Fusion a suicidal power source?

In summary, the article discusses how table top fusion is still in its early stages, but has the potential to provide a solution to our energy problems in the future. There are concerns about the process of table top fusion, but if it ever becomes a practical option, it would only use a small amount of water.
  • #1
MonstersFromTheId
142
1
I'm sure most saw the article in today's NY Times on "table top fusion".
(For those who haven't...)

http://www.nytimes.com/aponline/science/AP-Tabletop-Fusion.html?hp&ex=1114660800&en=6ac101f390e18d4d&ei=5094&partner=homepage

And the article does mention that this experiment doesn't do much in the way of offering a solution to our energy problems, at least not this week, or even this year, but then again, over enough time, who knows?
What worries me about fusion is that I don't understand the process very well. I really don't want to start a thread that's going to devolve into a debunking argument, but I've got a question, and I was hoping someone in here would know a bit more about this than I do (not exactly a stretch).

K; from what I understand you take a pair (actually lots of pairs) of deuterium atoms (which are basically weird hydrogen atoms, hydrogen atoms from "heavy water"), you smack 'em together, or squeeze 'em together almost too tightly to imagine, and you get a helium atom along with one incredible amount of energy.
What bugs me about this idea is that it seems to turn hydrogen into helium, and you NEED hydrogen. Without hydrogen you can't have water. Now assuming fusion power actually does become practical, I can see where a few fusion power plants eating up hydrogen wouldn't be a problem, but... If you got to the point where fusion power was the *primary* "power source of the future", where dammed near everything on the planet was dependent on it, wouldn't that start to... well... dehydrate our beautiful little blue world?

Or is it the case that even having to generate ten times the amount of power we use now would require such miniscule amounts of hydrogen that it wouldn't really have any measurable effect on how much hydrogen is around, let alone start to threaten to "dehydrate" the planet?
 
Last edited by a moderator:
Physics news on Phys.org
  • #2
If we ever are able to generate power by fusing water we will have lots of time to work out the solution to your problem before it becomes a problem.
 
  • #3
"If we ever are able to generate power by fusing water we will have lots of time to work out the solution to your problem before it becomes a problem."
(snicker fit)
Better yet if we can learn to fuse manure, or even BETTER than that - Male Bovine Manure! (A.k.a. "massless manure" ;-) There's a LOT of that around)...

But seriously Integral, where do deuterium and trituim come from? If the ITER were to work tomarrow afternoon, after the party, where would the "fuel" come from for large scale power production? Ya got to understand that this kind of thing isn't as obvious to me as it is to you.
 
  • #4
By a quick "back of an envelope" calculation, I estimate that if the entire worlds energy for a year was supplied by fusion, it would only use up about 1/150,000 of the world's water supply.
Besides, with fusion power, we could most likely be able to build spacecraft capable of going out and collecting all that water spread out in the solar system in the form of ice.
 
  • #5
Janus said:
Besides, with fusion power, we could most likely be able to build spacecraft capable of going out and collecting all that water spread out in the solar system in the form of ice.
That amount of energy would also allow us to initiate even more powerful fusion reactions, such as helium-lithium and really get us going. :biggrin:
 
  • #6
150,000 years using the water on earth? Still seems like a low-ball. What kind of energy consumption are we using in your calculation and how much water exists on earth?
 
Last edited:
  • #7
Janus said:
By a quick "back of an envelope" calculation, I estimate that if the entire worlds energy for a year was supplied by fusion, it would only use up about 1/150,000 of the world's water supply.
Besides, with fusion power, we could most likely be able to build spacecraft capable of going out and collecting all that water spread out in the solar system in the form of ice.

EEEK!
That sounds friggin HUGE! I realize that's just a b.o.t.e., only in the ball park if you count the parking lot kinda quicky estimate, but... still.
Settle me down here a bit.
That SOUNDS like another way of saying that if all of the world's energy needs were met just by fusion and nuthin else, for just a single year(!), "global warming" would be the very LEAST of our problems. I mean if 1/150,000th of the world's entire water supply went up in helium - in just a year(!), and then kept doing that, year after year after year, holy cr@p! Wouldn't that radically, and I mean RADICALLY change things like the weather?
In a situation like that it seems to me that we'd better be dammed sure that we have infrasturcture in place to go get all that water spread out in the solar system LONG before we EVER allow ourselves to become anything close to heavily dependant on fusion power.
 
Last edited:
  • #8
Janus said:
By a quick "back of an envelope" calculation, I estimate that if the entire worlds energy for a year was supplied by fusion, it would only use up about 1/150,000 of the world's water supply.
That seems high - how did you get that?
 
  • #9
Monster, that's 150,000 years worth of power we're talking about. Thats like saying before we ever decide to cut down a single tree in a forest (and take a year to do it), we better have plans immediately to fix the problems we make. Plus of course, its affect per year would be just like a single tree in a forest lol.
 
  • #10
MonstersFromTheId said:
EEEK!
That sounds friggin HUGE! I realize that's just a b.o.t.e., only in the ball park if you count the parking lot kinda quicky estimate, but... still.
Settle me down here a bit.
That SOUNDS like another way of saying that if all of the world's energy needs were met just by fusion and nuthin else, for just a single year(!), "global warming" would be the very LEAST of our problems. I mean if 1/150,000th of the world's entire water supply went up in helium - in just a year(!), and then kept doing that, year after year after year, holy cr@p! Wouldn't that radically, and I mean RADICALLY change things like the weather?
In a situation like that it seems to me that we'd better be dammed sure that we have infrasturcture in place to go get all that water spread out in the solar system LONG before we EVER allow ourselves to become anything close to heavily dependant on fusion power.
He would not build up in the atmosphere if that is what you are attempting to say. He is to light to remain in our atmosphere, it would be lost to space. Seems to me like you are being a bit reactionary here. I guess you think it is better to keep burning fossil fuels? :uhh:
 
  • #11
it would only use up about 1/150,000 of the world's water supply.
This number is useless without knowing what you mean by "world's water supply". 1/150 000 of all water is a lot, it would reduce the sealevel by almost 20 mm a year and might kill us all fairly rapidly.

Besides, with fusion power, we could most likely be able to build spacecraft capable of going out and collecting all that water spread out in the solar system in the form of ice.
That is pure science fiction. There is nothing to suggest that humans will ever be able to collect anything of size from anywhere in the solar system.

Seems to me like you are being a bit reactionary here. I guess you think it is better to keep burning fossil fuels?
What would you prefer, live without oil or without water?
 
  • #12
Bjørn Bæverfjord said:
This number is useless without knowing what you mean by "world's water supply". 1/150 000 of all water is a lot, it would reduce the sealevel by almost 20 mm a year and might kill us all fairly rapidly.
Let's put this into a more everyday perspective. Depending upon the efficiency of the plant, a fusion generator would use between 500 and 1000 gallons of deuterium/tritium to supply the full energy needs of Chicago or Los Angeles for a year. Deuterium composes about 0.02% of all naturally occurring water, and tritium is derived from lithium rather than water.

Bjørn Bæverfjord said:
That is pure science fiction. There is nothing to suggest that humans will ever be able to collect anything of size from anywhere in the solar system.
Rubbish! It's science fact. There's never been any question that we can do it. The only debate is whether or not we will do it, and which of several practical methods will be utilized.
 
  • #13
It would use 1/150,000 of the worlds deuterium each year, not 1/150,000 of the world's water. Only a small part of the water in the ocean has deuterium in it (heavy water or HDO).
 
  • #14
russ_watters said:
That seems high - how did you get that?

Your right, it is. I went back over my calculation and realized that I skipped a step (converting km³ to m³ when figuring the volume of the oceans), this drops the fraction down by a factor of 1,000,000,000.
 
  • #15
Bjørn Bæverfjord said:
That is pure science fiction. There is nothing to suggest that humans will ever be able to collect anything of size from anywhere in the solar system.
Oh come on! Remember, we are already assuming that we have practical, controlled fusion power. If we really needed that water, that in itself would give us the means to go out and get it.
 
  • #16
And if we cant, we can at least give ourselves a pat on the back for surviving for such a long time :D

lol nice conversion error there too. I remember doing E=mc^2 and getting mad at someone who got an answer 3 OOM smaller then mine (hehe... so mass isn't in grams :D)
 
  • #17
Pengwuino said:
I remember doing E=mc^2 and getting mad at someone who got an answer 3 OOM smaller then mine (hehe... so mass isn't in grams :D)
Hey, thanks for showing me how to write E=mc^2 without having superscript available! I didn't even know my keyboard had one of these ^^^ keys until I saw your post. So now I can tell him to run E=mc^2*0.04 through his brain and see how much efficiency we're really talking about. :biggrin:
 
Last edited:
  • #18
What would you prefer, live without oil or without water?

Running out of oil is just a matter time. So the choice is not oil or water, it is use water or revert to the preindustrial age.
 
  • #19
Man, what if someone found a way to synthesize petroleum... All hell would break loose.
 
  • #20
Pengwuino said:
Man, what if someone found a way to synthesize petroleum... All hell would break loose.
What's the big deal? All you need is a dinosaur and some really big pliers...
 
  • #21
Pliers, check.
 
  • #22
Probos76 said:
Is it possible to find fusion process going on in the universe?

Probos76, meet the Sun. Sun, meet Probos76.

Just don't look at the Sun too long...

Zz.
 
  • #23
Running out of oil is just a matter time. So the choice is not oil or water, it is use water or revert to the preindustrial age.
So given then choice you would live without both, a brilliant choice if I may say so.

Your right, it is. I went back over my calculation and realized that I skipped a step (converting km³ to m³ when figuring the volume of the oceans), this drops the fraction down by a factor of 1,000,000,000.
That is a much more sensible number, it might even keep us going until the end without resorting to science facts from the makers of Star Trek.
 
  • #24
Bjørn Bæverfjord said:
So given then choice you would live without both, a brilliant choice if I may say so.

Actually, you seem to be reading exactly the opposite of what I am from that statement. It appears to me he's saying we had *better* use the water unless we're willing to go back to the 18th century technology-wise.

That is a much more sensible number, it might even keep us going until the end without resorting to science facts from the makers of Star Trek.

The thing about Star Trek is that the numbers just don't add up. It's essentially hand-waving on the part of the writers. No physics known today allows us to do what they do on the show.

On the other hand, activities like mining water from a comet or 3He from the lunar surface seem to be possible using currently known physics. We can run the numbers and it seems likely that we *can* do it someday. I think a good analogy would be a person in the 40's trying to figure out how to put men on the moon. You had a long way to go technologically from the V-2 rocket to the Saturn V and a lot of bugs to work out along the way, but the numbers would indicate it was at least feasible.
 
  • #25
Actually, you seem to be reading exactly the opposite of what I am from that statement. It appears to me he's saying we had *better* use the water unless we're willing to go back to the 18th century technology-wise.
If look what was said before then he was saying that it is better to use up the worlds oceans at a rate of 20 mm a year and increase power consumption by a factor of 1 000 000 000 and kill us all in no time rather than to reduce power consumption in half and live on just like before.

think a good analogy would be a person in the 40's trying to figure out how to put men on the moon.
That was imagined quite successfully a century before. Now that we know how difficult it is, it does not seem likely that we will ever be able to bring in sizable portions of the Oort cloud to feed a fusion reactor that is large enough keep the planet above boiling.
 
  • #26
Are you guys seriously worried about running out of water? Come on! The water doesn't even have to be "drinking water."
 
  • #27
This is another case of the media getting science wrong. Fusion isn't the big thing to come out of this experiment; A more potent result would be the possibility of a portable neutron generator.
 
  • #28
Actually, you seem to be reading exactly the opposite of what I am from that statement. It appears to me he's saying we had *better* use the water unless we're willing to go back to the 18th century technology-wise.

This is exactly what I mean.
If look what was said before then he was saying that it is better to use up the worlds oceans at a rate of 20 mm a year and increase power consumption by a factor of 1 000 000 000 and kill us all in no time rather than to reduce power consumption in half and live on just like before.

I am not sure where you got that number from, I think it is off by orders of magnitude.

Janus, what was your final number, you did not make it explicitly clear.

If we do not find an alternative to oil soon, the chances for our civilization to last another 100yrs is dismal. The only feasible energy source available to us is fusion, anything else is stop gap, a temporary band-aid. And yes the ultimate solution is to cut our use of energy, 1/2 is not enough to really make a difference. That would just delay the onset of the next pre industrial age by a few years. I tend to believe that once the slide to pre industrial life style begins it will not end until we return to the stone age. Unless we can find a replacement energy source the end of oil means the end of civilization as we know it.

The end of oil is coming. So go ahead get in your gas hog suv, condemn your great grand children to a life like you can not even imagine. (just my opinion on a gloomy day)
 
  • #29
Pengwuino said:
Man, what if someone found a way to synthesize petroleum... All hell would break loose.
Fischer-Tropsch synthesis - developed in 1923 in Germany - a basis of synfuel. The process is named after F. Fischer and H. Tropsch, the German coal researchers who discovered it.

see - http://www.fischer-tropsch.org/site_map.htm

As for fusion using up hydrogen, the Earth accumulates a fair amont of hydrogen from the solar wind, IIRC.

But clearly, except for solar power (and wind, geothermal, and hydro-electric) all sources of energy are derived from 'consumable' sources, i.e. fossil fuels and nuclear fuels are simply energy storage systems, which can eventually be exhausted without proper planning. But I suppose those will be problems for future generations, as IMO, the current generations are perhaps too lazy or to selfish to address these issues. :grumpy:
 
  • #30
Pengwuino said:
Man, what if someone found a way to synthesize petroleum... All hell would break loose.


Look up thermo-depolymerization (been in a few threads on here) where just about any carbon-based materials can be made into useable petro products. In an interview on Science Channel's "Techknowledge" TV show the creator claims the use of all waste (including agricultural) with the TDP process could supply the US with enough petro to meet its energy needs.

And I was also going to ask if the yield from fusion is anywhere even our current levels of fission why we would need such massive amounts of water but the math has been corrected.
 
  • #31
Integral said:
This is exactly what I mean.
Janus, what was your final number, you did not make it explicitly clear.

Rerunning the numbers through a spreadsheet, with the following data;

World yearly energy usage: 404 quads. (1 quad = 1 x 10^15 BTU or 1.054 x 10^18 joules.

volume of the oceans : 317,000,000 cubic miles.

percentage of mass converted to energy by hydrogen fusion : 0.4%

The fraction of the mass of water due to hydrogen: 1/9

World energy usage: 404 * 1.054e+18 = 4.258E+20 J

Amount of water needed to provide this much energy via fusion:

4.258E+20 J/ (3e8m/s)² * 9/ .004 = 10,645,400 kg.

(compare this to the 4 billion tons of coal alone the world burns in one year. )

Oceans' volume


317,000,000 * 4.09 = 1296530000 km³
* 1000³ = 1.297E+18 m³
* 1000 = 1.297E+21 Liters

converted to kg:

= 1.297E+21 kg.

1.297E+21 kg/10,645,400 kg = 8.211E-15
or
0.0000000000008211% of the world's oceans used a year.
 
  • #32
Omg we can only survive for 1.22 trillion years on fusion :(
 
  • #33
I am not sure where you got that number from, I think it is off by orders of magnitude.
That was the original number that you accepted, I just tried to point out that you were happy to choose suicide instead of any of several sustainable paths.

The corrected number puts everything in a different light as it does not point to a rapid disaster.
 
  • #34
Janus;
Thanks for the numbers, makes it easier to get a grip.
What was worrying me about the original 1/1000,000ths of the planet's water supply per year was that relatively tiny changes in the amount of over all water could possibly have signifigant effects on things like weather.
1/10,000th of all water gone in a century seemed a bit of a cause for concern seeing as how:
1) Once the water is gone it ain't NEVER comin back. This isn't like polluting water, it's out and out destroying it permanently.
2) As we're learning now, once you're addicted to a particular power source it can be a very difficult habit to kick.
3) Increases in energy useage don't look likely to flatline anytime soon, so basing calculations on *current* needs is certainly debatable.

All of which, for me at least added up to an "EEEK!"

But... "0.0000000000008211% of the world's oceans used a year." is one heck of a lot less scary number. With a rate of loss that low, a deadly attack by five headed space aliens would be a lot more likely to keep me up nights.
 
  • #35
Yah and come on, in a trillino years (the inverse of that number), we'll have figured something out lol.
 

Similar threads

  • Science Fiction and Fantasy Media
Replies
16
Views
2K
  • Astronomy and Astrophysics
Replies
19
Views
3K
Replies
1
Views
783
  • High Energy, Nuclear, Particle Physics
Replies
19
Views
3K
Replies
1
Views
3K
  • High Energy, Nuclear, Particle Physics
Replies
6
Views
2K
  • Special and General Relativity
Replies
7
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
18
Views
9K
  • High Energy, Nuclear, Particle Physics
Replies
7
Views
3K
Replies
28
Views
6K
Back
Top