Energy and Human Ambitions on a Finite Planet, 2021a

425
conduction b<strong>and</strong>
is the energy level a step up from that of electrons in the valance b<strong>and</strong>. Electrons in the
conduction b<strong>and</strong> are very loosely bound <strong>and</strong> freely w<strong>and</strong>er about the crystal, hopping from one
atom to the next, <strong>and</strong> therefore able to contribute to a current. 202, 203, 422, 435, 438
confinement
in the context of fusion refers to the trapping <strong>and</strong> holding of a high-temperature plasma, usually
by magnetic means. 265
conservation of energy
says that energy is never created or destroyed, only shifting from one form to another. 70, 91–93,
95, 246, 393, 394, 425
conservation of mass-energy
extends conservation of energy to include mass, so that the combined mass-plus-energy of a
closed system is never created or destroyed, only shifting from one form to another (mass-energy
exchange via E mc 2 ). 246
control rod
is used in a nuclear fission reactor to absorb neutrons so that the chain reaction does not get out
of control <strong>and</strong> cause a meltdown. 251, 255, 256, 432
COP
coefficient of performance. 97, 99, 335, 424
Coulomb
(C) is the SI unit of electric charge.Anelectron has a charge of −1.6 × 10 −19 C <strong>and</strong> a proton has a
charge of +1.6 × 10 −19 C. 77, 422, 424, 427
coupled
refers to the tight connection often seen between energy/resource use <strong>and</strong> economic scale (as
measured, for instance, by GDP). 18, 425
critical mass
is the mass of fissile material (assumed to be in spherical form) above which a self-sustained
chain reaction will occur. Below this, the material poses no danger. Right at critical mass, the
material will limp along in a slow chain reaction. Above this threshold—super-critical—an
235
exponential runaway detonation will occur, <strong>and</strong> is the basis of nuclear weapons. For U,
239
critical mass is 52 kg (a bit smaller than a volleyball), <strong>and</strong> for Pu, it is 10 kg, <strong>and</strong> about the
size of an American softball. 262
CSP
concentrated solar power. 220, 424, 436
current
is a measure of charge flow, expressed in the SI unit of Amps. 77, 85, 202, 203, 205, 422, 425, 436
D–D fusion
uses deuterons ( 2 H nuclei) as the fuel for fusion, achieving an energy density of 137 million
kcal/g. 265
death rate
quantifies the number of deaths per 1,000 people per year, typically. Numbers tend to be in the
5–30 range. 38, 426
decay chain
refers to a consecutive series of radioactive decays. 244, 245
decoupling
is the notion that economic activities need not incur a large energy or resource cost, breaking
the tendency for economic scale to be tightly coupled to physical goods. 20
© 2021 T. W. Murphy, Jr.; Creative Commons Attribution-NonCommercial 4.0 International Lic.; Freely available at:
https://escholarship.org/uc/energy_ambitions.