Solar Power Satellites

[Arbolus]

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.

I haven't read the article, so I don't know if this is addressed. But the way I see it, assuming the amount of energy beamed down remains constant in the long term, the rate of heat radiation will increase as the temperature rises and we'll reach a new equilibrium. The world might be a few degrees warmer than it is at present, but the difference would be much less than what we can expect from global warming if we keep burning hydrocarbons.

[Lexif]

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.

So you say renewable energy solutions including this space project are only for the rich and do not help the third world, but fusion will? Are you kidding me? The real problem in these countries is a lack of good governance and of access to education. I'm sure a huge centralised ultra-high-tech power station will last really long in Nigeria. After all, look at all their nuclear power plants! /sarcasm

If you want to tackle real third world energy problems, try stuff like supplying poor people around the world with cheap ovens. They save a lot of expensive wood (people in some regions pay most of their scarce income for firewood because of the huge damand) and emissions are hugely reduced, and a lot less people die by accident.

I haven't read the article, so I don't know if this is addressed. But the way I see it, assuming the amount of energy beamed down remains constant in the long term, the rate of heat radiation will increase as the temperature rises and we'll reach a new equilibrium. The world might be a few degrees warmer than it is at present, but the difference would be much less than what we can expect from global warming if we keep burning hydrocarbons.

I guess the effect will depend on where in the atmosphere the energy is absorbed. That there is an equilibrium depends on a constant energy usage, but it will quickly rise. And "a few degrees warmer" would be catastrophical, considering that's the global average. But I guess that argument is just a distraction from the real flaws of this project.

[andrewas]

Earth receives about 174PW from the sun. A few GW from orbital solar are not going to have a significant effect on global temperatures.

[Seret]

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).

As solid state devices solar panels have a pretty long life. Most of the ones installed 20 years ago are working fine with only minor degradation in performance, which is extremely long-lived for semiconductor devices. The actual panels themselves are very, very reliable, and easily work off the impact of their manufacture during their lifetime. Some of the associated kit like inverters display lifetimes more typical of electronics (5-10 years) but again these don't result in a negative lifecycle impact for the system as a whole.

There's no such thing as a free lunch, any solution will carry some embodied energy and impact from its manufacture. The question is whether the overall lifecycle impact is positive or negative. To be viable a renewable technology has to be net positive impact, and all the renewables we currently deploy in large quantities do that if specced and installed properly.

Earth receives about 174PW from the sun. A few GW from orbital solar are not going to have a significant effect on global temperatures.

This.

[Warshawski]

Earth receives about 174PW from the sun. A few GW from orbital solar are not going to have a significant effect on global temperatures.

Most certainly this. A GW and a PW are several orders of magnitude apart. The Earth won't even notice, except in that the coal and oil plants we shut down will no longer be producing the toxins that they currently are during normal operation and pumping them into the atmosphere. I daresay the world, if it is truly warming, will return to normal, even cool off!

[Nuke]

So you say renewable energy solutions including this space project are only for the rich and do not help the third world, but fusion will? Are you kidding me? The real problem in these countries is a lack of good governance and of access to education. I'm sure a huge centralised ultra-high-tech power station will last really long in Nigeria. After all, look at all their nuclear power plants! /sarcasm

If you want to tackle real third world energy problems, try stuff like supplying poor people around the world with cheap ovens. They save a lot of expensive wood (people in some regions pay most of their scarce income for firewood because of the huge damand) and emissions are hugely reduced, and a lot less people die by accident.

tokamak fusion in the 3rd world, hell no. too big, too complex, too expensive. polywell fusion, maybe. bussard was pushing p-b11 fusion, an aneutronic reaction capable of direct conversion. but polywells are cheap enough that you can just replace them after they take a certain amount of neutron damage, so d-d reactors will likely come first. he also discribed a plan involving retrofitting coal fired plants with a polywell heat source, using the existing thermodynamic hardware. with fusion brings things like water desalination and with it better agriculture to the developing world. fusion will come and it will have a huge impact on the world. im pretty much convinced that polywall will beat iter/demo by several decades.

[nhnifong]

Maybe this is a little off topic, but I've always wondered, Why are scientists so certain that global warming would be bad? What it turns more of Earth's land area into tropical rainforest and increases the biodiversity in those places? What if it increases the amount of fresh water and arable land available to us?

[Thaniel]

Maybe this is a little off topic, but I've always wondered, Why are scientists so certain that global warming would be bad? What it turns more of Earth's land area into tropical rainforest and increases the biodiversity in those places? What if it increases the amount of fresh water and arable land available to us?

I´m hazarding a guess here, but secretely, every scientist who haven´t heard about how earth´s climate have changed over the millenias, and are still scared to death by the prospect of global warming, probably harbour a secret fear of raptors..... Or warm weather. Not sure wich, but change that realy only challenge logistics and architecture shouldn´t justify the fear we see in some.

[Seret]

Maybe this is a little off topic, but I've always wondered, Why are scientists so certain that global warming would be bad? What it turns more of Earth's land area into tropical rainforest and increases the biodiversity in those places? What if it increases the amount of fresh water and arable land available to us?

Ask any climate scientist, they'll tell you that there would in fact be some positive effects of a warmer, more CO2 rich atmosphere (plants grow better, for example). However, the main issue is that the atmosphere is a big machine that runs on heat. More heat means more severe weather, which is overall bad. We also lack a really good understanding of the exact mechanisms of feedback and balance that the Earth uses to maintain equilibrium, and tinkering with things you don't fully understand is rightly viewed as highly unwise. It's quite possible that there are feedback loops that would kick in at certain points and lead to accelerated heating. If that happened the issue would move from becoming an inconvenience to a crisis.

You might be right that long-term (ie: in a million years) a warmer Earth could result in new highly biodiverse habitats, but when viewed at the human scale (say the next few thousand years) you'd see loss of biodiversity as species failed to adapt quickly enough to the changes. You can't blame us for looking at our world through the filter of human time spans. Sure, it may be true that the Earth has warmed more in the past, but that doesn't help us dealing with any change that occurs now.

[PakledHostage]

Maybe this is a little off topic, but I've always wondered, Why are scientists so certain that global warming would be bad? What it turns more of Earth's land area into tropical rainforest and increases the biodiversity in those places? What if it increases the amount of fresh water and arable land available to us?

Part of the problem is the effect it will likely have on the existing arable land and availability of fresh water. Places like India, China, Russia, plus large areas in North America and Europe are as fertile as they are due to the current climate. Factors such as how much snow falls in the Himalaya, Alps and Rocky mountains and how and when it melts to irrigate crops during the summer growing season are important to our food production. Those fertile lands are home to the world's most powerful countries. What happens geopolitically as the "haves" become the "have nots"?

[NGTOne]

What happens geopolitically as the "haves" become the "have nots"?

Wow, I never expected to cause a discussion this big.

Anyways, here's my question: couldn't the haves use technology to compensate for changes in land fertility? For instance, I've read about a number of different initiatives to build automated, fully climate-controlled indoor farms. While our diets in the Western world might change, the end result might be that we muddle through, while other states have a chance to prosper.

[Anton P. Nym]

The biggest objection to SPS right now is political, but not in the "lacking of will" sense.

Right now the best way we have to get the power down to Earth is directed microwaves, or maybe a MASER (like a laser, but in microwave frequencies), beaming to an antenna. I can't recall which wag pointed this out, but the colloquial term for a device that projects multiple gigawatts of microwaves at a target is "death ray". Any government putting one up would face huge objections from every other government on the same hemisphere concerned about it being weaponised. (And no government would welcome private enterprise putting up a potential WMD.)

-- Steve

[NGTOne]

The biggest objection to SPS right now is political, but not in the "lacking of will" sense.

Right now the best way we have to get the power down to Earth is directed microwaves, or maybe a MASER (like a laser, but in microwave frequencies), beaming to an antenna. I can't recall which wag pointed this out, but the colloquial term for a device that projects multiple gigawatts of microwaves at a target is "death ray". Any government putting one up would face huge objections from every other government on the same hemisphere concerned about it being weaponised. (And no government would welcome private enterprise putting up a potential WMD.)

-- Steve

As mentioned above, both by other posters and the 70s-era NASA/DoE reference design (which is still the gold standard for powersat designs; nobody has, to my knowledge, come up with a more complete design - my own investigation into this is ongoing, please correct me if I'm mistaken on this), if you were using a straight microwave transmitter, your groundside energy density would be insufficient to cook a TV dinner, let alone people or other valuable stuff. Even as much as 5 GW, when spread over a 10km-diameter circle, isn't a hell of a lot per m^2. I wouldn't stand (fly? float? EVA, I guess) in front of the transmitter, but you'd be fine on the receiving end.

Lasers and MASERs are a different story, though - there might be objections there, as the beam IS concentrated enough to do some damage. Not quite sure how MASERs would affect stuff/people (again, not a physicist), but I know a laser with a power of 5GW, even operating in a continuous mode (prototype military lasers operate in a high-power pulsed mode - greater energy delivered per time unit, but limited operational time) would be enough to do some damage. Upside is, when you're in GEO, it's hard to hit anything smaller than a building, even with a laser - your tracking has to be unbelievably precise, to very small fractions of a degree.

Edited August 14, 2013 by NGTOne

[Nuke]

Wow, I never expected to cause a discussion this big.

Anyways, here's my question: couldn't the haves use technology to compensate for changes in land fertility? For instance, I've read about a number of different initiatives to build automated, fully climate-controlled indoor farms. While our diets in the Western world might change, the end result might be that we muddle through, while other states have a chance to prosper.

we have the capacity (technology, industry, money) to switch over to large scale hydroponic production should things go south for us. only reason we dont is its cheaper just to use the land. on the other hand i know some people who do hydroponic gardening who say its just as cheap as using soil it probibly just doesn't scale up well.

Edited August 14, 2013 by Nuke

[NGTOne]

we have the capacity (technology, industry, money) to switch over to large scale hydroponic production should things go south for us. only reason we dont is its cheaper just to use the land. on the other hand i know some people who do hydroponic gardening who say its just as cheap as using soil it probibly just doesn't scale up well.

I meant in the event that the land should become unsuitable for agriculture (for whatever reason). And I seem to recall reading some articles about groups and companies experimenting with large-scale hydroponic farming. I mean, you can't grow wheat hydroponically (the scale required for a reasonable yield is on the order of ludicrous), but a lot of other crops, you can.

[Nuke]

the tipping point will be when its cheaper to farm a crop in a large farm building than it is to grow it outside, in terms of cost per unit. more so than the land becoming unusable. this is of course on a per crop basis. some crops will move over at a faster rate. its probibly good that it will go indoors before the soil becomes completely unusable. since it allows for the land to be reclaimed by nature at a much faster rate. it will be one of those things greatly enhanced by fusion. that will likely be the thing that drops the cost of hydroponics into a competitive range.

[NGTOne]

it will be one of those things greatly enhanced by fusion.

Or powersats

[Seret]

Or powersats

What do powersats actually do that is better or cheaper than ground-mounted PV though? It's simply a more expensive, more dangerous, more complicated way of achieving the same thing.

[andrewas]

Orbital solar can generate electricity 24/7 and almost independently of the weather. It can directly replace a fossil fuel or nuclear power station. Ground-based solar can only operate while the sun is up, and are highly dependent on the weather, so it can never be more than a supplement to other power stations unless the grid has huge energy storage facilities, and energy storage on that scale is a hard problem.

[NGTOne]

Ground-based solar can only operate while the sun is up, and are highly dependent on the weather, so it can never be more than a supplement to other power stations unless the grid has huge energy storage facilities, and energy storage on that scale is a hard problem.

A much harder problem (technologically, at any rate) than power satellites

A US Office of Technology Assessment (OTA) report on space-based solar power actually made this exact conclusion in the early '80s, before ground-based PV had had a chance to take off (it was far more expensive then than today). They also correctly predicted the fact that most solar generation would be decentralized (for example, panels on the roofs of homes and businesses, generating for internal use to supplement grid power) rather than centralized (large solar "farms" in sunny locations).

The mistake a lot of people make, I think, is to assume that terrestrial solar or wind can be integrated into baseload ("always-on") generating capacity - it's not reliable enough for that, and we haven't solved the energy-storage problem enough to make it so. You can't predict when the sun will shine or the wind will blow, and you certainly can't make your customers tailor their electricity use to the weather. In space, the sun is always on (though, naturally, the particulars vary based on your orbit), which means a space-based solar plant is a baseload system, like a nuclear plant, and can keep generating consistent amounts of power around the clock.

Edited August 15, 2013 by NGTOne

[Seret]

It can directly replace a fossil fuel or nuclear power station.

Only if it could produce energy more cheaply than them, which it can't. Space-based power would be expensive so would only be economically viable to sell it at peak times when the price is higher. In order for it to supply base load you'd need some kind of large subsidy programme and fixed contracts. That means a government would have to take it on as a pet project and be happy to pour money into it. That seems unlikely, they'd get a better return on their money by subsidising less technologically risky renewables.

Bottom line is that if it made economic sense, you'd have seen more movement on it in the last few decades. Even some of the other renewables that have large technological hurdles such as tidal stream have seen more development. Tidal is about the only other renewable that's suited for base load, incidentally. Part of the reason it hasn't been widely deployed is the same problem as above. Base load power is cheap, so it's incredibly hard to make a viable economic case for a new technology that can't match the cost efficiency of the old thermal plants.

[Moon Goddess]

George Friedman thinks the US military will fund the construction of PowerSats in the 2050's to power the Powered armor during our war with Japan and Turkey after Turkey destroys power plants in Eastern Europe while trying to invade Poland.

Not that I trust his book but well stranger things have happened.

[ForumHelper]

[...] while trying to invade Poland.

Invaded again? Come on... how many times can we be invaded.

[Moon Goddess]

Well, I guess you can just keep getting invaded till it works... obviously when you are no longer poland, no one can invade poland.

Don't worry, the turks are never able to get the support from Germany they were expected so the invasion never makes it to poland proper, just wrecks your occupied territory in the Balkans. However you don't get the proper respect you feel you deserve from the US in the peace treaty and may side with Mexico in the 2100's war.

Totally off topic nonsense over, I apologize, if anyone is curious it's a book called Next 100 years.

[andrewas]

Only if it could produce energy more cheaply than them, which it can't. Space-based power would be expensive so would only be economically viable to sell it at peak times when the price is higher.

Remember that the costs of orbital solar are mostly upfront or constant. That is, you pay a fortune to construct and launch it in the first place, and once its up there maintenance costs and so on are ongoing, but actually generating power with it is cheap. Switching it off to only sell at peak rate makes no sense because you aren't saving anything, you're just not using the generator capacity you paid a fortune for. Unless, again, you have the ability to store huge quantities of energy, in which case you could charge up your storage at night and sell it at peak rate, but as mentioned, energy storage on that scale is a hard problem.

Bottom line is that if it made economic sense, you'd have seen more movement on it in the last few decades. Even some of the other renewables that have large technological hurdles such as tidal stream have seen more development. Tidal is about the only other renewable that's suited for base load, incidentally. Part of the reason it hasn't been widely deployed is the same problem as above. Base load power is cheap, so it's incredibly hard to make a viable economic case for a new technology that can't match the cost efficiency of the old thermal plants.

Oil prices are rising, the political issues around nuclear are getting worse if anything. Environmental restrictions are getting tighter, which will raise the cost of running fossil fuel plants. And the third world is going to start burning fuel in a big way at some point.

At the same time, spaceflight has been getting cheaper, and the many heavy payloads generated by orbital solar would drive the price per launch down further.

So, while it didn't make economic sense in the past, at some point in the future it may be the only way forward. Or maybe they will get fusion working before then.