Renewable Energy

What is nuclear fusion?
Answered by Craig C. Freudenrich and Discovery Channel
  • Craig C. Freudenrich

    Craig C. Freudenrich

  • Discovery Channel

    Discovery Channel

  1. Nuclear power plants that currently operate around the world use a process called nuclear fission to create heat energy for making electricity. In this process, a neutron splits a heavy atom of uranium into two lighter atoms. The split is accompanied by a large amount of heat energy and more neutrons. However, the lighter atoms are radioactive wastes that cannot be harnessed for more energy. The downside is that the process produces toxic waste that will remain in place for centuries. How do plants dispose of it?

    A better question to ask is: What if you could generate the same amount of heat energy without creating radioactive wastes? This is what nuclear fusion does.

    We see and benefit from nuclear fusion every day. It’s the process that powers the sun. Instead of splitting heavy radioactive atoms, nuclear fusion combines lighter atoms to form heavier ones. Specifically, two fuels abundant in nature -- isotopes of hydrogen [deuterium (12H) and tritium (13H)]) -- combine to form helium isotopes (23He, 24He), neutrons (01n) and energy:

    Deuterium-deuterium fusion:  12H + 12H →  23He + 01n + energy

    Deuterium-tritium fusion:  12H + 13H →  24He + 01n + energy

    As mentioned above, nuclear fusion does not produce radioactive wastes. However, it’s not easy to get these atoms close enough to fuse. It takes intense heat and pressure to overcome the repulsive forces between the atoms of the hydrogen isotopes. In fact, the plant must heat the isotopes to temperatures even hotter than the sun to make them form a sort of gas-plasma substance. Efforts are underway to duplicate the sun's energy-producing ability. A joint project from MIT and Columbia University has placed a high-intensity magnet inside the hot plasma to duplicate planetary magnetic fields. They'll next work on scaling the energy confinement to produce power [source: MIT].

    Economical nuclear fusion power plants are not yet feasible, but when they are, the fuels used in nuclear fusion represent a long-term and sustainable energy solution. Scientists are constructing an experimental reactor that could lead the way to demonstrating how fusion could be commercially viable [source: IAEA].

    Nuclear Fusion Qa1

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  2. If you want to crank out some energy in this solar system, you might as well emulate the biggest show in town: the sun. The process is called nuclear fusion, and involves fusing atoms rather than splitting them apart as in nuclear fission. Both processes produce vast amounts of energy, but fusion produces significantly less waste and less radiation. Technology will have to improve somewhat before this is a valid energy source on Earth, however. Currently, man-made fusion reactors would likely expend more energy than they produce.

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