This is a draft of a summary I'm doing on alternatives to tokamak fusion. It seems to me that if any of these alternatives could be developed into commercial applications within the next 1 to 5 decades, it would be the most important invention since...well, fire. I know that sounds incredibly hyperbolic, but consider this: Let's say any of these technologies could be developed such that they could compete with coal or nuclear fission in the operating cost to generate electricity (that's about 2 cents per kilowatt hour in the United States). Well, fusion is vastly more environmentally friendly than coal or nuclear fission, so the non-tokamak fusion alternative would very quickly replace all the world's coal and nuclear fission power plants. It would also replace natural gas power plants, because it would be cheaper. Finally, it would represent an essentially limitless supply of electricity...and dramatically hasten the day when automobiles use electricity (e.g. plug-in hybrids) for most or even all of their power.
GENERAL
SUMMARY
Description: This document
contains summaries of alternatives to standard (tokamak) fusion. The
general positive attribute of these alternatives
is that they appear to require far smaller equipment expenditures to
create fusion. In many cases, the amount of money required to
create fusion—although not a break-even rates—is less than $1
million. None of these alternatives are as far along developmentally
as tokamak fusion, but it seems possible that some alternatives might
“leapfrog” tokamak fusion, given the current developmental path
of tokamak fusion (i.e., a break-even test reactor a decade away, and
commercial reactors at least 2-3 decades into the future...if not
more).
Pluses:
Alternative
technologies appear to require significantly smaller equipment
expenditures to achieve fusion, compared to the standard tokamak.
All
these alternative technologies are significantly less studied than
standard tokamak fusion, so it should be possible for “newcomers”
to the field to quickly make important contributions...particularly
given the smaller equipment expense to generate fusion.
These
technologies generate no long-lived radioactive materials.
Fusion
creates very large amounts of energy in a very small space; a 20 MW
(megawatt) power plant (comparable to the UNC power plant) could fit
in a 2-car garage. Therefore, even densely populated areas such as
New York City could generate all their power needs locally.
These
technologies produce no greenhouse gases; no air pollution in fact.
Further, they also require no mining or resource extraction to
provide fuel to the plant.
Minuses:
By
far the most serious potential minus to all these technologies is
that they might conceivably be used to produce powerful explosions.
This is not to say that any of them could generate such explosions
by accident; merely that people with malicious intent might be able
to produce powerful explosions. Given the inexpensive nature of
these technologies, such weapons would not necessarily even require
expenditures by governments; small groups might be able to produce
the devices.
PLASMA
FOCUS REACTOR (HYDROGEN-BORON FUSION)
Description:
Focus fusion reactors use a plasma focus device and hydrogen-boron
fuel to achieve fusion. This requires a much higher temperature than
conventional (deuterium-tritium) fusion; hydrogen-boron fusion
requires a temperature of approximately 1 billion degrees Kelvin.
“The plasma
focus device consists of two cylindrical copper or beryllium
electrodes nested inside each other. The outer electrode is generally
no more than 6-7 inches in diameter and a foot long. The electrodes
are enclosed in a vacuum chamber with a low pressure gas (the fuel
for the reaction) filling the space between them. A pulse of
electricity from a capacitor bank (an energy storage device) is
discharged across the electrodes. For a few millionths of a second,
an intense current flows from the outer to the inner electrode
through the gas. This current starts to heat the gas and creates an
intense magnetic field. Guided by its own magnetic field, the current
forms itself into a thin sheath of tiny filaments; little whirlwinds
of hot, electrically-conducting gas called plasma. This sheath
travels to the end of the inner electrode where the magnetic fields
produced by the currents pinch and twist the plasma into a tiny,
dense ball only a few thousandths of an inch across called a
plasmoid. All of this happens without being guided by external
magnets. The magnetic fields very quickly collapse, and these
changing magnetic fields induce an electric field which causes a beam
of electrons to flow in one direction and a beam of ions (atoms that
have lost electrons) in the other. The electron beam heats the
plasmoid thus igniting fusion reactions which add more energy to the
plasmoid. So in the end, the ion and electron beams contain more
energy than was input by the original electric current. These beams
of charged particles are directed into decelerators which act like
particle accelerators in reverse. Instead of using electricity to
accelerate charged particles they decelerate charged particles and
generate electricity. Some of this electricity is recycled to power
the next fusion pulse while the excess, the net energy, is the
electricity produced by the fusion power plant.” (Focus Fusion
Society, 2005).
Pluses:
▪ Generates
electricity directly (from a particle decelerator); therefore, a
steam generator is not required. This is claimed to significantly
reduce capital cost.
▪ Does not require external magnets
to contain plasma.
▪ Appears to
be technically far along in development (fusion apparently achieved,
and claimed to be within striking distance of breakeven).
Minuses:
▪ Requires
even higher temperatures than standard (deuterium-tritium) fusion.
Researchers:
Eric
Lerner, Lawrenceville Plasma Physics (LPP), Inc.
Bruce
Freeman, Texas A&M.
Hank
Oona, Los Alamos National Laboratory.
References:
PES
Network, Inc., 2006. “Sandia Z-Pinch and Focus Fusion Compared.”
Available at: Comparison of Z-Pinch and Focus Fusion
Focus
Fusion Society, 2006. “Lawrenceville Plasma Physics and Chilean
Nuclear Commission Initiate Experimental Collaboration to Test
Scientific Feasibility of Focus Fusion. Available at: Focus Fusion feasibility test in Chile
3. SONOFUSION
Description: Sonofusion is an
extension of the phenomenon of sonoluminescence, which occurs when a
cavitation bubble collapses. Sonofusion as produced by Taleyarkhan
(Purdue) involves use of deuterated acetone (i.e., the hydrogen in
the acetone is in the form of deuterium, which is necessary for
fusion to occur).
Pluses:
▪ Appears to be mechanically very
simple.
Minuses:
▪ None apparent.
Researchers:
R.
P. Taleyarkhan at Purdue University (formerly of Oak Ridge National
Laboratory).
D,
Felipe Getain (Impulse Devices Inc.)
Acoustic
Fusion Technology Energy Consortium (AFTEC, consisting of: Boston
University; Impulse Devices, Inc.; Purdue University; University of
Mississippi; and the University of Washington Center for Industrial
and Medical Ultrasound).
References:
Acoustic
Fusion Technology Energy Consortium (AFTEC), 2005. “AFTEC
formed.” Available at:
AFTEC formed.
About.com,
2005. “Rusi Taleyarkhan - Bubble Fusion.” Available at: Sonofusion (aka, "bubble fusion")
PYROELECTRIC
CRYSTAL FUSION
Description: “In April 2005,
Seth Putterman's group at UCLA published a paper describing a new
method of nuclear fusion based on pyroelectric crystals. In the
experiment a pyroelectric crystal, lithium tantalate (LiTaO3),
was heated 25 C in low-pressure (0.7 Pa) deuterium gas generating a
potential of 100 kV. The electric field of 25 GV per meter, focussed
by a tungsten needle, ionizes the deuterium which is accelerated into
a target of erbium deuteride (ErD2).
There the deuterium nuclei fuse about once in every million
collisions to produce helium atoms and about 1000 neutrons per
second.”
Pluses:
▪ Appears to be mechanically very
simple.
▪ Appears to produce fusion (in
miniscule amounts) with extremely simple equipment.
Minuses:
▪ May never be capable of generating
breakeven energy.
References:
“Pyroelectric
Crystal Fusion.” Available
at: Pyroelectric crystal fusion
-
COLLIDING ELECTRON SPIRAL TOROIDS REACTOR (CESTR)
Description:
In a manner similar to ball lighting, electrical spiral toroids
generate their own magnetic containment fields. The CESTR attempts
to collide toroids of boron and hydrogen to produce hydrogen-boron
fusion.
References:
Electron
Power Systems, Inc. Explanation of the technology. Available at: Electron Power Systems, CESTR reactor
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