Energy and Human Ambitions on a Finite Planet, 2021a

15 Nuclear <strong>Energy</strong> 266
walls of the chamber, despite its constituents zipping around at speeds
around 1,000 km/s! This feat can be sort-of managed via magnetic fields
bending the paths of the fast-moving charged particles into circles. But
turbulence in the plasma plagues attempts to confine the D–T mixture
at temperatures high enough to produce fusion yield.
Box 15.6: Successful Fusion
Note that besides stars as an example of successful fusion, we have
managed to create artificial fusion in a net-energy-positive manner in
theformofthehydrogen bomb. This is indeed a fusion device, but
we could not call it controlled fusion. It actually takes a fission bomb
(plutonium) right next to the D–T mixture in a hydrogen bomb to
heat up the D–T enough to undergo fusion. It’s neat (<strong>and</strong> awful) that
it works <strong>and</strong> is demonstrated, but it’s no way to run a power plant.
If a 45 million degree plasma could be confined in a stable fashion, the
heat generated by the reactions 64 could be used to make steam <strong>and</strong>
run a traditional power plant—replacing the flame symbol in Fig. 6.2
(p. 90) with something much fancier. The scheme, therefore, requires first
heating a plasma to unbelievable temperatures in order for the plasma
to self-generate enough additional heat through fusion that the game
shifts to one of keeping the plasma cool enough to produce a steady rate
of fusion without blowing itself out. In this scenario, the heat extracted
from the cooling flow makes steam. It’s the most elaborate 65 possible
source of heat to boil water. It may be a bit like working hard to develop
a light saber whose only use will be as a letter opener.
64: ...in the form of radioactive release
back to the plasma
65: Should we be proud if we succeed, or
embarrassed at the lengths we had to go to?
15.5.1 Fuel Abundance
Deuterium—an isotope of hydrogen—is found in 0.0115% of hydrogen, 66
Therefore sea water is chock-full of deuterium. The global 18 TW appetite 67: . . . one H
which means that the occasional H 2 O molecule is actually HDO. 67
would need 3 × 10 32 deuterium atoms per year for D–D or 2 × 10 32 each
of deuterium <strong>and</strong> tritium atoms per year for D–T. Running with this
latter number for the comparatively easier D–T reaction, we would
need to process 9 × 10 35 water molecules each year to find the requisite
deuterium. This corresponds to 26 million tons of water, which is a cubic
volume about 300 m on a side. Yes, that’s large, but the ocean is larger.
Also, it corresponds to a volume of 0.16 billion barrels per year, which
is about 200 times smaller than our annual oil consumption. Thus, the
volume required should be not at all challenging. 68 The ocean volume
is 60 billion times larger than our 300-m-sided cube, implying that we
have enough deuterium for 60 billion years. The sun will not live that
long, so let’s say that we have sufficient deuterium on Earth.
66: See the Chart of the Nuclides abundance
information in Figure 15.4.
1 , one 2 H <strong>and</strong> one oxygen
68: Ocean water is far easier to access than
underground oil deposits, after all.
© 2021 T. W. Murphy, Jr.; Creative Commons Attribution-NonCommercial 4.0 International Lic.;
Freely available at: https://escholarship.org/uc/energy_ambitions.