Energy Density Of Fusion Fuel

Fusion releases millions of times more energy per unit mass than chemical fuels, which is why the required fuel mass is so small.

Nuclear versus chemical energy

Burning a fuel rearranges electrons and releases chemical-bond energy. Fusing nuclei taps the strong nuclear force and releases far more energy per reaction. Per unit mass of fuel, fusion yields on the order of a million times more energy than combustion. This single fact drives most of the fuel-supply advantages of fusion.

Why density implies abundance

High energy density means a plant consumes very little fuel mass. A tiny extraction rate from an enormous reservoir then supplies a great deal of energy, which is exactly why deuterium can be dilute in seawater yet still constitute an effectively unlimited supply. Density and abundance work together.

• Fusion energy per unit mass dwarfs chemical fuels
• Small fuel mass makes transport and storage trivial
• Dilute fuel is still abundant because so little is needed
• The breeder design point releases 88.7 MW of fusion power

Honest note

The 88.7 MW figure and the breeder's scientific gain of 3.424 are computed design targets, not measured performance. See fuel logistics and deuterium abundance.

Density is the root advantage

Almost every downstream benefit of fusion fuel traces back to its energy density. Small fuel mass follows from it, which makes logistics trivial and reserves easy; tolerance of dilute sources follows from it, which makes seawater a viable reservoir; and the negligible separation-energy penalty follows from it. Understanding the density is understanding why the fuel-supply case looks so different from every combustion or fission comparison.