Saturday, March 11, 2006

Fusion power out of our reach?

You may remember the movie "Back to the Future". At the end of it, "Doc" Brown returns from the future with his time machine, asking Marty to join in. As the car needs refueling for the flux capacitor, Doc puts some organic rubbish into the new Mr Fusion. They are ready to return to 2015.

We already know that 2000 was far away from what most of us expected to be when we were kids (and from what our parents expected too!). It's not surprising that nobody believes that Mr Fusion will be here in 9 years from now. But, sincerely, does anyone believe that we will have a single fusion plant in operation by 2015?

It's sad that expert people on this matter believe that usable fusion power is out of our reach.

This week we could read two discouraging comments on fusion power in top level scientific journals. Science has published a policy forum article titled "Fusion Power: Will It Ever Come?" that, at least for me, gives a devastating overview about the prospects of energy production through hot fusion. The report states that, contrarily to the reasonably fast transition to power plants in the case of fission power, fusion seems now almost as far from practical use as it was in the 1950's. Even for deuterium-tritium fusion, the combination that requires less energy, temperatures of 100 million Kelvin are required. Apart from the temperature requirements, a lot of tough technical needs have to be met together:

  • Massive absorbing blankets (to generate tritium and filter neutrons).
  • Tolerance to structural damage.
  • Extremely high vacuum.
  • Radiation shielding.
  • Tolerance to stresses from thermal cycling.
  • High performance remotely controlled equipment.
  • Magnetic field windings.
  • Cryogenic system to keep the superconductivity of the magnetic system.
To meet all this requirements in a practical way doesn't seem reasonable. All the fusion plant designs that have been made use extrapolations to calculate output. Even worse, the cost of the energy generated would be far from current prices, even if those extrapolations prove true.
Others may keep their hope, but hot fusion is something I don't expect to work anymore.

So what about bubble fusion?

Nature has published a report on bubble fusion that is as devastating as the policy forum published in Science. It says that since the publication in 2002 of Rusi Taleryarkhan's claims of successful table-top fusion through sonoluminescence, there have been no independent confirmation of those results. It seems now that an independent investigation performed by Nature raises serious doubts about the value of the original results. Apart from this, most scientists closely related to this kind of research do not have any hope of achieving energy generation through sonoluminescence bubble fusion.

As far as it is, it seems in the end that there is only one practical way to exploit hydrogen fusion: solar power.


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