Here's an uncomfortable question.

[Username17]

Why a planet? You want a relatively stable location RELATIVE TO YOU. That throws out almost all planets because they orbit differently than you do. The only stable points from a solar power perspective are the L4/L5 Earth/Moon points or the L4/L5 Earth/Sun points. Such locations can support MASSIVE structures where the only technical problem is the pressure of the solar wind.

Oh right. I almost forgot. Gravational lock equations don't only lead to a 1:1 lock. Mercury doesn't have one side facing the sun all the time. The number of days to a year, however is a perfect integer. So Mercury isn't as good for solar power collection as you might otherwise think.

Actually, there's the entire Clark Belt. And pretty much just that. We don't actually give a shit if the location is stable with respect to the Earth-Sun system. We care if it is hovering over a single point of the Earth at all times. And that's available in a narrow band around the equator. Which means that if you want to beam power down, that is where the receiver dish has to be. Which coincidentally means that it wants to be in the middle of the Pacific fucking Ocean.

Geostationary orbit for the win.

-Username17

[tzor]

Actually you do. There is this really big thing in space ... it's called the sun. Yes it's ironically fucking silly to have your solar aray system blocked from your receivers by ... THE SUN.

Anything in standard orbit around the sun (not counting an orbit at 90 degrees from the standard plane of orbits) will be obscured by the sun at some point because the orbital sped will not match the earth's.

Getting it collected and processed at the earth point is another problem. Even laser technoligy isn't all that perfectly focused at interplanetary distances and so the beam may actually be larger than the earth at that point. More than lkikely an Earth Sun L5 beam would reach a Earth Mooon L5 collection point where it would be relayed to one of more geo satelites for final transmission to receiving units on the earth.

[RobbyPants]

How would the sun block the satellite in a geostationary orbit?

[Username17]

Actually you do. There is this really big thing in space ... it's called the sun. Yes it's ironically fucking silly to have your solar aray system blocked from your receivers by ... THE SUN.

Anything in standard orbit around the sun (not counting an orbit at 90 degrees from the standard plane of orbits) will be obscured by the sun at some point because the orbital sped will not match the earth's.

Getting it collected and processed at the earth point is another problem. Even laser technoligy isn't all that perfectly focused at interplanetary distances and so the beam may actually be larger than the earth at that point. More than lkikely an Earth Sun L5 beam would reach a Earth Mooon L5 collection point where it would be relayed to one of more geo satelites for final transmission to receiving units on the earth.

What? No. You put the solar collectors into orbit around the Earth, not into orbit around the Sun. Because Sol is spitting out a fuck tonne of radiation and you don't actually have to be closer to it than the Earth already is in order to generate power, and your power transmission beam is necessarily going to be much narrower and disperse more with distance than the fucking Sun.

Geostationary orbit. Anything at Earth-Sun L5 is going to be sending shit that is so faint by the time it gets here that you might as well just pick up shit that the actual star is already putting out.

-Username17

[tzor]

How would the sun block the satellite in a geostationary orbit?

A solar power system physically in geostationary orbit will go dark every night due to the presence of the earth; it's really STUPID to do that. You need to place the actual power satelite in an orbit that doesn't get blocked by the earth. The geostationary satelite is the relay point. (In theory the satelites could relay to each other if the link isn't on the side of the planet you want.) So the question is to not keep anything from blocking the receiving station and the relay station(s).

[Username17]

How would the sun block the satellite in a geostationary orbit?

A solar power system physically in geostationary orbit will go dark every night due to the presence of the earth; it's really STUPID to do that. You need to place the actual power satelite in an orbit that doesn't get blocked by the earth. The geostationary satelite is the relay point. (In theory the satelites could relay to each other if the link isn't on the side of the planet you want.) So the question is to not keep anything from blocking the receiving station and the relay station(s).

Why do you think that the solar station needs to generate electricity 24 hours a day? The solar station is transmitting to a pickup station three thousand kilometers south of Cape Canaveral. You're going to be shipping that power north somehow, probably in giant tankers that travel for days or even weeks - like how we transmit power from oil wells in Venezuela to our cities today. There is simply no point in setting up elaborate relays so that the solar collection system can run night and day. With less equipment you could just set up a second collector on the other side of the planet and send the hydrogen tanks back to the motherland from each alternately. More likely still, you'd set up dozens of these fuckers, and the fact that each of them would be dark for 8 hours a day wouldn't even be something you noticed.

Actually of course, having your sats in the dark for a few hours a day is pretty much a necessity, since otherwise they will gradually accumulate heat until they break.

-Username17

[tussock]

What the fuck is with the satellites, Frank? For power? Solar to run the whole world today is 225,000 km^2. It's only 0.5% of the world's deserts, but it's a fuck-ton of stuff to put in space at $60 million a ton, when that'll probably cost you a thousand times the basic construction amount and take millennia to return the energy investment, assuming they last forever.

Maybe you mean something that's not stupid, but you build shit on the ground to make power, and putting anything in space uses power. A lot of it. Gravity well, eh.

[DSMatticus]

The point is that you use the energy on collectors in the Pacific Ocean and then you crack water in the ocean, and you distribute the hydrogen in canisters to the needy world's powerplants by boat and train.

This was Frank's original idea. The part where we're talking about space is because of something Grek said, and then Frank said something about the thing Grek said, and then Tzor said something about that, and then other things got said, and SPAAAAAAAAACE. I don't think anybody suggested space-based solar collectors were feasible, they're just disagreeing about the ways in which they are not infeasible.

[Username17]

What the fuck is with the satellites, Frank? For power? Solar to run the whole world today is 225,000 km^2. It's only 0.5% of the world's deserts, but it's a fuck-ton of stuff to put in space at $60 million a ton, when that'll probably cost you a thousand times the basic construction amount and take millennia to return the energy investment, assuming they last forever.

Maybe you mean something that's not stupid, but you build shit on the ground to make power, and putting anything in space uses power. A lot of it. Gravity well, eh.

The thing is that liquid storage is actually way more efficient than HVDC power lines. You can leave it in a pile for months or years when you don't need it, it's completely fungible, and transmission costs are less than the 3% loss per 1000 kilometers that high tension lines get. People don't like to live near high tension lines, high tension lines can't go everywhere, and when they get damaged the entire flow of energy stops to huge areas. Whole grids can go down because some jackass ran a jeep into a transformer.

The reality is that covering the US with High Tension lines to a central power generation system just isn't feasible. We aren't talking about a single set of power conduit to run across the 5000 kilometers of US territory (although that would by itself sink the idea, since that's roughly twice the length of the largest HVDC project ever contemplated: the Amazonas to São Paulo line to be completed next year or the year after), there are 5,700 power plants in the US according to the US Energy Information Agency. I think it's a fairly safe assumption that power plants exist in a roughly 1:1 correspondence with power grids, so you're really talking about thousands of HVDC lines that are mostly measured in the thousands of kilometers. You just can't make HVDC lines measured in the millions of kilometers and expect the grid to hold. And that's just the US. Want to talk about the difficulties of wiring up the whole fucking world? Or even just Canada? Ain't gonna happen.

You need something that can reroute itself. Which means shipping the power to the different local grids in solid or liquid form. Like how we do it now, only hopefully not by digging up non-renewable oil and then throwing the carbon into the atmosphere. Putting power in tanks and putting those tanks on ships or trains is still vastly more efficient and more reliable than any direct power transmission system short of magically inventing superconductive conduit tomorrow that we can cheaply produce in the literal billions of kilometers.

So when you start contemplating mega-power stations, whether they are thermal boreholes, solar farms, or fusion reactors, you need to find a way to convert that power into fuel that you can ship on actual ships to the various local power stations that supply local grids. It doesn't really matter if those systems are inefficient, because there is no other choice. Making hydrogen out in the middle of the Pacific Ocean happens to be the cleanest fuel cycle that it is possible to exist. I'm not saying it is necessarily cheaper or more efficient than coming up with some photosynthetic cell that produces hydrocarbons, I'm saying that it burns cleaner. Since it burns cleaner than anything else theoretically could.

-Username17

[tussock]

Since it burns cleaner than anything else theoretically could.

Assuming the production of future water splitters is eventually somewhat efficient and does not in itself pollute. But I'm still missing why we'd bother.

Yes, when all your power stations have the same efficiency, like today, no one transmits power far over HVDC (3% per 1000k, thanks) because you may as well build another one up north. That's now. Cool.

BTW: not single mega-plants, spreading smaller ones out across the best regions gives you a more reliable baseline. There's just limits to how far north you build solar plants, because transmission becomes more efficient. 40% wind up north, 20% wind down south, build more wind farms up north and transmit the power.

5000k? 80%+. Good enough. Even stuck in pumped storage along the way it's 65%+ overall.


But why put that power through a 50% hydrogen production stage and a max 60% hydrogen burning power generator? The worst you get transmission will be 65% efficient, usually much better: you can't get near that at best by shipping hydrogen, which means more power stations, not to mention double stations to make and then burn H2, which means more energy input per energy return in plant construction, which is very bad. 4.5 to 1 return on solar-thermal is low enough, maybe only 3 to 1 with a long transmission network. 1.5 to 1 with double plants and an intermediate stage? You may as well burn wood.


Direct thermal catalytic hydrogen might get you close in efficiency at the longest ranges, but energy return with double plants still looks like 2 to 1 or so.

Not going to happen. EROEI is everything with renewables. You don't build extra plants, nor build them where they work poorly, you build them where they work well and shift the power. Battery? Pump some water up a mountain.


HVDC networks aren't cheap, aren't easy to manage, aren't infinitely reliable, but this is a discussion about replacing the world's energy sources: it is what Europe's starting into right now, and what China has planned (AFAICT). Even coal plants average 15% downtime, you just deal with it.

[LargePrime]

I believe that the thing you are responding to is about there being no power future in Nuclear. According to actual boosters of Nuclear Power, there are five million tonnes of Uranium in the world, with a plurality of it in Australia. That will last the world about a century. If we made a big investment into nuke plants, it would last the world about a decade. Maybe two if we found some big unknown reserves somewhere. There is just no way to power the world on Uranium. There isn't enough Uranium.

Why are you saying there not enough uranium? Its not like it goes anywhere. You do what France does, and just reprocesses it, because a big chunk of use uranium is now plutonium, and plutonium has so much energy we make bombs out of it.

Nuclear power is basically a closed loop system for power and the only one that nets more power out than we put in. It is the only "more than perpetual energy" energy source we have.

[DSMatticus]

I believe that the thing you are responding to is about there being no power future in Nuclear. According to actual boosters of Nuclear Power, there are five million tonnes of Uranium in the world, with a plurality of it in Australia. That will last the world about a century. If we made a big investment into nuke plants, it would last the world about a decade. Maybe two if we found some big unknown reserves somewhere. There is just no way to power the world on Uranium. There isn't enough Uranium.

Why are you saying there not enough uranium? Its not like it goes anywhere. You do what France does, and just reprocesses it, because a big chunk of use uranium is now plutonium, and plutonium has so much energy we make bombs out of it.

Nuclear power is basically a closed loop system for power and the only one that nets more power out than we put in. It is the only "more than perpetual energy" energy source we have.

We have some truly impressive varieties of reactor, but they are not magical. They have non-zero depletion rates. And while we technically have enough uranium on the planet to last basically forever, most of it is in seawater or low grade ores. The technology is being improved, and it's promising, but economic feasibility of some of these techniques is still very much in question. Either you need an organized effort at the highest level of societies to spread and support sustainable nuclear techniques (as well as quite a few more engineering breakthroughs), or it has to turn out to be the most economically advantageous model. Which is the entire problem we're having with oil, and we're solving that one fantastically.

The prospects aren't nearly as bad as people in this thread have made it sound, but effectively sustainable uranium energy production is still a non-trivial problem.

[LargePrime]

As I understand it, it is fucken magic!

You literally you put in a rod of 4% 238 and you get a rod with more fuel, albeit of a different type, than you started with.

The US has a huge stockpile of "Nuclear waste" that we could reprocess and, according to some estimates, not really need any more virgin uranium.

Unless I am mistaken?

[DSMatticus]

You would be mistaken. Nuclear fission does not violate conservation of energy. I'm not an expert, but some cool things we actually can do:
1) We have some really efficient reactor designs that use a hundredth, perhaps a thousandth, of the fuel older reactors use. That's a big leap in fuel efficiency.

2) We have tricks to turn non-fissionable materials into fissionable materials, and to turn excess waste material into fissionable byproducts. These increase the amount of fuel we have available, but the input fuel energy is never greater than output fuel energy + electricity. Nothing can have an efficiency greater than 100%, that's absolutely impossible.

3) Uranium might be (most likely is) pretty abundant in seawater, but really hard to harvest due to extreme dilution. If, and that is a big if, we can find a way to feasibly and economically harvest it from seawater in a way that meets the world's uranium demands, then we have ourselves set for a very long time.

But none of these techniques result in a perpetual energy cycle. Current uranium use puts known accessible reserves running out in about a 100 years. Switching everything to the more efficient reactors puts that at a few thousand years, assuming demand increases as oil disappears. Throw in thorium and plutonium, we can maybe double or triple that. Maybe. Add seawater uranium, and I actually don't know but the answer is a very, very long time.

[LargePrime]

No its more like Magic. Nuclear power is FUCKING RAPING conservation of energy, by violating conservation of matter, right?

It is consuming matter, and using some of the released energy to put OTHER matter in a state where we can pull a shit ton MORE energy out of it than we could before. It CONSUMES small amounts of radioactive uranium to turn base uranium into plutonium. It fucken old school alchemy from a science. Newton is so proud he left the building, cause he knows we got this.

As you noted, I agree; I am not saying perpetual. There is waste, and mass is being consumed. But a few thousand+ years is a big deal. And no carbon load.

What the US calls nuclear waste is a fuel source in other countries. We just don't want more plutonium around, so we do not reprocess it. But we could, like they do in France et. al. right? Only an executive order stops it.

Re: Seawater.
If we assume a breeder reactor, and breeder=lots of low cost energy, then we can look at solving our drinking/crop water needs through desalination. Which seems to lead itself to harvesting uranium from seawater.

My point is that there is plenty of uranium, because we turn it into plutonium. And there is also thorium.

[Grek]

That isn't how nuclear power works. The fuel becomes less radioactive as it decays, not more. Eventually it decays all the way down to lead and you can't get any more nuclear power out of it.

[LargePrime]

That isn't how nuclear power works. The fuel becomes less radioactive as it decays, not more. Eventually it decays all the way down to lead and you can't get any more nuclear power out of it.

what?
what the what?

I do not have the skill of other denizens, so I'll go Socratic...

What do you think nuclear fuel is made of?
What do you think nuclear waste is made of?
How did the material change so dramatically?
Why do you think we do not reprocess our "nuclear waste"?
Why do you think France et. al. does?

My point has nothing to do with decay, it has to do with exposing 235 to radiation and creating plutonium.
And that point was to address Franks point that there is only 5MT of uranium. And my point is that it is 5MT of 238 the first time thru, then it becomes even more Tonnes of plutonium, as it converts the 235 filler material.

[Username17]

Nuclear waste is material that is still radioactive enough to give you cancer, but not radioactive enough to achieve critical mass. That means that it will sit there giving off radiation for a very long time, but you can't efficiently squeeze it to get more heat out of it in the short term.

Time to go to Wikipedia I guess:

Used nuclear fuel is a complex mixture of the fission products, uranium, plutonium and the transplutonium metals. In fuel which has been used at high temperature in power reactors it is common for the fuel to be heterogeneous; often the fuel will contain nanoparticles of platinum group metals such as palladium. Also the fuel may well have cracked, swollen and been used close to its melting point. Despite the fact that the used fuel can be cracked, it is very insoluble in water, and is able to retain the vast majority of the actinides and fission products within the uranium dioxide crystal lattice.

Fission Products are a wide variety of different atoms in the Yttrium to Ruthenium range and in the Iodine to Cerium range. Some of those are radioactive in a non-fuel sort of way, and a whole lot of them are poisonous, but they sure as hell are not reactor fuel.

Yes, some fusion occurs in a nuclear power pellet and you make some real plutonium, which you could extract to make an atomic battery. But you aren't talking about half the pellet, or a tenth of the pellet, or even a thousandth of the pellet. We're talking really stupidly tiny amounts of plutonium and very large amounts of iodine and lead.

-Username17

[LargePrime]

The amount of Plutonium that is created varies upon the process.

All The US weapon grade Plutonium come from uranium breeder reactors, and it is hella more created that the tiny fraction you suggest. Also note that we DO NOT REPROCESS, because we do not want to harvest the Plutonium, which suggests hella more than micro grams per tonne. As noted other countries DO reprocess, and their processes produce much more Plutonium, which they reuse as MORE POWER. It also produces significantly less waste. They even store the "waste" figuring they will eventually figure out how to reprocess/reuse it for even more power.

So while it is possible to have process that creates crap, it does not have to.

The point is that we can turn that 5MT of 238 into even more power the second time around.

EDIT
http://en.wikipedia.org/wiki/Spent_nuclear_fuel
it suggests that, from what I assume to be a typical US GE reactor, 1% is PU and 96% is uranium.

So where did you get "We're talking really stupidly tiny amounts of plutonium and very large amounts of iodine and lead", Frank?

also http://en.wikipedia.org/wiki/Nuclear_reprocessing
"the breeder reactor can employ not only the recycled plutonium and uranium in spent fuel, but all the actinides, closing the nuclear fuel cycle and potentially multiplying the energy extracted from natural uranium by more than 60 times."

Throw in thorium, given 3-4 times more of it than uranium, should have a ~16-22MT supply, and the potential energy problem goes away.

[DSMatticus]

No its more like Magic. Nuclear power is FUCKING RAPING conservation of energy, by violating conservation of matter, right?

Conservation of matter and conservation of energy are the same thing. e=mc^2; matter is energy that has twisted itself into a strange shape and adopted the property of mass. That is a gross oversimplification, but the sum of energy produced in a system including the energy stored as matter is never going to be higher than the sum of input energies. That is literally impossible. You seem to be aware of this, though, so whatever.

As for the actual lifespan of nuclear energy; at current consumption rates, we run out of U-235 in 100 years. We can use U-238, which multiplies the available reserves by about ~140. We can also use thorium, which multiplies reserves by about ~3-4. Reprocessing has a theoretical maximum efficiency of 95%, but no one is actually currently reprocessing at better than 30%. A major shift to nuclear energy will increase consumption 6-7 times of what it is now, and as the developing world... well, develops, energy demands will increase some amount. The current estimates for all this (without reprocessing) are about 8000 years if we switch over to fast breeder reactors right now this very instant. With the highest current reprocessing rates, it won't even double that; with double the highest current reprocessing rate, it will barely double that. That's basically it. Using the fast reactors that burn everything and the whole world doing reprocessing twice as hardcore as France does it now gets us 16,000 years of nuclear fuel using today's electricity consumption.

Now, admittably, sixteen thousand years is a long time. But it's not problem solved, and that's seriously best case scenario using high grade ores and reality is going to undershoot that because we're stupid and we make bad decisions. Making nuclear fission last "effectively forever" depends on the ability to feasibly harvest low concentration material, like in seawater, which is not a sound assumption.

[Koumei]

For what it's worth, it's very optimistic to assume humans will still even exist in 16,000 years.

[LargePrime]

DSMatticus;
Thanks for this discussion. Honestly I was gently worried I would be eviscerated in typical TGD fashion.

Your last analysis has for more specificity than mine, which I appreciate. The time horizon we are discussing is far off into The Haze from my point of view, so I did not think it productive to carry out as precisely.

I am curious why you feel ocean filtering will never be a sound assumption? http://www.jaea.go.jp/jaeri/english/ff/ff43/topics.html

For completeness I would like to point out that I think the viable alternatives previously mentioned are also just as valuable. These also add to your timeline calculations above.

Only posted to point out/correct an error I noticed about nuclear energy/uranium availability/viability.

Regarding violating the law. It read to me that you were referring to 19th century versions of conservation laws, not 20th century versions.

[cthulhu]

I'm pretty sure that for a number of locations solar is still better. For Australia for example, large scale solar is a no brainer (water is the main issue). You still need hydrogen fuel production to handle overnight loads.

Realistically I suspect the best solution is going to be a hybrid. This is the best discussion I have ever seen of how we might achieve a zero fossil fuel's energy base:

www.withouthotair.com/

[Whatever]

For what it's worth, it's very optimistic to assume humans will still even exist in 16,000 years.

I'm not so sure about that. Remember, if you killed 99% of the people on earth, that'd leave 70 million people still running around.

Since this is the Den, it's worth examining what it would take to actually kill every man, woman, and child on the face of the earth.

First of all, bullets are not going to do it. Nor are conventional bombs. No matter what kind of crazy terrorist group you get together, you just cannot kill everyone. Even if you destroy society, there will be survivors.

Nor is any kind of general climate change or natural disaster going to spell the end of everything. People live basically everywhere on the planet that can even marginally support human life, so even changes that cause massive starvation and population crashes will not wipe out everyone.

A sufficiently large nuclear war might do it. If we could wipe out most life on earth, then starvation and radiation might be enough to nail the survivors.

An especially virulent plague might also do the trick, although it'd be tough to get absolutely everyone infected. It would have to be universally lethal, extremely contagious, and very slow to take effect. Even then, you might have small pockets of survivors.

An asteroid impact could manage it. If the rock was big enough, you'd wipe out all life on earth.

There are a few sci-fi scenarios that could also wipe out all human life, and we should not discount them.

First is, of course, robots. We could build machines that kill off everyone, maybe even nanobots. This is currently an unlikely prospect, especially since that level of technology would imply the possibility of countermeasures (even nuking whole continents would leave the possibility of survivors elsewhere).

Second would be aliens, I guess. If they manage to show up and are for some reason hostile, they could probably kill everyone.

There's just not a lot of other ways to actually see humanity go extinct. We've lived through ice ages and the like before, we can do it again. By "we" I mean "a few random survivors from the collapse of society" but the point stands.

[erik]

For what it's worth, it's very optimistic to assume humans will still even exist in 16,000 years.

Well, it almost certainly won't be humanity as we know it.

Does it count if we modify our bodies and consciousness to such an extent that we are completely different?

Or are you espousing one of these?