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Wednesday, 24 November 2010
We could have fusion power pretty quickly - if we ask for the right sort.

We could be as little as five years away from clean, cheap fusion power.  All we'd have to do is stop funding the wrong sort of fusion reactor, and try building one that works.

Fusion, if you need a refresher, is one of two nuclear reactions that can give us energy.

Nuclear fission, the reaction we now use in nuclear power plants, splits the center (or "nucleus") of a heavy atom like uranium, thorium or plutonium into smaller atoms to release energy in the form of heat and radiation.  We also use fission in nuclear weapons.

Nuclear fusion is a reaction in which light atoms like hydrogen, lithium, boron or helium are fused together into larger atoms, which also releases energy and radiation.  Nuclear fusion is used along with fission in some nuclear weapons (usually the ones called "hydrogen bombs").

Nuclear fusion is harder to make happen outside of a hydrogen bomb.  So far, fusion reactors are great, huge things that consume more power than they make because trying to make thermonuclear fusion happen in a confined space requires heavy hydrogen isotopes (a mixture of deuterium and tritium) to be bombarded with intense beams of energy. 

The elusive goal of thermonuclear fusion research is to get more energy from the fusion reaction than you have to pump into the fuel to cause the reaction to happen.  By contrast, the very first fission nuclear reactor (under the west stands at Amos Alonzo Stagg Field at the University of Chicago in 1942) made more energy than it consumed (essentially none) from the beginning.

And because the hydrogen-helium fusion reaction emits neutrons, thermonuclear fusion reactors large and powerful enough to make electrical power will create large amounts of nuclear waste as parts of the reactor have to be removed and replaced as the cloud of neutrons makes them radioactive, and eventually, structurally weak.  Neutron embrittlement of steel will be one of the besetting problems of the type of fusion reactor that we've been trying to get to work so far. 

But there are different ways to make this reaction happen that haven't really been explored with the money and energy that have gone into the big-iron thermonuclear reactors built so far, such as the monstrous ITER reactor under construction in France (with American help in funding and design). 

Possibly the most promising one - one which its developers say could be producing power in as little as three to five years - is the Bussard Polywell fusion reactor.

The late Dr. Robert Bussard, the father of the concept of the "interstellar ramscoop," was one of the major exponents of the inertial confinement fusion (ICF) concept.

Not many years ago, Dr. Bussard presented a talk at Google entitled "Should Google go Nuclear?" (amid rumors that Sergei Brin and some of the other investors in Google were thinking about funding him):

For those who, like me, like written presentations of technical data better, there's a written transcript:

and a Web page on the progress made by Dr. Bussard's group:

ICF doesn't have to emit or use neutrons - the boron-11 (80% of natural boron is boron-11) + proton (ionized hydrogen) inertial confinement reaction emits no neutrons and it emits charged particles that can be captured in the magnetically-active inertial confinement grid to produce electrical current directly. 

Boron-11 + proton  -->  several Helium  nuclei + a lot of energy which is captured when the Helium nuclei hit the containment grid after the reaction

Producing electrical current in the reactor is something no other reactor design, fusion or fission, does.  It's brilliant - it has far fewer systems and parts than other reactor designs.  Instead of a huge concrete reactor dome next to a large concrete building holding the generators and water pumps and auxiliary diesel generators, a Bussard Polywell fusion power reactor would sit in a single building, about a story or two tall.   The transformers would be the same, because electrical power is electrical power.

What's better is that the power wasted when a nuclear reactor or an oil or coal furnace heats water into steam to spin electrical generators, then pumps the water from the cooled steam back into the reactor is not wasted in this design.  Much more of the energy made by the Bussard Polywell design goes out of the reactor as electricity.

Finally, and best of all - no meltdowns.  When a Polywell fusion reactor breaks, it just stops.  No explosions, no radioactivity, no muss, and no fuss.

Calculations indicate that a full-scale Polywell IEC reactor could produce as much as 128 gigawatts of power.  Normal fission reactors and oil and coal power plants top out at 1 - 2 gigawatts. 

And Polywell fusion reactors are much, much cheaper to build per unit of energy generated than current nuclear reactors - which, since nuclear power is already the cheapest sort of power to make (except possibly hydroelectricity, which in most countries requires the flooding of vast tracts of land to create the needed reservoirs of water behind power dams), would make them the cheapest power plants per unit of energy to make anywhere.

The projected cost to build the first power-generating Polywell IEC reactor is about $200 million, with a generating capacity of a gigawatt.  The reactor would be 4 meters (about 4.3 yards or 13 feet) across and weigh 14 tons.  You could install one inside a medium-sized freighter.

By comparison, it costs between $2,000 million ($2 billion) and $3,800 million ($3.8 billion) dollars to build modern fission power plants for a generating capacity of 1.05 and 1.15 gigawatts.

So electricity made by Polywell fusion plants could cost up to nineteen times less than electricity generated by existing nuclear plants.  And if the boron-11 + proton reaction can be made to work in large Polywell reactors, this would be CLEAN nuclear power, with no neutrons and very little, perhaps no radioactive waste.

Say that three-fourths of your utility bill is related to power generation costs and fuel, and your power is all made by nuclear power plants (both very conservative assumptions favoring present-day utilities).  If you pay 12 cents/kilowatt-hour for power, 9 cents of that may be traceable to power plant operations and fuel. 

Replace the current power plant with a Polywell fusion power plant, and this part of your electricity rate drops to 0.47 cent.  Your overall power rate becomes 3.47 cents instead of 12 cents.  You get to spend 8.5 cents per kilowatt-hour you use on other things, assuming your power use remains the same.  Your power bill drops by 71 percent.

If you, for the sake of argument, use 2,000 kilowatt-hours of power a month, your power bill is 240 dollars a month if you pay 12 cents per kilowatt-hour.  Drop that rate to 4.8 cents and your bill drops to $69.40.

Interestingly, power output in Polywell reactors varies exponentially with physical size.

Double that hypothetical 4-meter Polywell reactor in size and you get a reactor theoretically capable of generating 128 gigawatts!

I don't know how much that 8-meter Polywell reactor would cost to build, but even if it cost a billion dollars, the part of your electricity bill traceable to power plant construction and operation would be reduced up to 128 times.

Using that analysis of mine again, this part of your present 12 cents per kilowatt-hour electrical power rate falls to 0.07 cents.  Your rate could drop to 3.07 cents per kilowatt-hour. 

Say again that you use two thousand kilowatt-hours a month.  At 12 cents per kilowatt-hour, now you pay $240 a month for power.  At 3.07 cents per kilowatt-hour, that bill is now $61.40 most of it payroll, debt service, maintenance of the power distribution grid, etc.  The power generation cost (assuming a 128 gigawatt power plant) for 2000 kilowatt-hours would be $1.40.

Since nuclear power right now is twice as cheap as coal power and many times cheaper than oil, even cheaper still than natural gas, the cost advantage of Polywell fusion power over fossil power is even greater.

Why aren't we spending even a fraction of the money ($18 billion, to date) we have spent and are spending to help build unpromising fusion technology such as the big-iron, barely break-even, not commercially useful ITER reactor in France to develop Polywell fusion reactors, instead?

Good question. thought so, too.  Their take on why the US Government is still funding yesterday's thermonuclear fusion program rather than jumping on today's technology is in this document: Why the U.S. Isn’t Funding A Promising Energy Technology

Posted by V.P. Frickey at 9:56 PM EST
Updated: Tuesday, 9 August 2011 8:33 PM EDT
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