Filed under:


It's Not Conventional Fusion

Conventional approach to fusion revolves around the Tokamak. Here we see a Tokamak magnetic field and current:

Conventional Fusion vs. Focus Fusion


Share
Posted by Admin on Jul 13, 2006 at 09:25 PM
Tools: Print | | chat (1) Comments

Energy production has three main elements:  fuel, reactor and generator (why these three?).  Conventional fusion and focus fusion differ significantly in their approach to these three elements:

  • Fuel:  Focus Fusion uses a different fuel, hydrogen and boron, rather than the conventional Deuterium and Tritium. 
  • Reactor:  It uses a much smaller, inexpensive, more elegant reactor, the Dense Plasma Focus.  In contrast, conventional approaches to fusion revolve around the tokamak, a large, unwieldy and very expensive device that has consumed billions of dollars in research money and is still very far from achieving net energy. 
  • Generator:The Focus Fusion approach seeks to generate electricity directly. The tokamak is designed to generate heat which then has to be converted to electricity using expensive turbines and generators.

Fuel + Reactor + Generator.

In a conventional power plant, the cost of electricity is driven by two factors: the cost of fuel, and the cost of building the power plant (the cost of salaries and maintenance are small compared to these two).

The cost of the power plant can be further broken down into the cost of the thing that turns fuel into heat (for coal plants it’s the “furnace” where coal is burned, for nuclear fission it’s the “reactor”) and the thing that converts the heat into electricity (the generator).

Note that the generator is often one of the most expensive components of a power plant. In a power plant, the furnace (or reactor) uses fuel to create heat. The heat is applied to water to create steam. (Yes, most of modern energy is still made with a glorified steam engine). The high-temperature steam is then channeled through a turbine, which has many fan-blades attached to a shaft. As the steam moves over the blades, it causes the shaft to spin. This spinning shaft is connected to the rotor of a generator, and the generator produces electricity. For more information on Generators, click here

In sum:

cost of fuel
+ cost of reactor

  +  cost of generator  

cost of electricity

COAL:  In the case of coal, the cost of the fuel would relate to mining the coal and all the financial, health and environmental costs associated with that process. As for the furnace (a.k.a. boiler), it’s cheap - basically a big cast iron stove with some conveyer belt for the fuel. So the big costs for a coal plant are the fuel itself and the generator, but not the furnace. [For a detailed breakdown of coal plant costs, click here on Appendix E of the DOE‘s report on Market-Based Advanced Coal Power Systems.]

NUCLEAR FISSION: A nuclear fission plant basically eliminates the fuel cost.  It uses maybe a ton of fuel a year instead of many thousand tons. But fission uses the exact same expensive generator. And a fission “furnace” (the nuclear reactor) costs a lot more than a coal furnace. Add in costs of regulation, cleanup, etc. and fission winds up costing more than coal.  [Click here for more on the difference between fission and fusion.]

This brings us to fusion.

Fuel

The conventional approach to fusion uses deuterium and tritium as its fuel of choice. Click here for more on deuterium-tritium fusion as compared to boron-hydrogen. In general, when deuterium and tritium are fused together there are two protons and three neutrons. This unstable configuration then splits into a helium atom (two protons and two neutrons) and a high energy neutron. These neutrons create heat and radioactive materials just as in a fission reactor. The heat is then used to heat water and run an expensive generator just as in a typical power plant.

The fusion process involving deuterium and tritium still produces radioactivity (although not as much as a fission plant). Also, tritium does not occur in nature. It has to be created in a reactor, it’s very expensive, it’s radioactive, and it’s used in making nuclear weapons. It therefore brings up a lot of security issues.

The unconventional approach to fusion taken by the Plasma Focus inventors begins with the use of a different fuel. Boron-11 is an atom that contains five protons and six neutrons. Boron-11 can fuse with a hydrogen atom (one proton, no neutrons.) This makes six protons and six neutrons which is exactly enough for three helium atoms with no left over neutrons. The helium atoms then fly off at high speeds carrying the fusion energy. So hydrogen-boron fusion can create energy without releasing neutrons, essentially without radioactivity.

If it doesn’t release neutrons, then how will it heat water and run the generator? Well actually, that’s the big innovation here. The goal is to produce electricity directly and eliminate the expensive generator. When hydrogen and boron fuse in a plasma focus they release energy in the form of a beam of charged particles - nuclei of helium atoms. This beam can be converted directly to electricity through a kind of high-tech transformer. This will be discussed in the Generator section.

So why, you may wonder, are researchers spending so much time on deuterium-tritium fusion when hydrogen-boron has clear advantages? The reason is that deuterium-tritium fusion is easier to ignite. It requires temperatures of only 100 million Kelvin while hydrogen-boron fusion requires 1 billion Kelvin. [These temperatures are possible to achieve. Please see our Billion Degree Breakthrough page.]

Unfortunately, many fusion researchers have spent their careers developing the tokamak which cannot reach the temperatures required for hydrogen-boron fusion. Rather than looking for new ideas, the fusion research establishment has decided that the safety issues related to tritium and the radioactive waste produced by deuterium-tritium fusion is acceptable.

This brings us to the reactor.

Furnace/reactor

A tokamak fills a gymnasium-sized room and costs several hundred million dollars to build. Tokamaks and most other fusion devices use powerful magnets to attempt to stabilize the plasma (extremely hot, electrically conducting gas in which the fusion reactions occur). This task has been compared to “lifting gelatin with rubber bands.” The tokamak has yet to produce net energy, but even if it did, the cost of that energy would still be high simply because the reactor itself is so expensive. Unfortunately, many researchers (perhaps enamored of the very size and complexity of the thing) are not willing to look at other, simpler devices that take a different approach.

Sometimes in order to think big, you need to think small.

The Plasma Focus takes an elegant, small scale approach. It takes advantage of the natural instabilities of the plasma, so that the plasma’s own magnetic fields compress it and heat it. In short, The plasma focus works with the plasma instead of against it, in a much smaller space.

A complete Focus Fusion reactor could be contained in a very small building, perhaps no larger than a two car garage, and there is room for further miniaturization. Such devices would cost less than $500,000 to build, less than one percent of the price of a tokamak.

Generator vs. Transformer

The conventional approach to fusion research would produce neutrons which produce heat just as in a fission reactor.  The heat would have to be converted to electricity using the same old 19th century generator concept.  The cost of the energy would still be very high.  Thermal pollution would still be a big factor.

In contrast, the Focus Fusion researchers intend to eliminate the generator.  Instead, a transformer would be used to convert the electricity generated by the fusion into electricity useful to us.  This is possible because the product of the hydrogen-boron reaction is, itself, electricity. 

With mass production, it is expected that the cost of each reactor/transformer will be far less than the cost of research funds spent to design the first reactor, and substantially less than any nuclear, coal, hydro or oil-based power plants currently available.

In conclusion, conventional approaches to fusion have no hope of being any cheaper than current sources of power because even if they achieve net energy, the cost of the reactor and generator are still prohibitively high. In contrast, Focus Fusion will be cheap because all three of our elements: fuel, reactor, and generator are cheap.


Your involvement makes a big difference! Join online, or send checks payable to Focus Fusion Society, 128 Lincoln Blvd., Middlesex, NJ 08846.

Comments

For a more in depth discussion, start a thread in the forums.
There is one comment.



Brian H's avatar

Staying with the cost/hp theme, the Industrial Revolution reduced the cost of what had been a day’s labor by some large factor by using steam instead of human or animal muscle (it is amusing to note that Watt deliberately calibrated what he called a horsepower at about double the strength of the average pit horse/pony, to make people feel they were really getting a deal!).

Now, the cost of a horsepower is about to take another huge drop, this time from the steam cost (which we are in effect still using, since steam turbines generate electricity).  The consequences will be just as far-reaching.


Post a Comment

Log In to comment.
Not a member? Register.

Notify me of follow-up comments?
The world needs fusion.
Fusion needs you!


Do Stuff!
Join!

or send checks payable to:
Focus Fusion Society
128 Lincoln Blvd.
Middlesex, NJ 08846


Join:
forums
twitter
facebook
rss feed
flickr
donate
Youtube
zotero
Focus Fusion Society on LinkedIn
google