too many launches. But I have not read the tehcnical details of their plan.
Re:ambitious? (Score:4, Informative)
The article did not say oil would run out, just affordable oil.
Here is a summary
The problem is not peak oil, but peak affordable oil.
We are already there, the big oil companies have cut back exploration because the cannot make money even at $100/barrel.
High oil prices choke off growth in our economy
With little or no growth, we cannot pay our debts.
As in 2008, unpayable debt will crack our financial system
As not in 2008, the central banks have shot most of their “arrows” and have few left in their quiver.
With a broken financial system, we will have the social chaos that was barely avoided in 2008