Mining the moon for unlimited Energy.

Gordon D. Pusch wrote:

Unfortunately, we do =NOT= have the _FAINTEST_ clue as to how to build
a fusion reactor that could burn the stuff without a net _LOSS_ of energy.
It takes temperatures and plasma densities more than an _ORDER OF MAGNITUDE
HIGHER_ than D/T fusion to "ignite" even the "easiest" He3-burning reaction,
and it is not clear that such a reactor could =EVER= "break even," since
its bremsstrahlung loss rate likewise exceeds its energy generation rate
by more than an order of magnitude. Trying to "burn" He3 is like trying
to burn soaking wet paper --- it costs more heat than you get out of it.

Where does this 'exceeds its energy generation rate by more than an order
of magnitude' come from? The ideal situation I recall (optimal plasma
conditions, 'hot ion mode') was 19% of the energy goes into bremsstrahlung.


Furthermore, it would be cheaper to _MANUFACTURE_ He3 on the Earth by
"breeding" Tritium and waiting for it to decay than to mine it on the
Moon and ship it back to Earth. So quite bluntly, this lunatic idea
is pure moonshine.

A contained, underground 1 MT explosion could produce several kilograms
of tritium (and ultimately 3He).

The biggest problem with lunar 3He is that the energy required to extract
it from the regolith is substantial; even if this energy does not exceed
the fusion energy content of the gas, it will be a significant fraction
of it. You don't want to have to build a 100 MW powerplant on the moon
in order to fuel a 1 GW powerplant on earth; the cost of the former would
dwarf the cost of the latter.

Paul

Sanjay wrote:

Hello Friends,

There is plenty of energy on moons crust that if we can mine Helium 3
Gas out of Moons crust we can solve all our energy needs for 1000
years.

A pound of Helium-3 is having energy equivalent of 1 Million ton of
Coal.

You may view the Full Article he

http://www.softtanks.com/Todays_Arti...p?Topic=Energy

Fusion of helium-3 does not produce greenhouse emissions, and mining
it would do little environmental harm The moon doesn`t have air or
water. So, there won`t be any of that kind of pollution.

So after Earth next mining target will be Moon.

Bye
Sanjay

http://www.softtanks.com/Todays_Arti...p?Topic=Energy


This will be cool, once we *have* commercial fusion reactors (and
economical access to the Moon, which is likely to come sooner)....

And assuming we'll use fuision cycles that require it He3.


--

You know what to remove, to reply....

"Paul F. Dietz" writes:

Gordon D. Pusch wrote:

Unfortunately, we do =NOT= have the _FAINTEST_ clue as to how to build
a fusion reactor that could burn the stuff without a net _LOSS_ of energy.
It takes temperatures and plasma densities more than an _ORDER OF MAGNITUDE
HIGHER_ than D/T fusion to "ignite" even the "easiest" He3-burning reaction,
and it is not clear that such a reactor could =EVER= "break even," since
its bremsstrahlung loss rate likewise exceeds its energy generation rate
by more than an order of magnitude. Trying to "burn" He3 is like trying
to burn soaking wet paper --- it costs more heat than you get out of it.

Where does this 'exceeds its energy generation rate by more than an order
of magnitude' come from? The ideal situation I recall (optimal plasma
conditions, 'hot ion mode') was 19% of the energy goes into bremsstrahlung.

That's not what I remember from Art Carlson's (sadly defunct) webpage
summarizing the Rider Thesis. What I remember was that bremsstrahlung
losses exceed energy generation by a factor of 15; I will have to dig out
the copy of the Rider Thesis Jim Logajan kindly loaned me and see if I can
find the exact figure, but I'm pretty sure that a factor of 15 is correct.

Note also that one of Rider's main claims was that fancy "non-equilibrium"
concepts such as "hot ion mode" don't work: =ALL= "reactor-type" fusion
plasmas relax to thermodynamic equilibrium FAR faster than they generate
fusion energy, and attempts to _keep_ them far from equilibrium will
always cost more additional energy than they will produce.


Furthermore, it would be cheaper to _MANUFACTURE_ He3 on the Earth by
"breeding" Tritium and waiting for it to decay than to mine it on the
Moon and ship it back to Earth. So quite bluntly, this lunatic idea
is pure moonshine.

A contained, underground 1 MT explosion could produce several kilograms
of tritium (and ultimately 3He).

If you're willing to do that, then you might as well go whole hog and build
a PACER system for power generation --- but not in _my_ backyard !!! 8-(


The biggest problem with lunar 3He is that the energy required to extract
it from the regolith is substantial; even if this energy does not exceed
the fusion energy content of the gas, it will be a significant fraction
of it. You don't want to have to build a 100 MW powerplant on the moon
in order to fuel a 1 GW powerplant on earth; the cost of the former would
dwarf the cost of the latter.

Agreed.


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

On Fri, 30 Jan 2004 21:15:50 -0600, "Jonathan Wilson"
wrote:

Given that we can do that economically, it might still make more sense to
scoop it out of the atmospheres of the giant planets than to strip-mine the
surface of the moon.

It bears thinking about: don't know if I want my great-great-grandkids
looking up at night and seeing Lunar Pit Mine Number 12 where Tycho used to
be.

The moon's basically just a ball of the stuff you find in the slag
heaps beside mines; it's by definition impossible to harm it.

However, lunar regolith is an extremely poor source of helium-3; the
atmospheres of gas giants are likely to contain a lot more of the
stuff, if we ever get to the point of having a use for it.

--
"Sore wa himitsu desu."
To reply by email, remove
the small snack from address.
http://www.esatclear.ie/~rwallace

"Paul F. Dietz" writes:

Gordon D. Pusch wrote:

Unfortunately, we do =NOT= have the _FAINTEST_ clue as to how to build
a fusion reactor that could burn the stuff without a net _LOSS_ of energy.
It takes temperatures and plasma densities more than an _ORDER OF MAGNITUDE
HIGHER_ than D/T fusion to "ignite" even the "easiest" He3-burning reaction,
and it is not clear that such a reactor could =EVER= "break even," since
its bremsstrahlung loss rate likewise exceeds its energy generation rate
by more than an order of magnitude. Trying to "burn" He3 is like trying
to burn soaking wet paper --- it costs more heat than you get out of it.

Where does this 'exceeds its energy generation rate by more than an order
of magnitude' come from? The ideal situation I recall (optimal plasma
conditions, 'hot ion mode') was 19% of the energy goes into bremsstrahlung.

Hmph. On re-examining Rider's dissertation, it appears you are correct,
and my memory of a factor of 15 was wildly wrong. Assuming quasi-neutrality,
separate maxwellian distributions for ions and electrons, =NO_ energy losses
except bremsstrahlung, and that =ALL= the fusion-product power can somehow
be magically recycled back into heating the fuel ions and _NOT_ into heating
the electrons, Rider gets:

fuel | P_brem/P_fus
--------+--------------
D-T | 0.007
D-He3 | 0.19
D-D | 0.35
He3-He3 | 1.39
p-B11 | 1.74
p-Li6 | 4.81

So assuming "magic power recycling" and the most wildly optimistic energy loss
assumptions imaginable short of somehow magically removing all the electrons
from the plasma [e.g., "Penning-trap fusion" (which is utterly hopeless due
to the space-charge limit)], D-He3 and D-D are marginally possible, but pure
He3 burners and other "advanced" fuel combinations cannot generate net energy.

And all this does not begin to address the higher ignition temperature needed,
or the higher density needed to make up for the lower reaction cross-section
without making the reactor unreasonably enormous. So while perhaps He3 burning
_may_ not be utterly physically impossible if one is allowed to assume "magic"
technology, it certainly still appears to be more than a little implausible!


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

(Sanjay) wrote in message om...
Hello Friends,


There is plenty of energy on moons crust that if we can mine Helium 3
Gas out of Moons crust we can solve all our energy needs for 1000
years.

A pound of Helium-3 is having energy equivalent of 1 Million ton of
Coal.

You may view the Full Article he

http://www.softtanks.com/Todays_Arti...p?Topic=Energy

Fusion of helium-3 does not produce greenhouse emissions, and mining
it would do little environmental harm The moon doesn`t have air or
water. So, there won`t be any of that kind of pollution.


ROFL! What are you drinking? Read the other posts in this thread.

Harry C.

You don't want to have to build a 100 MW powerplant on the moon
in order to fuel a 1 GW powerplant on earth; the cost of the former would
dwarf the cost of the latter.

And if we, as humans, ever have the capacity for such big projects in space, we
won't *need* mines on the moon for 3He. SPS is equally doable with a space
infrastructure, and its technology, unlike fusion reactors, is currently in
being.

don't know if I want my great-great-grandkids
looking up at night and seeing Lunar Pit Mine Number 12 where Tycho used to
be.

You'd be dead; what would it matter??? IAC, I don't imagine we will ever see
manmade naked-eye landmarks upon the moon.

(Gordon D. Pusch) wrote in message ...
(Sanjay) writes:


There is plenty of energy on moons crust that if we can mine Helium 3
Gas out of Moons crust we can solve all our energy needs for 1000
years.

Unfortunately, we do =NOT= have the _FAINTEST_ clue as to how to build
a fusion reactor that could burn the stuff without a net _LOSS_ of energy.
It takes temperatures and plasma densities more than an _ORDER OF MAGNITUDE
HIGHER_ than D/T fusion to "ignite" even the "easiest" He3-burning reaction,
and it is not clear that such a reactor could =EVER= "break even," since
its bremsstrahlung loss rate likewise exceeds its energy generation rate
by more than an order of magnitude. Trying to "burn" He3 is like trying
to burn soaking wet paper --- it costs more heat than you get out of it.

Any idea who started this theory that He3 is easy to burn?

I know Zubrin did chapters on it in his book Entering Space. Is he guilty?


A pound of Helium-3 is having energy equivalent of 1 Million ton of
Coal.

..But that factoid is of _ABSOLUTELY NO VALUE_ if He3 can't be "burned"
in a reactor.

(Gordon D. Pusch) wrote:
"Paul F. Dietz" writes:
Where does this 'exceeds its energy generation rate by more than an
order of magnitude' come from? The ideal situation I recall (optimal
plasma conditions, 'hot ion mode') was 19% of the energy goes into
bremsstrahlung.

That's not what I remember from Art Carlson's (sadly defunct) webpage
summarizing the Rider Thesis. What I remember was that bremsstrahlung
losses exceed energy generation by a factor of 15; I will have to dig
out the copy of the Rider Thesis Jim Logajan kindly loaned me and see
if I can find the exact figure, but I'm pretty sure that a factor of
15 is correct.

MIT has placed many of it's students thesis online. Todd Rider's thesis can
be viewed entirely online he

http://theses.mit.edu/Dienst/UI/2.0/...1?nsections=13