The problem with fusion...

[Nitack]

I have just finished reading a chapter on energy and such in the book Physics for Future Presidents. Part of that chapter addressed what exactly fusion is and why it is the holy grail of the worlds energy dilemma. Force two hydrogen atoms together and you get an amazing amount of energy released, exactly what happens in the sun.

 

Here is my dilemma and would love for some one to point out the flaw in my logic. We eventually discover an efficient and economical way to force two hydrogen atoms together and harness the amazing energy released. WOO HOO, happy days :lol:!

 

BUT... now we have a helium atom that was created. Individually not a problem. But what happens a thousand years from now when we have been converting massive amounts of hydrogen to helium in order to reap the energy rewards? I realize that helium is a mostly inert gas and that hydrogen is the most prevalent element in the universe. However, what is the realistic long term effect? We can't really split all of that helium up back into hydrogen, according to the laws of thermodynamics it would take as much energy (or more given efficiency losses) to do that as we gained from forcing the molecules together. Eventually we will have altered the elemental balance on our planet.

 

I chose to ask about a 1000 years from now because that is a realistic amount of time to expect humans to be around and possibly feel repercussions. Maybe we would have to operate fusion for a hundred thousand years to actually start impacting the planet, I don't know the exact numbers. But as I read it occurred to me that fusion would have some similarities to our current global warming debate. Although rather than pumping more CO2 into the atmosphear (which the planet can fix over time and we are discovering options to try to do it ourselves), we instead of changed which molecules are more prevelent, which I don't think any natural phenomenon can fix, and we could not fix due to the energy that would be required to split those atoms back into hydrogen.

 

Maybe I am just missing something. Maybe the quantities of hydrogen are so vast that the amount of time to make an impact is mind boggling :shrug:. Just wanted to get a better understanding of the issue.

[Moontanman]

I have just finished reading a chapter on energy and such in the book Physics for Future Presidents. Part of that chapter addressed what exactly fusion is and why it is the holy grail of the worlds energy dilemma. Force two hydrogen atoms together and you get an amazing amount of energy released, exactly what happens in the sun.

 

Here is my dilemma and would love for some one to point out the flaw in my logic. We eventually discover an efficient and economical way to force two hydrogen atoms together and harness the amazing energy released. WOO HOO, happy days :lol:!

 

BUT... now we have a helium atom that was created. Individually not a problem. But what happens a thousand years from now when we have been converting massive amounts of hydrogen to helium in order to reap the energy rewards? I realize that helium is a mostly inert gas and that hydrogen is the most prevalent element in the universe. However, what is the realistic long term effect? We can't really split all of that helium up back into hydrogen, according to the laws of thermodynamics it would take as much energy (or more given efficiency losses) to do that as we gained from forcing the molecules together. Eventually we will have altered the elemental balance on our planet.

 

I chose to ask about a 1000 years from now because that is a realistic amount of time to expect humans to be around and possibly feel repercussions. Maybe we would have to operate fusion for a hundred thousand years to actually start impacting the planet, I don't know the exact numbers. But as I read it occurred to me that fusion would have some similarities to our current global warming debate. Although rather than pumping more CO2 into the atmosphear (which the planet can fix over time and we are discovering options to try to do it ourselves), we instead of changed which molecules are more prevelent, which I don't think any natural phenomenon can fix, and we could not fix due to the energy that would be required to split those atoms back into hydrogen.

 

Maybe I am just missing something. Maybe the quantities of hydrogen are so vast that the amount of time to make an impact is mind boggling :shrug:. Just wanted to get a better understanding of the issue.

 

Lots of helium is being released from with in the earth already, helium is indeed inert, it plays no role in our atmosphere and moves out into space over geologic time. More importantly a fusion power plant would not be a source of large quantities of helium. The reaction is so energetic it really doesn't produce as much helium as say a coal fired power house produces CO2, not even close. But fusion does have a dark heart, it's not usually talked about but a fusion plant does produce large amounts of neutrons, they make everything in and around the power plant radioactive. A hydrogen fusion power plant would have a relatively short life span and then have to abandoned and locked up for millions of years. A better idea is anutronic fusion, fusing two helium three atoms. No neutrons are produced and the power is electromagnetic so it can be changed into electricity with out a heat engine like all other power sources. No turbines, no generators, just photons turned into electricity. Of course there is a bad part to this, no helium three on the earth, you have to go to the moon to mine it from the lunar regolith but the amount of helium three you could carry in the space shuttle would be enough to run the USA for a year! Millions of years worth of helium three on the moon and then you have the surfaces of other airless worlds. Oh yeah, helium three fusion is the ultimate fossil fuel! It's fossilized solar wind!

[Jay-qu]

Except for the fact that He-3 in moon rocks is about 10-20 parts per billion.. so lots of processing needs to be done to yield an appreciable amount.

[Moontanman]

Except for the fact that He-3 in moon rocks is about 10-20 parts per billion.. so lots of processing needs to be done to yield an appreciable amount.

 

That is not as big a deal as you might think.

 

How moon rocks could power the future - LiveScience - MSNBC.com

[maddog]

I have just finished reading a chapter on energy and such in the book Physics for Future Presidents.

Yeah, I just finished reading this book over last weekend (started/finished

same -- it was soooo good!

 

Part of that chapter addressed what exactly fusion is and why it is the holy grail of the worlds energy dilemma. Force two hydrogen atoms together and you get an amazing amount of energy released, exactly what happens in the sun. Here is my dilemma and would love for some one to point out the flaw in my logic...

 

...Maybe the quantities of hydrogen are so vast that the amount of time to make an impact is mind boggling :beer:. Just wanted to get a better understanding of the issue.

 

Actually, I wasn't sure what you were driving at, so I am not aware of a flaw

without observing the flow of your logic.

 

As for worrying about having "too much" Helium (?), I don't see this as a

problem of any kind. In the universe Hydrogen is the most abundant

element (well known). Helium is the 2nd most abundant (also well known).

Production by fusion of all the planet "future" power plants would change

that "universal" percentage by any noticeable degree. NP.

 

maddog :)

[Nitack]

Yeah, I just finished reading this book over last weekend (started/finished

same -- it was soooo good!

 

 

 

Actually, I wasn't sure what you were driving at, so I am not aware of a flaw

without observing the flow of your logic.

 

As for worrying about having "too much" Helium (?), I don't see this as a

problem of any kind. In the universe Hydrogen is the most abundant

element (well known). Helium is the 2nd most abundant (also well known).

Production by fusion of all the planet "future" power plants would change

that "universal" percentage by any noticeable degree. NP.

 

maddog :beer:

 

My reasoning was less along the lines of more helium and more along the lines of less hydrogen. Hydrogen is a vital component of water and life. We convert enough of it to helium for the power and we get less water on the planet, possibly altering weather patterns in a way that makes global warming look easy to handle.

[freeztar]

My reasoning was less along the lines of more helium and more along the lines of less hydrogen. Hydrogen is a vital component of water and life. We convert enough of it to helium for the power and we get less water on the planet, possibly altering weather patterns in a way that makes global warming look easy to handle.

 

I don't really see that being a problem. There is so much H2 in and on Earth that I really don't think we'll run out. Bacterial byproducts (such as H2S) would provide plenty of H2 for energy use.

[maddog]

My reasoning was less along the lines of more helium and more along the lines of less hydrogen. Hydrogen is a vital component of water and life. We convert enough of it to helium for the power and we get less water on the planet, possibly altering weather patterns in a way that makes global warming look easy to handle.

 

Oh, well that is easy enough. As I was saying regarding abundance earlier.

Take the ratio of He/H in any environment (Universe, Solar System, Earth ...).

The change even after 1000 years of fusion production for our civilization,

even if we were to imagine all energy were by fusion. Then that ratio would

be relatively constant upto 6 digits of precision or more. You would notice no

depletion of hydrogen. Even in the book, the author implied to the Prez, to

get the source of Hydrogen from seawater. NP.

 

maddog

[Qfwfq]

We convert enough of it to helium for the power and we get less water on the planet, possibly altering weather patterns in a way that makes global warming look easy to handle.

Did you try looking up some actual quantitave info? You might be surprised. Unless of course you simply keep in mind the quantities of fuel used by currently existing fission reactors. Even deuterium (much better fuel than ordinary hydrogen) is far more plentiful around here than uranium is...:)

[Moontanman]

My reasoning was less along the lines of more helium and more along the lines of less hydrogen. Hydrogen is a vital component of water and life. We convert enough of it to helium for the power and we get less water on the planet, possibly altering weather patterns in a way that makes global warming look easy to handle.

 

Nitack, the sun will swell and kill all life on the Earth before we could use enough hydrogen to be able to measure it. Hydrogen fusion produces an enormous amount of power per gram fused. We have many billions of years of hydrogen in the earths oceans when used at any conceivable rate.

[Nitack]

Nitack, the sun will swell and kill all life on the Earth before we could use enough hydrogen to be able to measure it. Hydrogen fusion produces an enormous amount of power per gram fused. We have many billions of years of hydrogen in the earths oceans when used at any conceivable rate.

 

That is the answer to my question. thanks.