The Power That Lights The Stars

Nuclear fission has radically expanded humanity's potential energy resources. The achievement of controlled nuclear fusion will make them virtually infinite. The basic fuel for fusion is deuterium, which is an isotope of hydrogen that is called "heavy" because, in addition to having the standard proton in its nucleus that all hydrogens have, it also has a neutron, which doubles its weight. Deuterium is found naturally on Earth; one hydrogen atom out of every six thousand is deuterium. That might not seem like much, but because of the enormous energy released when a fusion reaction occurs, it's enough to endow each and every gallon of water on Earth, fresh or salt, with a fusion energy content equivalent to that obtained by burning 350 gallons of gasoline. To see what this means for the human future, take a look at the comparison of Earth's energy resources listed in table 11.2, where the resource size is given in terms of terawatt (TW = trillion watt) years. For comparison, currently humanity collectively uses about 13 TW of power. Earth's fusion resources are more than a million times greater than all other energy reserves put together. Even at ten times our current rate of consumption, there is enough fusion fuel on this planet (alone) to power our civilization for nearly a billion years.

Furthermore, fusion produces no greenhouse gases, and if done correctly, need not produce significant radioactive waste. When they collide, the deuterium nuclei fuse to form tritium or helium-3 (He-3) nuclei, plus some neutrons. The tritium and He-3 will then react with other deuteriums to produce ordinary helium (He-4) and common hydrogen (H-l), plus a few more neutrons. If the reactor is made of

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