Solar Power Satellites

[NGTOne]

So, back in the '70s, NASA and a bunch of space-exploration advocates proposed the idea of building solar power satellites ("powersats") - if memory serves, during the Summer Study. Fresh off the high of the Moon landings, the future of space exploration and exploitation looked bright.

Basically, the premise was, put a bunch of solar panels (or a solar furnace) in geosynchronous orbit, and beam power down to the surface using microwaves (microwave power transmission over long distances is well-understood and well-demonstrated, and was that way at the time). You end up with clean, consequence-free power 24/7/365, no questions asked (with about a 75-minute-long "night" period when the powersat passes behind the Earth).

Now, fast forward 40 years. Surface-based solar panels only collect power half the time at best (and aren't particularly efficient to boot), all the good rivers have been dammed, and wind turbines blow (pun intended). Nuclear fission plants are as popular as shag carpeting, and commercial fusion power is decades away. Even if you don't believe in peak oil or anthropogenic climate change, smog isn't much fun, so there's a big movement away from fossil fuel-based power generation.

Now, a number of different multinational corporate conglomerations and national governments (the only organizations with enough resources) have proposed the construction of powersats as the solution to a power-hungry world. In particular, Mitsubishi (yes, THAT Mitsu, that makes everything from cars to cargo ships) and the Indian and Chinese governments have floated proposals to do just this.

Now, the problem of powersats isn't a simple one:

In order to achieve efficient, large-scale power transfer, you need an antenna about 1km across in space (and phased arrays won't cut it - the thinned-array curse makes certain of that) and a receiver about 10km across on the ground. Most conservative estimates put the cost of a single powersat, generating about 4GW of power, anywhere between US$11B and US$320B, depending on engineering constraints and decisions (decisions made by people much smarter than me), and would require a multitude of Earth-based launches and large-scale orbital construction. As a means of comparison, conventional power plants, whether coal or nuclear, cost anywhere between US$3B and US$6B per GW upfront.

Now, the question I put to you, the KSP community, is thus:

Is it worth it?

What's a better hope for the future of our electrical grid? Space-based solar? Nuclear fusion? "Conventional" alternative energy sources? And will powersats ever have a piece of that grid at all?

[InspectorBumHat]

I have read a few pieces on "beaming down" solar energy from collectors in space, most recently in the New Scientist. In that though they describe a problem which is not immediately apparent. Only a set amount of energy reaches the earth and by adding to this (by basically expanding the area) will lead to the earth catching more energy than it reflects/absorbs and therefore, slowly, it will heat the planet. I'd imagine you would need several of these satellites to even begin noticing any differences but nevertheless it's certainly something to think about before everyone starts putting up these kinds of satellites.

Edited August 13, 2013 by InspectorBumHat
It's late give me a break

[nhnifong]

If it's only about $20 billion for one 4GW installation, it might happen. Elon Musk would probably build the first one, just cause he though it would be cool. But if it's more like $200 billion, We'll never build one. Much cheaper to build 4GW of solar panels.

I think the future of electrical energy production will continue to be dominated by fossil fuels until they are completely exhausted, with solar, wind, and nuclear picking up the slack depending on the geography and political attitude of each country.

[Drunkrobot]

It depends on how you get it up there. It would be much cheaper to set up a base on the Moon with a manufacturing centre and a mass driver, then use it to build the components of the solar station and launch them to LEO, than it is to launch the components from Earth. You could also just pave the Lunar surface with solar panels, and beam it from there. There power that could be collected from the Moon (at least, the day side), assuming a 20% efficiency in the in the panels themselves, would be measured in terawatts.

[Tw1]

My favorite power plant in simcity was based on this principle. Though the chance of heating the Earth is a fair point, we want to be reducing the warming, not adding to it.

[jwenting]

seeing as the planet's been cooling for 15 years now, and no sign of stopping, I'm not worried about heating

I'm far more worried about a beam going off target and hitting a city.

And I'm not so sure about the side effects of beaming gigawatts of microwave energy in a tight beam through the atmosphere. Ionisation anyone?

[KOCOUR]

And wouldnt be easier to stop being pussies about Nuclear energy, and build just more Reactors on earth? The most advanced ones could even use nuclear waste as fuel.

[DerekL1963]

You end up with clean, consequence-free power 24/7/365, no questions asked (with about a 75-minute-long "night" period when the powersat passes behind the Earth).

It's only consequence free if you have a magic method of transporting the materials.... otherwise, one of the consequences varies with the launch method. Rockets don't produce much pollution per annum - but a fair proportion of what they do produce gets dumped into the upper atmosphere, particularly the ozone layer.

[Tommygun]

Well considering that solar power is slowly getting better and cheaper, I would rather they spend a 100 billion on researching better solar technology and energy storage over the next 20 years than building a spaced based one that will end up costing ten times more than was originally estimated.

[Seret]

You end up with clean, consequence-free power 24/7/365

The consequences of a beam-steering failure are potentially severe. I don't fancy the idea of mega or gigawatts of microwave energy walking across the countryside.

The real problem with SSPS is simply cost. There's no market that you could economically sell the power into. Apart from the problem of getting many tons of hardware up to GEO at US$30,000 per kilo you'd need regular launches for maintenance, resupply and repairs (and how exactly do you do repairs up at GEO?), ground control, etc. For safety reasons it would make sense to put the receivers out to sea, but that would add to cost too.

You may have 24/7 power, but you won't be able to compete with the other base load power generators (nuclear, coal, gas) on cost. That means you be trying to supply peak demand where prices are higher. Demand peaks highest in the evening, with another small one in the morning. Even if you could get your cost per kWh down enough to compete with other peak generators (which seems unlikely IMO) you'd only be actually generating a few hours a day.

Bottom line is that it's an idea that requires a whole lot of risky and experimental ideas, and doesn't seem to offer a very attractive return on investment. What it needs is someone keen to blow some cash on working up the technologies at demonstrator scale. If the risks could be shown to be manageable then it might be possible to fund a larger more useful one.

[NGTOne]

It depends on how you get it up there. It would be much cheaper to set up a base on the Moon with a manufacturing centre and a mass driver, then use it to build the components of the solar station and launch them to LEO, than it is to launch the components from Earth. You could also just pave the Lunar surface with solar panels, and beam it from there. There power that could be collected from the Moon (at least, the day side), assuming a 20% efficiency in the in the panels themselves, would be measured in terawatts.

seeing as the planet's been cooling for 15 years now, and no sign of stopping, I'm not worried about heating

I'm far more worried about a beam going off target and hitting a city.

And I'm not so sure about the side effects of beaming gigawatts of microwave energy in a tight beam through the atmosphere. Ionisation anyone?

The consequences of a beam-steering failure are potentially severe. I don't fancy the idea of mega or gigawatts of microwave energy walking across the countryside.

The funny bit is, this issue is actually resolved by one of the design constraints - under the designs studied by the Summer Study and others, the beam ends up being incredibly wide when it hits Earth, on the order of about 10km across (hence the giant receiving antenna). What I read was that, even in the middle of the beam, the power level would be far less than US dosage regulations allow, and at the edges it would be about 1/4 of the level that we receive from universal background. Even 4GW disperses to fairly little when it has to fill a circle 10km across.

Not only that, but potential designs have been floated that would make beam-steering failure a literal impossibility, by making it physically impossible for the beam to go off course (using a pilot beam, such that the beam literally could not strike a location that didn't have a pilot beam receiver, or something to that effect - I'm not much of a physicist, so I can't claim to understand it particularly well).

Edited August 13, 2013 by NGTOne

[Lexif]

I wonder if you can't invest the same amount of money into lots and lots of solar panels in some desert, and create some way to store the energy for the night. You'd have to eat the transmission and storage losses, and the losses from the atmosphere, but would the solar sat really be cheaper?

The consequences of a beam-steering failure are potentially severe. I don't fancy the idea of mega or gigawatts of microwave energy walking across the countryside.

It might be seen as testing a potential weapon of mass destruction in orbit, and therefore be forbidden by the Outer Space Treaty and SALT2. If you are American and don't see the problem, ask yourself how you would feel about a chinese or russian power station like that. It might start a new kind of arms race.

[andrewas]

Its physically impossible to tighten the beam to less than about 10 kilometers, so if you misdirect a power satellite to point at a city, you can't accomplish much.

Now, if you want to see a weapon of mass destruction, consider asteroid mining. Somewhere, out in the belt, a group of <enemy country>'s troops builds a mass driver, and every one of your major cities is hit by huge lumps of iron before you can mount any kind of response.

[Seret]

a circle 10km across.

Which would mean you'd have to build a receiver 10km across. You'd have to build on the cheapest possible land you could find, such as deserts, and even then it would be cheaper to simply:

I wonder if you can't invest the same amount of money into lots and lots of solar panels in some desert, and create some way to store the energy for the night. You'd have to eat the transmission and storage losses, and the losses from the atmosphere, but would the solar sat really be cheaper?

There is an idea bouncing around to cover a sizable portion of the Sahara desert with PV, and export the power north to Europe.

Annual insolation at ground level at the equator is about 2100kWhm^-2, in space you'd get a little under 12,000kWhm^-2 if you had 24/7/365. So in order to be economically viable you'd need to able to do it for only 5.7 times the cost of ground-mounted. That seems pretty unlikely for something way up at geostationary orbit.

[jwenting]

And wouldnt be easier to stop being pussies about Nuclear energy, and build just more Reactors on earth? The most advanced ones could even use nuclear waste as fuel.

of course, but the powers that be are addicted to "green power" which in the dictionary of the left means solar and wind (in reality of course those aren't environmentally friendly at all, but that's another story) and allergic (through decades of indoctrination by "greenpeace" and their ilk) to the very words "nuclear" and "atom".

Indeed we can build (and even have built) reactors running on nuclear waste, but a few well placed fear campaigns about "making nuclear weapons materials" caused those to be shut down before they even were put into service. (read up on Kalkar). Utter nonsense, but the general population doesn't know that and has been indoctrinated enough they won't believe truth if it doesn't match the propaganda coming out of the "environmentalist" movement (which is also why the IPCC is still treated like they're godlike and can't lie, when everything they've said over the last 20 years has been thoroughly debunked as a pack of politically inspired lies).

[andrewas]

Energy storage is a hard problem. Battery technology simply does not scale to this level. Pumped hydro floods vast areas of land. There is an unproven scheme that pumps air underwater. Running an entire continent on stored power is going to be much more difficult than generating that power in the sahara in the first place.

On top of which, filling the Sahara with solar panels is going to have some environmental impact, and isn't a job is relish in the first place. Shifting sands make poor foundations, airblown sand would rapidly degrade the panels, and the occasional flash flood would wreak havoc with the system. Putting those panels in orbit may cost more upfront but constant operation and lower maintenance costs would probably save money in the long run.

[Sirrobert]

And wouldnt be easier to stop being pussies about Nuclear energy, and build just more Reactors on earth? The most advanced ones could even use nuclear waste as fuel.

This. The whole nuclear scare is just like people being afraid of airplanes, 1 problem gets blown up so much by the media that everyone thinks its happening all the time

[Seret]

Energy storage is a hard problem. Battery technology simply does not scale to this level. Pumped hydro floods vast areas of land.

It is, but storage isn't always required. Current grids generally manage without significant storage. Pumped hydro is the best we've got at the mo.

There is an unproven scheme that pumps air underwater.

There are also mature systems that store it underground. Although generally this is simply used to boost the efficiency of thermal plants, as compressing air is a major source of losses for them.

Running an entire continent on stored power is going to be much more difficult than generating that power in the sahara in the first place.

AIUI Desertec doesn't envisage any requirement for large-scale storage. It would work the same way as current cross-border interconnectors. It would just allow the northern African states to sell their available resource into the European market.

Edited August 13, 2013 by Seret

[The Jedi Master]

Usually, I would be concerned about the price tag, but this is the future of electric civilization we're talking here. If I had the authority, I'd say yea to the plan.

[Seret]

This. The whole nuclear scare is just like people being afraid of airplanes, 1 problem gets blown up so much by the media that everyone thinks its happening all the time

People are really bad at assessing risk in a rational way. They always perceive threats that are large and rare (eg: nuclear meltdown, plane crash) as being worse than threats that are routine (eg: driving a car). In reality that's backwards, but it's the way people's brains are wired.

[jwenting]

Not only that, but potential designs have been floated that would make beam-steering failure a literal impossibility, by making it physically impossible for the beam to go off course (using a pilot beam, such that the beam literally could not strike a location that didn't have a pilot beam receiver, or something to that effect - I'm not much of a physicist, so I can't claim to understand it particularly well).

a theoretical impossibility is in my experience an engineering certainty...

[jwenting]

On top of which, filling the Sahara with solar panels is going to have some environmental impact, and isn't a job is relish in the first place. Shifting sands make poor foundations, airblown sand would rapidly degrade the panels, and the occasional flash flood would wreak havoc with the system. Putting those panels in orbit may cost more upfront but constant operation and lower maintenance costs would probably save money in the long run.

and then there's the climate change resulting from the changed albedo, which given the large size will affect wind and precipitation patterns over thousands of kilometers, iow well outside the desert itself (and of course the desert wildlife and plants won't like it either).

[Drunkrobot]

the powers that be are addicted to "green power" which in the dictionary of the left means solar and wind (in reality of course those aren't environmentally friendly at all, but that's another story) and allergic (through decades of indoctrination by "greenpeace" and their ilk) to the very words "nuclear" and "atom".

Pray tell, what exactly does wind turbines and solar panels do to the environment, and how could it possibly be any worse than the hydrocarbon power plants we have right now? And how does it all connect with this "leftist conspiracy" that is trying to destroy the environment on purpose? In countries that have a lot of wind or sun, turbine farms and solar collector power plants are viable, and private turbines and panels mean a little less fossil fuel is needed every day.

You could imagine me as a hippy new age believer, but that would be incorrect. I wouldn't fear a nuclear reactor, the latest generations are making meltdowns physically impossible. But the problem with them is that they run on something that is not renewable. Uranium isn't going to run out before oil, but it will still run out. I stand by my opinion that, money no object, the space or Moon-based solar power stations are the best choice. The Sun is going to be here for quite a while, and the comments on "the microwaves heating the atmosphere" ignore the fact that the equivalent power from hydrocarbon power plants would heat up the planet way more.

[Lexif]

Annual insolation at ground level at the equator is about 2100kWhm^-2, in space you'd get a little under 12,000kWhm^-2 if you had 24/7/365. So in order to be economically viable you'd need to able to do it for only 5.7 times the cost of ground-mounted. That seems pretty unlikely for something way up at geostationary orbit.

Thanks, that's about what I thought. I remarked on storage to get to an upper bound for a comparable earth-bound project, not because I see that as an alternative. Say, let's use cheap solar panels and car batteries. My hunch is that you would still be off cheaper.

The total area needed for such a project is not that big. About 125x125 km² for all of Europe's power needs if you trust this publication from Desertec (should not be more than an order of magnitude off ):

https://de.wikipedia.org/wiki/Datei:DESERTEC-Map_large.jpg

That's about as large as all paved areas in Germany. (Got my data on that also on wiki, just to get an estimate.)

But Desertec is pretty much dead, and I suspect that it was a scheme that made some speculator very rich. It was always a pipedream. But I guess the USA would be much better suited to such projects, deserts relatively close to the population centres, politically less problematic (in theory).

[Nuke]

both semiconductors and composites use some pretty nasty chemicals in large quantities. chemicals that have to be produced in chemical plants, and im not sure what kind of byproducts result from that (likely nasty ones). not so much worried about the issue of bird strikes (house cats kill orders of magnitude more birds than wind turbines ever will, and im not giving them up any time soon), but its there. solar panels of today will be the tech trash of tomorrow, and we cant even deal with that in a sane way (our current solution is to send it to china for "recycling", with a blow torch).

the problem with green energy solutions is that they are all for the short term. they dont bring energy to everyone on the planet, only those that can afford it. space based solutions fall into this category as well. its to expensive to be viable for everyone, its definitely a hard sell to the first world. none of it brings fair global power distribution. the 3rd world will eventually rise to where we are now, and will spew coal fumes into the atmosphere like we have done to get here (much like china is now). they will have to tech up the way we have to get their own space based solar generation system. this will surely keep the world pumping carbon into the air for decades or even centuries to come. so i think fusion is the only long term solution.

the problem with fusion research is we always dump the cash on the most expensive method with the slowest results (anything involving a tokamak). the 50 years away comes from the fact that it takes 25 years just to build a fusion facility, thats before you do actual science. the iter plan is to build 2 reactors, iter, the proof of concept, and demo, an actual net power producing reactor. theres your 50 years. if you use bussard's yardstick fusion is only 10-20 years out, and his polywell concept will be producing net power for the us navy in no time. they know how big it needs to be, they knew how much power it would need to operate. the only thing left to do is build a full size reactor. and this is a reactor that can fit in most people's living room and cost a tiny fraction of what a tokamak based powerplant would cost to manufacture.