Pentagon in orbital solar power plan for world peace
Military techno-hippies: make 'leccy not war, man
Everyone knows that the US military is massively involved in American energy supplies. The deal is often said to be one of swapping blood for oil, though if it's just American blood we're on about the exchange rate is pretty good. Perhaps it would be more accurate to say that - overall - America swaps assorted explosives for oil.
Whatever. All that could change, at least in a sense, if some of the Pentagon's top thinkers get their way. Not only has the head of the US Air Force lately proposed that American warplanes should be fuelled on mushroom fuel: a new military plan has now come out advocating the use of solar powerplants in space to promote world peace. (And no, this isn't peace through superior firepower, or a desert called peace or any of those kinds of ironic military peace. It's peaceful peace where everyone gets cheap clean 'leccy.)
The new analysis (pdf), just out, comes from the National Security Space Office. It says that America should sink $10bn into building an orbiting solar power plant which would beam its juice down to the ground in the form of a high-energy microwave beam, which would hit a receiving antenna - "rectenna" - complex on the surface, and so get turned into electricity.
This is actually a fairly old idea, and has been pushed occasionally by various space advocates since the 1960s. Lovers of space-based solar power (SBSP) point out that many of the disadvantages of terrestrial solar are done away with. There are no cloudy days or even any atmosphere in space: thus solar power becomes consistent and dependable, potentially needing no backup capacity for night time or bad weather. SBSP also offers much more power for a given area of cells, about five times as much on average.
The ability to beam power down to wherever a rectenna can be erected could be useful, too, reducing earthly power transmission issues. The Pentagon particularly like this, as they often have to generate electricity in remote regions where there isn't any reliable grid to draw from. They frequently wind up paying top dollar for juice as a result, and having to drive convoys of tanker lorries full of generator fuel past grumpy, heavily-armed locals.
The space energy, too, would be green, clean and - in the present state of world space capability, anyway - free from the need to bargain for resources with dubious foreign despots.
On the minus side, SBSP platforms would be an order of magnitude bigger than anything yet constructed in space, and would require a similarly massive increase in space transport and infrastructure, and a serious drop in launch costs.
The Pentagon planners reckon that SBSP might be of some use for purely military or disaster-relief purposes. However, in order to accomplish their grander goals - clean, secure, affordable energy for the United States, world peace, etc. - a new generation of launch technology will be needed.
"In addition to the currently insufficient and extremely expensive launch fleet," the report says, "another issue is that most launches to Space today are on [Throwaway rockets]. Expendable vehicles will not support the business case for SBSP. Reusable Launch Vehicles [RLVs] will... Development of RLVs has likely been hindered by the lack of a sufficiently large market (payloads) thus far. Together, RLV and SBSP development can make one another viable."
The SBSP chaps seem to favour Two-Stage-to-Orbit, rocket powered fully re-usable launchers: essentially two rocketplanes stacked, the payload carrying one getting an initial piggyback ride from the other. They say this would involve very little in the way of new technology.
The study, says the Office, "was compiled through an innovative and collaborative approach that relied heavily upon voluntary internet discussions by more than 170 academic, scientific, technical, legal, and business experts around the world".
Expected rectenna array sizes are expected to be in the square km range.
But compare that to the size of solar arrays necessary to provide the same level of power, and generate excess capacity to be stored for nighttime, foul weather, and changing seasonal influx levels.
About 3 to 4 times the physical size plus massive storage facilities. And the whole lot is as toxic as Hell itself. Either during fabrication or inherently as with most battery technology.
The simplest rectenna element is a piece of bent wire and a fast diode rectifier. More complex ones with multiple elements and a backplane can achieve efficiencies as great as 90% with a receiver cost of just a handful of dollars per square meter.
Solar cells are expensive as hell. It makes sense to place them where the maximum wattage can be squeezed out of them. If it's affordable to do so.
And the effect microwaves have on the materials, items, critters and people in their way are very very dependent on the chosen wavelength. For fairly obvious reasons the first limiting factor is that for the purpose of power transmission the beam be as minimally affected as possible by the Earth's atmosphere. Thus it's affect on the atmosphere is equally minimal. One major element in the atmosphere, is water thus one frequency that certainly won't be chosen is the one used in microwave ovens. So strangely enough it's not going to speed cook any people or birds that manage to get in the way of a beam. At worst it would amount to a slight warming effect as some lesser element or compound in the body does adsorb a small proportion of any beam.
As for total waste heat input into the Earth's biosphere, it would be no different to today. That energy is generated and turned into useless heat regardless of it's source. Fossil energy sequestered in fossil fuels is the least of our problems. It's the greenhouse gases which modify the Earth's atmosphere to trap solar energy all over the many millions of square kilometers that face the sun every single second. The few terawatts we dirrectly add to the environment with our activities are nothing against the hundreds of terawatts (petawatts?) we're now adding indirectly through globlal warming.
And perhaps, one day as we get the hang of this strange idea of cooperation we can think about retuning a few transmitters to react with water, not to harm, but to tinker with the weather to redirect or sap the strength of dangerous storms and to create and/or steer beneficial rains over crops and catchment zones.
With abundant and sufficiently cheap energy virtually anything becomes possible. Even if we limit ourselves to the physical resources of Earth, magnetic separation of ionised sea salt could provide almost any rare element we could ever need. It's woefully inefficient but if the energy is cheap enough the rest is very basic engineering. Bucket particle physics.
My fear is not that launch system limitations will prove too expensive, but that they will become cheap too quickly for us to learn the lesson of cooperation properly if at all.
I once saw an article quite a few years ago that spoke of a microwave beam climbing launch vehicle. The basic idea was to focus part of the beam with a parabolic reflector to create a shockwave in the air ahead of the vehicle and creating a partial vacuum in front of the craft. The remainder of the beam was rectified and used to power a ring current around the perimeter of the craft which accelerated heat ionised air past the craft to create forward thrust. Rather ironically the shape of craft was two shallow bowls face to face, with a parabolic bowl inset into the upper surface. Claims were made in the article that the concept worked in wind tunnel tests. If it scales up and ever works in the real world launch costs would plummet to the point where virtually anyone could establish an orbital presence.
A recent development of solar cells which can be printed onto a substrate strike me as making the idea of SBSP even more attractive as solar cells can be rolled onto spools in thousand metre lengths and unwound onto gossamer frames in orbit. My guess is between and acre and a hectare of 12-14% efficient solar cells per ton mass.
It really is starting to look like it is doable, and may well be done soon. Leave it to the military alone and problems will ensue. If it happens, it must be with full international cooperation.
I can see it now...
...the little birdy flying along, happy as anything. It spies a shimmer in the air and its little birdy brain thinks "Updraft". It flies into that area where the energy is being beamed down from space....
Of course, no one will do anything until some idiot in an airplane strays off course...
... Tinfoil hat removed ...
@John Tocker - fair enough points, I have to admit I read the article a little too fast. Still, I'm more in favour of the alternatives;
> Frankly, I think wind farms, hydroelectric dams and large coal-fired power plants look frigging ugly
Yes, but is it really worth spending all the extra money on an orbiting power station just because you (and admittedly many others) object on aesthetic grounds?
> and the hydro dams and wind farms take up shitloads of space that could be better used for other purposes
Not sure what you mean by other purposes here. We're short of a lot of things on Earth but space isn't really one of them.
> Wind power and tidal power are not reliable and have to have some means of backup for when they are not at peak output.
Such as wind and tidal plants at other locations. Geothermal energy is pretty reliable where it can be had; maybe worth a bit of research?
> rocket technology required to build it would probably drop the cost of space travel to the point that "space tourism" (hell, that'd be a power station I'd be interested in visiting) to LEO and GEO might be affordable.