Video Solar Energy in Space is not Necessarily Easy to Harvest (Video) 85
Timothy Lord for Slashdot: So today you talked a little bit about efficiency and the idea of power efficiency when it comes to space missions. Can you explain that a little bit? And talk about you used the phrase of cost of the first kilowatt hour.
John: So there are a couple of big issues in all energy systems. The one is the cost what you must invest in order to put a new source of energy into place; and the second is sort of the recurring cost of the energy that comes from that new source of power. So whether it is a hydroelectric dam on earth or a nuclear power plant or a coal-fired power plant, these two considerations: the cost to have the power and then the cost of the electricity that comes from that new power source. And in space, in fact, the cost to deploy power and the cost of electricity that come from those power sources is wildly more expensive than the cost of energy here on earth. For example, a home here in the Austin Texas area might use 3 or 4 or 5 kilowatts of power, and for every kilowatt hour of energy that comes from that electrical power the cost might be 10 cents per kilowatt hour. Now in a place like Hawaii where energy must be shipped in, the cost of the power plant might be the same, but the cost of the electricity might be 25 cents a kilowatt hour, not 10 cents a kilowatt hour.
Slashdot: They have to bring in fuel?
John: Because they have to bring in the fuel. Typically in Hawaii it is a case of diesel oil. Now in more remote locations with a smaller industrial base, like say an island in the Bahamas or some place in Southeast Asia, it could be 40 cents a kilowatt hour. But in space not only is the cost of the system that is going to deliver the power much higher, the cost of electricity is much, much, much higher. So instead of that 10 cents per kilowatt hour that you might see on earth, the cost of electricity say for example on the International Space Station might be anywhere from $25 per kilowatt hour to $50 a kilowatt hour or more, i.e., 500 times to a 1000 times more than it would be here on earth. And if you look at ambitious things that we might want to do out on the Moon or in other places around the Solar System, sending people to Mars—none of that is going to happen without energy. And very little of those ambitious visions for the future are going to happen if the cost of energy is 500 or 1000 times more than the cost of that same energy here on earth.
Slashdot: So what are some implications that has when it comes to spaceflight? How does that help you to plan missions?
John: So if we had affordable and abundant energy for example in what is called the inner solar system, i.e., inside the orbit of the main belt asteroids you have abundant sunlight. If we had affordable and abundant power that we could use by harvesting that sunlight, it would make possible a wide range of very ambitious things, like developing the resources of the Moon, mining the resources of asteroids, sending people and things cheaply to destinations throughout the inner solar system—if the cost is say 10 cents or even 50 cents a kilowatt hour. If it is $500 a kilowatt hour doing any of those ambitious things is far more difficult.
Slashdot: Now when it comes to contributing to those costs, payload costs is a big reason, it is hard to put heavy things in space, are there other things that are significant too, like the availability of repair parts, what are the other factors besides the sheer payload cost?
John: Most people talk about the cost of the space transportation, it is always the thing that people talk about. People are, mostly men, are very excited about rockets, and access to space is one of the big cost drivers historically that people like to talk about. In fact, it is not usually the biggest one.
There are the big four, the biggest cost driver of doing anything in space is the cost of the space hardware itself. Because on earth, you manufacture tens of thousands to tens of millions of something, like tens of millions of personal computers, the cost per pound or the cost per kilogram comes down to $100 a kilogram, a couple of hundred dollars a pound. For space systems, where you make one, if it is just an automated system or a robot, it could be $20,000 a kilogram, $45,000 a pound. Or in the case of a human system, it could be $100,000 a kilogram---it all depends. But in any event, because you are making one or two or five, the cost per kilogram the cost of the mass of the hardware is the number one driver. Cost of access to space is also important, it tends to run something like $10,000 to $20,000 per kilogram to get to low earth orbit.
The cost of operations, i.e., how many people are involved on the ground to operate things in space is hugely important. You don’t expect to have anybody sitting back at Dell Computers or Apple standing by, to be on the phone with you for your computer, if they were there, the sustaining engineers who are on the ground some place in Texas or in California in India or China.
Slashdot: I expect there to be a call center. I don’t expect to be in space.
John: One person handles thousands of calls a day, not somebody sits standing by for your PC. In space it is the opposite, you got sustaining engineers standing by in case your system has a problem. So the cost of hardware, cost of launch, cost of operations people, cost of getting around in space. The short lifetime (I am going past four) but the short lifetimes of the systems in space. Hydroelectric power plants like Hoover Dam last for a century. A spacecraft tends to last ten to fifteen years. An aircraft lasts through thousands of flights but a launch vehicle is good for one. And so the short lifetime on this very expensive hardware, with these big ground crews, takes up a lot of money to do anything in space. You got to do something about all of these to really do ambitious things.
Slashdot: Now, the first factor you named... clearly that is a big factor, but does that get smaller as we use more commodity items? As quality of the available hardware goes up, we are not just billing just one.
John: That’s mass production. So the answer is it can come down, it can come down dramatically but it is through production, not necessarily through changing what you make it out of. If you look, for example, at a single DVD.. or Blu-Ray Disc if you prefer the different format, let’s suppose that you wanted to make a movie put it on Blu-Ray or DVD and you are only going to make one copy.. well, the cost of that material that is in the disc, it is just plastic.
Slashdot: It is not the polycarbonate, it is the factory.
John: It is everything that went into it. It is the making of the movie, the making of the content, the factory that made it, so you have to make lots of them, and even if you do make lots of them the material could either be gold and it would still cost you a few dollars, or it could be plastic and it is going to cost you a couple of cents.
Slashdot: Private space companies often talk about using commodity off-the-shelf hardware, it seems that is at least small part.
John: Well, but what they are doing there it is not so much that they are using a material that is a commodity material, they are using a piece a system that is a commercial piece, and so they are leveraging all of that production. If you can take advantage of solid state electronics that come out of consumer electronics, you don’t have to develop all of that independently, and you are leveraging all of that production that is back behind the scenes.
Slashdot: If a space program needs a... I believe... nowadays they won’t be starting from scratch.
John: Yeah, that’s true, exactly right.
Slashdot: So talk for just a moment about the future of energy in space, you mentioned solar, and solar is the obvious thing, because it is free, it is abundant, and we know how to at least get a pretty good return on solar. Are there other energy sources that are better done in space, because it seems like it is very expensive to put up even any kind of nuclear reactor.
John: Yeah. Well, on earth, there are really only two fundamental sources of energy: One is solar energy, and the other is the energy that is stored in radioactive materials inside the earth, whether it is geothermal, and it is coming from deep within the earth, it is still radioactivity inside the molten core of the earth that is bleeding to that heat, if it is near the surface then it is ore, it is mined and refined, it is uranium or what have you that is coming from the cloud out of which the solar system formed maybe 4.5 billion years ago. So those are the two fundamentals.
Slashdot: Where do you put fossil fuels in there?
John: Fossil fuels predominantly come either from past biological activities—coal and oil—or they are primordial they come from the cloud out of which the solar system formed. There has never been any biological activity on the Moon, Titan and Saturn, and yet there are hydrocarbon oceans on Saturn. All of that is primordial material. Similarly, there is natural gas on earth, which comes from biological activity, very very likely that deep within the earth there is natural gas that comes from CH4 it comes from primordial sources.
Slashdot: Let me ask you a silly question, which is Mars or the Moon, what drives you, if neither of those then what?
John: I want to answer your first question first I will come right back there on that other one. So in space there are really only two fundamental sources of energy, so it is either going to be nuclear material that you take with you from earth, or it is going to be solar energy which you harvest from the sun, and in the inner solar system, to my way of thinking, solar energy is so abundant, the source is free, the fuel is free, you have to deal with the system, but otherwise space solar power is a wildly competitive approach. Now back to the question of Moon or Mars—my personal feeling is that both are terrific goals. I have to confess that in the case of the Moon, it is three days away, six days round trip, we always know where to find it, and in terms of time, energy cost, the Moon is so much easier. So I see the Moon as the stepping stone sort of port on this the eighth continent I think it has been very nicely characterized as. It is the port from which humanity can step out into the solar system and even beyond. But I think it would be extraordinarily strange if ultimately we step out from our home not going by the way of the front porch, which is sitting there and available but rather climbing out a window. So going directly to Mars is somewhat illogical.
Slashdot: It also seems strange to go to the Moon and not have an ambition to go elsewhere.
John: Exactly. If you are not actually going to go anywhere it makes the Moon far less useful.
What about light (Score:2)
??
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Adding energy to Earth (Score:4, Interesting)
I just want to point out that solar energy captured by most of these satellites would have missed the Earth otherwise.
So we would be adding extra energy to the Earth, energy which would degrade with use to, you guessed it, heat.
Has anyone done the math on this to see whether doing this would actually help in the effort to limit global warming?
I suspect that the added heat would be tiny compared to displaced fossil fuel-burning carbon emission heat-trapping, but just though someone should crunch the numbers to make sure we wouldn't be shooting ourselves in the foot with this technology.
Re:Adding energy to Earth (Score:4, Funny)
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This reminds me of a major, major pet peeve I have. I have seen a number of business now (one in particular is a pizza parlor) that are running the indoor A/C units without the duct work that transfers the heat outside. Thus they are just sitting in the middle of the room running. Of course if you're right in front of it, the air is nice and cold. But blowing out behind it is the hot air, and because of the inefficiency of the compressor, blower motor, etc, the air coming out the back contains more heat
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My neighbours ended up with two of theirs up on a wall three feet away blowing hot air directly in two of my windows - the installer was an utter prick.
Re: Adding energy to Earth (Score:3)
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I suspect that the added heat would be tiny compared to displaced fossil fuel-burning carbon emission heat-trapping, but just though someone should crunch the numbers to make sure we wouldn't be shooting ourselves in the foot with this technology.
I'm not in a position to crunch the numbers, but my sense is that redirecting sunlight to replace burning of fossil fuels would be a net advantage when it comes to reducing global warming.
Burning fossil fuels would introduce waste heat, pretty much the same way that using redirected sunlight would. However, burning fossil fuels also introduces greenhouse gases that trap even more heat from sunlight, and these gases can hang around for a very long time. [epa.gov]
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In fact, a small increase in the Earth's albedo would more than make up for heat imported from space-based solar arrays.
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Thanks that's kind of what I was looking for and also what I generally assumed.
One slightly significant change I'd make to your assumptions is that you should factor in that we would want to get the energy for heating and transportation and industry also from the new electric power source (to replace fossil-fuel energy), so you might want to multiply your 3.5TW by anywhere from 5 to 10, depending on efficiency of conversion factors you assume. Also that's just today's consumption.
But your general point stil
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The current average grid power consumption over the course of a year is 3.5 TW and rapidly increasing year over year. When you run the numbers, this comes up to ~1.74e17 W hitting the Earth vs. an addition 3.5e9 W that needs to be transmitted at this present if I did the math correctly (granted you have perfect storage to buffer the variances).
Nitpick: 3.5 TW = 3.5e12 W, not 3.5e9 W.
But great post. Thanks for it.
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The earth absorbs and sheds massive amounts of (thermal) energy annually. It absolutely dwarfs the heat created by our energy production. Global warming is caused by a by-product of combustion altering the planet's ability to shed heat from sun. The minuscule amount of heat from our coal plants is a drop in the ocean compared to the solar heat trapped by the extra CO2.
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So we would be adding extra energy to the Earth, energy which would degrade with use to, you guessed it, heat.
This reminded me of Aruther Clarke's space Odyssey series, in the last one, he speaks of the ramifications of some of th eassumptions he made.
One of them was that zero point energy was real and useable.
THe immmedite result was that the captured energy due to inefficiencies in the device es using it, would create a "heat crisis" Capturing and sending Energy fmor space that would not normally have entered the lower atmosphere might have a similar though smaller effect.
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Still cleaner than burning fuels.
The problem isn't as much the adding energy to the system, but the adding energy and preventing it from escaping (as it is wont to do). The Earth wants to re-radiate energy into space, and the key component of global warming is that we've reduced it's ability to do so.
Okay, thanks for wasting me time. (Score:3)
Or was there some sort of relevant / interesting information in the article somewhere that I somehow didn't see?
And really, we're linking peoples' linkedin profiles in article summaries now?
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Maybe John Mankins is looking for a job in the solar power satellite industry, and so is seeding the internet with his chops to better get hired by one of the high powered companies in this industry?
He could also be marketing his company for a buyout and is trying to leave a way for the offers to be sent to him.
Simple: just run a cord down the space elevator. (Score:2)
>> coming up with a practical way to collect solar energy beyond our atmosphere...down to the Earth's surface
That's easy! You just run an big orange extension cord down the space elevator.
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Yep! Good enough for my neighbor Skeeter, good enough for NASA.
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>> coming up with a practical way to collect solar energy beyond our atmosphere...down to the Earth's surface
That's easy! You just run an big orange extension cord down the space elevator.
That's actually a better idea than the "Use Microwaves and BEAM it down" junk I've argued about in the past.
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Ah come on... They have to keep the "pie in the sky" ideas flowing or what's the point?
This whole idea gets even worse when you start to consider the efficiency of everything... Collecting the energy, converting it into a suitable form to transfer down to the surface, transferring it, collecting it AGAIN and converting it into something we can use. The overall losses alone says they are nuts, even before you start flinging huge pieces of heavy hardware into orbit...
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Not engineers, Space Nutters. Anyone with even a single neuron capable of rational thought will see that space-based solar power is firmly a fantasy, and will always stay that way.
If we had the energy and resources to build something like that, we don't have an energy and resource problem in the first place!
http://physics.ucsd.edu/do-the... [ucsd.edu]
Not this again (Score:2)
https://matter2energy.wordpress.com/2012/03/17/the-maury-equation-redux/
John and I had an exchange after he published a similar report some time ago.
In spite of pointing out the mathematical impossibility of the concept, here he is again pushing the same pipe dream.
Wouldn't using solar cells be very limiting? (Score:2)
If you used mirrors, heat and some sort of fluid medium to run pumps and a generator, the size of the installations would be unlimited. Of course, this would require moving parts and therefore, more maintenance. The solution to that might be to make thousands of small fluid medium solar units and assume that they will eventually fail and be replaced.
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If you just had the mirrors instead direct the solar energy down to a solar plant on the Earth's surface, there would be no need for anything beyond some gyro's for aiming.
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On the plus side, we'd be just 1 hackathon away from "baked Alaska" for everyone.
This has all been hashed out on /. before... (Score:5, Insightful)
... and there is simply no sane way that paying a MINIMUM 32 MJ/kg to move a kg from the earth's surface to low earth orbit -- that's the minimum that assumes perfect efficiency, which is all by itself pretty funny, multiply it by maybe 100 or 1000 to get an actual estimate -- is ever, ever, ever, ever, ever going to give you a ROI compared to installing solar cells on earth at an identical cost. And then you have to extra problem of getting the energy you harvest in orbit to the ground, which either involves putting a huge receiver somewhere to pick up relatively low intensity downbeamed microwaves (at some major hit in waste heat an inefficiency) OR using less ground area but building a super-maser in orbit that can cook an entire city to extra crispy in a few minutes.
What could go wrong?
Once again, when confronted with an idea that is so very, very, very far away from economically feasible or sane, the right thing to do is club the person suggesting that they will implement it all, with our money (natch!), while keeping ownership and control of the death ray -- I mean "orbital power station" -- is to knock them down and club them with a heavy blunt instrument until they stop twitching.
The guy in the movie about actually pretty much said just that. The only thing it might make sense to lift into orbit for power is solar cells for powering SPACE devices, vehicles, living quarters, or fusion plants once we manage to build one, assuming we can make one small enough and light enough and capable of rejecting heat in a vacuum enough to be able to operate for decades on a small fuel load.
rgb
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Thank you.
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is ever, ever, ever, ever, ever going to give you a ROI compared to installing solar cells on earth at an identical cost.
Putting conventional solar panels in space would indeed be silly. The only workable solutions involve mirrors used as solar concentrators and a ground station. In order to get the cost low enough the mirrors would have to either be some sort of expandable structure or something that could perhaps be manufactured off Earth. I don't think we have anything currently that would meet the expandable requirements though it's within the realm of the possible with sufficient research. For the manufacturing optio
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First off all: there is no need to multiply launch costs by a factor of 100 or 1000. That is just idiotic, hint: get a class at physics. ... and mildly said: it is disturbing.
Secondly: a launched solar PV plant runs with 100% yield 24/7 the who,e year, it is not affected by day/night cycles or seasons.
Third: your idea of 'club-ing' is quite different from mine
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Uh, I teach physics. In fact, I'm about to be late for class. 64 MJ/kg is escape energy, circular low orbit is half of that and I actually did and can do the computation(s) myself. In my head. Now, you figure out how to add 32 MJ/kg of total energy to something at 100% efficiency. Let me know how it is done.
rgb
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Wow, I pitty your students.
Now, you figure out how to add 32 MJ/kg of total energy to something at 100% efficiency.
a) you let it travel through a magnetic field
b) you let it travel through an electric field
c) you let it travel through a gravitational field
You see: plenty of ways to accelerate something with 100% efficiency.
I don't know how 'efficient' rockets are, but they don't need a factor of 100 or 1000 even in fuel versus lets say a electromagnetic launch system.
The 'inefficiency' if you want to call i
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Sigh. I pitty me, since you are obviously clueless about more things than I can easily fix.
Gravity can add energy to things with "100% efficiency", but only after you've done the work of raising them up in a gravitational field. Pretty much the same thing is true for electrostatic energy. Magnetic fields do no work (seriously, and don't argue with me as I'm teaching electrodynamics at this very moment and You Will Be Wrong of you say otherwise and I will cheerfully prove that:
dW/dt = q(\ve
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To orbit in a way that the satellite is
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You don't use a 'true' GEO orbit.
You place it lets say over 60 degrees north at night. Then it is not in the earth shadow. It would then appear to move straight south over half the day and then back north over the same latitude.
Even if you would place it in a true GEO, due to its distance from the earth, it would only be briefly in the night shadow.
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> a launched solar PV plant runs with 100% yield 24/7 the who,e year
And the exact same panels on the ground run at a relative 15 to 30% yield. So you might get three to six times as much energy by launching it into space. Yet that requires thousands of times more energy to launch.
A common /. meme is to complain about the patent system having allowed a bunch of "do it on a computer" BS, but this entire concept basically boils down to "do it in space" and the nerds who have never worked in the field all it
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Yeah, but you still miss the 'around the clock' point. There is no night in space if done right.
Imho the question how complex the conversion from light to microwaves will be.
There is plenty of room for improvements on the PV panel side, that are non economic on earth, but add relatively low costs if you consider the launch costs.
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Right, so if you have a space elevator, it makes sense. If you don't, it doesn't.
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Which basically parses to "it doesn't". Because a space elevator, aside from not being a free lunch, is about as likely as Satan eating snow-cones in mid-August.
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Which basically parses to "it doesn't". Because a space elevator, aside from not being a free lunch, is about as likely as Satan eating snow-cones in mid-August.
He's an angel, he can snap his fingers and make snow cones.
News? (Score:2)
Nothing in space is easy to harvest. I mean, it's in fucking space. If it were easy, we'd already be doing it.
Maybe I'm misunderstandng something..... (Score:2)
I'm confused... (Score:2)
Maybe I'm confused, but isn't the sun's energy already beamed down to Earth? Why launch an expensive and inefficient system into space at great cost when we can just install the system right here? What you save in launch costs would pay for a lot of capacity.
Solar energy in space is very easy to harvest (Score:2)
Getting the energy down to earth may be another matter--which is a case for building what needs to use the energy right there in space next to the collector.
These people are nuts.... (Score:3)
Just because something is "technically possible" does not mean it's a good idea. There are things that are *possible* technically, but impossible economically or so impractical due to size, complexity or other possible solutions exist which are not so hard/expensive that it doesn't make sense to do them. This idea of collecting energy in space, transferring it to the surface to be used is one of these ideas.
First, it's technically possible, but to do this on an industrial scale will requires HUGE systems to be build in space and on the surface. If you use microwaves to transfer the energy, the structures required are literally measured in kilometers, both in space and on the ground.
HOWEVER, it's not practical for economic reasons so it won't ever happen.
1. Throwing huge structures into orbit is pretty costly and energy intensive. Just getting the materials into orbit for a structure 1Km by 1Km is a daunting task, but then loading it up with solar panels, maneuvering devices to point both the solar arrays and transmission array is only going to add weight, complexity and expense.
2. Efficiency is going to be crap. Some folks claim 95% transfer using microwaves, but nobody is calculating the systems real losses going from solar panel output, into microwaves, transfer (at 95%), conversion back to something useful. I'd be willing to bet the attainable efficacy of this system would be below 50%, which means you have to fly twice the solar panel capacity than the energy you are going to get.
3. The ground station part is measured in Kilometers too. It's going to suck up a LOT of real estate in really large blocks to beam the energy down.
4. There are easier and cheaper ways to do the SAME thing. Oh yes, here is the BIG rub for these wide eyed nut jobs.... It's going to be more cost effective just to throw up solar panels on the surface and forego all the complexity and expense of collecting in space. Seriously less expensive for the same amount of power. It will be less expensive to initially build, it will be less expensive to maintain and I'll bet it will be more efficient. You can build this solar collector in the same (or smaller) tract of land than the Microwave collector, or spread it out into smaller tracts and avoid the expense of the legal fight necessary to put a 1Km by 1Km parcel of real estate to public use. Solar on the ground is cheaper, more cost effective and a whole lot more efficient.
My conclusion is it won't happen as much as we like the Pie in the Sky idea it is stupid one. The ROI isn't there and other viable options exist which do the same for less cost So while it's an interesting thought experiment, we need to be investing in things which have promise of being more practical if they can be made to work, things like Fusion power.
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...more practical if they can be made to work, things like Fusion power.
Or, you know, we could just build more practical power plants that already work, things like Fission power.
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There is that.... I was appealing to the environmentalists out there and avoiding them going nuclear by making such a provocative (yet true) statement. Fission does work, is safe, and we know how to use it.
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> Fission does work, is safe, and we know how to use it.
Indeed. Except it costs five times as much to build a fission power plant than to build enough wind turbines to produce the same amount of energy. Indeed, the wind turbines will only operate 30% of the time. But means the wind turbines cost 3 / 5 times as much as the fission plant. And that's precisely why everyone is building wind turbines and practically no one is building fission plants.
And when I say "everyone" and "practically no one", I includ
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> Fission does work, is safe, and we know how to use it.
Indeed. Except it costs five times as much to build a fission power plant than to build enough wind turbines to produce the same amount of energy.
Well, that may be true, but only as long as the wind is blowing.... Fission works ALL the time (or nearly so), Wind? Not so much.
Plus, I'd contend that the cost of Fission is not that far from Wind, but going by cost says Natural gas is first and in my world I'd build all sorts of generation capacity so we don't have all our eggs in a single basket.
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Except it costs five times as much to build a fission power plant than to build enough wind turbines to produce the same amount of energy. Indeed, the wind turbines will only operate 30% of the time. But means the wind turbines cost 3 / 5 times as much as the fission plant. And that's precisely why everyone is building wind turbines and practically no one is building fission plants...
Except that the fission power industry is more mature and has more in place infrastructure than wind. Even at a slightly higher cost we could build more capacity in a shorter time by building fission reactors rather than wind turbines, simply because of the pre-existing infrastructure investment.
Over the last 25 years we've installed under 100 GW of fission, a period in which we installed 370 GW of wind,
Right, for a combined capacity of 470GW, which would be *higher* had we been building as many fission reactors as we could, instead of irrationally pissing our collective pants over nuclear FUD.
In the long term, ren
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Well feel free to go do stupid stuff if you insist...
BTW - I have two kids, the oldest is in college making nearly straight "A's" in her third year of a STEM degree (enjoying a full scholarship) and my youngest is doing great in high school (better than his sister did actually.) Further, both kids where entirely home schooled except for one year they went to private school, with my wife and I serving as their teachers (I do the STEM subjects in the evening and she does the rest). So, I'm not so sure I co
John C. Mankins, Dumb Ass (Score:2)